Fix #6663: keep a duplicated nested aggregate inside its parent aggregate

Duplicating a linked aggregate (Ctrl+Shift+D) that is itself nested inside
another aggregate dropped the copy outside its parent instead of keeping
it nested.

Root cause: DuplicateMoveLinkedAggregate.execute_ifc_duplicate_linked_aggregate_operator
called tool.Root.recreate_aggregate(old_to_new) a second time, after
execute_ifc_duplicate_operator had already called it once (via
duplicate_ifc_objects) and, for the case where the parent aggregate itself
was not part of the duplication set, had already correctly restored the
new nested aggregate's assignment to that original parent. On the second,
redundant call, recreate_aggregate looks up the parent aggregate in
old_to_new again, still does not find it there (since the parent was
never duplicated), and its "parent not found" branch actively unassigns
the just-restored link, stranding the duplicate outside its parent.

Fix: drop the redundant second call. The plain duplicate path already
handles both cases correctly (parent duplicated and parent not duplicated).

Verified live in headless Blender 5.2 / Bonsai on the repo's own
test/files/linked-aggregates.ifc: nested Wall_01/Wall_02 wrapped into a
new aggregate "Nested" inside the existing "Assembly" aggregate, then
duplicated via bim.object_duplicate_move_linked_aggregate. Before the fix,
the new "Nested_01" aggregate had no parent aggregate; after the fix it
correctly remains aggregated by "Assembly". Also added a regression
scenario to test/bim/feature/geometry.feature covering this exact case,
manually traced against the existing step definitions (the full
pytest-bdd harness needs a network-provisioned Blender python to run
locally, so it hasn't been executed through pytest itself; CI will run
it). black + ruff clean.

Generated with the assistance of an AI coding tool.

.github/workflows/ci-bonsai-daily.yml

@@ -109,7 +109,7 @@ jobs:
           # Ensure Bonsai and ifcsverchok enable/disable works before uploading to extensions repo.
 
           # Download Blender.
-          wget -q -O blender.tar.xz https://download.blender.org/release/Blender5.1/blender-5.1.0-linux-x64.tar.xz
+          wget -q -O blender.tar.xz https://download.blender.org/release/Blender5.2/blender-5.2.0-linux-x64.tar.xz
           tar -xf blender.tar.xz
 
           # Setup Blender.
@@ -179,8 +179,7 @@ jobs:
           blender --online-mode --command extension install --enable --sync sun_position
 
           cd IfcOpenShell/src/bonsai
-          pip install pytest-blender
-          pip install pytest-bdd
+          pip install -r requirements-dev.txt
           blender --background --python scripts/setup_pytest.py
           blender --python-expr "import bonsai; print(bonsai.bbim_semver); import ifcopenshell; print(ifcopenshell.version)" --background
           make test

.github/workflows/ci-lint.yaml

@@ -27,10 +27,7 @@ jobs:
       - name: Install dependencies
         run: |
           curl -LsSf https://astral.sh/uv/install.sh | sh
-          uv tool install ruff
-          uv tool install black
-          uv tool install poethepoet
-          uv tool install ty==0.0.34
+          cat requirements-tools.txt | xargs -L1 uv tool install
 
       # black doesn't catch all syntax errors, so we check them explicitly.
       - name: Check syntax errors

.github/workflows/ci.yml

@@ -10,9 +10,13 @@ on:
       - 'src/ifcgeomserver/**'
       - 'src/ifcjni/**'
       - 'src/ifcmax/**'
+      - 'src/ifc5d/**'
+      - 'src/ifcedit/**'
+      - 'src/ifcmcp/**'
       - 'src/ifcopenshell-python/**'
       - '!src/ifcopenshell-python/docs/**'
       - 'src/ifcparse/**'
+      - 'src/ifcquery/**'
       - 'src/ifcwrap/**'
       - 'src/qtviewer/**'
       - 'src/svgfill/**'
@@ -51,7 +55,7 @@ jobs:
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
-          pip install xmlschema xsdata numpy lxml pytest isodate lark networkx tabulate python-dateutil shapely pyparsing
+          pip install xmlschema xsdata numpy lxml pytest isodate lark networkx tabulate python-dateutil shapely pyparsing psutil
           pip install src/bcf --no-deps
           pip install pytest-xdist==3.8.0
 
@@ -252,13 +256,26 @@ jobs:
           pip install deepdiff
           cd ../ifcdiff && make test || ERROR=1
           cd ../ifcpatch && make test || ERROR=1
+          pip install -e ../ifc5d --no-deps
+          pip install odfpy xlsxwriter
+          cd ../ifc5d && make test || ERROR=1
+          pip install -e ../ifcquery --no-deps
+          cd ../ifcquery && make test || ERROR=1
+          pip install -e ../ifcedit --no-deps
+          cd ../ifcedit && make test || ERROR=1
+          pip install mcp
+          pip install -e ../ifcmcp --no-deps
+          cd ../ifcmcp && make test || ERROR=1
           pip install -e ../ifctester --no-deps
           cd ../ifctester && make test || ERROR=1
           make build-ids-docs || ERROR=1
           # Run mathutils related tests at the end to ensure no other code is relying on mathutils.
+          # mathutils only has pre-built wheels for Python 3.13+; skip on older versions.
           cd ../ifcopenshell-python
-          pip install mathutils
-          make test-mathutils || ERROR=1
+          if python -c "import sys; sys.exit(0 if sys.version_info >= (3, 13) else 1)"; then
+            pip install mathutils
+            make test-mathutils || ERROR=1
+          fi
           if [ $ERROR -ne 0 ]; then
             echo "One or more tests failed";
             exit 1;

.gitignore

@@ -4,6 +4,8 @@
 /_deps-vs*-x*-installed/
 /_installed-vs*-x*/
 /build/
+/build.log
+/output/
 /src/examples/build/
 # ifctester docs output
 /src/ifctester/test/build/
@@ -22,12 +24,14 @@
 __pycache__
 *.py.bak
 venv
+uv.lock
 
 # Visual Studio Code files
 .vscode
 !.vscode/launch.json
 !.vscode/tasks.json
 .vs
+/*.code-workspace
 
 # PyCharm files
 .idea
@@ -126,5 +130,7 @@ src/ifcopenshell-python/ifcopenshell/express/*.exp.cache.dat
 
 # temp files from AI coding tools
 *.claude
+CLAUDE.local.md
 *.py.tmp*
 *.json.tmp*
+

cmake/CMakeLists.txt

@@ -27,13 +27,14 @@ endif()
 set(CMAKE_CXX_STANDARD_REQUIRED ON) # not necessary, but encouraged
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 
-if(VERSION_OVERRIDE)
-    file(READ "../VERSION" "RELEASE_VERSION_")
-    string(STRIP "${RELEASE_VERSION_}" RELEASE_VERSION)
-    message(STATUS "Detected version '${RELEASE_VERSION}'")
-else()
-    set(RELEASE_VERSION "0.8.0")
-endif()
+# The VERSION file in the repository root is the single source of truth for the
+# release version. Read it unconditionally so a plain source build reports the
+# real version through buildinfo.cpp instead of the stale hardcoded 0.8.0
+# fallback (see #8164). VERSION_OVERRIDE still controls the branch name used
+# when ADD_COMMIT_SHA embeds a commit sha.
+file(READ "../VERSION" "RELEASE_VERSION_")
+string(STRIP "${RELEASE_VERSION_}" RELEASE_VERSION)
+message(STATUS "Detected version '${RELEASE_VERSION}'")
 
 add_definitions(-D_DISABLE_CONSTEXPR_MUTEX_CONSTRUCTOR)
 
@@ -313,8 +314,12 @@ if(WASM_BUILD)
 else()
     # @todo review this, shouldn't this be all possible header-only now?
     # ... or rewritten using C++17 features?
+    # Boost.System has been header-only since 1.69 and its compiled stub library
+    # was dropped in newer Boost, so requesting it as a component makes
+    # find_package fail on Boost 1.70 and up (for example Boost 1.90). It is
+    # still pulled in transitively by thread / iostreams where needed, so do not
+    # request it explicitly.
     set(BOOST_COMPONENTS
-        system
         program_options
         regex
         thread
@@ -558,8 +563,8 @@ if(COMPILE_SCHEMA)
     # Bootstrap the parser
     message(STATUS "Compiling schema, this will take a while...")
     execute_process(
-        COMMAND ${PYTHON_EXECUTABLE} bootstrap.py express.bnf
-        WORKING_DIRECTORY ../src/ifcexpressparser
+        COMMAND ${PYTHON_EXECUTABLE} bootstrap.py
+        WORKING_DIRECTORY ../src/ifcopenshell-python/ifcopenshell/express
         OUTPUT_FILE express_parser.py
         RESULT_VARIABLE SUCCESS
     )
@@ -570,7 +575,7 @@ if(COMPILE_SCHEMA)
 
     # Generate code
     execute_process(
-        COMMAND ${PYTHON_EXECUTABLE} ../ifcexpressparser/express_parser.py ../../${COMPILE_SCHEMA}
+        COMMAND ${PYTHON_EXECUTABLE} ../ifcopenshell-python/ifcopenshell/express/express_parser.py ../../${COMPILE_SCHEMA}
         WORKING_DIRECTORY ../src/ifcparse
         OUTPUT_VARIABLE COMPILED_SCHEMA_NAME
     )
@@ -660,6 +665,11 @@ if(ADD_COMMIT_SHA)
     endif()
 endif(ADD_COMMIT_SHA)
 
+# Always expose the release version (from the VERSION file) to buildinfo.cpp so
+# that a build without commit-sha info reports the correct version instead of a
+# stale hardcoded fallback. See #8164.
+target_compile_definitions(IfcParse PRIVATE IFCOPENSHELL_VERSION_STRING=${RELEASE_VERSION})
+
 if(MSVC)
     # @todo still needs to be understood better, but the cgal and cgal-simple kernel cause multiply defined boost lambda placeholders _1 ... _3
     set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} /FORCE:MULTIPLE")

docker/.dockerignore

@@ -0,0 +1,3 @@
+.env
+*.pyc
+__pycache__

docker/.gitignore

@@ -0,0 +1,3 @@
+.env
+*.pyc
+__pycache__

docker/.ifcos_env

@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+# .ifcos_env
+# register autocompletes. just source the file in your shell, i.e. 
+# source .ifcos_env
+
+.ifcos_env() {
+    local cur prev opts
+    COMPREPLY=()
+    cur="${COMP_WORDS[COMP_CWORD]}"
+    prev="${COMP_WORDS[COMP_CWORD-1]}"
+
+    opts="create update up down restart build attach logs ps config remove help"
+
+    # Basic static completion
+    COMPREPLY=( $(compgen -W "${opts}" -- ${cur}) )
+
+    return 0
+}
+
+# Register the completion for the command "ifcos_env"
+complete -F .ifcos_env ./ifcos_env

docker/Dockerfile

@@ -0,0 +1,67 @@
+FROM rockylinux:9
+
+# Update system, enable CRB (needed by some EPEL packages) and install EPEL,
+# then install required packages + some common tools for a bit of command
+# line comfort. Combined into one layer so a later `create` always installs
+# against packages from the same dnf update, rather than layering fresh
+# installs on top of a stale cached "update" layer.
+RUN dnf update -y && \
+    dnf install -y epel-release && \
+    dnf config-manager --set-enabled crb && \
+    dnf install -y --allowerasing --setopt=install_weak_deps=False --setopt=tsflags=nodocs \
+                   bash-completion vim git curl wget which tree htop sudo   \
+                   gcc gcc-c++ autoconf automake bison make zip cmake      \
+                   python3 python3-pip                                    \
+                   bzip2 patch mesa-libGL-devel libffi-devel fontconfig-devel \
+                   sqlite-devel bzip2-devel zlib-devel openssl-devel xz-devel \
+                   readline-devel ncurses-devel libuuid-devel git-lfs      \
+                   findutils xz byacc ccache && \
+    git lfs install --system && \
+    dnf clean all && \
+    rm -rf /var/cache/dnf
+
+# Trust bind-mounted repos regardless of which user (root or builder) or host
+# UID owns them, rather than a per-user config that only one of them sees.
+RUN git config --system --add safe.directory '*'
+
+# Configure ccache. CCACHE_MAXSIZE (not `ccache -M`) because /ccache is a
+# volume mount point at runtime - anything `ccache -M` writes to a config
+# file under it during this build gets shadowed once the real volume is
+# mounted, so the size cap only actually takes effect via the env var.
+# 2G is generous: a full build (IfcParse+IfcGeom+IfcConvert+wrapper, one
+# Python version) measures ~300MB, and the volume is now shared across all
+# checkouts (see compose.yaml), so this covers several diverging branches.
+ENV CCACHE_DIR=/ccache
+ENV CCACHE_MAXSIZE=2G
+ENV PATH="/usr/lib/ccache:$PATH"
+
+# Non-root user matching the host UID/GID that bind-mounts the repo (default
+# 1000:1000, the common single-user-Linux-box case), so files the build
+# creates under the mount keep sane, non-root ownership on the host side.
+# Override with --build-arg USER_UID=$(id -u) --build-arg USER_GID=$(id -g)
+# if your host user has a different UID/GID.
+ARG USER_UID=1000
+ARG USER_GID=1000
+# groupadd fails outright if USER_GID is already taken by an existing
+# system group - which happens whenever a host's primary GID collides with
+# one baked into the rockylinux9 base image. The main real-world case is
+# macOS, where the default user's primary group is "staff" at GID 20, and
+# GID 20 is "games" on RHEL-family images. Only create the "builder" group
+# when that GID is actually free; otherwise useradd just attaches to
+# whichever group already owns it. Either way the builder user ends up
+# with the right GID for bind-mount ownership, which is all that matters.
+RUN (getent group "${USER_GID}" >/dev/null || groupadd -g "${USER_GID}" builder) \
+    && useradd -m -u "${USER_UID}" -g "${USER_GID}" -s /bin/bash builder \
+    && echo "builder ALL=(ALL) NOPASSWD:ALL" > /etc/sudoers.d/builder
+
+# Copied while still root: /bin is not writable by the builder user.
+COPY --from=ghcr.io/astral-sh/uv:0.11.27 /uv /uvx /bin/
+
+USER builder
+WORKDIR /__w/IfcOpenShell/IfcOpenShell
+
+# Installed as builder so managed Python interpreters land under builder's
+# $HOME, matching the user that actually runs the build.
+RUN uv python install
+
+CMD ["sleep", "infinity"]

docker/README.md

@@ -0,0 +1,78 @@
+Docker build environment
+========================
+
+This is a small utility to make it easy to compile a perfect `_ifcopenshell_wrapper.cpython-*-x86_64-linux-gnu.so`
+files.
+
+The reason for this tool is that I was trying to follow the web page directions, and my build was behaving differently
+to the release builds. Eventually I concluded that the differences between toolchains on the RHEL based rocky9 image
+and Ubuntu were just too great. Getting the build setup was already a lot of trial and error, so I thought I'd spend
+more time trying to reuse the github actions that perform the build, using a utility called `act`. I learnt a lot, in
+particular how much time, energy, and bandwidth Github waste. I also realised I was most of the way to a regular docker
+setup anyway, so I might as well just do that. So I've deconstructed all the github action steps, and turned it into
+a local docker build environment that uses the exact same base, tools, libraries, and build command/flags etc.
+
+Right now a Github action will:
+- launch the rocky9 base
+- upgrade all the packages
+- install a bunch of extra tools
+- do a recursive checkout of your repo
+- checkout the build repository
+- unpack dependencies
+- run the build script, making all python versions (5? right now I think)
+- create the .zip release files
+
+And it does _all_ of that _every_ time. This is not a fault of the action writers - it's just how Github seems to work.
+
+These dockers tools do the following differently, and it's actually a bit more powerful too:
+- build the base image once.
+- update the packages once.
+- install the extra tools once.
+- the repository is the one on your host, that gets bind mounted in the container as the working directory.
+- by adding an environment variable to .env, restricts to compiling for just a single python version.
+- when the build is finished the created files are right there under your local repositry (but not added to git) for
+  ease of access
+- each repository can have it's own build environment container.
+- the image is shared between those environments.
+- the containers share the ccache, so additional envs should get a helping hand.
+- it has a simple set of user friendly commands to drive it all.
+
+For example:
+``` bash
+# To see the commands (a superset of docker compose commands)
+./ifcos_env
+
+# Enable autocomplete of commands
+source .ifcos_env
+
+# First time commands
+./ifcos_env create
+./ifcos_env up
+./ifcos_env build
+
+# install and test library
+# find an issue
+# edit code
+./ifcos_env build
+
+# and so on. When done stop and optionally delete the container
+./ifcos_env stop
+./ifcos_env remove
+```
+
+To limit the build to one python version just add
+``` bash
+PY_TGT=py-311
+```
+or whichever version your Blender requires.
+
+You might see UNIQUE_ID in the .env file too. This keeps containers for separate folders, separate.
+
+System requirements
+1. Linux-x64 only at this time.
+2. Docker and docker-compose need to be installed.
+3. Have a good amount of disk space. (image is in /var (typically the root partition) and will be about 1.7 GB)
+4. The build action will create about 10GB in your repository folder. Make sure this partition is spacious
+   particularly if you intent on having multiple clones building.
+5. ... I think that covers most of it.
+

docker/SKILL.md

@@ -0,0 +1,186 @@
+---
+name: ifcopenshell-docker-build
+description: >-
+  Build a real ifcopenshell_wrapper (.so + .py) and IfcConvert locally via
+  the docker/ifcos_env toolchain, then wire them into a checkout for
+  running C++-dependent parts of the test suite (geometry, the SWIG
+  wrapper stub, the C++ parser). Use whenever a task needs to compile
+  IfcOpenShell's C++ core rather than just read/patch source - e.g.
+  reproducing or fixing a bug in src/ifcgeom, src/ifcparse, src/ifcwrap,
+  or validating util/scripts/validate_stub.py against the actual
+  generated wrapper.
+---
+
+# Building IfcOpenShell locally with docker/ifcos_env
+
+`docker/` mirrors the project's GitHub Actions build environment locally,
+in a persistent, non-root container with ccache so repeat builds are fast.
+See `docker/README.md` for the design rationale. Pure-Python changes don't
+need any of this - only reach for it when you need a real compiled
+`_ifcopenshell_wrapper*.so` or `IfcConvert` binary.
+
+## Placement
+
+This `docker/` folder must live as a direct child of the repo root you want
+to build (sibling of `src/`, `cmake/`, etc.) - `compose.yaml` and
+`ifcos_env` resolve the repo via `../` relative to wherever `docker/`
+itself sits, and bind-mount it into the container. If you're setting this
+up in a fresh clone, copy the whole `docker/` directory there first.
+
+## Setup
+
+```bash
+cd docker
+./ifcos_env create   # build the image (shared by name across all your clones/checkouts, so usually instant after the first time anywhere)
+./ifcos_env up        # create + start the container, clone/unpack the third-party dependency cache (~10GB, one-time per container)
+./ifcos_env build     # full build: all deps + IfcParse + IfcGeom + IfcConvert + the Python wrapper, for one Python version
+```
+
+`PY_TGT` and `UNIQUE_ID` live in `docker/.env` - `PY_TGT` (e.g. `py-311`)
+restricts the build to one Python version instead of building five;
+`UNIQUE_ID` is a hash of the folder path, recalculated on every `up`, so
+each checkout gets its own container/volumes automatically.
+
+A full first build takes ~1.5 hours (mostly compiling IfcOpenShell's own
+C++, not the cached third-party deps). After that, ccache makes incremental
+rebuilds of a couple of touched `.cpp` files **under a minute**.
+
+## Container lifecycle
+
+The container is long-lived (`sleep infinity`) so exec'd commands and
+ccache state persist between builds. Commands map directly onto Docker
+Compose's own container-vs-image distinction:
+
+```bash
+./ifcos_env up         # create the container if it doesn't exist, then start it (runs ready_repo too)
+./ifcos_env stop       # stop the container, keep it around
+./ifcos_env start      # start it back up (same container, same filesystem layer)
+./ifcos_env restart    # stop, then start
+./ifcos_env down       # remove the container (and its network) entirely
+./ifcos_env recreate   # down, then up - a fresh container
+```
+
+Named volumes (`ccache`) and the bind-mounted repo/`build/` are unaffected
+by `down`/`recreate` - only the container itself goes away, and `up`
+recreates it from the image.
+
+## Fast iteration
+
+Pass a target to `build` to skip the parts you don't need:
+
+```bash
+./ifcos_env build IfcConvert           # only the executables (IfcConvert, IfcGeomServer) - skips the Python wrapper entirely
+./ifcos_env build IfcOpenShell-Python  # only the SWIG Python wrapper - skips executables entirely
+./ifcos_env build                      # no target = everything (needed the first time, or after touching shared headers)
+```
+
+Use this to keep the edit -> rebuild -> test loop fast when debugging: if
+you're only touching `src/ifcgeom/`, build `IfcConvert`; if you're only
+exercising the Python API, build `IfcOpenShell-Python`.
+
+## Where the artifacts land
+
+Build output goes to `<repo_root>/build/Linux/x86_64/install/` on the host
+(bind-mounted, not just inside the container), owned by you (see
+"Container user" below):
+
+- `ifcopenshell/bin/IfcConvert` - the CLI binary
+- `python-<version>/lib/python<X.Y>/site-packages/ifcopenshell/_ifcopenshell_wrapper*.so`
+  and `ifcopenshell_wrapper.py` - the compiled wrapper + its generated
+  Python glue
+
+## Testing against a checkout (automated / AI-driven)
+
+`_ifcopenshell_wrapper*.so` and `ifcopenshell_wrapper.py` are already
+gitignored under `src/ifcopenshell-python/ifcopenshell/`, which is exactly
+where a normal in-tree build would put them - copy the two files there:
+
+```bash
+SRC=build/Linux/x86_64/install/python-3.11.8/lib/python3.11/site-packages/ifcopenshell
+cp "$SRC/_ifcopenshell_wrapper.cpython-311-x86_64-linux-gnu.so" src/ifcopenshell-python/ifcopenshell/
+cp "$SRC/ifcopenshell_wrapper.py" src/ifcopenshell-python/ifcopenshell/
+```
+
+Then, to run the test suite against it:
+
+```bash
+export PATH="$PWD/build/Linux/x86_64/install/ifcopenshell/bin:$PATH"   # for IfcConvert-dependent tests
+cd src/ifcopenshell-python/test
+PYTHONPATH="$PWD/.." python3.11 -m pytest -p no:pytest-blender .
+```
+
+(`-p no:pytest-blender` avoids the pytest-blender plugin trying to find a
+`blender` executable and failing collection entirely, even for non-Blender
+tests.) You'll need the matching Python version's `pip install`s too
+(numpy, shapely, isodate, lark, tabulate, pytest, ... - whatever the
+modules under test import) since this is a bare interpreter, not the
+project's pixi env.
+
+**This is the pattern to use for automated or AI-driven verification.**
+Don't use `try` (below) for that - it overwrites files in a real, live
+Blender installation, which isn't something an automated/AI workflow
+should ever do without the human explicitly asking for it in the moment.
+
+## Testing in Blender itself (human only)
+
+`try` copies the built wrapper straight into your actual Blender/Bonsai
+extension install, for manual in-Blender testing:
+
+```bash
+./ifcos_env try
+```
+
+It reads `BLENDER_USER_RESOURCE` from `.env` - set this to wherever
+Blender's user resource folder for the Bonsai extension actually lives on
+your system, which depends on your own Blender setup:
+
+```bash
+# in docker/.env
+BLENDER_USER_RESOURCE=~/.config/blender/bonsai/
+```
+
+`try` figures out the built Python version from `build/.../install/`
+(disambiguating with `PY_TGT` if more than one version was built) and
+copies the wrapper to
+`$BLENDER_USER_RESOURCE/extensions/.local/lib/python<X.Y>/site-packages/ifcopenshell/`.
+
+## Container user
+
+The image runs as a non-root `builder` user, UID/GID matching your host
+account (passed as `--build-arg` by `create` from `id -u`/`id -g`, so it
+adjusts automatically - no manual flag needed even if you're not 1000:1000).
+Files the build creates under the bind mount come out owned by you, not
+root. Passwordless `sudo` is available inside the container (e.g. via
+`attach`) for the rare case you need root for something ad hoc.
+
+If you're picking up an existing checkout that was previously built with
+an older, root-based image, you may hit `Permission denied` the first time
+you run `up`/`build` under the new image - `build/`, `.git/modules/`, the
+`ccache` volume, `output/`, and `build.log` can all be left root-owned from
+before. Fix it once via the container's own root (no host `sudo` needed):
+
+```bash
+docker exec -u root -w /__w/IfcOpenShell/IfcOpenShell <container-name> \
+    chown -R "$(id -u)":"$(id -g)" .git/modules build output build.log /ccache
+```
+
+(`<container-name>` is `ifcopenshell-<UNIQUE_ID>` - see `docker ps -a`.)
+
+## Other things worth knowing
+
+- **Linux x64 only.** `compose.yaml` pins `platform: linux/amd64`; on an
+  ARM host (e.g. Apple Silicon) this build isn't available.
+- **The final "Package .zip archives" step of `build()` has a pre-existing
+  bash syntax error**, unrelated to compilation - the actual build already
+  succeeded by that point (look for `Built IfcOpenShell...` in the output),
+  so this is safe to ignore if you only need the raw artifacts under
+  `build/.../install/`, not packaged release zips.
+- **`test_mmaped_stream` and similar `USE_MMAP`-dependent tests will fail**
+  against this build - `nix/build-all.py` is invoked with `USE_MMAP=OFF`
+  here. Not a bug in your code if you see it fail.
+- Only the bind-mounted `<repo>/build` lives on the host filesystem your
+  repo is checked out on. Anything the container writes *outside* that
+  mount lives in the container's own writable layer under Docker's data
+  root (commonly `/var/lib/docker`, i.e. usually your root partition) -
+  keep an eye on `df -h /` if you're running several of these containers
+  at once.

docker/compose.yaml

@@ -0,0 +1,15 @@
+name: ifcopenshell-${UNIQUE_ID}
+services:
+  ifcopenshell:
+    container_name: ifcopenshell-${UNIQUE_ID}
+    image: ifcopenshell-build-env:updated
+    platform: linux/amd64
+    volumes:
+      - type: bind
+        source: ../
+        target: /__w/IfcOpenShell/IfcOpenShell
+      - ccache:/ccache
+
+volumes:
+  ccache:
+    name: ifcopenshell-ccache-shared

docker/ifcos_env

@@ -0,0 +1,339 @@
+#!/bin/bash
+
+# ================== CONFIG ==================
+SCRIPT_NAME=$(basename "$0")
+ENV_FILE=".env"
+WORKDIR="/__w/IfcOpenShell/IfcOpenShell"
+NAMEPREFIX=ifcopenshell
+
+function set_env() {
+    # Load .env file if it exists
+    if [[ -f "$ENV_FILE" ]]; then
+        set -a
+        source "$ENV_FILE"
+        set +a
+        echo "✅ Loaded environment variables from $ENV_FILE"
+    else
+        echo "⚠️  No $ENV_FILE found, proceeding without it."
+    fi
+}
+
+set_env
+
+# ================ FUNCTIONS =================
+
+function create() {
+    echo "⭐ Creating image: ifcopenshell-build-env"
+    docker build -f Dockerfile \
+        --build-arg USER_UID="$(id -u)" --build-arg USER_GID="$(id -g)" \
+        -t ifcopenshell-build-env:updated .
+}
+
+function update() {
+    # The Dockerfile always builds FROM a clean rockylinux:9 and does
+    # `dnf update -y` as its first step, so re-running create() is enough
+    # to get fresh packages.
+    echo "⚡ Updating image: ifcopenshell-build-env"
+    create
+}
+
+function up() {
+    # Creates the container if it doesn't exist yet (and starts it either
+    # way) - this is the one that needs ready_repo, since a freshly created
+    # container has no submodules/dependency cache in place yet.
+    echo "🚀 Creating/starting stack: ifcopenshell-${UNIQUE_ID}"
+    unique          # Update UNIQUE_ID first
+    docker compose up -d "$@"   # Container must exist before ready_repo can exec into it.
+    ready_repo      # Ensure repo is recursive, and the build repo is in place.
+}
+
+function down() {
+    # Removes the container (and its network) entirely. Named volumes
+    # (ccache) and the bind-mounted repo/build/ survive; up() will recreate
+    # the container from scratch next time.
+    echo "🔥 Removing stack: ifcopenshell-${UNIQUE_ID}"
+    docker compose down "$@"
+}
+
+function stop() {
+    # Stops the existing container without removing it - the container,
+    # its filesystem layer, and its exec history all remain intact.
+    echo "🛑 Stopping stack: ifcopenshell-${UNIQUE_ID}"
+    docker compose stop "$@"
+}
+
+function start() {
+    # Starts a previously-stopped container back up. Does nothing (and
+    # won't create anything) if the container doesn't exist - use up() for
+    # that.
+    echo "▶️  Starting stack: ifcopenshell-${UNIQUE_ID}"
+    docker compose start "$@"
+}
+
+function restart() {
+    echo "🔄 Restarting stack (stop, then start)..."
+    stop
+    start
+}
+
+function recreate() {
+    echo "♻️  Recreating stack (down, then up)..."
+    down
+    up
+}
+
+function logs() {
+    echo "📜 Showing logs..."
+    docker compose logs -f "$@"
+}
+
+function ps() {
+    docker compose ps
+}
+
+function config() {
+    echo "🔍 Validated compose configuration:"
+    docker compose config
+}
+
+function remove() {
+    # Lower-level than down(): removes already-stopped containers without
+    # touching the compose network. Mostly useful after a plain stop().
+    echo "🗑️  Removing stopped containers: ifcopenshell-${UNIQUE_ID}"
+    docker compose rm "$@"
+}
+
+function unique() {
+    echo "🔧 Making stack name folder specific..."
+
+    REGEX="^UNIQUE_ID="
+
+    if [[ ! -f "$ENV_FILE" ]] || ! grep -qE "$REGEX" "$ENV_FILE"; then
+        echo -e "\nUNIQUE_ID=dummy\n" >> "$ENV_FILE"
+    fi
+
+    export UNIQUE_ID="$(pwd | sha256sum | cut -c -8)"
+
+    # `sed -i` takes incompatible syntax between GNU sed (Linux) and BSD sed
+    # (macOS) - `-si` is GNU-only and errors as "illegal option -- s" under
+    # BSD/macOS sed. Avoid -i altogether and do the in-place edit via a temp
+    # file + mv instead, which behaves identically with either sed.
+    local tmp_file
+    tmp_file="$(mktemp "${ENV_FILE}.XXXXXX")"
+    sed "s/^UNIQUE_ID=.*$/UNIQUE_ID=${UNIQUE_ID}/" "$ENV_FILE" > "$tmp_file"
+    mv "$tmp_file" "$ENV_FILE"
+
+    set_env
+}
+
+function ready_repo() {
+    echo "👍 Getting the repo ready to build..."
+    docker exec -i -w "${WORKDIR}" "${NAMEPREFIX}-${UNIQUE_ID}" bash -c '
+        set -euo pipefail   # Recommended for robustness
+
+        git submodule update --init --recursive
+
+        if [[ ! -d "build" ]]; then
+            git clone -b rockylinux9-x64 https://github.com/IfcOpenShell/build-outputs.git build
+        else
+            cd build
+            git pull
+            cd ..
+        fi
+
+        if [[ ! -d "build/Linux/x86_64/install/boost-1.86.0/" ]]; then
+            cd build
+            uv run ../nix/cache_dependencies.py unpack
+            cd ..
+        fi
+    '
+}
+
+function build() {
+    echo "☕ Execute the build, go make yourself a cuppa... I'll be a while"
+    local BUILD_TARGET="$1"
+    
+    docker exec -i -w "${WORKDIR}" -e PY_TGT="${PY_TGT}" -e BUILD_TARGET="${BUILD_TARGET}" "${NAMEPREFIX}-${UNIQUE_ID}" bash -c '
+        set -o pipefail
+        CXXFLAGS="-O3" CFLAGS="-O3 ${DARWIN_C_SOURCE}" ADD_COMMIT_SHA=1 BUILD_CFG=Release uv run ./nix/build-all.py -v ${PY_TGT:+-$PY_TGT} --diskcleanup ${BUILD_TARGET} 2>&1 | tee build.log
+    '
+    echo "🎒 Pack Dependencies"
+    docker exec -i -w "${WORKDIR}" "${NAMEPREFIX}-${UNIQUE_ID}" bash -c '
+        cd build
+        uv run ../nix/cache_dependencies.py pack
+    '
+
+    echo "🎁 Package .zip archives"
+    docker exec -i -w "${WORKDIR}" -e GITHUB_SHA="$(git rev-parse HEAD)" "${NAMEPREFIX}-${UNIQUE_ID}" bash -c '
+        OUTPUT_DIR=${PWD}/output
+        VERSION=v`cat VERSION`
+        mkdir -p ${OUTPUT_DIR}
+        cd ./build/`uname`/*/install/ifcopenshell
+
+        ls -d python-* | while read py_version; do
+            postfix=`echo ${py_version: -1} | sed s/[0-9]//`
+            numbers=`echo $py_version | grep -oE "[0-9]+\.[0-9]+" | tr -d "."`
+            py_version_major=python-${numbers}$postfix
+            pushd . > /dev/null
+            cd $py_version
+            if [ ! -d ifcopenshell ]; then
+                mkdir ../ifcopenshell_
+                mv * ../ifcopenshell_
+                mv ../ifcopenshell_ ifcopenshell
+            fi
+            [ -d ifcopenshell/__pycache__ ] && rm -rf ifcopenshell/__pycache__
+            find ifcopenshell -name "*.pyc" -delete
+            zip -r -qq ifcopenshell-${py_version_major}-${VERSION}-${GITHUB_SHA:0:7}-linux64.zip ifcopenshell/*
+            mv *.zip ${OUTPUT_DIR}/
+            popd > /dev/null
+        done
+
+        cd bin
+        if compgen -G "./*.zip" > /dev/null; then
+            rm *.zip 2>&1 >/dev/null || true
+        ls | while read exe; do
+            zip -qq -r ${exe}-${VERSION}-${GITHUB_SHA:0:7}-linux64.zip $exe
+        done
+        mv *.zip ${OUTPUT_DIR}/
+        cd ..
+      '
+}
+
+function attach() {
+    echo "🔦 Connect to interactive shell"
+    docker exec -it  -w "${WORKDIR}" "${NAMEPREFIX}-${UNIQUE_ID}" /bin/bash
+}
+
+function try() {
+    # Copies the freshly built wrapper into your actual Blender/Bonsai
+    # installation for manual, in-Blender testing. This is a human-only
+    # convenience: it overwrites files in your live Blender setup, so it's
+    # not something that should run unattended as part of an automated or
+    # AI-driven build/test loop (which should instead copy the wrapper into
+    # the repo's own src/ifcopenshell-python/ifcopenshell/ - see SKILL.md).
+    echo "🚴 Copying build artifacts into your Blender resource folder for testing"
+
+    if [[ -z "${BLENDER_USER_RESOURCE:-}" ]]; then
+        echo "❌ BLENDER_USER_RESOURCE is not set in .env."
+        echo "   Add a line pointing at wherever Blender's user resource folder for"
+        echo "   the Bonsai extension actually is on your system, e.g.:"
+        echo "     BLENDER_USER_RESOURCE=~/.config/blender/bonsai/"
+        return 1
+    fi
+
+    # Normalise: expand a leading ~ (in case it was quoted in .env and so
+    # never went through shell tilde-expansion when set_env sourced it),
+    # then resolve to an absolute, symlink-free path.
+    local resource="${BLENDER_USER_RESOURCE/#\~/$HOME}"
+    resource="$(realpath -m "$resource")"
+
+    local install_dir="../build/Linux/x86_64/install"
+    local py_dirs=("$install_dir"/python-*)
+    if [[ ${#py_dirs[@]} -gt 1 && -n "${PY_TGT:-}" ]]; then
+        # PY_TGT is compact (py-311); the install dirs are dotted
+        # (python-3.11.8) - reinsert the dot (assumes a single-digit major
+        # version, true for the Python 3.x line) before matching.
+        local py_tgt_digits="${PY_TGT#py-}"
+        local py_tgt_dotted="${py_tgt_digits:0:1}.${py_tgt_digits:1}"
+        local filtered=() d
+        for d in "${py_dirs[@]}"; do
+            [[ "$(basename "$d")" == "python-${py_tgt_dotted}."* ]] && filtered+=("$d")
+        done
+        [[ ${#filtered[@]} -gt 0 ]] && py_dirs=("${filtered[@]}")
+    fi
+    if [[ ${#py_dirs[@]} -ne 1 || ! -d "${py_dirs[0]}" ]]; then
+        echo "❌ Expected exactly one built python-* dir under $install_dir, found ${#py_dirs[@]}."
+        echo "   Run 'build' first, or set PY_TGT in .env to disambiguate a multi-version build."
+        return 1
+    fi
+
+    local py_minor
+    py_minor="$(basename "${py_dirs[0]}" | grep -oE '[0-9]+\.[0-9]+')"
+    local wrapper_dir="${py_dirs[0]}/lib/python${py_minor}/site-packages/ifcopenshell"
+    if [[ ! -f "$wrapper_dir/ifcopenshell_wrapper.py" ]]; then
+        echo "❌ Built wrapper not found at $wrapper_dir - run 'build' first."
+        return 1
+    fi
+
+    local target="$resource/extensions/.local/lib/python${py_minor}/site-packages/ifcopenshell"
+    mkdir -p "$target"
+    cp "$wrapper_dir"/_ifcopenshell_wrapper*.so "$target/"
+    cp "$wrapper_dir"/ifcopenshell_wrapper.py "$target/"
+    echo "✅ Copied wrapper into $target"
+}
+
+function clean() {
+    # Host-side only - doesn't touch the container, image, or ccache volume.
+    echo "💎 Clean the build and output folder up"
+    if [[ -d "../build" ]]; then
+        rm -rf ../build
+    fi
+    if [[ -d "../output" ]]; then
+        rm -rf ../output
+    fi
+}
+
+
+function help() {
+    cat <<EOF
+Usage: ./$SCRIPT_NAME <command>
+
+Available commands:
+  create      Build the rocky9-based image
+  update      Rebuild the image fresh, picking up OS package updates
+  up          Create the container if it doesn't exist yet, and start it
+  down        Remove the container entirely (docker compose down)
+  stop        Stop the container without removing it
+  start       Start a previously-stopped container
+  restart     stop, then start (same container, no recreation)
+  recreate    down, then up (fresh container)
+  build       Execute the IfcOpenShell build
+  attach      Connect to an interactive shell in the container
+  try         Copy the built wrapper into your Blender resource folder
+              (human-only - see BLENDER_USER_RESOURCE below, and SKILL.md
+              for the AI/automated-testing equivalent)
+  clean       Remove the build and output folders
+  logs        Follow container logs
+  ps          Show running containers
+  config      Validate and show compose config
+  remove      Remove stopped containers (docker compose rm)
+  help        Show this help
+
+Environment variables from .env are automatically loaded, including:
+  PY_TGT                  Restrict the build to one Python version, e.g. py-311
+  UNIQUE_ID               Recalculated automatically on every 'up', don't set by hand
+  BLENDER_USER_RESOURCE   Where 'try' copies the wrapper for manual testing, e.g.
+                          ~/.config/blender/bonsai/
+EOF
+}
+
+# ================= MAIN =================
+
+case "$1" in
+    create)         create ;;
+    update)         update ;;
+    up)             up "${@:2}" ;;
+    down)           down "${@:2}" ;;
+    stop)           stop "${@:2}" ;;
+    start)          start "${@:2}" ;;
+    restart)        restart ;;
+    recreate)       recreate ;;
+    build)          build "${@:2}" ;;
+    attach)         attach ;;
+    try)            try ;;
+    clean)          clean ;;
+    logs)           logs "${@:2}" ;;
+    ps)             ps ;;
+    config)         config ;;
+    remove)         remove ;;
+    help|-h|--help) help ;;
+    "")
+        echo "❌ No command provided."
+        help
+        ;;
+    *)
+        echo "❌ Unknown command: $1"
+        echo "Type './$SCRIPT_NAME help' for available commands."
+        exit 1
+        ;;
+esac

nix/build-all.py

@@ -50,7 +50,7 @@ Used environment variables:
     - ``NO_CLEAN`` - do not clean `ifcopenshell` build directories but continue working on current build
     (installed dependencies are never cleared).
     By default option is disabled, to enable pass any value from `1`, `on`, `true`.
-    - ``IFCOS_SCHEMAS`` - schemas to be built; defaults to cmake default (IFC2X3; IFC4; IFC4X3_ADD2) - to be supplied as `2x3;4`
+    - ``IFCOS_SCHEMAS`` - schemas to be built; defaults to cmake default (8 schemas), to be supplied as `2x3;4;4x3_add2`
     - ``USE_OCCT`` - whether to use official Open CASCADE instead of Community Edition
     (`true` by default, any other value is considered `false`)
     - ``WASM_PYTHON_PATH`` - path to WASM Python installation,
@@ -155,7 +155,7 @@ MPFR_VERSION = "3.1.6"  # latest is 4.1.0
 CGAL_VERSION = "v5.6.3"
 USD_VERSION = "23.05"
 TBB_VERSION = "2021.9.0"
-ROCKSDB_VERSION = "9.11.2"
+ROCKSDB_VERSION = "10.4.2"
 ZSTD_VERSION = "1.5.7"
 # binaries
 cp = "cp"
@@ -627,9 +627,10 @@ def build_dependency(
     build_tool_args: "list[str]",
     download_url: str,
     download_name: str,
+    *,
     download_tool: Literal["py", "git"] = download_tool_default,
     revision: "Union[str, None]" = None,
-    patch: "Union[str, list[str], None]" = None,
+    patch: list[str] | None = None,
     shell=None,
     pre_compile_subs: "Sequence[tuple[str, str, str]]" = (),
     additional_files: "Union[dict[str, str], None]" = None,
@@ -714,8 +715,6 @@ def build_dependency(
                 urlretrieve(url, os.path.join(extract_dir, path))
 
     if patch is not None:
-        if isinstance(patch, str):
-            patch = [patch]
         for p in patch:
             patch_abs = (SCRIPT_PATH / p).absolute().__str__()
             if os.path.exists(patch_abs):
@@ -724,6 +723,8 @@ def build_dependency(
                 except Exception as e:
                     # Assert that the patch has already been applied
                     run(["patch", "-p1", "--batch", "--reverse", "--dry-run", "-i", patch_abs], cwd=extract_dir)
+            else:
+                raise FileNotFoundError(patch_abs)
 
     if shell is not None:
         sp.run(shell, shell=True, check=True, cwd=extract_dir)
@@ -1171,6 +1172,14 @@ if "cgal" in targets:
         os.environ["CC"] = MAC_CROSS_COMPILE_INTEL_CC
         gmp_args.extend(MAC_CROSS_COMPILE_INTEL_AUTOCONF_HOST_ARGS)
 
+    # Fixes configure failing to find a working compiler under GCC 15's default -std=gnu23.
+    # Issue presumably will be resolved in any next gmp version, but currently the last one is 6.3.0.
+    # Patch is just applying fix from upstream meantion below:
+    # https://gmplib.org/list-archives/gmp-bugs/2025-February/005561.html
+    gmp_patches = ["./patches/gmp/001-fix-std23.patch"]
+    if GMP_VERSION != "6.3.0":
+        raise Exception(f"GMP_VERSION changed to {GMP_VERSION}, check whether {gmp_patches} is still needed.")
+
     build_dependency(
         name=f"gmp-{GMP_VERSION}",
         mode="autoconf",
@@ -1178,6 +1187,7 @@ if "cgal" in targets:
         pre_compile_subs=(
             [("build/config.h", "HAVE_OBSTACK_VPRINTF 1", "HAVE_OBSTACK_VPRINTF 0")] if "wasm" in flags else []
         ),
+        patch=gmp_patches,
         # Sometimes ftp.gnu.org is very slow, use ftpmirror.gnu.org as a workaround.
         download_url="https://ftpmirror.gnu.org/gnu/gmp/",
         download_name=f"gmp-{GMP_VERSION}.tar.bz2",

nix/patches/gmp/001-fix-std23.patch

@@ -0,0 +1,27 @@
+Fixes configure failing to find a working compiler under GCC 15's default
+-std=gnu23 (upstream fix: https://gmplib.org/repo/gmp/rev/8e7bb4ae7a18).
+
+Upstream fix is patching `acinclude.m4`, but since in the release tarball
+all macros are already expanded to `configure` script, so we're patching
+all occurrences of that macro.
+
+--- a/configure
++++ b/configure
+@@ -6568,7 +6568,7 @@
+
+ #if defined (__GNUC__) && ! defined (__cplusplus)
+ typedef unsigned long long t1;typedef t1*t2;
+-void g(){}
++void g(int,t1 const*,t1,t2,t1 const*,int){}
+ void h(){}
+ static __inline__ t1 e(t2 rp,t2 up,int n,t1 v0)
+ {t1 c,x,r;int i;if(v0){c=1;for(i=1;i<n;i++){x=up[i];r=x+1;rp[i]=r;}}return c;}
+@@ -8187,7 +8187,7 @@
+
+ #if defined (__GNUC__) && ! defined (__cplusplus)
+ typedef unsigned long long t1;typedef t1*t2;
+-void g(){}
++void g(int,t1 const*,t1,t2,t1 const*,int){}
+ void h(){}
+ static __inline__ t1 e(t2 rp,t2 up,int n,t1 v0)
+ {t1 c,x,r;int i;if(v0){c=1;for(i=1;i<n;i++){x=up[i];r=x+1;rp[i]=r;}}return c;}

nix/patches/occt/88af392.patch

@@ -1,32 +0,0 @@
-http://git.dev.opencascade.org/gitweb/?p=occt.git;a=commitdiff;h=0ab4e621833f4eae945a3762c9a29ee12e2eec53#patch1
-diff --git a/src/HLRBRep/HLRBRep_InternalAlgo.cxx b/src/HLRBRep/HLRBRep_InternalAlgo.cxx
-index ca885ca..c13cb06 100644 (file)
---- a/src/HLRBRep/HLRBRep_InternalAlgo.cxx
-+++ b/src/HLRBRep/HLRBRep_InternalAlgo.cxx
-@@ -165,7 +165,7 @@ void HLRBRep_InternalAlgo::Update ()
-       SB.Bounds(v1,v2,e1,e2,f1,f2);
- 
-       for (Standard_Integer e = e1; e <= e2; e++) {
--        HLRBRep_EdgeData ed = aEDataArray.ChangeValue(e);
-+        HLRBRep_EdgeData& ed = aEDataArray.ChangeValue(e);
-         HLRAlgo::DecodeMinMax(ed.MinMax(), TheMin, TheMax);
-        if (FirstTime) {
-          FirstTime = Standard_False;
-@@ -307,7 +307,7 @@ void HLRBRep_InternalAlgo::InitEdgeStatus ()
-   Standard_Integer nf = myDS->NbFaces();
- 
-   for (Standard_Integer e = 1; e <= ne; e++) {
--    HLRBRep_EdgeData ed = aEDataArray.ChangeValue(e);
-+    HLRBRep_EdgeData& ed = aEDataArray.ChangeValue(e);
-     if (ed.Selected()) ed.Status().ShowAll();
-   }
- //  for (Standard_Integer f = 1; f <= nf; f++) {
-@@ -368,7 +368,7 @@ void HLRBRep_InternalAlgo::Select ()
-     Standard_Integer nf = myDS->NbFaces();
-     
-     for (Standard_Integer e = 1; e <= ne; e++) {
--      HLRBRep_EdgeData ed = aEDataArray.ChangeValue(e);
-+      HLRBRep_EdgeData& ed = aEDataArray.ChangeValue(e);
-       ed.Selected(Standard_True);
-     }
-     

nix/patches/pr622.patch

@@ -1,22 +0,0 @@
-From a0deb4ce8b43cf3c8b8c0a4225c6be5296446dbd Mon Sep 17 00:00:00 2001
-From: Adam Eri <adam.eri@blackmirror.media>
-Date: Tue, 3 Sep 2019 23:30:20 +0200
-Subject: [PATCH] Resolves compile error on macOS
-
-Resolves "no member named 'isnan' in namespace 'std'" on macOS
----
- GeneratedSaxParser/src/GeneratedSaxParserUtils.cpp | 1 +
- 1 file changed, 1 insertion(+)
-
-diff --git a/GeneratedSaxParser/src/GeneratedSaxParserUtils.cpp b/GeneratedSaxParser/src/GeneratedSaxParserUtils.cpp
-index 1f9a3eef..dd6f5c59 100644
---- a/GeneratedSaxParser/src/GeneratedSaxParserUtils.cpp
-+++ b/GeneratedSaxParser/src/GeneratedSaxParserUtils.cpp
-@@ -10,6 +10,7 @@
- 
- #include "GeneratedSaxParserUtils.h"
- #include <math.h>
-+#include <cmath>
- #include <memory>
- #include <string.h>
- #include <limits>

pyproject.toml

@@ -1,13 +1,8 @@
 [project]
 name = "IfcOpenShell"
 version = "0.0.0"
-dependencies = [
-    "black==26.3.1",
-    "ruff==0.15.12",
-    "poethepoet",
-    "ty==0.0.32",
-    "gersemi==0.26.1",
-]
+# Don't provide requires-python explicitly
+# allowing pyprojects to set their own (e.g. bonsai and general ifcopenshell version differ).
 
 [tool.black]
 line-length = 120
@@ -43,6 +38,7 @@ exclude = [
 # then they will be inherited by projects' .toml files.
 # This allows using assuming different Python version for different projects.
 [tool.ruff]
+line-length = 120
 exclude = [
     # Submodules.
     "src/ifcopenshell-python/ifcopenshell/express",
@@ -83,92 +79,39 @@ ignore = [
 ]
 
 [tool.ty.rules]
-all = "ignore"
+all = "error"
 
 # Structural rules (no deep type inference needed, easier to adapt).
-abstract-method-in-final-class = "error"
-ambiguous-protocol-member = "error"
-conflicting-declarations = "error"
-conflicting-metaclass = "error"
-cyclic-class-definition = "error"
-cyclic-type-alias-definition = "error"
-dataclass-field-order = "error"
-duplicate-base = "error"
-duplicate-kw-only = "error"
-empty-body = "error"
-escape-character-in-forward-annotation = "error"
-final-on-non-method = "error"
-final-without-value = "error"
-ignore-comment-unknown-rule = "error"
-implicit-concatenated-string-type-annotation = "error"
-inconsistent-mro = "error"
-ineffective-final = "error"
-instance-layout-conflict = "error"
-invalid-dataclass = "error"
-invalid-dataclass-override = "error"
-invalid-enum-member-annotation = "error"
-invalid-explicit-override = "error"
-invalid-frozen-dataclass-subclass = "error"
-invalid-generic-class = "error"
-invalid-generic-enum = "error"
-invalid-ignore-comment = "error"
-invalid-legacy-positional-parameter = "error"
-invalid-legacy-type-variable = "error"
-invalid-named-tuple = "error"
-invalid-newtype = "error"
-invalid-overload = "error"
-invalid-paramspec = "error"
-invalid-protocol = "error"
-invalid-syntax-in-forward-annotation = "error"
-invalid-total-ordering = "error"
-invalid-type-alias-type = "error"
-invalid-type-checking-constant = "error"
-invalid-type-guard-definition = "error"
-invalid-type-variable-bound = "error"
-invalid-type-variable-constraints = "error"
-invalid-typed-dict-header = "error"
-invalid-typed-dict-statement = "error"
-override-of-final-method = "error"
-override-of-final-variable = "error"
-possibly-missing-import = "error"
-possibly-missing-submodule = "error"
 # Has false positives due to ty walrus operator bug.
-# possibly-unresolved-reference = "error"
-raw-string-type-annotation = "error"
-redundant-final-classvar = "error"
-shadowed-type-variable = "error"
-subclass-of-final-class = "error"
-super-call-in-named-tuple-method = "error"
-unavailable-implicit-super-arguments = "error"
-unbound-type-variable = "error"
-undefined-reveal = "error"
-unresolved-global = "error"
-unresolved-import = "error"
-unresolved-reference = "error"
-unused-ignore-comment = "error"
-unused-type-ignore-comment = "error"
-useless-overload-body = "error"
+possibly-unresolved-reference = "ignore"
+# Maybe later, requires to specify element types for all generics.
+missing-type-argument = "ignore"
+# Conflicts with `bpy` props defined using annotations.
+invalid-type-form = "ignore"
 
 # Non-structural rules:
-deprecated = "error"
-zero-stepsize-in-slice = "error"
-possibly-missing-implicit-call = "error"
-unused-awaitable = "error"
-
-# Function argument rules:
 # Conflicts with `ifcopenshell.api.geometry.add_representation` type of callables we have, confusing them with a module.
-# call-non-callable = "error"
-conflicting-argument-forms = "error"
+call-non-callable = "ignore"
+# bpy is missing some context manager implementations.
+invalid-context-manager = "ignore"
+# Doesn't go well with `bpy.ops.xxx.yyy`.
+unresolved-attribute = "ignore"
 # Too many false positives.
-# invalid-argument-type = "error"
-missing-argument = "error"
-parameter-already-assigned = "error"
-positional-only-parameter-as-kwarg = "error"
-too-many-positional-arguments = "error"
-unknown-argument = "error"
-# Has a lot of warnings due to current ty walrus operator issues.
-# index-out-of-bounds = "error"
-# unresolved-attribute = "error"
+invalid-argument-type = "ignore"
+invalid-method-override = "ignore"
+invalid-assignment = "ignore"
+invalid-parameter-default = "ignore"
+missing-override-decorator = "ignore"
+invalid-yield = "ignore"
+invalid-return-type = "ignore"
+non-callable-init-subclass = "ignore"
+not-iterable = "ignore"
+possibly-missing-attribute = "ignore"
+no-matching-overload = "ignore"
+not-subscriptable = "ignore"
+unsupported-dynamic-base = "ignore"
+unsupported-operator = "ignore"
+type-assertion-failure = "ignore"
 
 [tool.ty.environment]
 extra-paths = [
@@ -215,6 +158,18 @@ exclude = [
 
 [tool.poe.tasks]
 
+dev-setup.sequence = [
+    {cmd = "uv sync"},
+    {cmd = "uv pip install -e ./src/bsdd/"},
+    {cmd = "uv pip install -e ./src/ifcopenshell-python/[advanced,dev]"},
+    {cmd = "uv pip install -e ./src/ifcedit/"},
+    {cmd = "uv pip install -e ./src/ifcpatch/"},
+    {cmd = "uv pip install -e ./src/ifcquery/"},
+    {cmd = "uv pip install -e './src/ifcmcp/[mcp]'"},
+    {cmd = "uv pip install -r src/bonsai/requirements-dev.txt"},
+]
+dev-setup.help = "Install repo packages in editable mode"
+
 ruff = "ruff check"
 
 black = "black ."
@@ -243,6 +198,7 @@ cmake-format = "gersemi . --in-place"
 # --ignore unresolved-reference: walrus operator false positives in ty.
 cmd = """
     ty check
+    nix/
     src/bcf
     src/bsdd
     src/ifc2ca

requirements-tools.txt

@@ -0,0 +1,5 @@
+black==26.3.1
+ruff==0.15.12
+poethepoet
+ty==0.0.59
+gersemi==0.26.1

src/bonsai/bonsai/bim/data/pset/EPset_Drawing.ifc

@@ -5,7 +5,7 @@ FILE_NAME('EPset_Drawing.ifc','2020-01-01T00:00:00',$,$,'EPset_Drawing','EPset_D
 FILE_SCHEMA(('IFC4'));
 ENDSEC;
 DATA;
-#1=IFCPROPERTYSETTEMPLATE('2JhNIvqZrFnAgxfhK0XVQX',$,'EPset_Drawing','',.PSET_OCCURRENCEDRIVEN.,'IfcAnnotation/DRAWING',(#23,#22,#27,#24,#19,#12,#26,#9,#8,#7,#6,#4,#18,#11,#5,#20,#25,#14,#10,#17,#28,#16,#3,#21,#13,#15,#2));
+#1=IFCPROPERTYSETTEMPLATE('2JhNIvqZrFnAgxfhK0XVQX',$,'EPset_Drawing','',.PSET_OCCURRENCEDRIVEN.,'IfcAnnotation/DRAWING',(#23,#22,#27,#24,#29,#30,#19,#12,#26,#9,#8,#7,#6,#4,#18,#11,#5,#20,#25,#14,#10,#17,#28,#16,#3,#21,#13,#15,#2));
 #2=IFCSIMPLEPROPERTYTEMPLATE('23JavTMk98ZxXhrUEnjAcf',$,'TargetView','',.P_SINGLEVALUE.,'IfcLabel',$,$,$,$,$,.READWRITE.);
 #3=IFCSIMPLEPROPERTYTEMPLATE('1yVWUt5H9DAOuu0OaMMLpe',$,'Scale','The scale of this drawing represented as a numerator and denominator, such as 1/100',.P_SINGLEVALUE.,'IfcLabel',$,$,$,$,$,.READWRITE.);
 #4=IFCSIMPLEPROPERTYTEMPLATE('3gsuPBtU93b8f0gg1pjkq6',$,'HumanScale','The scale of this drawing in human readable format, such as 1:100',.P_SINGLEVALUE.,'IfcLabel',$,$,$,$,$,.READWRITE.);
@@ -33,5 +33,7 @@ DATA;
 #26=IFCSIMPLEPROPERTYTEMPLATE('2iwERDOW55Pf4hCbuFRe1Q',$,'FillMode','Method to fill areas seen in projection',.P_SINGLEVALUE.,'IfcLabel',$,$,$,$,$,.READWRITE.);
 #27=IFCSIMPLEPROPERTYTEMPLATE('1YF$qLzBzF19Io8aB2N8cE',$,'CutMode','Method for cutting geometry',.P_SINGLEVALUE.,'IfcLabel',$,$,$,$,$,.READWRITE.);
 #28=IFCSIMPLEPROPERTYTEMPLATE('1YSnFzurrEyRNtoLdmmddP',$,'BringToFront','The objects with these SVG classes will render in front of all other objects.Ex: IfcBeam, IfcColumn',.P_SINGLEVALUE.,'IfcText',$,$,$,$,$,.READWRITE.);
+#29=IFCSIMPLEPROPERTYTEMPLATE('0lP6Y8q9v2QhDnR4sT7uVx',$,'PerspectiveShiftX','Horizontal perspective camera shift stored as drawing metadata using Blender camera shift units.',.P_SINGLEVALUE.,'IfcReal',$,$,$,$,$,.READWRITE.);
+#30=IFCSIMPLEPROPERTYTEMPLATE('2mR8b1NcW5EoFyG7hJ9kLp',$,'PerspectiveShiftY','Vertical perspective camera shift stored as drawing metadata using Blender camera shift units.',.P_SINGLEVALUE.,'IfcReal',$,$,$,$,$,.READWRITE.);
 ENDSEC;
 END-ISO-10303-21;

src/bonsai/bonsai/bim/handler.py

@@ -320,9 +320,11 @@ def loadIfcStore(scene: bpy.types.Scene) -> None:
     IfcStore.purge()
     refresh_ui_data()
     if not tool.Ifc.get():
+        tool.Autosave.cancel_timer()
         return
     tool.Ifc.schema()
     IfcStore.relink_all_objects()
+    tool.Autosave.reset_timer()
 
 
 @persistent

src/bonsai/bonsai/bim/ifc.py

@@ -46,7 +46,7 @@ IFC_CONNECTED_TYPE = Union[bpy.types.Material, bpy.types.Object]
 class OperationData(TypedDict):
     id: int
     guid: NotRequired[str]
-    obj: str
+    obj: NotRequired[str]
 
 
 class EditObjectOperationData(TypedDict):

src/bonsai/bonsai/bim/import_ifc.py

@@ -980,8 +980,13 @@ class IfcImporter:
                     if unit.Name == "METRE":
                         if not unit.Prefix:
                             bpy.context.scene.unit_settings.length_unit = "METERS"
-                        else:
+                        elif f"{unit.Prefix}METERS" in ("KILOMETERS", "CENTIMETERS", "MILLIMETERS", "MICROMETERS"):
                             bpy.context.scene.unit_settings.length_unit = f"{unit.Prefix}METERS"
+                        else:
+                            # Blender's length_unit enum has no entry for other
+                            # SI prefixes (e.g. DECIMETERS), so fall back to
+                            # adaptive display instead of failing to open.
+                            bpy.context.scene.unit_settings.length_unit = "ADAPTIVE"
                 else:
                     bpy.context.scene.unit_settings.system = "IMPERIAL"
                     name = unit.Name.lower()

src/bonsai/bonsai/bim/module/aggregate/decorator.py

@@ -20,7 +20,6 @@ import blf
 import bpy
 import gpu
 import ifcopenshell.util.element
-from bpy.types import SpaceView3D
 from bpy_extras import view3d_utils
 from gpu_extras.batch import batch_for_shader
 from mathutils import Vector
@@ -28,12 +27,6 @@ from mathutils import Vector
 import bonsai.tool as tool
 
 
-def transparent_color(color, alpha=0.1):
-    color = [i for i in color]
-    color[3] = alpha
-    return color
-
-
 def create_bounding_box(objs):
     # Initialize the bounding box coordinates
     min_x, min_y, min_z = float("inf"), float("inf"), float("inf")
@@ -79,26 +72,8 @@ def create_bounding_box(objs):
     return indices, edges
 
 
-class AggregateDecorator:
-    is_installed = False
-    handlers = []
-
-    @classmethod
-    def install(cls, context):
-        if cls.is_installed:
-            cls.uninstall()
-        handler = cls()
-        cls.handlers.append(SpaceView3D.draw_handler_add(handler.draw_aggregate, (context,), "WINDOW", "POST_VIEW"))
-        cls.is_installed = True
-
-    @classmethod
-    def uninstall(cls):
-        for handler in cls.handlers:
-            try:
-                SpaceView3D.draw_handler_remove(handler, "WINDOW")
-            except ValueError:
-                pass
-        cls.is_installed = False
+class AggregateDecorator(tool.Blender.ViewportDecorator):
+    draw_method = "draw_aggregate"
 
     def dotted_line_shader(self):
         vert_out = gpu.types.GPUStageInterfaceInfo("my_interface")
@@ -153,14 +128,6 @@ class AggregateDecorator:
         shader.uniform_float("u_Scale", 25)
         batch.draw(shader)
 
-    def draw_batch(self, shader_type, content_pos, color, indices=None):
-        if not tool.Blender.validate_shader_batch_data(content_pos, indices):
-            return
-        shader = self.line_shader if shader_type == "LINES" else self.shader
-        batch = batch_for_shader(shader, shader_type, {"pos": content_pos}, indices=indices)
-        shader.uniform_float("color", color)
-        batch.draw(shader)
-
     def draw_aggregate(self, context):
         props = tool.Aggregate.get_aggregate_props()
         self.addon_prefs = tool.Blender.get_addon_preferences()
@@ -191,12 +158,13 @@ class AggregateDecorator:
                 aggregates.append(obj)
                 continue
 
+            aggregate = None
             aggregates_list = tool.Aggregate.get_aggregates_recursively(element)
             if props.in_aggregate_mode and props.editing_aggregate:
                 index = aggregates_list.index(tool.Ifc.get_entity(props.editing_aggregate))
                 if index > 0:
                     aggregate = aggregates_list[index - 1]
-            else:
+            elif aggregates_list:
                 aggregate = aggregates_list[-1]
             if aggregate:
                 aggregates.append(tool.Ifc.get_object(aggregate))
@@ -225,39 +193,11 @@ class AggregateDecorator:
             self.draw_custom_batch(line, decorator_color_unselected)
 
 
-class AggregateModeDecorator:
-    is_installed = False
-    handlers = []
-
-    @classmethod
-    def install(cls, context):
-        if cls.is_installed:
-            cls.uninstall()
-        handler = cls()
-        cls.handlers.append(
-            SpaceView3D.draw_handler_add(handler.draw_aggregate_name, (context,), "WINDOW", "POST_PIXEL")
-        )
-        cls.handlers.append(
-            SpaceView3D.draw_handler_add(handler.draw_aggregate_empty, (context,), "WINDOW", "POST_VIEW")
-        )
-        cls.is_installed = True
-
-    @classmethod
-    def uninstall(cls):
-        for handler in cls.handlers:
-            try:
-                SpaceView3D.draw_handler_remove(handler, "WINDOW")
-            except ValueError:
-                pass
-        cls.is_installed = False
-
-    def draw_batch(self, shader_type, content_pos, color, indices=None):
-        if not tool.Blender.validate_shader_batch_data(content_pos, indices):
-            return
-        shader = self.line_shader if shader_type == "LINES" else self.shader
-        batch = batch_for_shader(shader, shader_type, {"pos": content_pos}, indices=indices)
-        shader.uniform_float("color", color)
-        batch.draw(shader)
+class AggregateModeDecorator(tool.Blender.ViewportDecorator):
+    draw_methods = (
+        ("draw_aggregate_name", "POST_PIXEL"),
+        ("draw_aggregate_empty", "POST_VIEW"),
+    )
 
     def draw_aggregate_name(self, context):
         if context.mode == "EDIT_MESH":

src/bonsai/bonsai/bim/module/boundary/decorator.py

@@ -56,11 +56,6 @@ class BoundaryDecorator:
         unselected_elements_color = self.addon_prefs.decorator_color_unselected
         special_elements_color = self.addon_prefs.decorator_color_special
 
-        def transparent_color(color, alpha=0.1):
-            color = [i for i in color]
-            color[3] = alpha
-            return color
-
         gpu.state.point_size_set(6)
         gpu.state.blend_set("ALPHA")
 
@@ -109,7 +104,11 @@ class BoundaryDecorator:
 
         if unselected_edges:
             self.draw_batch("LINES", unselected_vertices, special_elements_color, unselected_edges)
-            self.draw_batch("TRIS", unselected_vertices, transparent_color(special_elements_color), unselected_tris)
+            self.draw_batch(
+                "TRIS", unselected_vertices, tool.Blender.transparent_color(special_elements_color), unselected_tris
+            )
         if selected_edges:
             self.draw_batch("LINES", selected_vertices, selected_elements_color, selected_edges)
-            self.draw_batch("TRIS", selected_vertices, transparent_color(selected_elements_color), selected_tris)
+            self.draw_batch(
+                "TRIS", selected_vertices, tool.Blender.transparent_color(selected_elements_color), selected_tris
+            )

src/bonsai/bonsai/bim/module/brick/data.py

@@ -156,16 +156,13 @@ class BrickschemaReferencesData:
         for rel in getattr(tool.Ifc.get_entity(bpy.context.active_object), "HasAssociations", []):
             if rel.is_a("IfcRelAssociatesLibrary"):
                 reference = rel.RelatingLibrary
-                if tool.Ifc.get_schema() == "IFC2X3" and "#" not in reference.ItemReference:
-                    continue
-                if tool.Ifc.get_schema() != "IFC2X3" and "#" not in reference.Identification:
+                identification = tool.Document.get_external_reference_id(reference)
+                if not identification or "#" not in identification:
                     continue
                 results.append(
                     {
                         "id": reference.id(),
-                        "identification": (
-                            reference.ItemReference if tool.Ifc.get_schema() == "IFC2X3" else reference.Identification
-                        ),
+                        "identification": identification,
                         "name": reference.Name or "Unnamed",
                     }
                 )

src/bonsai/bonsai/bim/module/clash/decorator.py

@@ -18,43 +18,17 @@
 
 import blf
 import gpu
-from bpy.types import SpaceView3D
 from bpy_extras.view3d_utils import location_3d_to_region_2d
-from gpu_extras.batch import batch_for_shader
 from mathutils import Vector
 
 import bonsai.tool as tool
 
 
-class ClashDecorator:
-    is_installed = False
-    handlers = []
-
-    @classmethod
-    def install(cls, context):
-        if cls.is_installed:
-            cls.uninstall()
-        handler = cls()
-        cls.handlers.append(SpaceView3D.draw_handler_add(handler.draw_text, (context,), "WINDOW", "POST_PIXEL"))
-        cls.handlers.append(SpaceView3D.draw_handler_add(handler.draw_geometry, (context,), "WINDOW", "POST_VIEW"))
-        cls.is_installed = True
-
-    @classmethod
-    def uninstall(cls):
-        for handler in cls.handlers:
-            try:
-                SpaceView3D.draw_handler_remove(handler, "WINDOW")
-            except ValueError:
-                pass
-        cls.is_installed = False
-
-    def draw_batch(self, shader_type, content_pos, color, indices=None):
-        if not tool.Blender.validate_shader_batch_data(content_pos, indices):
-            return
-        shader = self.line_shader if shader_type == "LINES" else self.shader
-        batch = batch_for_shader(shader, shader_type, {"pos": content_pos}, indices=indices)
-        shader.uniform_float("color", color)
-        batch.draw(shader)
+class ClashDecorator(tool.Blender.ViewportDecorator):
+    draw_methods = (
+        ("draw_text", "POST_PIXEL"),
+        ("draw_geometry", "POST_VIEW"),
+    )
 
     def draw_text(self, context):
         self.addon_prefs = tool.Blender.get_addon_preferences()

src/bonsai/bonsai/bim/module/clip_box/__init__.py

@@ -52,8 +52,27 @@ def _on_depsgraph_update(scene, depsgraph):
     tool.ClipBox.on_depsgraph_update_caps(scene, depsgraph)
 
 
+@persistent
+def _on_load_pre(filepath):
+    # Tear down any in-flight clip-box timers before Blender frees the
+    # WM / screens / areas / regions for the loading file. A refresh timer
+    # that survives the teardown fires against the new file's freshly-
+    # allocated regions before their GPU state is wired, CTD-ing inside
+    # GPU_matrix_ortho_set. The gate also blocks the depsgraph IFC-reload
+    # branch and is held closed until on_pre_view fires for the first time
+    # on the new file (first paint = GPU contexts wired).
+    tool.ClipBox._file_loading = True
+    tool.ClipBox._post_load_paint_pending = True
+    tool.ClipBox._cancel_pending_refresh()
+    tool.ClipBox._cancel_pending_cap_rebuild()
+
+
 @persistent
 def _on_load_post(filepath):
+    # The _file_loading gate is NOT cleared here: load_post fires before
+    # the new file's first paint, so GPU contexts may still be uninitialised.
+    # on_pre_view consumes _post_load_paint_pending to open the gate at the
+    # safe moment and kick the post-load re-arm.
     # Restore the per-scene clip-box list from the project's BBIM_ClipBoxes
     # pset. Runs after the standard load_post that creates Blender objects.
     tool.ClipBox._last_seen_object_matrices.clear()
@@ -71,6 +90,8 @@ def register():
     tool.ClipBox.reset_ownership()
     if _on_depsgraph_update not in bpy.app.handlers.depsgraph_update_post:
         bpy.app.handlers.depsgraph_update_post.append(_on_depsgraph_update)
+    if _on_load_pre not in bpy.app.handlers.load_pre:
+        bpy.app.handlers.load_pre.append(_on_load_pre)
     if _on_load_post not in bpy.app.handlers.load_post:
         bpy.app.handlers.load_post.append(_on_load_post)
     if _draw_handler_pre is None:
@@ -97,8 +118,11 @@ def unregister():
         _draw_handler_pre = None
     if _on_load_post in bpy.app.handlers.load_post:
         bpy.app.handlers.load_post.remove(_on_load_post)
+    if _on_load_pre in bpy.app.handlers.load_pre:
+        bpy.app.handlers.load_pre.remove(_on_load_pre)
     if _on_depsgraph_update in bpy.app.handlers.depsgraph_update_post:
         bpy.app.handlers.depsgraph_update_post.remove(_on_depsgraph_update)
+    tool.ClipBox._cancel_pending_refresh()
     tool.ClipBox._cancel_pending_cap_rebuild()
     tool.ClipBox._last_seen_object_matrices.clear()
     tool.ClipBox.clear_clip_planes()

src/bonsai/bonsai/bim/module/document/data.py

@@ -127,36 +127,25 @@ class ObjectDocumentData:
                 identification = None
 
                 if is_information:
-                    if tool.Ifc.get_schema() == "IFC2X3":
-                        identification = relating_document.DocumentId
-                    else:
-                        identification = relating_document.Identification
+                    identification = tool.Document.get_document_information_id(relating_document)
 
                     location = getattr(relating_document, "Location", None)
                     description = getattr(relating_document, "Description", "No description")
                 else:
                     description = relating_document.Description
-                    if tool.Ifc.get_schema() == "IFC2X3":
-                        reference_to_document = relating_document.ReferenceToDocument
-                        if not name and reference_to_document:
-                            name = reference_to_document[0].Name
+                    referenced_document = tool.Document.get_reference_document(relating_document)
 
-                        identification = relating_document.ItemReference
-                        if not identification and reference_to_document:
-                            identification = reference_to_document[0].DocumentId
-                        location = relating_document.Location
-                    else:
-                        referenced_document = relating_document.ReferencedDocument
-                        if not name and referenced_document:
-                            name = referenced_document.Name
+                    if not name and referenced_document:
+                        name = referenced_document.Name
 
-                        identification = relating_document.Identification
-                        if not identification and referenced_document:
-                            identification = referenced_document.Identification
+                    identification = tool.Document.get_external_reference_id(relating_document)
+                    if not identification and referenced_document:
+                        identification = tool.Document.get_document_information_id(referenced_document)
 
-                        location = relating_document.Location
-                        if location is None and referenced_document:
-                            location = referenced_document.Location
+                    location = relating_document.Location
+                    # IFC2X3 IfcDocumentInformation has no Location to fall back to.
+                    if location is None and referenced_document and tool.Ifc.get_schema() != "IFC2X3":
+                        location = referenced_document.Location
 
                 location = cls.convert_to_file_uri(location) if location else None
 

src/bonsai/bonsai/bim/module/drawing/gizmos.py

@@ -82,7 +82,15 @@ import math
 from collections.abc import Callable, Iterator
 from dataclasses import dataclass
 from enum import Enum
-from typing import Any, ClassVar, Literal, Optional, Protocol, runtime_checkable
+from typing import (
+    TYPE_CHECKING,
+    Any,
+    ClassVar,
+    Literal,
+    Optional,
+    Protocol,
+    runtime_checkable,
+)
 
 import blf
 import bpy
@@ -105,6 +113,9 @@ from mathutils.kdtree import KDTree
 import bonsai.tool as tool
 from bonsai.bim.module.drawing.shaders import ExtrusionGuidesShader
 
+if TYPE_CHECKING:
+    import bmesh
+
 SNAP_POINT_SIZE = 10.0
 SNAP_POINT_COLOR = (1.0, 0.5, 0.0, 1.0)
 SNAP_MAX_RADIUS = 50.0
@@ -2035,7 +2046,9 @@ class TexturedQuadGizmoMixin(StaticTrisGizmoMixin):
 
     def setup(self) -> None:
         super().setup()
-        from bonsai.bim.module.drawing import gizmo_textures
+        from bonsai.bim.module.drawing import (
+            gizmo_textures,  # ty: ignore[unresolved-import]
+        )
 
         self._quad_batch = batch_for_shader(
             gizmo_textures.get_shader(),
@@ -2044,7 +2057,9 @@ class TexturedQuadGizmoMixin(StaticTrisGizmoMixin):
         )
 
     def draw(self, context: bpy.types.Context) -> None:
-        from bonsai.bim.module.drawing import gizmo_textures
+        from bonsai.bim.module.drawing import (
+            gizmo_textures,  # ty: ignore[unresolved-import]
+        )
 
         texture = gizmo_textures.get_icon_texture(self.icon_name)
         if texture is None:

src/bonsai/bonsai/bim/module/drawing/handler.py

@@ -50,6 +50,9 @@ def set_active_camera_resolution(scene: bpy.types.Scene) -> None:
     if camera.type != props.camera_type:
         camera.type = props.camera_type
 
+    if props.update_props and (drawing := tool.Ifc.get_entity(camera_obj)):
+        tool.Drawing.sync_perspective_camera_shifts(drawing, camera)
+
     ortho_scale, aspect_ratio = props.get_scale_and_aspect_ratio()
     scene_render = scene.render
     if (camera.ortho_scale != ortho_scale) or not tool.Cad.is_x(

src/bonsai/bonsai/bim/module/drawing/helper.py

@@ -189,14 +189,20 @@ def format_distance(
             if hasattr(length_unit, "Prefix") and length_unit.Prefix:
                 unit_length = length_unit.Prefix + length_unit.Name
             unit_length_mapping = {
+                "MILE": "MILES",
                 "FOOT": "FEET",
                 "INCH": "INCHES",
+                "KILOMETRE": "KILOMETERS",
                 "METRE": "METERS",
                 "DECIMETRE": "DECIMETERS",
                 "CENTIMETRE": "CENTIMETERS",
                 "MILLIMETRE": "MILLIMETERS",
+                "MICROMETRE": "MICROMETERS",
             }
-            unit_length = unit_length_mapping[unit_length]
+            # Fall through for units without a dedicated formatter (e.g.
+            # HECTOMETRE) so they use the adaptive branch instead of a
+            # KeyError (#8255).
+            unit_length = unit_length_mapping.get(unit_length, unit_length)
         # For now we only format area in IFC Units
         if area_unit := ifcopenshell.util.unit.get_project_unit(tool.Ifc.get(), "AREAUNIT"):
             area_unit_symbol = " " + ifcopenshell.util.unit.get_unit_symbol(area_unit)

src/bonsai/bonsai/bim/module/drawing/operator.py

@@ -57,7 +57,7 @@ import shapely
 from bpy_extras.image_utils import load_image
 from bpy_extras.io_utils import ImportHelper
 from lxml import etree
-from mathutils import Color, Vector
+from mathutils import Color, Matrix, Vector
 
 import bonsai.bim.export_ifc
 import bonsai.bim.handler
@@ -602,6 +602,7 @@ class CreateDrawing(bpy.types.Operator):
         context_type: Literal["body", "annotation"],
         drawing_elements: set[ifcopenshell.entity_instance],
         target_view: str,
+        link_matrix: Optional[Matrix] = None,
     ) -> None:
         drawing_elements = drawing_elements.copy()
         contexts_: list[list[int]] = getattr(contexts, context_type)
@@ -613,9 +614,19 @@ class CreateDrawing(bpy.types.Operator):
                 geom_settings.set("dimensionality", ifcopenshell.ifcopenshell_wrapper.CURVES_SURFACES_AND_SOLIDS)
                 geom_settings.set("iterator-output", ifcopenshell.ifcopenshell_wrapper.NATIVE)
 
-                if ifc.by_id(context[0]).ContextType == "Plan" and "PLAN_VIEW" in target_view:
+                is_plan = ifc.by_id(context[0]).ContextType == "Plan" and "PLAN_VIEW" in target_view
+                z_offset = (0.002 if target_view == "PLAN_VIEW" else -0.002) if is_plan else 0.0
+
+                if link_matrix is not None:
+                    unit_scale = ifcopenshell.util.unit.calculate_unit_scale(ifc)
+                    t = link_matrix.to_translation()
+                    offset = (t.x / unit_scale, t.y / unit_scale, t.z / unit_scale + z_offset)
+                    geom_settings.set("model-offset", offset)
+                    q = link_matrix.to_quaternion()
+                    geom_settings.set("model-rotation", (q.x, q.y, q.z, q.w))
+                elif z_offset:
                     # A 2mm Z offset to combat Z-fighting in plan or RCPs
-                    geom_settings.set("model-offset", (0.0, 0.0, 0.002 if target_view == "PLAN_VIEW" else -0.002))
+                    geom_settings.set("model-offset", (0.0, 0.0, z_offset))
 
                 geom_settings.set("context-ids", context)
                 it = ifcopenshell.geom.iterator(
@@ -923,11 +934,16 @@ class CreateDrawing(bpy.types.Operator):
 
         bim_props = tool.Blender.get_bim_props()
         prefs = tool.Blender.get_addon_preferences()
-        files = {bim_props.ifc_file: tool.Ifc.get()}
+        # Map ifc_path → (ifc_file, link_matrix); main file has no link_matrix (None)
+        files: dict[str, tuple[ifcopenshell.file, Optional[Matrix]]] = {bim_props.ifc_file: (tool.Ifc.get(), None)}
 
         props = tool.Project.get_project_props()
         for link in props.get_loaded_links_for_drawings():
-            files[link.filepath] = self.get_linked_file(link)
+            try:
+                link_matrix = tool.Project.calculate_link_matrix(link)
+            except Exception:
+                link_matrix = None
+            files[link.filepath] = (self.get_linked_file(link), link_matrix)
 
         target_view = ifcopenshell.util.element.get_psets(self.camera_element)["EPset_Drawing"]["TargetView"]
         self.setup_serialiser(target_view)
@@ -935,7 +951,13 @@ class CreateDrawing(bpy.types.Operator):
         tree = ifcopenshell.geom.tree()
         tree.enable_face_styles(True)
 
-        for ifc_path, ifc in files.items():
+        # Accumulated across every file in the loop below (main model plus any
+        # linked models) so the SHAPELY fill pass after the loop covers all of
+        # them, not just whichever file happened to be processed last.
+        raycast_objs = set()
+        elements_with_faces = set()
+
+        for ifc_path, (ifc, link_matrix) in files.items():
             # Don't use draw.main() just whilst we're prototyping and experimenting
             # TODO: hash paths are never used
             ifc_hash = hashlib.md5(ifc_path.encode("utf-8")).hexdigest()
@@ -944,13 +966,24 @@ class CreateDrawing(bpy.types.Operator):
             self.serialiser.setFile(ifc)
             drawing_elements = tool.Drawing.get_drawing_elements(self.camera_element, ifc_file=ifc)
 
+            if self.cprops.fill_mode == "SHAPELY":
+                for element in drawing_elements.copy():
+                    if element.is_a("IfcAnnotation"):
+                        continue
+                    obj = tool.Ifc.get_object(element)
+                    if obj and obj.type == "MESH" and len(obj.data.polygons):
+                        elements_with_faces.add(element.GlobalId)
+                        raycast_objs.add(obj)
+
             # Get all representation contexts to see what we're dealing with.
             # Drawings only draw bodies and annotations (and facetation, due to a Revit bug).
             # A drawing prioritises a target view context first, followed by a model view context as a fallback.
             # Specifically for PLAN_VIEW and REFLECTED_PLAN_VIEW, any Plan context is also prioritised.
             contexts = self.get_linework_contexts(ifc, target_view)
-            self.serialize_contexts_elements(ifc, tree, contexts, "body", drawing_elements, target_view)
-            self.serialize_contexts_elements(ifc, tree, contexts, "annotation", drawing_elements, target_view)
+            self.serialize_contexts_elements(ifc, tree, contexts, "body", drawing_elements, target_view, link_matrix)
+            self.serialize_contexts_elements(
+                ifc, tree, contexts, "annotation", drawing_elements, target_view, link_matrix
+            )
 
             if tool.Ifc.get() == ifc and self.camera_element not in drawing_elements:
                 with profile("Camera element"):
@@ -1017,16 +1050,6 @@ class CreateDrawing(bpy.types.Operator):
             # shapely variant
             group = root.find("{http://www.w3.org/2000/svg}g")
 
-            raycast_objs = set()
-            elements_with_faces = set()
-            for element in drawing_elements.copy():
-                if element.is_a("IfcAnnotation"):
-                    continue
-                obj = tool.Ifc.get_object(element)
-                if obj and obj.type == "MESH" and len(obj.data.polygons):
-                    elements_with_faces.add(element.GlobalId)
-                    raycast_objs.add(obj)
-
             projections = root.xpath(
                 ".//svg:g[contains(@class, 'projection')]", namespaces={"svg": "http://www.w3.org/2000/svg"}
             )
@@ -1683,6 +1706,12 @@ class CreateDrawing(bpy.types.Operator):
             key=lambda a: (
                 tool.Drawing.get_annotation_z_index(a),
                 1 if ifcopenshell.util.element.get_predefined_type(a) == "TEXT" else 0,
+                # Deterministic tiebreaker so equal-priority annotations keep a
+                # stable order across sessions. Without it the order comes from
+                # the set union above, which depends on entity hashes (and thus
+                # the file pointer), shuffling annotations between Blender
+                # restarts. See #6608.
+                a.id(),
             ),
         )
 
@@ -2319,7 +2348,10 @@ class ActivateDrawingBase(tool.Ifc.Operator):
     bl_description = (
         "Activates the selected drawing view.\n\n"
         + "ALT+CLICK to keep the viewport position.\n\n"
-        + "SHIFT+CLICK to load a quick preview of the drawing view"
+        + "SHIFT+CLICK to load a quick preview of the drawing view.\n\n"
+        + "SHIFT+CTRL+CLICK to load the annotations of all selected drawings without switching views, "
+        + "then select their cameras (the first selected drawing's camera becomes active).\n\n"
+        + "SHIFT+CTRL+ALT+CLICK to do the same but also select the annotations, not just the cameras"
     )
 
     drawing: bpy.props.IntProperty()
@@ -2335,13 +2367,32 @@ class ActivateDrawingBase(tool.Ifc.Operator):
         default=False,
         options={"SKIP_SAVE"},
     )
+    load_selected_annotations: bpy.props.BoolProperty(
+        name="Load Selected Annotations",
+        description="Load the annotations of all selected drawings without switching the active view.",
+        default=False,
+        options={"SKIP_SAVE"},
+    )
+    include_annotations_in_selection: bpy.props.BoolProperty(
+        name="Include Annotations In Selection",
+        description="Also select the loaded annotation objects, not just the drawing cameras.",
+        default=False,
+        options={"SKIP_SAVE"},
+    )
 
     if TYPE_CHECKING:
         drawing: int
         should_view_from_camera: bool
         use_quick_preview: bool
+        load_selected_annotations: bool
+        include_annotations_in_selection: bool
 
     def invoke(self, context, event) -> set["rna_enums.OperatorReturnItems"]:
+        if event.type == "LEFTMOUSE" and event.shift and event.ctrl:
+            self.load_selected_annotations = True
+            if event.alt:
+                self.include_annotations_in_selection = True
+            return self.execute(context)
         if event.type == "LEFTMOUSE" and event.alt:
             self.should_view_from_camera = False
         if event.type == "LEFTMOUSE" and event.shift:
@@ -2354,6 +2405,37 @@ class ActivateDrawingBase(tool.Ifc.Operator):
         if props.is_editing_drawings == False:
             bpy.ops.bim.load_drawings()
 
+        if self.load_selected_annotations:
+            objs_to_select = []
+            active_camera = None
+            for d in props.drawings:
+                if not (d.is_drawing and d.is_selected):
+                    continue
+                selected_drawing = tool.Ifc.get().by_id(d.ifc_definition_id)
+                # Importing the camera (if missing) ensures the drawing's
+                # collection exists so the annotations get collected into it.
+                if not (camera := tool.Ifc.get_object(selected_drawing)):
+                    camera = tool.Drawing.import_drawing(selected_drawing)
+                group = tool.Drawing.get_drawing_group(selected_drawing)
+                tool.Drawing.import_annotations_in_group(group)
+
+                if active_camera is None:
+                    active_camera = camera
+                objs_to_select.append(camera)
+                if self.include_annotations_in_selection:
+                    for element in tool.Drawing.get_group_elements(group) or []:
+                        if element.is_a("IfcAnnotation") and element.ObjectType != "DRAWING":
+                            if annotation_obj := tool.Ifc.get_object(element):
+                                objs_to_select.append(annotation_obj)
+
+            # Select the checked drawings' objects, with the first drawing's camera as active.
+            bpy.ops.object.select_all(action="DESELECT")
+            for obj in objs_to_select:
+                obj.select_set(True)
+            if active_camera is not None:
+                context.view_layer.objects.active = active_camera
+            return {"FINISHED"}
+
         drawing = tool.Ifc.get().by_id(self.drawing)
         dprops = tool.Drawing.get_document_props()
 
@@ -2439,7 +2521,10 @@ class ActivateDrawing(bpy.types.Operator, ActivateDrawingBase):
     bl_description = (
         "Activates the selected drawing view.\n\n"
         + "ALT+CLICK to keep the viewport position.\n\n"
-        + "SHIFT+CLICK to load a quick preview of the drawing view"
+        + "SHIFT+CLICK to load a quick preview of the drawing view.\n\n"
+        + "SHIFT+CTRL+CLICK to load the annotations of all selected drawings without switching views, "
+        + "then select their cameras (the first selected drawing's camera becomes active).\n\n"
+        + "SHIFT+CTRL+ALT+CLICK to do the same but also select the annotations, not just the cameras"
     )
 
 
@@ -3501,7 +3586,7 @@ class EditSheet(bpy.types.Operator, tool.Ifc.Operator):
         if sheet.is_a("IfcDocumentInformation"):
             self.document_type = "SHEET"
             self.name = sheet.Name
-            self.identification = sheet.DocumentId if tool.Ifc.get_schema() == "IFC2X3" else sheet.Identification
+            self.identification = tool.Document.get_document_information_id(sheet)
         elif sheet.is_a("IfcDocumentReference") and tool.Drawing.get_reference_description(sheet) == "TITLEBLOCK":
             self.document_type = "TITLEBLOCK"
         else:

src/bonsai/bonsai/bim/module/drawing/prop.py

@@ -604,6 +604,7 @@ class BIMCameraProperties(PropertyGroup):
         return tool.Blender.get_active_uilist_element(dprops.drawing_styles, self.active_drawing_style_index)
 
     # For now, this JSON dump are all the parameters that determine a camera's "Block representation"
+    # Perspective camera shift is stored in EPset_Drawing and intentionally excluded here.
     # By checking this, you will know whether or not the camera IFC representation needs to be refreshed
     def update_representation(self, matrix_world: Matrix) -> bool:
         """Update ``representation`` based on current camera properties and the provided world matrix.

src/bonsai/bonsai/bim/module/drawing/svgwriter.py

@@ -903,12 +903,8 @@ class SvgWriter:
                     continue
                 sheet = tool.Drawing.get_reference_document(sheet_reference)
                 if sheet:
-                    if tool.Ifc.get_schema() == "IFC2X3":
-                        reference_id = sheet_reference.ItemReference or "-"
-                        sheet_id = sheet.DocumentId or "-"
-                    else:
-                        reference_id = sheet_reference.Identification or "-"
-                        sheet_id = sheet.Identification or "-"
+                    reference_id = tool.Document.get_external_reference_id(sheet_reference) or "-"
+                    sheet_id = tool.Document.get_document_information_id(sheet) or "-"
                     return (reference_id, sheet_id)
                 break
         return ("-", "-")

src/bonsai/bonsai/bim/module/drawing/ui.py

@@ -99,6 +99,10 @@ class BIM_PT_camera(Panel):
         if props.target_view == "MODEL_VIEW":
             row = self.layout.row()
             row.prop(props, "camera_type")
+            if props.camera_type == "PERSP":
+                row = self.layout.row(align=True)
+                row.prop(camera_data, "shift_x", text="Camera Shift X/Y:")
+                row.prop(camera_data, "shift_y", text="")
 
         row = self.layout.row()
         row.prop(props, "linework_mode")

src/bonsai/bonsai/bim/module/geometry/decorator.py

@@ -16,8 +16,6 @@
 # You should have received a copy of the GNU General Public License
 # along with Bonsai.  If not, see <http://www.gnu.org/licenses/>.
 
-from collections.abc import Sequence
-
 import blf
 import bpy
 import gpu
@@ -25,15 +23,16 @@ import ifcopenshell
 import numpy as np
 from bpy.types import SpaceView3D
 from bpy_extras.view3d_utils import location_3d_to_region_2d
-from gpu_extras.batch import batch_for_shader
 from mathutils import Matrix, Vector
 
 import bonsai.tool as tool
 
 
-class ItemDecorator:
-    is_installed = False
-    handlers = []
+class ItemDecorator(tool.Blender.ViewportDecorator):
+    draw_methods = (
+        ("draw_text", "POST_PIXEL"),
+        ("draw", "POST_VIEW"),
+    )
     objs: dict[str, dict[str, list]]
     obj_is_selected: dict[str, bool]
     obj_is_boolean: dict[str, list[ifcopenshell.entity_instance]]
@@ -119,23 +118,6 @@ class ItemDecorator:
             "special_edges": special_edges,
         }
 
-    @classmethod
-    def uninstall(cls):
-        for handler in cls.handlers:
-            try:
-                SpaceView3D.draw_handler_remove(handler, "WINDOW")
-            except ValueError:
-                pass
-        cls.is_installed = False
-
-    def draw_batch(self, shader_type, content_pos, color, indices=None):
-        if not tool.Blender.validate_shader_batch_data(content_pos, indices):
-            return
-        shader = self.line_shader if shader_type == "LINES" else self.shader
-        batch = batch_for_shader(shader, shader_type, {"pos": content_pos}, indices=indices)
-        shader.uniform_float("color", color)
-        batch.draw(shader)
-
     def draw_text(self, context):
         self.addon_prefs = tool.Blender.get_addon_preferences()
         selected_elements_color = self.addon_prefs.decorator_color_selected
@@ -163,11 +145,6 @@ class ItemDecorator:
         blf.disable(font_id, blf.SHADOW)
 
     def draw(self, context: bpy.types.Context) -> None:
-        def transparent_color(color: Sequence[float], alpha: float = 0.05) -> list[float]:
-            color = [i for i in color]
-            color[3] = alpha
-            return color
-
         self.addon_prefs = tool.Blender.get_addon_preferences()
         selected_elements_color = self.addon_prefs.decorator_color_selected
         unselected_elements_color = self.addon_prefs.decorator_color_unselected
@@ -197,15 +174,33 @@ class ItemDecorator:
                     if context.mode != "OBJECT":
                         continue
                     self.draw_batch("LINES", data["verts"], selected_elements_color, data["edges"])
-                    self.draw_batch("TRIS", data["verts"], transparent_color(selected_elements_color), data["tris"])
+                    self.draw_batch(
+                        "TRIS",
+                        data["verts"],
+                        tool.Blender.transparent_color(selected_elements_color, alpha=0.05),
+                        data["tris"],
+                    )
                     self.draw_batch("LINES", data["special_verts"], selected_elements_color, data["special_edges"])
                 elif self.obj_is_boolean[obj_name]:
                     self.draw_batch("LINES", data["verts"], special_elements_color, data["edges"])
-                    self.draw_batch("TRIS", data["verts"], transparent_color(special_elements_color), data["tris"])
+                    self.draw_batch(
+                        "TRIS",
+                        data["verts"],
+                        tool.Blender.transparent_color(special_elements_color, alpha=0.05),
+                        data["tris"],
+                    )
                     self.draw_batch("LINES", data["special_verts"], special_elements_color, data["special_edges"])
                 else:
                     self.draw_batch(
-                        "LINES", data["verts"], transparent_color(unselected_elements_color, alpha=0.2), data["edges"]
+                        "LINES",
+                        data["verts"],
+                        tool.Blender.transparent_color(unselected_elements_color, alpha=0.2),
+                        data["edges"],
+                    )
+                    self.draw_batch(
+                        "TRIS",
+                        data["verts"],
+                        tool.Blender.transparent_color(special_elements_color, alpha=0.05),
+                        data["tris"],
                     )
-                    self.draw_batch("TRIS", data["verts"], transparent_color(special_elements_color), data["tris"])
                     self.draw_batch("LINES", data["special_verts"], special_elements_color, data["special_edges"])

src/bonsai/bonsai/bim/module/geometry/operator.py

@@ -1531,8 +1531,13 @@ class DuplicateMoveLinkedAggregate(bpy.types.Operator):
             old_to_new = OverrideDuplicateMove.execute_ifc_duplicate_operator(self, context, linked=True)
             all_old_to_new.update(old_to_new)  # Collect all duplicates
 
-            # Recreate aggregate structure
-            tool.Root.recreate_aggregate(old_to_new)
+            # Note: execute_ifc_duplicate_operator() above already recreates the aggregate
+            # structure for us (including reassigning to an unduplicated parent aggregate, see
+            # its "Restore parent aggregate relationships" step). Calling
+            # tool.Root.recreate_aggregate() again here is not just redundant: since the parent
+            # aggregate is never part of `old_to_new` when it wasn't itself duplicated,
+            # recreate_aggregate()'s "parent not found" branch actively *unassigns* the just
+            # restored parent link, stranding a duplicated nested aggregate outside its parent (#6663).
 
             # Copy linked aggregate data
             copy_linked_aggregate_data(old_to_new)

src/bonsai/bonsai/bim/module/geometry/ui.py

@@ -17,9 +17,9 @@
 # along with Bonsai.  If not, see <http://www.gnu.org/licenses/>.
 
 import bpy
+import ifcopenshell.util.unit
 from bpy.types import Menu, Panel, UIList
 
-import ifcopenshell.util.unit
 import bonsai.bim
 import bonsai.tool as tool
 from bonsai.bim.helper import prop_with_search

src/bonsai/bonsai/bim/module/georeference/decorator.py

@@ -21,7 +21,6 @@ from math import radians
 import blf
 import gpu
 import ifcopenshell.util.geolocation
-from bpy.types import SpaceView3D
 from bpy_extras.view3d_utils import location_3d_to_region_2d
 from gpu_extras.batch import batch_for_shader
 from mathutils import Matrix, Vector
@@ -30,27 +29,11 @@ import bonsai.tool as tool
 from bonsai.bim.module.georeference.data import GeoreferenceData
 
 
-class GeoreferenceDecorator:
-    is_installed = False
-    handlers = []
-
-    @classmethod
-    def install(cls, context):
-        if cls.is_installed:
-            cls.uninstall()
-        handler = cls()
-        cls.handlers.append(SpaceView3D.draw_handler_add(handler.draw_text, (context,), "WINDOW", "POST_PIXEL"))
-        cls.handlers.append(SpaceView3D.draw_handler_add(handler.draw_geometry, (context,), "WINDOW", "POST_VIEW"))
-        cls.is_installed = True
-
-    @classmethod
-    def uninstall(cls):
-        for handler in cls.handlers:
-            try:
-                SpaceView3D.draw_handler_remove(handler, "WINDOW")
-            except ValueError:
-                pass
-        cls.is_installed = False
+class GeoreferenceDecorator(tool.Blender.ViewportDecorator):
+    draw_methods = (
+        ("draw_text", "POST_PIXEL"),
+        ("draw_geometry", "POST_VIEW"),
+    )
 
     def draw_batch(self, shader_type, content_pos, color, indices=None, should_scale=True):
         if not tool.Blender.validate_shader_batch_data(content_pos, indices):
@@ -197,6 +180,10 @@ class GeoreferenceDecorator:
         decorator_color_error = self.addon_prefs.decorator_color_error
 
         gpu.state.blend_set("ALPHA")
+        # The georef gizmo is a coordinate-system overlay: it must communicate
+        # orientation regardless of model contents, so depth testing is bypassed.
+        original_depth_test = gpu.state.depth_test_get()
+        gpu.state.depth_test_set("ALWAYS")
 
         self.line_shader = gpu.shader.from_builtin("POLYLINE_UNIFORM_COLOR")
         self.line_shader.bind()  # required to be able to change uniforms of the shader
@@ -335,6 +322,8 @@ class GeoreferenceDecorator:
                 self.draw_batch("LINES", verts, decorator_color_special, edges)
                 self.draw_dashed_line(location * 3, location * 6, decorator_color_error)
 
+        gpu.state.depth_test_set(original_depth_test)
+
     def draw_dashed_line(self, start, end, colour, should_scale=True):
         direction = (end - start).normalized()
         distance = (end - start).length

src/bonsai/bonsai/bim/module/library/data.py

@@ -103,9 +103,7 @@ class LibraryReferencesData:
                 results.append(
                     {
                         "id": library.id(),
-                        "identification": (
-                            library.ItemReference if tool.Ifc.get_schema() == "IFC2X3" else library.Identification
-                        ),
+                        "identification": tool.Document.get_external_reference_id(library),
                         "name": library.Name or "Unnamed",
                     }
                 )

src/bonsai/bonsai/bim/module/light/decorator.py

@@ -20,44 +20,18 @@
 import blf
 import bpy
 import gpu
-from bpy.types import SpaceView3D
 from bpy_extras.view3d_utils import location_3d_to_region_2d
-from gpu_extras.batch import batch_for_shader
 from mathutils import Matrix, Vector
 
 import bonsai.tool as tool
 from bonsai.bim.module.light.data import SolarData
 
 
-class SolarDecorator:
-    is_installed = False
-    handlers = []
-
-    @classmethod
-    def install(cls, context):
-        if cls.is_installed:
-            cls.uninstall()
-        handler = cls()
-        cls.handlers.append(SpaceView3D.draw_handler_add(handler.draw_text, (context,), "WINDOW", "POST_PIXEL"))
-        cls.handlers.append(SpaceView3D.draw_handler_add(handler.draw_geometry, (context,), "WINDOW", "POST_VIEW"))
-        cls.is_installed = True
-
-    @classmethod
-    def uninstall(cls):
-        for handler in cls.handlers:
-            try:
-                SpaceView3D.draw_handler_remove(handler, "WINDOW")
-            except ValueError:
-                pass
-        cls.is_installed = False
-
-    def draw_batch(self, shader_type, content_pos, color, indices=None):
-        if not tool.Blender.validate_shader_batch_data(content_pos, indices):
-            return
-        shader = self.line_shader if shader_type == "LINES" else self.shader
-        batch = batch_for_shader(shader, shader_type, {"pos": content_pos}, indices=indices)
-        shader.uniform_float("color", color)
-        batch.draw(shader)
+class SolarDecorator(tool.Blender.ViewportDecorator):
+    draw_methods = (
+        ("draw_text", "POST_PIXEL"),
+        ("draw_geometry", "POST_VIEW"),
+    )
 
     def draw_text(self, context: bpy.types.Context) -> None:
         self.addon_prefs = tool.Blender.get_addon_preferences()

src/bonsai/bonsai/bim/module/misc/operator.py

@@ -418,6 +418,13 @@ class ImportQuickFavorites(bpy.types.Operator):
     bl_description = "Import operators from Blender's Quick Favorites menu, including their configured properties"
     bl_options = {"REGISTER", "UNDO"}
 
+    @classmethod
+    def poll(cls, context):
+        if bpy.app.version[:2] not in tool.Misc.QuickFavorites.OFFSET_USER_MENUS:
+            cls.poll_message_set(f"Blender version {bpy.app.version_string} is not supported.")
+            return False
+        return True
+
     def execute(self, context) -> set["rna_enums.OperatorReturnItems"]:
         props = tool.Misc.get_misc_props()
         props.quick_favorites.clear()

src/bonsai/bonsai/bim/module/model/__init__.py

@@ -27,6 +27,7 @@ import bonsai.tool as tool
 from . import (
     array,
     covering,
+    decorator,
     door,
     external,
     grid,
@@ -110,6 +111,7 @@ classes = (
     wall.GizmoWallFilletPreview,
     wall.GizmoWallFilletReedit,
     wall.GizmoWallFilletToggleOpenings,
+    wall.GizmoPairDisconnect,
     wall.GizmoSlabEdition,
     wall.GizmoSlabUnjoinWalls,
     wall.GizmoWallJoinIntersection,
@@ -279,9 +281,7 @@ classes = (
     mep.MEPAddObstruction,
     mep.MEPAddTransition,
     mep.MEPAddBend,
-    mep.MEPUnjoinAtPort,
     mep.MEPRemoveTerminalFitting,
-    mep.MEPUnjoinPair,
     mep.SelectMEPPathMembers,
     mep.MEPJoinSegments,
     mep_bend_preview.EnableBendPreview,

src/bonsai/bonsai/bim/module/model/array.py

@@ -329,6 +329,7 @@ class _ArrayEditMixin(ParametricEditMixinBase):
         # Unhide the (possibly newly-regenerated) children so the user sees
         # the committed result. Mirrors the hide in ``_enable_one``.
         cls._set_children_visibility(element, hidden=False)
+        tool.Array.select_only_parent(obj, context)
 
     @classmethod
     def _cancel_one(cls, obj: bpy.types.Object) -> None:
@@ -421,22 +422,28 @@ class RegenerateArray(bpy.types.Operator, tool.Ifc.Operator):
         pset = ifcopenshell.util.element.get_pset(parent_element, "BBIM_Array")
         arrays = json.loads(pset["Data"])
         pset = tool.Ifc.get().by_id(pset["id"])
-        for array in arrays:
-            for child in set(array["children"]):
-                try:
-                    child_element = tool.Ifc.get().by_guid(child)
-                except RuntimeError:
-                    continue
-                if child_obj := tool.Ifc.get_object(child_element):
-                    tool.Geometry.delete_ifc_object(child_obj)
-            array["children"].clear()
-        # Always operate on the parent — this operator can be invoked with
-        # either the parent OR any array child as active_object (the per-child
-        # gizmo group fires it from a child selection). Using ``obj`` /
-        # ``element`` directly would feed a child to ``regenerate_array`` and
-        # constrain children against a sibling, silently corrupting the array.
-        tool.Model.regenerate_array(parent, arrays)
-        tool.Array.constrain_children_to_parent(parent_element)
+        # Coalesce host recuts across the child-delete loop, the regenerate,
+        # and the per-child opening mirror: each fans out its own host body
+        # recut without the batch wrapper.
+        with tool.Geometry.batch_host_recut():
+            for array in arrays:
+                for child in set(array["children"]):
+                    try:
+                        child_element = tool.Ifc.get().by_guid(child)
+                    except RuntimeError:
+                        continue
+                    if child_obj := tool.Ifc.get_object(child_element):
+                        tool.Geometry.delete_ifc_object(child_obj)
+                array["children"].clear()
+            # Always operate on the parent — this operator can be invoked with
+            # either the parent OR any array child as active_object (the per-child
+            # gizmo group fires it from a child selection). Using ``obj`` /
+            # ``element`` directly would feed a child to ``regenerate_array`` and
+            # constrain children against a sibling, silently corrupting the array.
+            tool.Model.regenerate_array(parent, arrays)
+            tool.Array.constrain_children_to_parent(parent_element)
+
+        tool.Array.select_only_parent(parent, context)
 
 
 class RemoveArray(bpy.types.Operator, tool.Ifc.Operator):
@@ -471,23 +478,24 @@ class RemoveArray(bpy.types.Operator, tool.Ifc.Operator):
         except:
             return {"FINISHED"}
 
-        if self.keep_objs:
-            tool.Array.bake_children_transform(element, self.item)
-            tool.Array.set_children_lock_state(element, self.item, False)
+        with tool.Geometry.batch_host_recut():
+            if self.keep_objs:
+                tool.Array.bake_children_transform(element, self.item)
+                tool.Array.set_children_lock_state(element, self.item, False)
 
-        if not self.keep_objs:
-            data[self.item]["count"] = 1
-        tool.Array.remove_constraints(parent_element)
-        tool.Model.regenerate_array(parent, data, array_layers_to_apply=[self.item] if self.keep_objs else [])
+            if not self.keep_objs:
+                data[self.item]["count"] = 1
+            tool.Array.remove_constraints(parent_element)
+            tool.Model.regenerate_array(parent, data, array_layers_to_apply=[self.item] if self.keep_objs else [])
 
-        pset = tool.Pset.get_element_pset(element, "BBIM_Array")
-        if len(data) == 1:
-            ifcopenshell.api.pset.remove_pset(tool.Ifc.get(), product=element, pset=pset)
-        else:
-            del data[self.item]
-            data = tool.Ifc.get().createIfcText(json.dumps(data))
-            ifcopenshell.api.pset.edit_pset(tool.Ifc.get(), pset=pset, properties={"Data": data})
-            tool.Array.constrain_children_to_parent(element)
+            pset = tool.Pset.get_element_pset(element, "BBIM_Array")
+            if len(data) == 1:
+                ifcopenshell.api.pset.remove_pset(tool.Ifc.get(), product=element, pset=pset)
+            else:
+                del data[self.item]
+                data = tool.Ifc.get().createIfcText(json.dumps(data))
+                ifcopenshell.api.pset.edit_pset(tool.Ifc.get(), pset=pset, properties={"Data": data})
+                tool.Array.constrain_children_to_parent(element)
 
 
 class SelectArrayParent(bpy.types.Operator):

src/bonsai/bonsai/bim/module/model/decorator.py

@@ -53,12 +53,6 @@ from bonsai.bim.module.drawing.gizmos import (
 from bonsai.bim.module.drawing.helper import format_distance
 
 
-def transparent_color(color, alpha=0.1):
-    color = [i for i in color]
-    color[3] = alpha
-    return color
-
-
 def highlight_color(color, alpha=0.1):
     color = [i + (1 - i) * 0.5 for i in color]
     return color
@@ -133,7 +127,7 @@ class ProfileDecorator:
 
     def draw_faces(self, bm, vertices_coords):
         """Submit a non-mutating beauty-triangulated TRIS batch over ``bm``'s faces."""
-        faces_color = transparent_color(self.addon_prefs.decorator_color_special)
+        faces_color = tool.Blender.transparent_color(self.addon_prefs.decorator_color_special)
         tool.Blender.draw_bmesh_face_tris(bm, vertices_coords, faces_color, self.draw_batch)
 
     def __call__(self, context, get_custom_bmesh=None, draw_faces=False, exit_edit_mode_callback=None):
@@ -263,7 +257,7 @@ class ProfileDecorator:
         self.draw_batch("LINES", all_vertices, unselected_elements_color, unselected_edges)
         self.draw_batch("LINES", all_vertices, selected_elements_color, selected_edges)
 
-        self.draw_batch("POINTS", unselected_vertices, transparent_color(unselected_elements_color, 0.5))
+        self.draw_batch("POINTS", unselected_vertices, tool.Blender.transparent_color(unselected_elements_color, 0.5))
         self.draw_batch("POINTS", error_vertices, error_elements_color)
         self.draw_batch("POINTS", special_vertices, special_elements_color)
         self.draw_batch("POINTS", selected_vertices, selected_elements_color)
@@ -354,9 +348,11 @@ class ProfileDecorator:
         return points, listEdg
 
 
-class PolylineDecorator:
-    is_installed = False
-    handlers = []
+class PolylineDecorator(tool.Blender.ViewportDecorator):
+    # draw_methods declares only the always-bound handler so the base's
+    # __init_subclass__ validation passes; the override install below
+    # conditionally registers up to four more handlers based on ui_only.
+    draw_methods = (("draw_input_ui", "POST_PIXEL"),)
     event = None
     input_type = None
     input_ui = None
@@ -392,15 +388,6 @@ class PolylineDecorator:
             cls.handlers.append(SpaceView3D.draw_handler_add(handler, (context,), "WINDOW", "POST_VIEW"))
         cls.is_installed = True
 
-    @classmethod
-    def uninstall(cls):
-        for handler in cls.handlers:
-            try:
-                SpaceView3D.draw_handler_remove(handler, "WINDOW")
-            except ValueError:
-                pass
-        cls.is_installed = False
-
     @classmethod
     def update(
         cls,
@@ -459,14 +446,6 @@ class PolylineDecorator:
 
         return {"verts": verts, "edges": edges, "tris": tris}
 
-    def draw_batch(self, shader_type, content_pos, color, indices=None):
-        if not tool.Blender.validate_shader_batch_data(content_pos, indices):
-            return
-        shader = self.line_shader if shader_type == "LINES" else self.shader
-        batch = batch_for_shader(shader, shader_type, {"pos": content_pos}, indices=indices)
-        shader.uniform_float("color", color)
-        batch.draw(shader)
-
     def shader_config(self, context):
         self.addon_prefs = tool.Blender.get_addon_preferences()
         self.decorator_color = self.addon_prefs.decorations_colour
@@ -734,7 +713,9 @@ class PolylineDecorator:
             if self.polyline_data.measurement_type == "POLY_AREA" and area:
                 if float(area) > 0:
                     tris = self.calculate_polygon(polyline_verts)["tris"]
-                    self.draw_batch("TRIS", polyline_verts, transparent_color(self.decorator_color_special), tris)
+                    self.draw_batch(
+                        "TRIS", polyline_verts, tool.Blender.transparent_color(self.decorator_color_special), tris
+                    )
 
         # Draw polyline with selected points
         self.line_shader.uniform_float("lineWidth", 2.0)
@@ -987,9 +968,8 @@ class PolylineDecorator:
             self.draw_batch("LINES", polyline_verts, decorator_color_unselected, polyline_edges)
 
 
-class ProductDecorator:
-    is_installed = False
-    handlers = []
+class ProductDecorator(tool.Blender.ViewportDecorator):
+    draw_method = "draw_product_preview"
     preview_mode: Literal["PROFILE_VERTICAL", "PROFILE_HORIZONTAL", "LAYER2", "LAYER3", "GENERIC"]
     relating_type = None
     obj_data: dict[str, list] = {}
@@ -1032,29 +1012,7 @@ class ProductDecorator:
         )
         cls.is_installed = True
 
-    @classmethod
-    def uninstall(cls):
-        for handler in cls.handlers:
-            try:
-                SpaceView3D.draw_handler_remove(handler, "WINDOW")
-            except ValueError:
-                pass
-        cls.is_installed = False
-
-    def draw_batch(self, shader_type, content_pos, color, indices=None):
-        if not tool.Blender.validate_shader_batch_data(content_pos, indices):
-            return
-        shader = self.line_shader if shader_type == "LINES" else self.shader
-        batch = batch_for_shader(shader, shader_type, {"pos": content_pos}, indices=indices)
-        shader.uniform_float("color", color)
-        batch.draw(shader)
-
     def draw_product_preview(self, context):
-        def transparent_color(color, alpha=0.1):
-            color = [i for i in color]
-            color[3] = alpha
-            return color
-
         self.addon_prefs = tool.Blender.get_addon_preferences()
         self.line_shader = gpu.shader.from_builtin("POLYLINE_UNIFORM_COLOR")
         self.line_shader.bind()  # required to be able to change uniforms of the shader
@@ -1086,7 +1044,7 @@ class ProductDecorator:
             data = self.get_generic_preview_data()
         if data:
             self.draw_batch("LINES", data["verts"], decorator_color, data["edges"])
-            self.draw_batch("TRIS", data["verts"], transparent_color(decorator_color), data["tris"])
+            self.draw_batch("TRIS", data["verts"], tool.Blender.transparent_color(decorator_color), data["tris"])
 
     def get_wall_preview_data(self):
         relating_type = self.relating_type
@@ -1619,34 +1577,8 @@ class ProductDecorator:
         return data
 
 
-class WallAxisDecorator:
-    is_installed = False
-    handlers = []
-
-    @classmethod
-    def install(cls, context):
-        if cls.is_installed:
-            cls.uninstall()
-        handler = cls()
-        cls.handlers.append(SpaceView3D.draw_handler_add(handler.draw_wall_axis, (context,), "WINDOW", "POST_VIEW"))
-        cls.is_installed = True
-
-    @classmethod
-    def uninstall(cls):
-        for handler in cls.handlers:
-            try:
-                SpaceView3D.draw_handler_remove(handler, "WINDOW")
-            except ValueError:
-                pass
-        cls.is_installed = False
-
-    def draw_batch(self, shader_type, content_pos, color, indices=None):
-        if not tool.Blender.validate_shader_batch_data(content_pos, indices):
-            return
-        shader = self.line_shader if shader_type == "LINES" else self.shader
-        batch = batch_for_shader(shader, shader_type, {"pos": content_pos}, indices=indices)
-        shader.uniform_float("color", color)
-        batch.draw(shader)
+class WallAxisDecorator(tool.Blender.ViewportDecorator):
+    draw_method = "draw_wall_axis"
 
     def draw_wall_axis(self, context):
         self.addon_prefs = tool.Blender.get_addon_preferences()
@@ -1665,7 +1597,7 @@ class WallAxisDecorator:
         self.line_shader.uniform_float("lineWidth", 2.0)
         for obj in context.selected_objects:
             element = tool.Ifc.get_entity(obj)
-            if element.is_a("IfcWall"):
+            if element and element.is_a("IfcWall"):
                 layers = tool.Model.get_material_layer_parameters(element)
                 axis = tool.Model.get_wall_axis(obj, layers)
                 side = [tuple(list(v) + [obj.location.z]) for v in axis["side"]]
@@ -1685,34 +1617,8 @@ class WallAxisDecorator:
                 self.draw_batch("LINES", arrow, unselected_elements_color, [(0, 1), (1, 2), (1, 3)])
 
 
-class SlabDirectionDecorator:
-    is_installed = False
-    handlers = []
-
-    @classmethod
-    def install(cls, context):
-        if cls.is_installed:
-            cls.uninstall()
-        handler = cls()
-        cls.handlers.append(SpaceView3D.draw_handler_add(handler.draw_wall_axis, (context,), "WINDOW", "POST_VIEW"))
-        cls.is_installed = True
-
-    @classmethod
-    def uninstall(cls):
-        for handler in cls.handlers:
-            try:
-                SpaceView3D.draw_handler_remove(handler, "WINDOW")
-            except ValueError:
-                pass
-        cls.is_installed = False
-
-    def draw_batch(self, shader_type, content_pos, color, indices=None):
-        if not tool.Blender.validate_shader_batch_data(content_pos, indices):
-            return
-        shader = self.line_shader if shader_type == "LINES" else self.shader
-        batch = batch_for_shader(shader, shader_type, {"pos": content_pos}, indices=indices)
-        shader.uniform_float("color", color)
-        batch.draw(shader)
+class SlabDirectionDecorator(tool.Blender.ViewportDecorator):
+    draw_method = "draw_wall_axis"
 
     def draw_wall_axis(self, context):
         self.addon_prefs = tool.Blender.get_addon_preferences()
@@ -1742,41 +1648,10 @@ class SlabDirectionDecorator:
             self.draw_batch("LINES", base, selected_elements_color, [(0, 1)])
 
 
-class FaceAreaDecorator:
-    is_installed = False
-    handlers = []
-
-    @classmethod
-    def install(cls, context):
-        if cls.is_installed:
-            cls.uninstall()
-        handler = cls()
-        cls.handlers.append(SpaceView3D.draw_handler_add(handler.draw_face_area, (context,), "WINDOW", "POST_VIEW"))
-        cls.is_installed = True
-
-    @classmethod
-    def uninstall(cls):
-        for handler in cls.handlers:
-            try:
-                SpaceView3D.draw_handler_remove(handler, "WINDOW")
-            except ValueError:
-                pass
-        cls.is_installed = False
-
-    def draw_batch(self, shader_type, content_pos, color, indices=None):
-        if not tool.Blender.validate_shader_batch_data(content_pos, indices):
-            return
-        shader = self.line_shader if shader_type == "LINES" else self.shader
-        batch = batch_for_shader(shader, shader_type, {"pos": content_pos}, indices=indices)
-        shader.uniform_float("color", color)
-        batch.draw(shader)
+class FaceAreaDecorator(tool.Blender.ViewportDecorator):
+    draw_method = "draw_face_area"
 
     def draw_face_area(self, context):
-        def transparent_color(color, alpha=0.1):
-            color = [i for i in color]
-            color[3] = alpha
-            return color
-
         self.addon_prefs = tool.Blender.get_addon_preferences()
         self.line_shader = gpu.shader.from_builtin("POLYLINE_UNIFORM_COLOR")
         self.line_shader.bind()  # required to be able to change uniforms of the shader
@@ -1797,12 +1672,16 @@ class FaceAreaDecorator:
             if data:
                 self.draw_batch("POINTS", data["verts"], decorator_color)
                 self.draw_batch("LINES", data["verts"], decorator_color, data["edges"])
-                self.draw_batch("TRIS", data["verts"], transparent_color(decorator_color, alpha=0.5), data["tris"])
+                self.draw_batch(
+                    "TRIS", data["verts"], tool.Blender.transparent_color(decorator_color, alpha=0.5), data["tris"]
+                )
 
 
-class BoundingBoxDecorator:
-    is_installed = False
-    handlers = []
+class BoundingBoxDecorator(tool.Blender.ViewportDecorator):
+    draw_methods = (
+        ("draw_bounding_box_wire_cube", "POST_VIEW"),
+        ("draw_dimension_text", "POST_PIXEL"),
+    )
 
     def __init__(self):
         context = bpy.context
@@ -1813,31 +1692,6 @@ class BoundingBoxDecorator:
         self.decorator_color_wire = (*theme.view_3d.bone_solid, 1)
         self.decorator_color_special = tool.Blender.get_addon_preferences().decorator_color_special
 
-    @classmethod
-    def install(cls, context):
-        if cls.is_installed:
-            cls.uninstall()
-        handler = cls()
-        cls.handlers.append(
-            bpy.types.SpaceView3D.draw_handler_add(
-                handler.draw_bounding_box_wire_cube, (context,), "WINDOW", "POST_VIEW"
-            )
-        )
-        cls.handlers.append(
-            bpy.types.SpaceView3D.draw_handler_add(handler.draw_dimension_text, (context,), "WINDOW", "POST_PIXEL")
-        )
-        cls.is_installed = True
-
-    @classmethod
-    def uninstall(cls):
-        for handler in cls.handlers:
-            try:
-                bpy.types.SpaceView3D.draw_handler_remove(handler, "WINDOW")
-            except Exception:
-                pass
-        cls.handlers.clear()
-        cls.is_installed = False
-
     @staticmethod
     def get_combined_bounding_box_corners(objects):
 
@@ -1910,14 +1764,6 @@ class BoundingBoxDecorator:
         ]
         return trihedron[best_origin]
 
-    def draw_batch(self, shader_type, content_pos, color, indices=None):
-        if not tool.Blender.validate_shader_batch_data(content_pos, indices):
-            return
-        shader = self.line_shader if shader_type == "LINES" else self.shader
-        batch = batch_for_shader(shader, shader_type, {"pos": content_pos}, indices=indices)
-        shader.uniform_float("color", color)
-        batch.draw(shader)
-
     def draw_text_background(self, context, coords_dim, text_dim):
         padding = 5
         theme = context.preferences.themes.items()[0][1]
@@ -2569,14 +2415,20 @@ class _ConnectedNetworkPathDecorator(tool.Blender.ViewportDecorator):
     CONNECTION_EPS_SQ = 1e-4 * 1e-4
 
     def __init__(self) -> None:
-        # Two-tier cache. Walk cache keyed on (start_guid, ifc_file): re-walk
-        # only on selection change or file reload. Compare ``ifc_file`` with
+        # Walk cache keyed on (start_guid, ifc_file, geom_gen). Stores STEP
+        # integer ids rather than ``entity_instance`` references — re-resolved
+        # via ``ifc_file.by_id`` on each cache hit. Structurally rules out
+        # the dangling-SWIG-handle class of bug: an entity removed between
+        # frames either bumps geom_gen (cache miss → re-walk) or fails to
+        # re-resolve (handled below by re-walking). Compare ``ifc_file`` with
         # ``is`` (not id()) so a GC-recycled id() can't produce a false hit.
         self._cached_start_guid: str | None = None
         self._cached_ifc_file: Any = None
-        self._cached_walk: list[Any] = []
-        # Geometry cache: shared TokenCache so resolved world-space lines +
-        # dots re-build on every depsgraph / undo / redo / load.
+        self._cached_geom_gen: int = -1
+        self._cached_walk_ids: list[int] = []
+        # Geometry cache: shared TokenCache. Key folds in geom_gen so IFC
+        # mutations that don't surface via the depsgraph still flush the
+        # resolved world-space lines and dots.
         self._geom_cache: TokenCache[
             tuple[
                 list[tuple[tuple[float, float, float], tuple[float, float, float]]],
@@ -2739,9 +2591,22 @@ class _ConnectedNetworkPathDecorator(tool.Blender.ViewportDecorator):
         start_guid = start_element.GlobalId
         if start_guid == self._failed_seed_guid:
             return
-        if start_guid == self._cached_start_guid and ifc_file is self._cached_ifc_file and self._cached_walk:
-            connected = self._cached_walk
-        else:
+        current_geom_gen = tool.Parametric.get_geom_generation()
+        connected: list[Any] | None = None
+        if (
+            start_guid == self._cached_start_guid
+            and ifc_file is self._cached_ifc_file
+            and current_geom_gen == self._cached_geom_gen
+            and self._cached_walk_ids
+        ):
+            try:
+                connected = [ifc_file.by_id(eid) for eid in self._cached_walk_ids]
+            except RuntimeError:
+                # An entity was removed without bumping geom_gen — rare but
+                # possible from non-operator code paths. Force a re-walk
+                # rather than feeding a stale handle to _build_geometry.
+                connected = None
+        if connected is None:
             try:
                 connected = self._walk(start_element)
             except Exception:
@@ -2750,12 +2615,13 @@ class _ConnectedNetworkPathDecorator(tool.Blender.ViewportDecorator):
 
                     traceback.print_exc()
                     self._walk_failure_logged = True
-                self._cached_walk = []
+                self._cached_walk_ids = []
                 self._failed_seed_guid = start_guid
                 return
             self._cached_start_guid = start_guid
             self._cached_ifc_file = ifc_file
-            self._cached_walk = connected
+            self._cached_geom_gen = current_geom_gen
+            self._cached_walk_ids = [e.id() for e in connected]
         if not connected:
             return
 
@@ -2770,7 +2636,7 @@ class _ConnectedNetworkPathDecorator(tool.Blender.ViewportDecorator):
 
         try:
             lines, free_points, connection_points = self._geom_cache.get_or_compute(
-                (start_guid, id(ifc_file)),
+                (start_guid, id(ifc_file), current_geom_gen),
                 lambda: self._build_geometry(connected),
             )
         except Exception:
@@ -2836,7 +2702,7 @@ class MEPSystemPathDecorator(_ConnectedNetworkPathDecorator):
         lines: list[tuple[tuple[float, float, float], tuple[float, float, float]]] = []
         port_positions: list[tuple[float, float, float]] = []
         for element in connected:
-            if element.is_a("IfcFlowSegment"):
+            if element and element.is_a("IfcFlowSegment"):
                 if not tool.Geometry.has_axis_representation(element):
                     continue
                 obj = tool.Ifc.get_object(element)

src/bonsai/bonsai/bim/module/model/host_add_opening_gizmo.py

@@ -33,6 +33,7 @@ from mathutils import Vector
 
 import bonsai.tool as tool
 from bonsai.bim.module.drawing import gizmos as gizmo
+from bonsai.bim.module.model.opening import is_filling_supported
 from bonsai.bim.module.model.wall import (
     _get_wall_geom_cached,
     _wall_camera_facing_icon_y,
@@ -52,6 +53,20 @@ def is_supported_host(element) -> bool:
     return tool.Parametric.is_path_connectable_wall(element) or element.is_a("IfcSlab") or element.is_a("IfcRoof")
 
 
+def is_supported_filling_or_opening(element) -> bool:
+    """Total predicate for the add-opening gizmo poll. ``None`` (raw Blender
+    mesh) is accepted because the operator converts unclassified meshes
+    into ``IfcOpeningElement`` instances. ``IfcOpeningElement`` is accepted
+    because reassigning an existing opening to a new host is a legal path
+    through the operator. Otherwise defer to the generator's own
+    supported-filling predicate."""
+    if element is None:
+        return True
+    if element.is_a("IfcOpeningElement"):
+        return True
+    return is_filling_supported(element)
+
+
 def _resolve_active_host(context: bpy.types.Context, n_selected: int):
     """Shared poll prologue: gizmo gate + selection cardinality + active-in-
     selected + IFC entity lookup + supported-host predicate. Returns the
@@ -72,12 +87,14 @@ def _resolve_active_host(context: bpy.types.Context, n_selected: int):
 
 
 class GizmoHostAddOpening(bpy.types.GizmoGroup, _WallGeomCachedBillboardingMixin):
-    """Activates when a host element (wall / slab / roof) is the active object
-    and exactly one other selected object is *not* itself a host.
+    """Activates when exactly two objects are selected and one is a fillable
+    host (wall / slab / roof) while the other is a valid filling (door /
+    window / existing opening, or a plain Blender mesh).
 
-    Renders a single ``VIEW3D_GT_add_opening`` icon at the void object's
-    projected location on the host. A click dispatches ``bim.add_opening``,
-    which handles any element exposing the ``HasOpenings`` inverse.
+    Selection-order independent: the host role is identified by class, not
+    by active state. The "+" icon anchors on the host's surface regardless
+    of which object was clicked first. The dispatched ``bim.add_opening``
+    operator also handles either order.
 
     Per-frame positioning keeps the icon facing the camera as the viewport
     orbits."""
@@ -90,22 +107,29 @@ class GizmoHostAddOpening(bpy.types.GizmoGroup, _WallGeomCachedBillboardingMixin
 
     @classmethod
     def poll(cls, context: bpy.types.Context) -> bool:
-        element = _resolve_active_host(context, n_selected=2)
-        if element is None:
+        if not _wall_gizmo_poll_gate(context):
             return False
-        # The operator itself filters on HasOpenings, but checking here keeps
-        # the icon from appearing on host classes that can't accept openings
-        # in the active IFC schema.
-        if not hasattr(element, "HasOpenings"):
+        selected = list(tool.Blender.get_selected_objects())
+        if len(selected) != 2:
             return False
         active = context.active_object
-        other = next(o for o in tool.Blender.get_selected_objects() if o is not active)
-        # Host + host pairings are claimed by host-specific gizmos (wall-join,
-        # extend-vertical, …) — suppress here so the add-opening icon never
-        # stacks on top of them.
-        if is_supported_host(tool.Ifc.get_entity(other)):
+        if active is None or active not in selected:
             return False
-        return True
+        a_element = tool.Ifc.get_entity(selected[0])
+        b_element = tool.Ifc.get_entity(selected[1])
+        return cls._is_apply_opening_pair(a_element, b_element) or cls._is_apply_opening_pair(b_element, a_element)
+
+    @staticmethod
+    def _is_apply_opening_pair(host_element, filling_element) -> bool:
+        """``host_element`` qualifies as a fillable host AND ``filling_element``
+        qualifies as a filling. Used twice with the operands swapped so the
+        gizmo polls true regardless of which of the two selected objects is
+        active."""
+        if not is_supported_host(host_element):
+            return False
+        if not hasattr(host_element, "HasOpenings"):
+            return False
+        return is_supported_filling_or_opening(filling_element)
 
     def setup(self, context: bpy.types.Context) -> None:
         default_color, highlight_color = self.get_decoration_colors()
@@ -114,18 +138,20 @@ class GizmoHostAddOpening(bpy.types.GizmoGroup, _WallGeomCachedBillboardingMixin
         )
 
     def position_gizmos(self, context: bpy.types.Context) -> None:
-        host_obj = context.active_object
-        if not host_obj:
+        selected = list(tool.Blender.get_selected_objects())
+        if len(selected) != 2:
             return
-        selected = tool.Blender.get_selected_objects()
-        other = next((o for o in selected if o is not host_obj), None)
-        if not other:
-            return
-        element = tool.Ifc.get_entity(host_obj)
-        if not element:
+        a, b = selected[0], selected[1]
+        a_element = tool.Ifc.get_entity(a)
+        b_element = tool.Ifc.get_entity(b)
+        if is_supported_host(a_element):
+            host_obj, host_element, other = a, a_element, b
+        elif is_supported_host(b_element):
+            host_obj, host_element, other = b, b_element, a
+        else:
             return
 
-        if tool.Parametric.is_path_connectable_wall(element):
+        if tool.Parametric.is_path_connectable_wall(host_element):
             world_pos = wall_anchor(context, self, host_obj, other)
         else:
             world_pos = layer3_anchor(host_obj, other)

src/bonsai/bonsai/bim/module/model/mep.py

@@ -38,6 +38,7 @@ import numpy as np
 from ifcopenshell.util.shape_builder import ShapeBuilder
 from mathutils import Matrix, Vector
 
+import bonsai.core.geometry
 import bonsai.core.root
 import bonsai.tool as tool
 from bonsai.bim.module.drawing import gizmos as gizmo
@@ -693,27 +694,6 @@ def get_connected_element_at_segment_port(segment, at_segment_start):
     return tool.System.get_port_relating_element(connected_port)
 
 
-def find_fitting_between_segments(segment_a, segment_b):
-    """Single IfcFlowFitting bridging segment_a and segment_b via ports, or
-    ``None`` if no fitting (or multiple fittings — only direct one-fitting
-    joins handled)."""
-    if not (segment_a.is_a("IfcFlowSegment") and segment_b.is_a("IfcFlowSegment")):
-        return None
-    b_ports_set = set(tool.System.get_ports(segment_b))
-    for a_port in tool.System.get_ports(segment_a):
-        connected_port = tool.System.get_connected_port(a_port)
-        if connected_port is None:
-            continue
-        fitting = tool.System.get_port_relating_element(connected_port)
-        if fitting is None or not fitting.is_a("IfcFlowFitting"):
-            continue
-        for fitting_port in tool.System.get_ports(fitting):
-            other_port = tool.System.get_connected_port(fitting_port)
-            if other_port is not None and other_port in b_ports_set:
-                return fitting
-    return None
-
-
 def _resolve_active_mep_segment(operator, context):
     """Return the operator's target ``IfcFlowSegment`` or ``None`` after reporting.
 
@@ -808,52 +788,6 @@ class MEPAddObstruction(bpy.types.Operator, tool.Ifc.Operator):
         return {"FINISHED"}
 
 
-class MEPUnjoinAtPort(bpy.types.Operator, tool.Ifc.Operator):
-    """Delete the IfcFlowFitting that bridges a segment's port to a second element.
-
-    Used when the connection at the port is in the JOINED state (the fitting
-    has at least one other port connecting to a different element). The
-    segment isn't resized — only the bridging fitting is removed. Refuses
-    to act on an OBSTRUCTION fitting (those are routed through
-    ``bim.mep_add_obstruction`` with mode=REMOVE which extends the segment
-    to absorb the freed length)."""
-
-    bl_idname = "bim.mep_unjoin_at_port"
-    bl_label = "Unjoin MEP Segment at Port"
-    bl_description = "Disconnect the segment from the fitting at the named port (deletes the fitting)"
-    bl_options = {"REGISTER", "UNDO"}
-    segment_id: bpy.props.IntProperty(name="Segment Element ID", default=0)
-    position: bpy.props.EnumProperty(
-        name="Port",
-        items=[
-            ("START", "At Start", "Operate on the segment's start port"),
-            ("END", "At End", "Operate on the segment's end port"),
-        ],
-        default="END",
-    )
-
-    def _execute(self, context):
-        resolved = _require_port_state(self, context, PORT_JOINED, "joining")
-        if resolved is None:
-            return {"CANCELLED"}
-        element, at_segment_start = resolved
-
-        fitting = get_connected_element_at_segment_port(element, at_segment_start)
-        if fitting is None or not fitting.is_a("IfcFlowFitting"):
-            self.report({"ERROR"}, "Connected port does not lead to a fitting.")
-            return {"CANCELLED"}
-        if getattr(fitting, "PredefinedType", None) == "OBSTRUCTION":
-            self.report({"ERROR"}, "Obstruction fittings are removed via bim.mep_add_obstruction (mode=REMOVE).")
-            return {"CANCELLED"}
-
-        fitting_obj = tool.Ifc.get_object(fitting)
-        if fitting_obj is None:
-            self.report({"ERROR"}, "Fitting has no Blender object.")
-            return {"CANCELLED"}
-        tool.Geometry.delete_ifc_object(fitting_obj)
-        return {"FINISHED"}
-
-
 class MEPRemoveTerminalFitting(bpy.types.Operator, tool.Ifc.Operator):
     """Remove the terminal fitting at a segment's named port.
 
@@ -906,44 +840,6 @@ class MEPRemoveTerminalFitting(bpy.types.Operator, tool.Ifc.Operator):
         return {"FINISHED"}
 
 
-class MEPUnjoinPair(bpy.types.Operator, tool.Ifc.Operator):
-    """Delete the IfcFlowFitting joining two selected MEP segments.
-
-    Removes the fitting; segments are left in place for the user to reposition."""
-
-    bl_idname = "bim.mep_unjoin_pair"
-    bl_label = "Unjoin MEP Segments"
-    bl_description = "Delete the fitting joining the two selected MEP segments"
-    bl_options = {"REGISTER", "UNDO"}
-
-    @classmethod
-    def poll(cls, context):
-        if not _n_mep_selected(2):
-            cls.poll_message_set("Select exactly 2 MEP segments joined by a fitting.")
-            return False
-        return True
-
-    def _execute(self, context):
-        selected_objs = tool.Blender.get_selected_objects()
-        elements = [tool.Ifc.get_entity(o) for o in selected_objs]
-        if any(e is None or not e.is_a("IfcFlowSegment") for e in elements):
-            self.report({"ERROR"}, "Both selected objects must be MEP segments.")
-            return {"CANCELLED"}
-        fitting = find_fitting_between_segments(elements[0], elements[1])
-        if fitting is None:
-            self.report({"ERROR"}, "No single fitting joins the selected segments.")
-            return {"CANCELLED"}
-        if getattr(fitting, "PredefinedType", None) == "OBSTRUCTION":
-            self.report({"ERROR"}, "Obstruction fittings are removed via bim.mep_add_obstruction (mode=REMOVE).")
-            return {"CANCELLED"}
-        fitting_obj = tool.Ifc.get_object(fitting)
-        if fitting_obj is None:
-            self.report({"ERROR"}, "Fitting has no Blender object.")
-            return {"CANCELLED"}
-        tool.Geometry.delete_ifc_object(fitting_obj)
-        return {"FINISHED"}
-
-
 class SelectMEPPathMembers(bpy.types.Operator):
     """Replace the selection with every MEP element reachable from the active
     one via IfcRelConnectsPorts — the entire connected distribution network."""
@@ -1782,6 +1678,11 @@ def _n_mep_selected(n: int) -> bool:
         element = tool.Ifc.get_entity(selected_obj)
         if element is None or not tool.System.is_mep_element(element):
             return False
+        # Array children mirror their parent's port topology. Writable MEP
+        # actions on a child get wiped by the next array regen, so gate the
+        # icons out at the visibility layer.
+        if tool.Array.is_array_child(element):
+            return False
     return True
 
 
@@ -2660,6 +2561,8 @@ def _active_is_flow_segment(obj: bpy.types.Object) -> bool:
     element = tool.Ifc.get_entity(obj)
     if element is None or not element.is_a("IfcFlowSegment"):
         return False
+    if tool.Array.is_array_child(element):
+        return False
     return tool.System.has_parametric_body(element)
 
 
@@ -2677,10 +2580,24 @@ def _active_mep_has_connected_neighbor(obj: bpy.types.Object) -> bool:
 
 
 def _active_is_bend_fitting(obj: bpy.types.Object) -> bool:
+    """True iff the active object is a parametric BEND fitting eligible for
+    the bend-preview re-edit path. Re-edit reads parameters from the type's
+    ``BBIM_Fitting`` pset, so that pset's presence is the ground truth for
+    re-editability — not the body representation class. The bend creation
+    path tessellates the swept-disk body as an upstream-geometry-kernel
+    workaround, so a freshly-committed bend's body contains only an
+    ``IfcTriangulatedFaceSet`` and ``has_parametric_body`` correctly
+    returns False for it; the pset gate is what keeps the pen icon
+    eligible."""
     element = tool.Ifc.get_entity(obj)
     if not _is_bend_fitting(element):
         return False
-    return tool.System.has_parametric_body(element)
+    if tool.Array.is_array_child(element):
+        return False
+    element_type = ifcopenshell.util.element.get_type(element)
+    if element_type is None:
+        return False
+    return ifcopenshell.util.element.get_pset(element_type, "BBIM_Fitting") is not None
 
 
 class GizmoMEPActions(bpy.types.GizmoGroup, gizmo.BaseIconActionGroup):
@@ -2763,20 +2680,20 @@ class GizmoMEPActions(bpy.types.GizmoGroup, gizmo.BaseIconActionGroup):
         ),
         IconActionConfig(
             name="unjoin_start",
-            icon="VIEW3D_GT_unjoin",
-            operator="bim.mep_unjoin_at_port",
+            icon="VIEW3D_GT_wall_link_toggle",
+            operator="bim.disconnect_elements",
             visibility_condition=lambda obj: _selection_size() == 1 and _active_is_flow_segment(obj),
         ),
         IconActionConfig(
             name="unjoin_end",
-            icon="VIEW3D_GT_unjoin",
-            operator="bim.mep_unjoin_at_port",
+            icon="VIEW3D_GT_wall_link_toggle",
+            operator="bim.disconnect_elements",
             visibility_condition=lambda obj: _selection_size() == 1 and _active_is_flow_segment(obj),
         ),
         IconActionConfig(
             name="unjoin_pair",
-            icon="VIEW3D_GT_unjoin",
-            operator="bim.mep_unjoin_pair",
+            icon="VIEW3D_GT_wall_link_toggle",
+            operator="bim.disconnect_elements",
             visibility_condition=lambda _active: _n_mep_selected(2),
         ),
     ]
@@ -2794,7 +2711,17 @@ class GizmoMEPActions(bpy.types.GizmoGroup, gizmo.BaseIconActionGroup):
         element = tool.Ifc.get_entity(obj)
         if element is None or not tool.System.is_mep_element(element):
             return False
-        return tool.System.has_parametric_body(element)
+        if tool.System.has_parametric_body(element):
+            return True
+        # Bend fittings carry their parametric definition in the type's
+        # ``BBIM_Fitting`` pset because the bend creation path tessellates
+        # the swept-disk body (upstream geometry-kernel workaround), so
+        # ``has_parametric_body`` returns False for them. Fall back to the
+        # pset gate so the pen icon (re_edit_bend) stays reachable.
+        element_type = ifcopenshell.util.element.get_type(element)
+        if element_type is None:
+            return False
+        return ifcopenshell.util.element.get_pset(element_type, "BBIM_Fitting") is not None
 
     def setup(self, context: bpy.types.Context) -> None:
         super().setup(context)
@@ -2802,11 +2729,13 @@ class GizmoMEPActions(bpy.types.GizmoGroup, gizmo.BaseIconActionGroup):
 
     @classmethod
     def _wire_anchored_icon_targets(cls, group) -> None:
-        """Pre-fill ``position`` (and ``mode`` for open-lock) on each anchored
-        icon so a click dispatches to the right port without a per-frame
-        property write; apply the warning-red hover colour to destructive
-        icons. Takes any object with ``action_<name>_gizmo`` attributes so
-        tests can exercise the wiring without instantiating the GizmoGroup."""
+        """Pre-fill ``position`` (and ``mode`` for open-lock) on the lock
+        icons so a click dispatches to the right port without a per-frame
+        property write, and pre-bind the unified ``bim.disconnect_elements``
+        operator on each unjoin icon so :py:meth:`position_gizmos` only has
+        to update the two GUIDs per frame. Takes any object with
+        ``action_<name>_gizmo`` attributes so tests can exercise the wiring
+        without instantiating the GizmoGroup."""
         for config_name, (_icon, position_arg) in cls.LOCK_ICON_CONFIGS.items():
             gz = getattr(group, f"action_{config_name}_gizmo", None)
             if gz is None:
@@ -2820,19 +2749,12 @@ class GizmoMEPActions(bpy.types.GizmoGroup, gizmo.BaseIconActionGroup):
                 op_props = gz.target_set_operator("bim.mep_remove_terminal_fitting")
                 op_props.position = position_arg
 
-        for config_name, position_arg in (("unjoin_start", "START"), ("unjoin_end", "END")):
-            gz = getattr(group, f"action_{config_name}_gizmo", None)
-            if gz is None:
-                continue
-            op_props = gz.target_set_operator("bim.mep_unjoin_at_port")
-            op_props.position = position_arg
-
-        warning_color = gizmo.get_warning_color_from_prefs(tool.Blender.get_addon_preferences())
+        group.unjoin_op_props = {}
         for config_name in cls.UNJOIN_CONFIGS:
             gz = getattr(group, f"action_{config_name}_gizmo", None)
             if gz is None:
                 continue
-            gz.color_highlight = warning_color
+            group.unjoin_op_props[config_name] = gz.target_set_operator("bim.disconnect_elements")
 
     def position_gizmos(self, context: bpy.types.Context) -> None:
         """Lay out icons across three regions: row above bbox top, segment
@@ -2899,6 +2821,10 @@ class GizmoMEPActions(bpy.types.GizmoGroup, gizmo.BaseIconActionGroup):
                 if not visible:
                     gz.hide = True
                     continue
+                if config.name.startswith("unjoin_"):
+                    if not self._bind_unjoin_at_port(config.name, obj, endpoint_kind == "START"):
+                        gz.hide = True
+                        continue
                 if segment_endpoints is None:
                     segment_endpoints = tool.Model.get_flow_segment_axis(obj)
                 start_world, end_world = segment_endpoints
@@ -2910,7 +2836,7 @@ class GizmoMEPActions(bpy.types.GizmoGroup, gizmo.BaseIconActionGroup):
                     if len(selected) == 2:
                         elements = [tool.Ifc.get_entity(o) for o in selected]
                         if all(e is not None and e.is_a("IfcFlowSegment") for e in elements):
-                            pair_fitting = find_fitting_between_segments(elements[0], elements[1]) or False
+                            pair_fitting = tool.System.find_bridging_fitting(elements[0], elements[1]) or False
                         else:
                             pair_fitting = False
                     else:
@@ -2922,6 +2848,13 @@ class GizmoMEPActions(bpy.types.GizmoGroup, gizmo.BaseIconActionGroup):
                     gz.hide = True
                     continue
 
+                if config.name == "unjoin_pair":
+                    selected = tool.Blender.get_selected_objects()
+                    pair_elements = [tool.Ifc.get_entity(o) for o in selected]
+                    if not self._bind_unjoin_pair(pair_elements):
+                        gz.hide = True
+                        continue
+
                 if not bend_anchor_attempted:
                     bend_anchor = compute_mep_join_location()
                     bend_anchor_attempted = True
@@ -2950,3 +2883,33 @@ class GizmoMEPActions(bpy.types.GizmoGroup, gizmo.BaseIconActionGroup):
         if name in self.ENDPOINT_CONFIGS:
             return self.ICON_SCALE * self.ENDPOINT_SCALE_RATIO
         return self.ICON_SCALE
+
+    def _bind_unjoin_at_port(self, config_name: str, segment_obj: bpy.types.Object, at_segment_start: bool) -> bool:
+        """Resolve the fitting at the named port and bind both GUIDs on the
+        pre-wired ``bim.disconnect_elements`` op_props. Returns False when
+        the partner is unresolvable (port not joined to a disconnectable
+        fitting), and the caller hides the icon."""
+        element = tool.Ifc.get_entity(segment_obj)
+        if element is None:
+            return False
+        fitting = get_connected_element_at_segment_port(element, at_segment_start)
+        if fitting is None or not fitting.is_a("IfcFlowFitting"):
+            return False
+        if getattr(fitting, "PredefinedType", None) == "OBSTRUCTION":
+            return False
+        op_props = self.unjoin_op_props[config_name]
+        op_props.element_a_guid = element.GlobalId
+        op_props.element_b_guid = fitting.GlobalId
+        return True
+
+    def _bind_unjoin_pair(self, pair_elements: list[ifcopenshell.entity_instance | None]) -> bool:
+        """Bind both segment GUIDs on the pair-disconnect icon's pre-wired
+        ``bim.disconnect_elements`` op_props. Returns False when either side
+        is missing a GlobalId (e.g. selection lost an active object), and
+        the caller hides the icon."""
+        if len(pair_elements) != 2 or any(e is None for e in pair_elements):
+            return False
+        op_props = self.unjoin_op_props["unjoin_pair"]
+        op_props.element_a_guid = pair_elements[0].GlobalId
+        op_props.element_b_guid = pair_elements[1].GlobalId
+        return True

src/bonsai/bonsai/bim/module/model/opening.py

@@ -240,6 +240,15 @@ def _store_batch_in_cache(cache_key: tuple[int, str], batch: "gpu.types.GPUBatch
     _batch_cache[cache_key] = (epoch, batch)
 
 
+def is_filling_supported(element) -> bool:
+    """True when Bonsai's opening generator can derive an opening from this
+    element. IFC's schema permits any IfcElement as a filling; Bonsai
+    currently supports only IfcDoor and IfcWindow because those are the
+    classes with OverallWidth/OverallHeight attributes (or their types'
+    ELEVATION_VIEW profiles) that the generator can consume."""
+    return element is not None and element.is_a() in ("IfcDoor", "IfcWindow")
+
+
 class FilledOpeningGenerator:
     def generate(
         self,
@@ -409,18 +418,16 @@ class FilledOpeningGenerator:
                 representation = tool.Geometry.get_representation_by_context(voided_element, context)
                 assert representation
 
-                bonsai.core.geometry.switch_representation(
-                    tool.Ifc,
-                    tool.Geometry,
-                    obj=voided_obj,
-                    representation=representation,
-                )
+                tool.Geometry.recut_host(voided_obj, representation)
 
     def regenerate_from_type(self, usecase_path: str, ifc_file: ifcopenshell.file, settings: dict[str, Any]) -> None:
         relating_type = settings["relating_type"]
 
-        for related_object in settings["related_objects"]:
-            self._regenerate_from_type(related_object)
+        # Filling type-switch on an array of fillings fans out N host recuts —
+        # one per related object — without batching. Coalesce them.
+        with tool.Geometry.batch_host_recut():
+            for related_object in settings["related_objects"]:
+                self._regenerate_from_type(related_object)
 
     def _regenerate_from_type(self, related_object: ifcopenshell.entity_instance) -> None:
         filling = related_object
@@ -469,12 +476,7 @@ class FilledOpeningGenerator:
             representation = tool.Geometry.get_active_representation(voided_obj)
             if not representation:
                 continue
-            bonsai.core.geometry.switch_representation(
-                tool.Ifc,
-                tool.Geometry,
-                obj=voided_obj,
-                representation=representation,
-            )
+            tool.Geometry.recut_host(voided_obj, representation)
 
     def generate_opening_from_filling(
         self,
@@ -609,6 +611,31 @@ class RecalculateFill(bpy.types.Operator, tool.Ifc.Operator):
         return context.selected_objects
 
     def _execute(self, context):
+        # N selected fillings × M voided host parts would fire N×M host recuts
+        # without batching. Coalesce per host.
+        with tool.Geometry.batch_host_recut():
+            return self._recalculate_fills(context)
+
+    def _recalculate_fills(self, context):
+        # Refresh each selected filling's mapped opening source before
+        # recutting the host. Dedup by source id covers the common shared-
+        # source case in one rewrite while leaving unrelated sibling sources
+        # untouched.
+        seen_source_ids: set[int] = set()
+        for obj in context.selected_objects:
+            element = tool.Ifc.get_entity(obj)
+            if not element or not element.FillsVoids:
+                continue
+            opening = element.FillsVoids[0].RelatingOpeningElement
+            body = tool.Geometry.get_body_representation(opening)
+            if body is None:
+                continue
+            source = tool.Geometry.resolve_mapped_representation(body)
+            if source.id() in seen_source_ids:
+                continue
+            seen_source_ids.add(source.id())
+            tool.Model.regenerate_filling_opening_body(element)
+
         for obj in context.selected_objects:
             element = tool.Ifc.get_entity(obj)
             if not element or not element.FillsVoids:
@@ -637,12 +664,7 @@ class RecalculateFill(bpy.types.Operator, tool.Ifc.Operator):
                 if building_obj and building_obj.data:
                     representation = tool.Geometry.get_active_representation(building_obj)
                     if representation:
-                        bonsai.core.geometry.switch_representation(
-                            tool.Ifc,
-                            tool.Geometry,
-                            obj=building_obj,
-                            representation=representation,
-                        )
+                        tool.Geometry.recut_host(building_obj, representation)
 
         # Refresh cut decorator
         DecoratorData.cut_cache.clear()
@@ -964,27 +986,29 @@ class EditOpenings(Operator, tool.Ifc.Operator):
         for opening_element in opening_elements:
             opening_obj = tool.Ifc.get_object(opening_element)
 
-            similar_openings = bonsai.core.geometry.get_similar_openings(tool.Ifc, opening_element)
-            similar_openings_building_objs = bonsai.core.geometry.get_similar_openings_building_objs(
-                tool.Ifc, similar_openings
-            )
-            building_objs.update(similar_openings_building_objs)
-
             if opening_obj:
-                if tool.Ifc.is_edited(opening_obj):
-                    tool.Geometry.run_geometry_update_representation(obj=opening_obj)
-                    bonsai.core.geometry.edit_similar_opening_placement(
-                        tool.Geometry, opening_element, similar_openings
-                    )
-                elif tool.Ifc.is_moved(opening_obj):
-                    bonsai.core.geometry.edit_object_placement(tool.Ifc, tool.Geometry, tool.Surveyor, obj=opening_obj)
+                opening_edited = tool.Ifc.is_edited(opening_obj)
+                opening_moved = tool.Ifc.is_moved(opening_obj)
+                # Sibling walls only need a viewport-level refresh when the
+                # opening's shape or placement actually changed — a pure
+                # show/hide toggle leaves them in their existing state.
+                if opening_edited or opening_moved:
+                    similar_openings = bonsai.core.geometry.get_similar_openings(tool.Ifc, opening_element)
+                    similar_openings_building_objs = bonsai.core.geometry.get_similar_openings_building_objs(
+                        tool.Ifc, similar_openings
+                    )
+                    building_objs.update(similar_openings_building_objs)
+                    if opening_edited:
+                        tool.Geometry.run_geometry_update_representation(obj=opening_obj)
+                    else:
+                        bonsai.core.geometry.edit_object_placement(
+                            tool.Ifc, tool.Geometry, tool.Surveyor, obj=opening_obj
+                        )
                     bonsai.core.geometry.edit_similar_opening_placement(
                         tool.Geometry, opening_element, similar_openings
                     )
+                    building_objs.update(self.get_all_building_objects_of_similar_openings(opening_element))
 
-                building_objs.update(
-                    self.get_all_building_objects_of_similar_openings(opening_element)
-                )  # NB this has nothing to do with clone similar_opening
                 tool.Ifc.unlink(element=opening_element)
                 if props.representation_obj == opening_obj:
                     props.representation_obj = None
@@ -1022,6 +1046,12 @@ class CloneOpening(Operator, tool.Ifc.Operator):
         return True
 
     def _execute(self, context):
+        # The voided host may be an aggregate whose parts each get recut.
+        # Coalesce per host so a many-parts aggregate doesn't fan out.
+        with tool.Geometry.batch_host_recut():
+            return self._clone_opening(context)
+
+    def _clone_opening(self, context):
         # NOTE: Operator displayed in UI only with IfcOpeningElement being active.
         ifc_file = tool.Ifc.get()
         objects = bpy.context.selected_objects
@@ -1051,12 +1081,7 @@ class CloneOpening(Operator, tool.Ifc.Operator):
                 continue
             representation = tool.Geometry.get_active_representation(obj)
             assert representation
-            bonsai.core.geometry.switch_representation(
-                tool.Ifc,
-                tool.Geometry,
-                obj=obj,
-                representation=representation,
-            )
+            tool.Geometry.recut_host(obj, representation)
 
         return {"FINISHED"}
 

src/bonsai/bonsai/bim/module/model/profile.py

@@ -1002,6 +1002,14 @@ class EnableEditingExtrusionAxis(bpy.types.Operator, tool.Ifc.Operator):
     def _execute(self, context):
         self.unit_scale = ifcopenshell.util.unit.calculate_unit_scale(tool.Ifc.get())
         obj = context.active_object
+
+        # Commit any in-progress parametric (gizmo) draft on this object
+        # before switching to axis-edit. Otherwise the in-memory draft
+        # state is overwritten when the axis mesh is imported below,
+        # silently discarding the user's pending dimension edits.
+        if feature := tool.Parametric.is_object_editing(obj):
+            tool.Parametric.commit_object_draft(obj, feature.finish_op)
+
         element = tool.Ifc.get_entity(obj)
 
         axis = ifcopenshell.util.representation.get_representation(element, "Model", "Axis", "GRAPH_VIEW")

src/bonsai/bonsai/bim/module/model/railing.py

@@ -138,7 +138,7 @@ def update_bbim_railing_pset(element: ifcopenshell.entity_instance, railing_data
 
 def generate_wall_mounted_handrail_preview(
     obj: bpy.types.Object,
-    props: "BIMRailingProperties",
+    props: "prop.BIMRailingProperties",
     path_data: dict[str, Any],
     si_conversion: float,
 ) -> None:
@@ -860,7 +860,9 @@ class GizmoRailingSchematic(bpy.types.GizmoGroup, gizmo.BaseSchematicGizmoGroup)
         terminal_world = anchor + billboard_rot @ view_rotation @ terminal_local
         self.terminal_gizmo.matrix_basis = gizmo.billboarded_at(terminal_world, billboard_rot, 0.18)
 
-    def update_editing_gizmos(self, context: bpy.types.Context, mw: "Matrix", props: "BIMRailingProperties") -> None:
+    def update_editing_gizmos(
+        self, context: bpy.types.Context, mw: "Matrix", props: "prop.BIMRailingProperties"
+    ) -> None:
         """Hide the pen gizmo while polyline path-edit is active; reposition the cycle icon.
 
         The base class shows the pen gizmo whenever ``is_editing`` is False,

src/bonsai/bonsai/bim/module/model/slab.py

@@ -620,6 +620,14 @@ class EnableEditingExtrusionProfile(bpy.types.Operator, tool.Ifc.Operator):
     def _execute(self, context):
         self.unit_scale = ifcopenshell.util.unit.calculate_unit_scale(tool.Ifc.get())
         obj = context.active_object
+
+        # Commit any in-progress parametric (gizmo) draft on this object
+        # before switching to profile-edit. Otherwise the in-memory draft
+        # state is overwritten when the profile mesh is imported below,
+        # silently discarding the user's pending dimension edits.
+        if feature := tool.Parametric.is_object_editing(obj):
+            tool.Parametric.commit_object_draft(obj, feature.finish_op)
+
         element = tool.Ifc.get_entity(obj)
 
         body = ifcopenshell.util.representation.get_representation(element, "Model", "Body", "MODEL_VIEW")

src/bonsai/bonsai/bim/module/model/ui.py

@@ -22,9 +22,9 @@ from collections.abc import Iterable
 from typing import TYPE_CHECKING, Any
 
 import bpy
+import ifcopenshell.util.unit
 from bpy.types import Panel
 
-import ifcopenshell.util.unit
 import bonsai.bim
 import bonsai.tool as tool
 from bonsai.bim.helper import prop_with_search

src/bonsai/bonsai/bim/module/model/wall.py

@@ -400,13 +400,13 @@ class DisconnectElements(_CommitWallDraftsFirstMixin, bpy.types.Operator, tool.I
             )
             return
         path_objs: list[bpy.types.Object] = []
-        for rel, kind in rels:
+        for subject, kind in rels:
             bonsai.core.connection.disconnect_rel(
                 tool.Ifc,
                 tool.Geometry,
                 tool.Model,
                 tool.Connection,
-                rel=rel,
+                subject=subject,
                 kind=kind,
                 elem=elem_a,
                 partner=elem_b,

src/bonsai/bonsai/bim/module/nest/decorator.py

@@ -20,7 +20,6 @@ import blf
 import bpy
 import gpu
 import ifcopenshell.util.element
-from bpy.types import SpaceView3D
 from bpy_extras import view3d_utils
 from gpu_extras.batch import batch_for_shader
 from mathutils import Vector
@@ -28,12 +27,6 @@ from mathutils import Vector
 import bonsai.tool as tool
 
 
-def transparent_color(color, alpha=0.1):
-    color = [i for i in color]
-    color[3] = alpha
-    return color
-
-
 def create_bounding_box(objs):
     # Initialize the bounding box coordinates
     min_x, min_y, min_z = float("inf"), float("inf"), float("inf")
@@ -79,26 +72,8 @@ def create_bounding_box(objs):
     return indices, edges
 
 
-class NestDecorator:
-    is_installed = False
-    handlers = []
-
-    @classmethod
-    def install(cls, context):
-        if cls.is_installed:
-            cls.uninstall()
-        handler = cls()
-        cls.handlers.append(SpaceView3D.draw_handler_add(handler.draw_nest, (context,), "WINDOW", "POST_VIEW"))
-        cls.is_installed = True
-
-    @classmethod
-    def uninstall(cls):
-        for handler in cls.handlers:
-            try:
-                SpaceView3D.draw_handler_remove(handler, "WINDOW")
-            except ValueError:
-                pass
-        cls.is_installed = False
+class NestDecorator(tool.Blender.ViewportDecorator):
+    draw_method = "draw_nest"
 
     def dotted_line_shader(self):
         vert_out = gpu.types.GPUStageInterfaceInfo("my_interface")
@@ -154,14 +129,6 @@ class NestDecorator:
         shader.uniform_float("u_Scale", 25)
         batch.draw(shader)
 
-    def draw_batch(self, shader_type, content_pos, color, indices=None):
-        if not tool.Blender.validate_shader_batch_data(content_pos, indices):
-            return
-        shader = self.line_shader if shader_type == "LINES" else self.shader
-        batch = batch_for_shader(shader, shader_type, {"pos": content_pos}, indices=indices)
-        shader.uniform_float("color", color)
-        batch.draw(shader)
-
     def draw_nest(self, context: bpy.types.Context) -> None:
         props = tool.Nest.get_nest_props()
         if props.in_nest_mode:
@@ -226,35 +193,11 @@ class NestDecorator:
             self.draw_custom_batch(line, decorator_color_unselected)
 
 
-class NestModeDecorator:
-    is_installed = False
-    handlers = []
-
-    @classmethod
-    def install(cls, context):
-        if cls.is_installed:
-            cls.uninstall()
-        handler = cls()
-        cls.handlers.append(SpaceView3D.draw_handler_add(handler.draw_nest_name, (context,), "WINDOW", "POST_PIXEL"))
-        cls.handlers.append(SpaceView3D.draw_handler_add(handler.draw_nest_empty, (context,), "WINDOW", "POST_VIEW"))
-        cls.is_installed = True
-
-    @classmethod
-    def uninstall(cls):
-        for handler in cls.handlers:
-            try:
-                SpaceView3D.draw_handler_remove(handler, "WINDOW")
-            except ValueError:
-                pass
-        cls.is_installed = False
-
-    def draw_batch(self, shader_type, content_pos, color, indices=None):
-        if not tool.Blender.validate_shader_batch_data(content_pos, indices):
-            return
-        shader = self.line_shader if shader_type == "LINES" else self.shader
-        batch = batch_for_shader(shader, shader_type, {"pos": content_pos}, indices=indices)
-        shader.uniform_float("color", color)
-        batch.draw(shader)
+class NestModeDecorator(tool.Blender.ViewportDecorator):
+    draw_methods = (
+        ("draw_nest_name", "POST_PIXEL"),
+        ("draw_nest_empty", "POST_VIEW"),
+    )
 
     def draw_nest_name(self, context):
         if context.mode == "EDIT_MESH":

src/bonsai/bonsai/bim/module/patch/__init__.py

@@ -21,6 +21,7 @@ import bpy
 from . import operator, prop, ui
 
 classes = (
+    operator.AddIfcPatchPreset,
     operator.ExecuteIfcPatch,
     operator.ExtractSelectedElements,
     operator.RunMigratePatch,
@@ -28,6 +29,7 @@ classes = (
     operator.SelectIfcPatchOutput,
     operator.UpdateIfcPatchArguments,
     prop.BIMPatchProperties,
+    ui.BIM_MT_ifc_patch_presets,
     ui.BIM_PT_patch,
 )
 

src/bonsai/bonsai/bim/module/patch/operator.py

@@ -18,11 +18,12 @@
 
 import json
 from pathlib import Path
-from typing import TYPE_CHECKING, cast
+from typing import TYPE_CHECKING
 
 import bpy
 import ifcopenshell
 import ifcpatch
+from bl_operators.presets import AddPresetBase
 from bpy_extras.io_utils import ExportHelper, ImportHelper
 
 import bonsai.bim.handler
@@ -77,6 +78,27 @@ class ExecuteIfcPatch(bpy.types.Operator):
             return False
         return True
 
+    def invoke(self, context, event):
+        # Migrating IFC4 → IFC2X3 is lossy (enum drops, IFC4-only classes
+        # become IfcBuildingElementProxy, tessellated meshes get rebuilt as
+        # IfcFacetedBrep). Confirm before running so the user knows.
+        if tool.Patch.migration_is_lossy_downgrade():
+            return context.window_manager.invoke_props_dialog(self, width=480)
+        return self.execute(context)
+
+    def draw(self, context):
+        layout = self.layout
+        layout.label(text="Downgrading to IFC2X3 is lossy.", icon="ERROR")
+        column = layout.column(align=True)
+        column.label(text="Geometry will be preserved as faithfully as possible:")
+        column.label(text="• IfcIndexedPolyCurve → IfcPolyline (arcs approximated by chords)")
+        column.label(text="• IfcPolygonalFaceSet / IfcTriangulatedFaceSet → IfcFacetedBrep")
+        column.separator()
+        column.label(text="The following information is lost:")
+        column.label(text="• IFC4-only classes (IfcLamp, IfcPipeSegment, …) → IfcBuildingElementProxy")
+        column.label(text="• PredefinedType enum values absent from IFC2X3 are dropped")
+        column.label(text="  (original class + enum saved as ObjectType, e.g. 'IfcLamp/COMPACTFLUORESCENT')")
+
     def execute(self, context):
         props = tool.Patch.get_patch_props()
         recipe_name = props.ifc_patch_recipes
@@ -100,8 +122,8 @@ class ExecuteIfcPatch(bpy.types.Operator):
         if props.should_load_from_memory and tool.Ifc.get():
             args["file"] = tool.Ifc.get()
         else:
-            args["input"] = cast(str, props.ifc_patch_input)
-            args["file"] = cast(ifcopenshell.file, ifcopenshell.open(props.ifc_patch_input))
+            args["input"] = props.ifc_patch_input
+            args["file"] = ifcopenshell.open(props.ifc_patch_input)
 
         # Store this in case the patch recipe resets the Blender session, such as by loading a new project.
         ifc_patch_output = props.ifc_patch_output or props.ifc_patch_input
@@ -224,3 +246,38 @@ class ExtractSelectedElements(bpy.types.Operator):
         query = tool.Search.get_query_for_selected_elements()
         props.ifc_patch_args_attr[0].string_value = query
         return {"FINISHED"}
+
+
+class AddIfcPatchPreset(AddPresetBase, bpy.types.Operator):
+    """Save / remove ifc-patch argument presets, scoped per recipe.
+
+    Presets live in the standard Blender preset directory under
+    ``bonsai/ifc_patch/<recipe>/`` so a preset created for ``ExtractElements``
+    does not pollute the preset list for ``Migrate``. Persistence across files
+    and sessions is inherited from Blender's preset system."""
+
+    bl_idname = "bim.add_ifc_patch_preset"
+    bl_label = "Add IFC Patch Preset"
+    preset_menu = "BIM_MT_ifc_patch_presets"
+    preset_defines = ["props = bpy.context.scene.BIMPatchProperties"]
+
+    @property
+    def preset_subdir(self) -> str:
+        return tool.Patch.get_preset_subdir()
+
+    @property
+    def preset_values(self) -> list[str]:
+        # `Attribute.get_value_name()` returns the storage field for the
+        # argument's data_type (string_value, bool_value, …). For file
+        # arguments it returns the wrapping PointerProperty (`filepath_value`)
+        # — the scalar path the preset needs is `.single_file` on that.
+        props = tool.Patch.get_patch_props()
+        values = []
+        for i, arg in enumerate(props.ifc_patch_args_attr):
+            field = arg.get_value_name()
+            if not field:
+                continue
+            if arg.data_type == "file":
+                field = f"{field}.single_file"
+            values.append(f"props.ifc_patch_args_attr[{i}].{field}")
+        return values

src/bonsai/bonsai/bim/module/patch/prop.py

@@ -71,6 +71,15 @@ def get_ifcpatch_recipes(self: "BIMPatchProperties", context: bpy.types.Context)
 
 def update_ifc_patch_recipe(self: "BIMPatchProperties", context: bpy.types.Context) -> None:
     bpy.ops.bim.update_ifc_patch_arguments(recipe=self.ifc_patch_recipes)
+    # Blender's script.execute_preset mutates the menu class's bl_label to
+    # the loaded preset's display name (used as a "currently selected"
+    # indicator). The label persists across recipe changes — making the new
+    # recipe's menu falsely show the previous recipe's preset name. Reset
+    # the label to the menu's canonical title so it always matches the
+    # active recipe's preset list.
+    menu_cls = getattr(bpy.types, "BIM_MT_ifc_patch_presets", None)
+    if menu_cls is not None:
+        menu_cls.bl_label = "IFC Patch Presets"
 
 
 class BIMPatchProperties(PropertyGroup):

src/bonsai/bonsai/bim/module/patch/ui.py

@@ -29,6 +29,20 @@ if TYPE_CHECKING:
     from bonsai.bim.prop import Attribute
 
 
+class BIM_MT_ifc_patch_presets(bpy.types.Menu):
+    """Lists ifc-patch presets for the currently selected recipe.
+
+    ``preset_subdir`` is resolved per draw so switching recipes swaps the
+    preset list without re-registering the menu."""
+
+    bl_label = "IFC Patch Presets"
+    preset_operator = "script.execute_preset"
+
+    def draw(self, context: bpy.types.Context) -> None:
+        self.preset_subdir = tool.Patch.get_preset_subdir()
+        bpy.types.Menu.draw_preset(self, context)
+
+
 class BIM_PT_patch(bpy.types.Panel):
     bl_label = "Patch"
     bl_idname = "BIM_PT_patch"
@@ -66,6 +80,11 @@ class BIM_PT_patch(bpy.types.Panel):
                 row.operator("bim.patch_query_from_selected", text="", icon="EYEDROPPER")
 
         if props.ifc_patch_args_attr:
+            preset_row = layout.row(heading="Preset", align=True)
+            preset_row.menu("BIM_MT_ifc_patch_presets", text=BIM_MT_ifc_patch_presets.bl_label)
+            preset_row.operator("bim.add_ifc_patch_preset", text="", icon="ADD")
+            preset_row.operator("bim.add_ifc_patch_preset", text="", icon="REMOVE").remove_active = True
+
             draw_callback = draw_callback_ if props.ifc_patch_recipes == "ExtractElements" else None
             draw_attributes(props.ifc_patch_args_attr, layout, callback=draw_callback)
 

src/bonsai/bonsai/bim/module/project/__init__.py

@@ -18,6 +18,8 @@
 
 import bpy
 
+import bonsai.tool as tool
+
 from . import decorator, gizmo, operator, prop, ui, workspace
 
 classes = (
@@ -58,6 +60,8 @@ classes = (
     operator.LinkIfc,
     operator.LoadBlendMetadataAndIFC,
     operator.LoadLink,
+    operator.AutosavePrompt,
+    operator.LoadAutosavedRecoveryPopup,
     operator.LoadLinkedProject,
     operator.LoadProject,
     operator.LoadProjectElements,
@@ -136,6 +140,7 @@ def register():
 def unregister():
     if not bpy.app.background:
         bpy.utils.unregister_tool(workspace.ExploreTool)
+    tool.Autosave.cancel_timer()
     del bpy.types.Scene.BIMProjectProperties
     del bpy.types.Scene.MeasureToolSettings
     bpy.app.handlers.load_post.remove(decorator.toggle_decorations_on_load)

src/bonsai/bonsai/bim/module/project/decorator.py

@@ -42,12 +42,6 @@ def toggle_decorations_on_load(*args):
     # as queried object is linked from separate .blend file.
 
 
-def transparent_color(color, alpha=0.1):
-    color = [i for i in color]
-    color[3] = alpha
-    return color
-
-
 class ProjectDecorator:
     installed = None
 
@@ -80,11 +74,6 @@ class ProjectDecorator:
         unselected_elements_color = self.addon_prefs.decorator_color_unselected
         special_elements_color = self.addon_prefs.decorator_color_special
 
-        def transparent_color(color, alpha=0.1):
-            color = [i for i in color]
-            color[3] = alpha
-            return color
-
         gpu.state.point_size_set(6)
         gpu.state.blend_set("ALPHA")
 
@@ -110,7 +99,9 @@ class ProjectDecorator:
 
         if geom.selected_edges:
             self.draw_batch("LINES", selected_vertices, selected_elements_color, geom.selected_edges)
-            self.draw_batch("TRIS", selected_vertices, transparent_color(selected_elements_color), geom.selected_tris)
+            self.draw_batch(
+                "TRIS", selected_vertices, tool.Blender.transparent_color(selected_elements_color), geom.selected_tris
+            )
 
 
 class ClippingPlaneDecorator:
@@ -145,11 +136,6 @@ class ClippingPlaneDecorator:
         unselected_elements_color = self.addon_prefs.decorator_color_unselected
         special_elements_color = self.addon_prefs.decorator_color_special
 
-        def transparent_color(color, alpha=0.1):
-            color = [i for i in color]
-            color[3] = alpha
-            return color
-
         gpu.state.point_size_set(6)
         gpu.state.blend_set("ALPHA")
 
@@ -210,37 +196,21 @@ class ClippingPlaneDecorator:
 
             if unselected_edges:
                 self.draw_batch("LINES", unselected_vertices, special_elements_color, unselected_edges)
-                self.draw_batch("TRIS", unselected_vertices, transparent_color(special_elements_color), unselected_tris)
+                self.draw_batch(
+                    "TRIS", unselected_vertices, tool.Blender.transparent_color(special_elements_color), unselected_tris
+                )
             if selected_edges:
                 self.draw_batch("LINES", selected_vertices, selected_elements_color, selected_edges)
-                self.draw_batch("TRIS", selected_vertices, transparent_color(selected_elements_color), selected_tris)
+                self.draw_batch(
+                    "TRIS", selected_vertices, tool.Blender.transparent_color(selected_elements_color), selected_tris
+                )
 
 
-class MeasureDecorator:
-    is_installed = False
-    handlers = []
-
-    @classmethod
-    def install(cls, context):
-        if cls.is_installed:
-            cls.uninstall()
-        handler = cls()
-        cls.handlers.append(
-            SpaceView3D.draw_handler_add(handler.draw_measurements_text, (context,), "WINDOW", "POST_PIXEL")
-        )
-        cls.handlers.append(
-            SpaceView3D.draw_handler_add(handler.draw_measurements_poly, (context,), "WINDOW", "POST_VIEW")
-        )
-        cls.is_installed = True
-
-    @classmethod
-    def uninstall(cls):
-        for handler in cls.handlers:
-            try:
-                SpaceView3D.draw_handler_remove(handler, "WINDOW")
-            except ValueError:
-                pass
-        cls.is_installed = False
+class MeasureDecorator(tool.Blender.ViewportDecorator):
+    draw_methods = (
+        ("draw_measurements_text", "POST_PIXEL"),
+        ("draw_measurements_poly", "POST_VIEW"),
+    )
 
     def draw_measurements_text(self, context):
         PolylineDecorator().select_and_draw_measurements_text(context)

src/bonsai/bonsai/bim/module/project/operator.py

@@ -985,8 +985,10 @@ class LoadProject(bpy.types.Operator, IFCFileSelector, ImportHelper):
         ),
         default=False,
     )
+    skip_autosave_recovery: bpy.props.BoolProperty(default=False, options={"HIDDEN", "SKIP_SAVE"})
     use_detailed_tooltip: bpy.props.BoolProperty(default=False, options={"HIDDEN"})
     filename_ext = ".ifc"
+    skip_recent: bpy.props.BoolProperty(default=False, options={"HIDDEN", "SKIP_SAVE"})
 
     if TYPE_CHECKING:
         filepath: str
@@ -995,6 +997,7 @@ class LoadProject(bpy.types.Operator, IFCFileSelector, ImportHelper):
         use_relative_path: bool
         should_start_fresh_session: bool
         import_without_ifc_data: bool
+        skip_autosave_recovery: bool
         use_detailed_tooltip: bool
 
     @classmethod
@@ -1041,7 +1044,33 @@ class LoadProject(bpy.types.Operator, IFCFileSelector, ImportHelper):
 
         return tooltip
 
+    def check_autosave_recovery(self, context: bpy.types.Context) -> bool:
+        if self.skip_autosave_recovery:
+            return False
+        autosaved_filepath = tool.Autosave.get_newer_autosaved_path(self.get_filepath_abs())
+        if not autosaved_filepath:
+            return False
+        # Fire-and-forget: don't propagate this popup's own RUNNING_MODAL
+        # return value up as if *this* operator were running modally too -
+        # we never call modal_handler_add() on ourselves, so the window
+        # manager would be left tracking a modal operator with no handler,
+        # corrupting its operator bookkeeping until it crashes later when
+        # the (real) popup modal handler is closed.
+        bpy.ops.bim.load_autosaved_recovery_popup(
+            "INVOKE_DEFAULT",
+            original_filepath=str(self.get_filepath_abs()),
+            autosaved_filepath=autosaved_filepath,
+            is_advanced=self.is_advanced,
+            use_relative_path=self.use_relative_path,
+            should_start_fresh_session=self.should_start_fresh_session,
+            import_without_ifc_data=self.import_without_ifc_data,
+        )
+        return True
+
     def execute(self, context):
+        if self.check_autosave_recovery(context):
+            return {"FINISHED"}
+
         if (
             tool.Blender.get_addon_preferences().save_metadata_blend_file
             and self.should_start_fresh_session
@@ -1136,7 +1165,8 @@ class LoadProject(bpy.types.Operator, IFCFileSelector, ImportHelper):
             props.should_save_metadata_for_this_file = metadata_doc is not None
 
             tool.Blender.register_toolbar()
-            tool.Project.add_recent_ifc_project(self.get_filepath_abs())
+            if not self.skip_recent:
+                tool.Project.add_recent_ifc_project(self.get_filepath_abs())
 
             if self.is_advanced:
                 pass
@@ -1149,10 +1179,13 @@ class LoadProject(bpy.types.Operator, IFCFileSelector, ImportHelper):
         except:
             bonsai.last_error = traceback.format_exc()
             raise
+        tool.Autosave.reset_timer()
         return {"FINISHED"}
 
     def invoke(self, context, event):
         if self.filepath:
+            if self.check_autosave_recovery(context):
+                return {"FINISHED"}
             return self.execute(context)
         return ImportHelper.invoke(self, context, event)
 
@@ -1294,6 +1327,11 @@ class LoadProjectElements(bpy.types.Operator):
             if element.IsDecomposedBy:
                 for subelement in element.IsDecomposedBy[0].RelatedObjects:
                     decomposed_elements.add(subelement)
+            # IfcSurfaceFeature (e.g. road markings) adhere to a host element
+            # via IfcRelAdheresToElement, a [1:1] hierarchical relationship in
+            # the same family as aggregation, containment and nesting (IFC4.3).
+            for rel in getattr(element, "HasSurfaceFeatures", ()):
+                decomposed_elements.update(rel.RelatedSurfaceFeatures)
         if decomposed_elements:
             self.append_decomposed_elements(decomposed_elements)
         elements.update(decomposed_elements)
@@ -1422,6 +1460,7 @@ class LinkIfc(bpy.types.Operator, ImportHelper, tool.Ifc.Operator):
                 new.ifc_definition_id = reference.id()
             new.name = filepath
             new.filepath = filepath
+            new.query = self.query
             bpy.ops.bim.load_link(link_index=-1, use_cache=self.use_cache, query=self.query)
 
 
@@ -1492,6 +1531,10 @@ class LoadLink(bpy.types.Operator, tool.Ifc.Operator):
 
     def _execute(self, context):
         self.link = tool.Project.get_project_props().links[self.link_index]
+        # Fall back to the Link's stored query so callers that omit it
+        # still replay the filter the link was created with.
+        if not self.query and self.link.query:
+            self.query = self.link.query
         filepath = Path(tool.Ifc.resolve_uri(self.link.filepath))
         if not filepath.exists():
             self.report({"ERROR"}, f"File does not exist: '{filepath}'")
@@ -1659,13 +1702,36 @@ class ReloadLink(bpy.types.Operator):
     bl_description = "Reload the selected file"
 
     link_index: bpy.props.IntProperty(name="Link Index")
+    query: bpy.props.StringProperty(
+        name="Query",
+        description=(
+            "Custom selector query to use to load element from a linked model. E.g. 'IfcElement'.\n\n"
+            "Default query - IfcElement, but excluding IfcProxy, IfcSpatialStructureElement, IfcSpatialElement, IfcFeatureElement."
+        ),
+    )
 
     if TYPE_CHECKING:
         link_index: int
+        query: str
+
+    def invoke(self, context, event):
+        link = tool.Project.get_project_props().links[self.link_index]
+        self.query = link.query
+        return context.window_manager.invoke_props_dialog(self)
+
+    def draw(self, context):
+        assert self.layout
+        self.layout.prop(self, "query", placeholder="IfcElement")
 
     def execute(self, context):
+        link = tool.Project.get_project_props().links[self.link_index]
+        # An unset query means the operator was called without the dialog
+        # (e.g. from a script) - preserve the link's stored query instead
+        # of overwriting it with the empty default.
+        if self.properties.is_property_set("query"):
+            link.query = self.query
         bpy.ops.bim.unload_link(link_index=self.link_index)
-        return bpy.ops.bim.load_link(link_index=self.link_index, use_cache=False) or {"FINISHED"}
+        return bpy.ops.bim.load_link(link_index=self.link_index, use_cache=False, query=link.query) or {"FINISHED"}
 
 
 class ToggleLinkSelectability(bpy.types.Operator):
@@ -1914,6 +1980,7 @@ class ExportIFC(bpy.types.Operator, ExportHelper):
     json_compact: bpy.props.BoolProperty(name="Export Compact IFCJSON", default=False)
     should_save_as: bpy.props.BoolProperty(name="Should Save As", default=False, options={"HIDDEN"})
     use_relative_path: bpy.props.BoolProperty(name="Use Relative Path", default=False)
+    skip_recent: bpy.props.BoolProperty(default=False, options={"HIDDEN", "SKIP_SAVE"})
 
     if TYPE_CHECKING:
         filter_glob: str
@@ -1974,6 +2041,18 @@ class ExportIFC(bpy.types.Operator, ExportHelper):
         return {"FINISHED"}
 
     def _execute(self, context):
+        project_props = tool.Project.get_project_props()
+        project_props.use_relative_project_path = self.use_relative_path
+
+        # Fallback if filepath is not set
+        if not getattr(self, "filepath", None) or self.filepath.strip() in ("", ".ifc"):
+            props = tool.Blender.get_bim_props()
+            if props.ifc_file:
+                self.filepath = str(tool.Blender.ensure_blender_path_is_abs(Path(props.ifc_file)))
+            else:
+                self.report({"ERROR"}, "No filepath available for saving.")
+                return {"CANCELLED"}
+
         committed, failed_commits = tool.Parametric.commit_pending_edits()
         # Previews are session-transient — discard rather than commit. Sibling
         # gizmo polls gate on each preview's is_active flag, and a stuck flag
@@ -2036,7 +2115,8 @@ class ExportIFC(bpy.types.Operator, ExportHelper):
         settings.logger.info("Export finished in {:.2f} seconds".format(time.time() - start))
         print("Export finished in {:.2f} seconds".format(time.time() - start))
         # New project created in Bonsai should be in recent projects too.
-        tool.Project.add_recent_ifc_project(Path(output_file))
+        if not self.skip_recent:
+            tool.Project.add_recent_ifc_project(Path(output_file))
         props = tool.Project.get_project_props()
         if props.use_relative_project_path and bpy.data.is_saved:
             output_file = os.path.relpath(output_file, bpy.path.abspath("//"))
@@ -2070,6 +2150,7 @@ class ExportIFC(bpy.types.Operator, ExportHelper):
             )
 
         bonsai.bim.handler.refresh_ui_data()
+        tool.Autosave.reset_timer()
 
     @classmethod
     def description(cls, context, properties):
@@ -2078,6 +2159,123 @@ class ExportIFC(bpy.types.Operator, ExportHelper):
         return "Save the IFC file.  Will save both .IFC/.BLEND files if synced together"
 
 
+class LoadAutosavedRecoveryPopup(bpy.types.Operator):
+    bl_idname = "bim.load_autosaved_recovery_popup"
+    bl_label = "Recover Autosaved File"
+    bl_options = {"REGISTER", "UNDO"}
+
+    original_filepath: bpy.props.StringProperty(options={"SKIP_SAVE"})
+    autosaved_filepath: bpy.props.StringProperty(options={"SKIP_SAVE"})
+    is_advanced: bpy.props.BoolProperty(default=False, options={"SKIP_SAVE"})
+    use_relative_path: bpy.props.BoolProperty(default=False, options={"SKIP_SAVE"})
+    should_start_fresh_session: bpy.props.BoolProperty(default=True, options={"SKIP_SAVE"})
+    import_without_ifc_data: bpy.props.BoolProperty(default=False, options={"SKIP_SAVE"})
+
+    def draw(self, context):
+        layout = self.layout
+        layout.label(text="A newer autosaved copy was found:", icon="INFO")
+        layout.label(text=os.path.basename(self.autosaved_filepath))
+        layout.separator()
+        layout.label(text="Do you want to load the autosaved version instead?")
+        layout.label(text="(Cancel will load the original)")
+
+    def invoke(self, context, event):
+        # invoke_props_dialog is modal - unlike invoke_popup/popup_menu, it
+        # isn't dismissed by the mouse simply leaving its bounds. It always
+        # renders both a fixed "Cancel" button and this confirm_text one, so
+        # the question is framed as Yes/Cancel rather than adding separate
+        # Load buttons on top.
+        return context.window_manager.invoke_props_dialog(
+            self, width=420, title="Recover Autosaved File", confirm_text="Yes"
+        )
+
+    def _load_kwargs(self, filepath: str, skip_recent: bool) -> dict:
+        return dict(
+            filepath=filepath,
+            skip_autosave_recovery=True,  # Prevent infinite loop
+            is_advanced=self.is_advanced,
+            use_relative_path=self.use_relative_path,
+            should_start_fresh_session=self.should_start_fresh_session,
+            import_without_ifc_data=self.import_without_ifc_data,
+            skip_recent=skip_recent,
+        )
+
+    @staticmethod
+    def _defer(callback) -> None:
+        def on_timer() -> None:
+            callback()
+            return None
+
+        # bim.load_project (with should_start_fresh_session, our default)
+        # calls wm.read_homefile(), which tears down the window
+        # manager/screens/regions. Calling that synchronously from this
+        # dialog's execute()/cancel() - themselves invoked from deep inside
+        # Blender's modal handling for this popup's button click - frees
+        # data that the still-on-stack caller dereferences once we return,
+        # segfaulting Blender. Deferring by one timer tick runs the reload
+        # after the popup's own modal handling has fully unwound. The
+        # callback only closes over plain values (not `self`), since the
+        # operator instance itself may no longer be valid by the time the
+        # timer fires.
+        bpy.app.timers.register(on_timer, first_interval=0.0)
+
+    def execute(self, context):
+        kwargs = self._load_kwargs(self.autosaved_filepath, skip_recent=True)
+        original_filepath = self.original_filepath
+
+        def load_and_repoint() -> None:
+            bpy.ops.bim.load_project(**kwargs)
+            # Re-point tracking at the original path so future saves write
+            # back to it, not "_autosaved.ifc".
+            tool.Ifc.set_path(original_filepath)
+
+        self._defer(load_and_repoint)
+        return {"FINISHED"}
+
+    def cancel(self, context):
+        # Also reached via Escape or a click outside the dialog, not just Cancel.
+        kwargs = self._load_kwargs(self.original_filepath, skip_recent=False)
+        self._defer(lambda: bpy.ops.bim.load_project(**kwargs))
+
+
+class AutosavePrompt(bpy.types.Operator):
+    bl_idname = "bim.autosave_prompt"
+    bl_label = "Autosave Reminder"
+    bl_options = set()
+
+    def invoke(self, context, event):
+        return context.window_manager.invoke_props_dialog(
+            self, width=400, confirm_text="Save", title="Autosave Reminder"
+        )
+
+    def draw(self, context):
+        layout = self.layout
+        layout.label(text="The autosave timer has expired.", icon="INFO")
+        layout.label(text="Would you like to save your IFC project now?")
+
+    def execute(self, context):
+        # Get current IFC path
+        props = tool.Blender.get_bim_props()
+        current_ifc_path = props.ifc_file
+
+        if not current_ifc_path:
+            self.report({"WARNING"}, "No IFC file path set. Please save manually.")
+            tool.Autosave.reset_timer()
+            return {"CANCELLED"}
+
+        # Call save_project with explicit filepath using EXEC_DEFAULT
+        result = bpy.ops.bim.save_project(
+            "EXEC_DEFAULT", filepath=current_ifc_path, should_save_as=False, skip_recent=True
+        )
+
+        tool.Autosave.reset_timer()
+        return result
+
+    def cancel(self, context):
+        tool.Autosave.reset_timer()
+        return {"CANCELLED"}
+
+
 class LoadLinkedProject(bpy.types.Operator, ImportHelper):
     bl_idname = "bim.load_linked_project"
     bl_label = "Load Project For Viewing Only"

src/bonsai/bonsai/bim/module/project/prop.py

@@ -260,6 +260,11 @@ class Link(PropertyGroup):
         description="STEP ID of the IfcDocumentReference when linked to a parent IFC project. Zero when no parent IFC exists",
         default=0,
     )
+    query: StringProperty(
+        name="Query",
+        description="Selector query used to filter elements when loading the linked model",
+        default="",
+    )
 
     if TYPE_CHECKING:
         name: str
@@ -275,6 +280,7 @@ class Link(PropertyGroup):
         include_in_drawings: bool
         empty_handle: Union[bpy.types.Object, None]
         ifc_definition_id: int
+        query: str
 
 
 class EditedObj(PropertyGroup):

src/bonsai/bonsai/bim/module/project/ui.py

@@ -28,9 +28,8 @@ from bpy.types import Menu, Panel, UIList
 import bonsai.bim
 import bonsai.tool as tool
 from bonsai.bim.helper import draw_attributes, prop_with_search
-from bonsai.bim.ifc import IfcStore, is_cache_locked_by_other_process
+from bonsai.bim.ifc import IfcStore
 from bonsai.bim.module.project.data import LinksData, ProjectData
-from bonsai.bim.ui import draw_multiline_text
 
 if TYPE_CHECKING:
     from bonsai.bim.module.project.prop import (
@@ -167,20 +166,6 @@ class BIM_PT_project(Panel):
         if pprops.is_loading:
             self.draw_advanced_loading_ui(context)
         elif self.file or props.ifc_file:
-            if is_cache_locked_by_other_process():
-                box = self.layout.box()
-                box.alert = True
-                row = box.row(align=True)
-                row.label(text="IFC Already Open in Another Blender Instance", icon="ERROR")
-                row.operator("bim.dismiss_multi_instance_warning", text="", icon="CANCEL")
-                draw_multiline_text(
-                    box.column(align=True),
-                    "This file is open in another Blender instance. Editing the same "
-                    "IFC from two instances at once can lose your work or display "
-                    "outdated geometry. Close the other Blender instances to continue safely.",
-                    context=context,
-                )
-
             if props.has_blend_warning:
                 box = self.layout.box()
                 box.alert = True
@@ -190,35 +175,6 @@ class BIM_PT_project(Panel):
                 op.uri = "https://docs.bonsaibim.org/guides/troubleshooting.html#saving-and-loading-blend-files"
                 row.operator("bim.close_blend_warning", text="", icon="CANCEL")
 
-            if pending := pprops.pending_opening_recut:
-                box = self.layout.box()
-                box.alert = True
-                box.label(text="Opening Cuts Skipped", icon="ERROR")
-                draw_multiline_text(
-                    box.column(align=True),
-                    f"{len(pending)} element(s) had too many openings to cut during load. "
-                    f"Apply to recompute their meshes, or dismiss to leave them as they are.",
-                    context=context,
-                )
-                row = box.row(align=True)
-                row.operator("bim.select_pending_opening_cuts", text="Select Elements", icon="RESTRICT_SELECT_OFF")
-                row.operator("bim.apply_pending_opening_cuts", text="Apply Openings", icon="PLAY")
-                row.operator("bim.dismiss_pending_opening_cuts", text="", icon="CANCEL")
-
-            if pending := pprops.pending_array_repair:
-                box = self.layout.box()
-                box.alert = True
-                box.label(text="Arrays With Missing Children", icon="ERROR")
-                draw_multiline_text(
-                    box.column(align=True),
-                    f"{len(pending)} array parent(s) reference child GUIDs that don't exist in this file. "
-                    f"The arrays loaded incomplete. Select to inspect, or dismiss.",
-                    context=context,
-                )
-                row = box.row(align=True)
-                row.operator("bim.select_pending_array_repair", text="Select Elements", icon="RESTRICT_SELECT_OFF")
-                row.operator("bim.dismiss_pending_array_repair", text="", icon="CANCEL")
-
             if props.ifc_file:
                 self.draw_loaded_project_ui(context)
             else:

src/bonsai/bonsai/bim/module/spatial/decorator.py

@@ -18,43 +18,17 @@
 
 import blf
 import gpu
-from bpy.types import SpaceView3D
 from bpy_extras.view3d_utils import location_3d_to_region_2d
-from gpu_extras.batch import batch_for_shader
 from mathutils import Vector
 
 import bonsai.tool as tool
 
 
-class GridDecorator:
-    is_installed = False
-    handlers = []
-
-    @classmethod
-    def install(cls, context):
-        if cls.is_installed:
-            cls.uninstall()
-        handler = cls()
-        cls.handlers.append(SpaceView3D.draw_handler_add(handler.draw_text, (context,), "WINDOW", "POST_PIXEL"))
-        cls.handlers.append(SpaceView3D.draw_handler_add(handler.draw, (context,), "WINDOW", "POST_VIEW"))
-        cls.is_installed = True
-
-    @classmethod
-    def uninstall(cls):
-        for handler in cls.handlers:
-            try:
-                SpaceView3D.draw_handler_remove(handler, "WINDOW")
-            except ValueError:
-                pass
-        cls.is_installed = False
-
-    def draw_batch(self, shader_type, content_pos, color, indices=None):
-        if not tool.Blender.validate_shader_batch_data(content_pos, indices):
-            return
-        shader = self.line_shader if shader_type == "LINES" else self.shader
-        batch = batch_for_shader(shader, shader_type, {"pos": content_pos}, indices=indices)
-        shader.uniform_float("color", color)
-        batch.draw(shader)
+class GridDecorator(tool.Blender.ViewportDecorator):
+    draw_methods = (
+        ("draw_text", "POST_PIXEL"),
+        ("draw", "POST_VIEW"),
+    )
 
     def draw_text(self, context):
         if not tool.Blender.is_addon_enabled():

src/bonsai/bonsai/bim/module/structural/decorator.py

@@ -31,11 +31,17 @@ import bonsai.tool as tool
 from bonsai.bim.module.structural.load_decoration_data import ShaderInfo
 
 
-class LoadsDecorator:
+class LoadsDecorator(tool.Blender.ViewportDecorator):
     """Decorator to show structural loads in 3D"""
 
-    is_installed = False
-    handlers = []
+    # draw_methods exists to satisfy ViewportDecorator.__init_subclass__'s
+    # method-existence check; the override install below is what actually
+    # registers handlers (the POST_VIEW binding passes no context arg, which
+    # the base's generic install cannot express).
+    draw_methods = (
+        ("draw_load_values", "POST_PIXEL"),
+        ("__call__", "POST_VIEW"),
+    )
     decoration_data = None
     text_info = []
     shader_info = []
@@ -54,15 +60,6 @@ class LoadsDecorator:
         cls.update()
         cls.is_installed = True
 
-    @classmethod
-    def uninstall(cls) -> None:
-        for handler in cls.handlers:
-            try:
-                SpaceView3D.draw_handler_remove(handler, "WINDOW")
-            except ValueError:
-                pass
-        cls.is_installed = False
-
     @classmethod
     def update(cls) -> None:
         cls.decoration_data.update()

src/bonsai/bonsai/bim/module/structural/load_decoration_data.py

@@ -71,7 +71,11 @@ class LoadByDirection(TypedDict):
 
 ProcessedLoad = TypedDict(
     "ProcessedLoad",
-    {"linear loads": LoadByDirection, "max linear load": float, "discrete loads": list[list[DiscreteConfigItem]]},
+    {
+        "linear loads": dict[str, LoadByDirection] | None,
+        "max linear load": float,
+        "discrete loads": list[list[DiscreteConfigItem]],
+    },
 )
 
 
@@ -845,13 +849,16 @@ class ShaderInfo:
         v = l1[1] + fac * (pos - l1[0])
         return v
 
-    def interpolate(self, pos: float, loadinfo: list[LoadConfigItem], start: int, end: int, key: str) -> np.ndarray:
+    def interpolate(self, pos: float, loadinfo: list[LoadConfigItem], start: int, end: int) -> np.ndarray:
         """interpolate the result vectors between load poits"""
         result = np.zeros(6)
         for i in range(6):
-            value1 = [loadinfo[start]["pos"], loadinfo[start][key][i]]  # [position, force_component]
-            value2 = [loadinfo[end]["pos"], loadinfo[end][key][i]]  #      [position, force_component]
-            result[i] = self.interp1d(value1, value2, pos)  #             interpolated [position, force_component]
+            # [position, force_component]
+            value1 = [loadinfo[start]["pos"], loadinfo[start]["load values"][i]]
+            # [position, force_component]
+            value2 = [loadinfo[end]["pos"], loadinfo[end]["load values"][i]]
+            # interpolated [position, force_component]
+            result[i] = self.interp1d(value1, value2, pos)
         return result
 
     def get_before_and_after(self, pos: float, load_config_list: list[list[LoadConfigItem]]) -> dict[str, list[float]]:
@@ -895,8 +902,8 @@ class ShaderInfo:
                         load_before += config[end]["load values"]
 
                 elif end - start == 1:
-                    load_before += self.interpolate(pos, config, start, end, "load values")
-                    load_after += self.interpolate(pos, config, start, end, "load values")
+                    load_before += self.interpolate(pos, config, start, end)
+                    load_after += self.interpolate(pos, config, start, end)
                 start += 1
                 end -= 1
         return_value = {"before": load_before.tolist(), "after": load_after.tolist()}

src/bonsai/bonsai/bim/module/style/operator.py

@@ -744,7 +744,7 @@ class EnableEditingSurfaceStyle(bpy.types.Operator):
         if self.ifc_class == "IfcSurfaceStyleLighting":
 
             def callback(attribute_name: str, _: object, data: dict[str, Any]) -> None:
-                assert attributes
+                assert attributes is not None
                 color = attributes.add()
                 assert isinstance(color, ColourRgb)
                 color.name = attribute_name
@@ -782,34 +782,40 @@ class EditSurfaceStyle(bpy.types.Operator, tool.Ifc.Operator):
     def _execute(self, context):
         self.props = tool.Style.get_style_props()
         self.style = tool.Ifc.get().by_id(self.props.is_editing_style)
+        prev_update_graph = self.props.update_graph
+        self.props["update_graph"] = False
 
-        style_elements = tool.Style.get_style_elements(self.style)
-        # NOTE: currently this operator is used to edit existing (and only existing) IfcSurfaceStyles
-        # or new or existing IfcSurfaceStyle components (shading, etc)
-        # which is kind of confusing.
-        if self.props.is_editing_class == "IfcSurfaceStyle":
-            self.surface_style = self.style
-        else:
-            self.surface_style = style_elements.get(self.props.is_editing_class, None)
-            self.shading_style = style_elements.get("IfcSurfaceStyleShading", None)
-            self.rendering_style = style_elements.get("IfcSurfaceStyleRendering", None)
-            self.texture_style = style_elements.get("IfcSurfaceStyleWithTextures", None)
+        try:
+            style_elements = tool.Style.get_style_elements(self.style)
 
-        if self.surface_style:
-            result = self.edit_existing_style()
-        else:
-            result = self.add_new_style()
+            # NOTE: currently this operator is used to edit existing (and only existing) IfcSurfaceStyles
+            # or new or existing IfcSurfaceStyle components (shading, etc)
+            # which is kind of confusing.
+            if self.props.is_editing_class == "IfcSurfaceStyle":
+                self.surface_style = self.style
+            else:
+                self.surface_style = style_elements.get(self.props.is_editing_class, None)
+                self.shading_style = style_elements.get("IfcSurfaceStyleShading", None)
+                self.rendering_style = style_elements.get("IfcSurfaceStyleRendering", None)
+                self.texture_style = style_elements.get("IfcSurfaceStyleWithTextures", None)
 
-        if result:
-            return result
+            if self.surface_style:
+                result = self.edit_existing_style()
+            else:
+                result = self.add_new_style()
 
-        tool.Style.disable_editing()
-        core.load_styles(tool.Style, style_type=self.props.style_type)
+            if result:
+                return result
 
-        # restore selected style type
-        material = tool.Ifc.get_object(self.style)
-        msprops = tool.Style.get_material_style_props(material)
-        msprops.active_style_type = msprops.active_style_type
+            tool.Style.disable_editing()
+            core.load_styles(tool.Style, style_type=self.props.style_type)
+
+            # restore selected style type
+            material = tool.Ifc.get_object(self.style)
+            msprops = tool.Style.get_material_style_props(material)
+            msprops.active_style_type = msprops.active_style_type
+        finally:
+            self.props["update_graph"] = prev_update_graph
 
     def edit_existing_style(self) -> None:
         ifc_file = tool.Ifc.get()
@@ -1231,4 +1237,5 @@ class RemoveSurfaceStyle(bpy.types.Operator, tool.Ifc.Operator):
         surface_style = tool.Style.get_style_elements(style)[props.is_editing_class]
         ifcopenshell.api.style.remove_surface_style(ifc_file, surface_style)
         core.disable_editing_style(tool.Style)
+        core.load_styles(tool.Style, style_type=props.style_type)
         return {"FINISHED"}

src/bonsai/bonsai/bim/module/style/prop.py

@@ -185,6 +185,13 @@ class ColourRgb(PropertyGroup):
     # to fit blender.bim.helper.draw_attribute
     is_optional = False
     special_type = ""
+    data_type = ""
+    ifc_class = ""
+    use_explorer_ui = False
+
+    @property
+    def display_name(self):
+        return self.name
 
     def get_value_name(self, *args, **kwargs):
         return "color_value"

src/bonsai/bonsai/bim/module/style/ui.py

@@ -176,8 +176,30 @@ class BIM_PT_styles(Panel):
         row.prop(self.props, "reflectance_method")
 
         if self.props.reflectance_method not in ("PHYSICAL", "NOTDEFINED", "FLAT"):
-            self.layout.label(text="Supported reflectance methods are:")
-            self.layout.label(text="PHYSICAL / NOTDEFINED / FLAT")
+            self.layout.label(
+                text=f"{self.props.reflectance_method} will be skipped: only PHYSICAL / NOTDEFINED / FLAT are supported",
+                icon="ERROR",
+            )
+        elif self.props.reflectance_method in ("PHYSICAL", "NOTDEFINED"):
+            if self.props.specular_colour_class == "IfcColourRgb":
+                self.layout.label(
+                    text="Metallic color is IFC-only in PHYSICAL/NOTDEFINED and does not affect Blender appearance",
+                    icon="ERROR",
+                )
+        elif self.props.reflectance_method == "FLAT":
+            if self.props.diffuse_colour_class == "IfcNormalisedRatioMeasure":
+                self.layout.label(
+                    text="Emissive ratio is IFC-only in FLAT Reflectance method and does not affect Blender appearance",
+                    icon="ERROR",
+                )
+            self.layout.label(
+                text="Specular value is IFC-only in FLAT Reflectance method and does not affect Blender appearance",
+                icon="ERROR",
+            )
+            self.layout.label(
+                text="Highlight value is IFC-only in FLAT Reflectance method and does not affect Blender appearance",
+                icon="ERROR",
+            )
 
         row = self.layout.row(align=True)
         row.label(text="Emissive" if self.props.reflectance_method == "FLAT" else "Diffuse")
@@ -232,6 +254,8 @@ class BIM_PT_styles(Panel):
         row.operator("bim.add_surface_texture", text="", icon="ADD")
         if textures:
             self.layout.prop(self.props, "uv_mode")
+            if self.props.uv_mode in ("Generated", "Camera"):
+                self.layout.label(text="Not available in SOLID Mode", icon="INFO")
 
         for i, texture in enumerate(textures):
             split = self.layout.split(factor=0.30, align=True)
@@ -244,6 +268,22 @@ class BIM_PT_styles(Panel):
             op_clear = row.operator("bim.remove_texture_map", text="", icon="X")
             op_path.texture_map_index = op_clear.texture_map_index = i
 
+            reflectance = self.props.reflectance_method
+            mode = texture.mode
+            if reflectance == "FLAT":
+                if mode != "EMISSIVE":
+                    self.layout.label(
+                        text=f"{mode} will be skipped: only EMISSIVE is supported for Render Reflectance FLAT",
+                        icon="ERROR",
+                    )
+            elif reflectance in ("PHYSICAL", "NOTDEFINED"):
+                _SUPPORTED = {"DIFFUSE", "NORMAL", "METALLICROUGHNESS", "EMISSIVE", "OCCLUSION"}
+                if mode not in _SUPPORTED:
+                    self.layout.label(
+                        text=f"{mode} will be skipped: not supported for Render Reflectance PHYSICAL/NOTDEFINED",
+                        icon="ERROR",
+                    )
+
     def draw_externally_defined_surface_style(self):
         row = self.layout.row()
         op = row.operator("bim.browse_external_style", icon="APPEND_BLEND", text="Append From Blend File")
@@ -252,10 +292,17 @@ class BIM_PT_styles(Panel):
         bonsai.bim.helper.draw_attributes(self.props.external_style_attributes, self.layout, enable_search=True)
 
     def draw_refraction_surface_style(self):
+        self.layout.label(
+            text="Refraction values are IFC-only and do not affect Blender surface appearance",
+            icon="ERROR",
+        )
         bonsai.bim.helper.draw_attributes(self.props.refraction_style_attributes, self.layout, enable_search=True)
-        row = self.layout.row(align=True)
 
     def draw_lighting_surface_style(self):
+        self.layout.label(
+            text="Lighting values are IFC-only and do not affect Blender surface appearance",
+            icon="ERROR",
+        )
         bonsai.bim.helper.draw_attributes(self.props.lighting_style_colours, self.layout)
 
     def draw_edit_ui(self, edit_label: str):

src/bonsai/bonsai/bim/module/system/decorator.py

@@ -31,12 +31,6 @@ ERROR_ELEMENTS_COLOR = (1, 0.2, 0.322, 1)  # RED
 UNSPECIAL_ELEMENT_COLOR = (0.2, 0.2, 0.2, 1)  # GREY
 
 
-def transparent_color(color, alpha=0.1):
-    color = [i for i in color]
-    color[3] = alpha
-    return color
-
-
 @persistent
 def toggle_decorations_on_load(*args):
     props = tool.System.get_system_props()
@@ -80,7 +74,7 @@ class SystemDecorator:
 
     def draw_faces(self, bm, vertices_coords):
         """Submit a non-mutating beauty-triangulated TRIS batch over ``bm``'s faces."""
-        faces_color = transparent_color(self.addon_prefs.decorator_color_special)
+        faces_color = tool.Blender.transparent_color(self.addon_prefs.decorator_color_special)
         tool.Blender.draw_bmesh_face_tris(bm, vertices_coords, faces_color, self.draw_batch)
 
     def __call__(self, context, get_custom_bmesh=None, draw_faces=False, exit_edit_mode_callback=None):
@@ -128,13 +122,15 @@ class SystemDecorator:
         self.shader = gpu.shader.from_builtin("UNIFORM_COLOR")
         self.shader.bind()
 
-        self.draw_batch("LINES", all_vertices, transparent_color(unselected_elements_color), unselected_edges)
+        self.draw_batch(
+            "LINES", all_vertices, tool.Blender.transparent_color(unselected_elements_color), unselected_edges
+        )
         self.draw_batch("LINES", all_vertices, selected_elements_color, selected_edges)
         self.draw_batch("LINES", all_vertices, UNSPECIAL_ELEMENT_COLOR, arc_edges)
         self.draw_batch("LINES", all_vertices, special_elements_color, preview_edges)
         self.draw_batch("LINES", all_vertices, special_elements_color, roof_angle_edges)
 
-        self.draw_batch("POINTS", unselected_vertices, transparent_color(unselected_elements_color, 0.5))
+        self.draw_batch("POINTS", unselected_vertices, tool.Blender.transparent_color(unselected_elements_color, 0.5))
         self.draw_batch("POINTS", error_vertices, ERROR_ELEMENTS_COLOR)
         self.draw_batch("POINTS", special_vertices, special_elements_color)
         self.draw_batch("POINTS", selected_vertices, selected_elements_color)

src/bonsai/bonsai/bim/module/type/operator.py

@@ -65,10 +65,28 @@ class AssignType(bpy.types.Operator, tool.Ifc.Operator):
             if active_drawing:
                 active_target_view = tool.Drawing.get_drawing_target_view(active_drawing)
 
+        compatible: list[tuple[bpy.types.Object, ifcopenshell.entity_instance]] = []
+        skipped_classes: set[str] = set()
         for obj in related_objects:
             element = tool.Ifc.get_entity(obj)
             if not element or not element.is_a("IfcObject"):
                 continue
+            if not tool.Type.is_relating_type_compatible(element, relating_type):
+                skipped_classes.add(element.is_a())
+                continue
+            compatible.append((obj, element))
+
+        if skipped_classes:
+            self.report(
+                {"WARNING"},
+                f"Skipped {', '.join(sorted(skipped_classes))}: not a valid occurrence for " f"{relating_type.is_a()}.",
+            )
+
+        if not compatible:
+            self.report({"ERROR"}, f"No selected object can be typed by {relating_type.is_a()}.")
+            return {"CANCELLED"}
+
+        for obj, element in compatible:
             core.assign_type(tool.Ifc, tool.Model, tool.Type, element=element, type=relating_type)
 
             # Switch to the drawing's target view if available
@@ -376,12 +394,22 @@ class DuplicateType(bpy.types.Operator, tool.Ifc.Operator):
         if self.assign_selected_objects:
             selected_objects = tool.Blender.get_selected_objects()
             prefs = tool.Blender.get_addon_preferences()
+            skipped_classes: set[str] = set()
             for selected_obj in selected_objects:
                 selected_element = tool.Ifc.get_entity(selected_obj)
-                if selected_element and selected_element.is_a("IfcObject"):
-                    core.assign_type(tool.Ifc, tool.Model, tool.Type, element=selected_element, type=new)
-                    if prefs.occurrence_name_style == "TYPE":
-                        selected_obj.name = tool.Model.generate_occurrence_name(new, selected_element.is_a())
+                if not selected_element or not selected_element.is_a("IfcObject"):
+                    continue
+                if not tool.Type.is_relating_type_compatible(selected_element, new):
+                    skipped_classes.add(selected_element.is_a())
+                    continue
+                core.assign_type(tool.Ifc, tool.Model, tool.Type, element=selected_element, type=new)
+                if prefs.occurrence_name_style == "TYPE":
+                    selected_obj.name = tool.Model.generate_occurrence_name(new, selected_element.is_a())
+            if skipped_classes:
+                self.report(
+                    {"WARNING"},
+                    f"Skipped {', '.join(sorted(skipped_classes))}: not a valid occurrence for " f"{new.is_a()}.",
+                )
 
         if obj in context.selectable_objects:
             tool.Blender.select_and_activate_single_object(context, new_obj)

src/bonsai/bonsai/bim/module/void/operator.py

@@ -26,7 +26,7 @@ import bonsai.bim.handler
 import bonsai.core.geometry
 import bonsai.core.root
 import bonsai.tool as tool
-from bonsai.bim.module.model.opening import FilledOpeningGenerator
+from bonsai.bim.module.model.opening import FilledOpeningGenerator, is_filling_supported
 
 
 class AddOpening(bpy.types.Operator, tool.Ifc.Operator):
@@ -34,11 +34,13 @@ class AddOpening(bpy.types.Operator, tool.Ifc.Operator):
     bl_label = "Apply Opening"
     bl_options = {"REGISTER", "UNDO"}
     bl_description = (
-        "Apply opening objects to an Element.\n\n"
-        "The Element and the openings to be applied should be selected. The order of selection is not important.\n"
-        "Opening can be just a Blender mesh object.\n\n"
-        "Shift+click: keep the filling at its current matrix_world — skip the wall-axis snap "
-        "and the rl1/rl2 Z-elevation default that the regular click applies."
+        "Cuts openings in a wall, slab, or roof using selected shape objects — "
+        "doors, windows, existing openings, or plain (non-IFC) meshes. "
+        "Selection order doesn't matter.\n\n"
+        "Doors and windows also fill the opening. Other IFC classes are currently "
+        "unsupported by the opening generator and get skipped with a warning.\n\n"
+        "Shift+click: keep each opening at its shape object's current position "
+        "instead of snapping to the wall."
     )
 
     # Toggled by ``invoke`` when the user holds SHIFT during a gizmo / hotkey
@@ -59,6 +61,12 @@ class AddOpening(bpy.types.Operator, tool.Ifc.Operator):
         return self.execute(context)
 
     def _execute(self, context):
+        # Multi-opening drops on the same host fan out N update_representation
+        # writes + N switch_representation recuts without batching. Coalesce.
+        with tool.Geometry.batch_host_recut():
+            return self._add_openings(context)
+
+    def _add_openings(self, context):
         selected_objects = context.selected_objects
         target_object = selected_objects[0]
 
@@ -78,8 +86,14 @@ class AddOpening(bpy.types.Operator, tool.Ifc.Operator):
                     self.report({"INFO"}, "You can't add an opening to another opening.")
                     continue
                 elif not element1.is_a("IfcOpeningElement") and not element2.is_a("IfcOpeningElement"):
-                    if element1.is_a("IfcWindow") or element1.is_a("IfcDoor"):  # Add a fill to an element.
+                    if is_filling_supported(element1):  # Add a fill to an element.
                         obj1, obj2 = obj2, obj1
+                    elif not is_filling_supported(element2):
+                        self.report(
+                            {"INFO"},
+                            f"Cannot apply {element2.is_a()} as an opening — Bonsai currently supports only IfcDoor and IfcWindow as parametric fillings.",
+                        )
+                        continue
                     FilledOpeningGenerator().generate(
                         obj2,
                         obj1,
@@ -165,7 +179,7 @@ class AddOpening(bpy.types.Operator, tool.Ifc.Operator):
                             voided_obj.scale = (1.0, 1.0, 1.0)
                             tool.Ifc.finish_edit(voided_obj)
                         else:
-                            bpy.ops.bim.update_representation(obj=voided_obj.name)
+                            tool.Geometry.update_host_representation(voided_obj)
 
                     if tool.Ifc.is_moved(voided_obj):
                         bonsai.core.geometry.edit_object_placement(
@@ -174,12 +188,7 @@ class AddOpening(bpy.types.Operator, tool.Ifc.Operator):
 
                     representation = tool.Geometry.get_active_representation(voided_obj)
                     assert representation
-                    bonsai.core.geometry.switch_representation(
-                        tool.Ifc,
-                        tool.Geometry,
-                        obj=voided_obj,
-                        representation=representation,
-                    )
+                    tool.Geometry.recut_host(voided_obj, representation)
                 tool.Geometry.lock_scale(voided_obj)
 
             if not has_visible_openings:
@@ -217,12 +226,7 @@ class RemoveOpening(bpy.types.Operator, tool.Ifc.Operator):
             if building_obj and building_obj.data:
                 representation = tool.Geometry.get_active_representation(building_obj)
                 assert representation
-                bonsai.core.geometry.switch_representation(
-                    tool.Ifc,
-                    tool.Geometry,
-                    obj=building_obj,
-                    representation=representation,
-                )
+                tool.Geometry.recut_host(building_obj, representation)
         tool.Geometry.unlock_scale_object_with_openings(obj)
         tool.Geometry.clear_cache(element)
         return {"FINISHED"}

src/bonsai/bonsai/bim/ui.py

@@ -39,21 +39,10 @@ from natsort import natsorted
 import bonsai.bim
 import bonsai.bim.helper
 import bonsai.tool as tool
+from bonsai.bim.ifc import is_cache_locked_by_other_process
 from bonsai.bim.module.bsdd.prop import BIMBSDDProperties, BSDDProperty
-from bonsai.bim.module.model.prop import (
-    BIMDoorProperties,
-    BIMRailingProperties,
-    BIMRoofProperties,
-    BIMStairProperties,
-    BIMWindowProperties,
-)
-from bonsai.bim.module.model.ui import (
-    draw_door_properties,
-    draw_railing_properties,
-    draw_roof_properties,
-    draw_stair_properties,
-    draw_window_properties,
-)
+from bonsai.bim.module.model import prop as _model_prop
+from bonsai.bim.module.model import ui as _model_ui
 from bonsai.bim.module.pset.prop import IfcProperty
 from bonsai.bim.prop import Attribute
 
@@ -278,34 +267,29 @@ class BIM_UL_panel_visibilities(bpy.types.UIList):
 class GizmoPreferences(bpy.types.PropertyGroup):
     """Aggregator for parametric gizmo visibility settings. One flat bool per
     parametric feature; controls whether that feature's gizmo group polls
-    visible in the viewport."""
+    visible in the viewport.
+
+    The per-feature ``<name>: BoolProperty`` fields are derived from
+    ``tool.Parametric.EDIT_TYPES`` at module load — adding a new parametric
+    type to the registry automatically surfaces its toggle here, with no
+    parallel hand-maintained list to keep in sync."""
 
     draw_gizmos_in_3d_viewport: BoolProperty(
         name="Draw Gizmos In 3D Viewport",
         default=True,
         description="Show interactive gizmos in the 3D viewport for parametric elements",
     )
-    door: BoolProperty(name="Door", default=True)
-    window: BoolProperty(name="Window", default=True)
-    stair: BoolProperty(name="Stair", default=True)
-    railing: BoolProperty(name="Railing", default=True)
-    roof: BoolProperty(name="Roof", default=True)
-    array: BoolProperty(name="Array", default=True)
-    pipe_segment: BoolProperty(name="Pipe Segment", default=True)
-    duct_segment: BoolProperty(name="Duct Segment", default=True)
-    wall: BoolProperty(name="Wall", default=True)
 
     if TYPE_CHECKING:
         draw_gizmos_in_3d_viewport: bool
-        door: bool
-        window: bool
-        stair: bool
-        railing: bool
-        roof: bool
-        array: bool
-        pipe_segment: bool
-        duct_segment: bool
-        wall: bool
+
+
+for _gizmo_pref_entry in tool.Parametric.EDIT_TYPES:
+    GizmoPreferences.__annotations__[_gizmo_pref_entry.name] = BoolProperty(
+        name=_gizmo_pref_entry.name.replace("_", " ").title(),
+        default=True,
+    )
+del _gizmo_pref_entry
 
 
 class DocPreferences(bpy.types.PropertyGroup):
@@ -401,11 +385,22 @@ class DocPreferences(bpy.types.PropertyGroup):
 
 
 class DefaultParameters(bpy.types.PropertyGroup):
-    door: bpy.props.PointerProperty(type=BIMDoorProperties)
-    window: bpy.props.PointerProperty(type=BIMWindowProperties)
-    railing: bpy.props.PointerProperty(type=BIMRailingProperties)
-    roof: bpy.props.PointerProperty(type=BIMRoofProperties)
-    stair: bpy.props.PointerProperty(type=BIMStairProperties)
+    """Per-type preset values used to seed new parametric instances.
+
+    The ``<name>: PointerProperty`` fields are derived from the subset of
+    ``tool.Parametric.EDIT_TYPES`` flagged ``has_default_parameters=True``,
+    each pointing at the matching ``BIM<Name>Properties`` class. Adding a
+    new entry with that flag automatically surfaces a preferences section
+    and gives the create operator a preset to copy from."""
+
+
+for _default_params_entry in tool.Parametric.EDIT_TYPES:
+    if not _default_params_entry.has_default_parameters:
+        continue
+    DefaultParameters.__annotations__[_default_params_entry.name] = bpy.props.PointerProperty(
+        type=getattr(_model_prop, _default_params_entry.props_attr),
+    )
+del _default_params_entry
 
 
 class BIM_ADDON_preferences(bpy.types.AddonPreferences):
@@ -582,6 +577,43 @@ class BIM_ADDON_preferences(bpy.types.AddonPreferences):
     should_disable_undo_on_save: BoolProperty(
         name="Disable Undo When Saving (Faster saves, no undo for you!)", default=False
     )
+
+    def update_autosave_settings(self, context: bpy.types.Context) -> None:
+        if self.autosave_enabled:
+            tool.Autosave.reset_timer()
+        else:
+            tool.Autosave.cancel_timer()
+
+    autosave_enabled: BoolProperty(
+        name="Enable IFC Autosave Timer",
+        description="Periodically remind you to save or automatically create a backup copy of the IFC file",
+        default=False,
+        update=update_autosave_settings,
+    )
+    autosave_interval_minutes: bpy.props.IntProperty(
+        name="Autosave Interval (Minutes)",
+        description="Time between autosave reminders or backups. The timer resets whenever you open or save a project",
+        default=10,
+        min=1,
+        max=1440,
+        update=update_autosave_settings,
+    )
+    autosave_mode: bpy.props.EnumProperty(
+        name="Autosave Mode",
+        items=[
+            (
+                "PROMPT",
+                "Prompt to Save",
+                "Show a dialog offering to save the IFC project when the timer expires",
+            ),
+            (
+                "BACKUP",
+                "Automatic Backup",
+                "Save a backup copy as filename_autosaved.ifc when the timer expires",
+            ),
+        ],
+        default="PROMPT",
+    )
     should_stream: BoolProperty(name="Stream Data From IFC-SPF (Only for advanced users)", default=False)
     should_always_cache: BoolProperty(
         name="Always Cache Geometry",
@@ -694,6 +726,9 @@ class BIM_ADDON_preferences(bpy.types.AddonPreferences):
         bsdd_load_test_dictionaries: bool
         bsdd_baseurl: str
         should_disable_undo_on_save: bool
+        autosave_enabled: bool
+        autosave_interval_minutes: int
+        autosave_mode: Literal["PROMPT", "BACKUP"]
         should_stream: bool
         should_always_cache: bool
         occurrence_name_style: Literal["CLASS", "TYPE", "CUSTOM"]
@@ -827,40 +862,27 @@ class BIM_ADDON_preferences(bpy.types.AddonPreferences):
 
     def draw_default_parameters(self, layout: bpy.types.UILayout, context: bpy.types.Context) -> None:
         box = layout.box()
-        bonsai.bim.helper.draw_expandable_panel(
-            box,
-            context,
-            "Door",
-            lambda _layout, _context: draw_door_properties(_layout, self.default_parameters.door),
-        )
-        bonsai.bim.helper.draw_expandable_panel(
-            box,
-            context,
-            "Window",
-            lambda _layout, _context: draw_window_properties(_layout, self.default_parameters.window),
-        )
-        bonsai.bim.helper.draw_expandable_panel(
-            box,
-            context,
-            "Railing",
-            lambda _layout, _context: draw_railing_properties(_layout, self.default_parameters.railing),
-        )
-        bonsai.bim.helper.draw_expandable_panel(
-            box,
-            context,
-            "Roof",
-            lambda _layout, _context: draw_roof_properties(_layout, self.default_parameters.roof),
-        )
-        bonsai.bim.helper.draw_expandable_panel(
-            box,
-            context,
-            "Stair",
-            lambda _layout, _context: draw_stair_properties(_layout, self.default_parameters.stair),
-        )
+        for entry in tool.Parametric.EDIT_TYPES:
+            if not entry.has_default_parameters:
+                continue
+            props = getattr(self.default_parameters, entry.name)
+            draw_props = getattr(_model_ui, f"draw_{entry.name}_properties")
+            bonsai.bim.helper.draw_expandable_panel(
+                box,
+                context,
+                entry.name.replace("_", " ").title(),
+                lambda _layout, _context, _draw=draw_props, _props=props: _draw(_layout, _props),
+            )
 
     def draw_other_settings(self, layout: bpy.types.UILayout, context: bpy.types.Context) -> None:
         layout.prop(self, "opening_focus_opacity")
         layout.prop(self, "should_disable_undo_on_save")
+        layout.separator()
+        layout.label(text="Autosave:")
+        layout.prop(self, "autosave_enabled")
+        if self.autosave_enabled:
+            layout.prop(self, "autosave_interval_minutes")
+            layout.prop(self, "autosave_mode")
         layout.prop(self, "should_stream")
         layout.prop(self, "should_always_cache")
         layout.label(text="bSDD:")
@@ -974,6 +996,50 @@ class BIM_PT_tabs(Panel):
             op.uri = "https://docs.bonsaibim.org/guides/troubleshooting.html#saving-and-loading-blend-files"
             row.operator("bim.close_blend_warning", text="", icon="CANCEL")
 
+        if is_cache_locked_by_other_process():
+            box = self.layout.box()
+            box.alert = True
+            row = box.row(align=True)
+            row.label(text="IFC Already Open in Another Blender Instance", icon="ERROR")
+            row.operator("bim.dismiss_multi_instance_warning", text="", icon="CANCEL")
+            draw_multiline_text(
+                box.column(align=True),
+                "This file is open in another Blender instance. Editing the same "
+                "IFC from two instances at once can lose your work or display "
+                "outdated geometry. Close the other Blender instances to continue safely.",
+                context=context,
+            )
+
+        pprops = tool.Project.get_project_props()
+        if pending := pprops.pending_opening_recut:
+            box = self.layout.box()
+            box.alert = True
+            box.label(text="Opening Cuts Skipped", icon="ERROR")
+            draw_multiline_text(
+                box.column(align=True),
+                f"{len(pending)} element(s) had too many openings to cut during load. "
+                f"Apply to recompute their meshes, or dismiss to leave them as they are.",
+                context=context,
+            )
+            row = box.row(align=True)
+            row.operator("bim.select_pending_opening_cuts", text="Select Elements", icon="RESTRICT_SELECT_OFF")
+            row.operator("bim.apply_pending_opening_cuts", text="Apply Openings", icon="PLAY")
+            row.operator("bim.dismiss_pending_opening_cuts", text="", icon="CANCEL")
+
+        if pending := pprops.pending_array_repair:
+            box = self.layout.box()
+            box.alert = True
+            box.label(text="Arrays With Missing Children", icon="ERROR")
+            draw_multiline_text(
+                box.column(align=True),
+                f"{len(pending)} array parent(s) reference child GUIDs that don't exist in this file. "
+                f"The arrays loaded incomplete. Select to inspect, or dismiss.",
+                context=context,
+            )
+            row = box.row(align=True)
+            row.operator("bim.select_pending_array_repair", text="Select Elements", icon="RESTRICT_SELECT_OFF")
+            row.operator("bim.dismiss_pending_array_repair", text="", icon="CANCEL")
+
         gprops = tool.Geometry.get_geometry_props()
         # Check that Blender mode and IFC Mode do match.
         if context.mode == "OBJECT" and gprops.mode in ("OBJECT", "ITEM"):

src/bonsai/bonsai/core/connection.py

@@ -22,11 +22,18 @@
 
 Used by both ``bim.disconnect_elements`` (explicit user disconnect) and the
 connection cascade in ``tool.Geometry.delete_ifc_object`` (implicit
-disconnect-on-delete). Each rel kind returned by
+disconnect-on-delete). Each kind returned by
 :py:meth:`bonsai.tool.connection.Connection.find_rels` /
 :py:meth:`find_rels_for_element` maps to a single arm here, so adding a new
-rel kind means extending one dispatch table — both call sites benefit
+kind means extending one dispatch table — both call sites benefit
 automatically and the AST forward-compat guard enforces coverage.
+
+The ``subject`` parameter is the entity whose teardown effects the
+disconnect: for ``"path"`` / ``"element"`` / ``"element-top"`` kinds it
+carries an ``IfcRel*`` relationship entity (the rel that gets removed);
+for ``"mep-pair-fitting"`` it carries an ``IfcFlowFitting`` (the fitting
+that gets deleted). The slot is uniform on intent — the dispatch decides
+the teardown mechanism by kind.
 """
 
 from __future__ import annotations
@@ -37,25 +44,24 @@ import bonsai.core.geometry
 from bonsai.core.model import regenerate_wall_to_underside
 
 if TYPE_CHECKING:
-    import bpy
     import ifcopenshell
 
     import bonsai.tool as tool
 
 
 def disconnect_rel(
-    ifc: "type[tool.Ifc]",
-    geometry: "type[tool.Geometry]",
-    model: "type[tool.Model]",
-    connection: "type[tool.Connection]",
-    rel: "ifcopenshell.entity_instance",
+    ifc: type[tool.Ifc],
+    geometry: type[tool.Geometry],
+    model: type[tool.Model],
+    connection: type[tool.Connection],
+    subject: ifcopenshell.entity_instance,
     kind: str,
-    elem: "ifcopenshell.entity_instance",
-    partner: "ifcopenshell.entity_instance",
+    elem: ifcopenshell.entity_instance,
+    partner: ifcopenshell.entity_instance,
     skip_elem_recreate: bool = False,
     skip_partner_recreate: bool = False,
 ) -> None:
-    """Run the post-disconnect cleanup for one rel.
+    """Run the post-disconnect cleanup for one connection.
 
     ``elem`` and ``partner`` are the two endpoints. The ``skip_*_recreate``
     flags suppress per-side regenerate / recreate work — used by the
@@ -65,7 +71,7 @@ def disconnect_rel(
     runs on both sides.
     """
     if kind == "path":
-        bonsai.core.geometry.remove_connection(geometry, connection=rel)
+        bonsai.core.geometry.remove_connection(geometry, connection=subject)
         if not skip_elem_recreate:
             elem_obj = ifc.get_object(elem)
             if elem_obj is not None:
@@ -75,11 +81,11 @@ def disconnect_rel(
             if partner_obj is not None:
                 model.recreate_wall(partner, partner_obj)
     elif kind == "element-top":
-        wall, _slab = connection.orient_element_top(rel, elem, partner)
+        wall, _slab = connection.orient_element_top(subject, elem, partner)
         ifc.run(
             "geometry.disconnect_element",
-            relating_element=rel.RelatingElement,
-            related_element=rel.RelatedElement,
+            relating_element=subject.RelatingElement,
+            related_element=subject.RelatedElement,
         )
         # Skip the wall-side regenerate when the wall is itself being deleted —
         # either it's the elem of this cascade pass, or it's the partner that
@@ -92,8 +98,16 @@ def disconnect_rel(
     elif kind == "element":
         ifc.run(
             "geometry.disconnect_element",
-            relating_element=rel.RelatingElement,
-            related_element=rel.RelatedElement,
+            relating_element=subject.RelatingElement,
+            related_element=subject.RelatedElement,
         )
+    elif kind == "mep-pair-fitting":
+        if skip_elem_recreate and subject is elem:
+            return
+        if skip_partner_recreate and subject is partner:
+            return
+        fitting_obj = ifc.get_object(subject)
+        if fitting_obj is not None:
+            geometry.delete_ifc_object(fitting_obj)
     else:
-        raise ValueError(f"Unknown rel kind: {kind!r}")
+        raise ValueError(f"Unknown kind: {kind!r}")

src/bonsai/bonsai/core/drawing.py

@@ -302,9 +302,15 @@ def add_drawing(
         context=drawing.get_body_context(),
         ifc_representation_class=None,
     )
+
+    drawings_parent_group = drawing.ensure_drawings_parent_group()
+
     group = ifc.run("group.add_group")
     ifc.run("group.edit_group", group=group, attributes={"Name": drawing_name, "ObjectType": "DRAWING"})
     ifc.run("group.assign_group", group=group, products=[element])
+
+    ifc.run("group.assign_group", group=drawings_parent_group, products=[group])
+
     collector.assign(camera)
     pset = ifc.run("pset.add_pset", product=element, name="EPset_Drawing")
     if drawing.get_unit_system() == "METRIC":
@@ -335,7 +341,10 @@ def add_drawing(
         },
     )
     drawing.setup_shading_styles_path(shading_styles_path)
-    information = ifc.run("document.add_information")
+
+    drawings_parent_document = drawing.ensure_drawings_parent_document()
+
+    information = ifc.run("document.add_information", parent=drawings_parent_document)
     uri = drawing.get_default_drawing_path(drawing_name)
     reference = ifc.run("document.add_reference", information=information)
     if ifc.get_schema() == "IFC2X3":
@@ -363,9 +372,13 @@ def duplicate_drawing(
     drawing_tool.set_name(new_drawing, drawing_name)
     group = drawing_tool.get_drawing_group(new_drawing)
     ifc.run("group.unassign_group", group=group, products=[new_drawing])
+
+    drawings_parent_group = drawing_tool.ensure_drawings_parent_group()
+
     new_group = ifc.run("group.add_group")
     ifc.run("group.edit_group", group=new_group, attributes={"Name": drawing_name, "ObjectType": "DRAWING"})
     ifc.run("group.assign_group", group=new_group, products=[new_drawing])
+    ifc.run("group.assign_group", group=drawings_parent_group, products=[new_group])
     if should_duplicate_annotations:
         new_annotations: list[ifcopenshell.entity_instance] = []
         annotation_objs = [ifc.get_object(a) for a in drawing_tool.get_group_elements(group) if a != drawing]
@@ -381,7 +394,9 @@ def duplicate_drawing(
     old_reference = drawing_tool.get_drawing_document(new_drawing)
     ifc.run("document.unassign_document", products=[new_drawing], document=old_reference)
 
-    information = ifc.run("document.add_information")
+    drawings_parent_document = drawing_tool.ensure_drawings_parent_document()
+
+    information = ifc.run("document.add_information", parent=drawings_parent_document)
     uri = drawing_tool.get_default_drawing_path(drawing_name)
     reference = ifc.run("document.add_reference", information=information)
     if ifc.get_schema() == "IFC2X3":

src/bonsai/bonsai/core/product.py

@@ -1,64 +0,0 @@
-# Bonsai - OpenBIM Blender Add-on
-# Copyright (C) 2026
-#
-# This file is part of Bonsai.
-#
-# Bonsai is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# Bonsai is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with Bonsai.  If not, see <http://www.gnu.org/licenses/>.
-#
-# This file was generated with the assistance of an AI coding tool.
-
-from __future__ import annotations
-
-import math
-from collections.abc import Iterable
-from typing import TYPE_CHECKING
-
-import bonsai.core.geometry
-
-if TYPE_CHECKING:
-    import bpy
-
-    import bonsai.tool as tool
-
-
-Z_ROTATION_ALIGNMENT_TOLERANCE = 1e-9
-
-
-def _z_rotation_diff(target_z: float, source_z: float) -> float:
-    """Signed Z-Euler difference wrapped to [-π, π]."""
-    return (target_z - source_z + math.pi) % (2 * math.pi) - math.pi
-
-
-def copy_z_rotation_to_selected(
-    ifc: type[tool.Ifc],
-    geometry: type[tool.Geometry],
-    surveyor: type[tool.Surveyor],
-    *,
-    active: bpy.types.Object,
-    targets: Iterable[bpy.types.Object],
-    flip: bool = False,
-) -> int:
-    """Apply ``active``'s Z-Euler rotation to each target."""
-    source_z = surveyor.get_z_rotation(active)
-    if flip:
-        source_z += math.pi
-    rotated = 0
-    for obj in targets:
-        if abs(_z_rotation_diff(surveyor.get_z_rotation(obj), source_z)) < Z_ROTATION_ALIGNMENT_TOLERANCE:
-            continue
-        surveyor.set_z_rotation(obj, source_z)
-        rotated += 1
-        if ifc.get_entity(obj) is not None:
-            bonsai.core.geometry.edit_object_placement(ifc, geometry, surveyor, obj=obj)
-    return rotated

src/bonsai/bonsai/core/tool.py

@@ -254,7 +254,6 @@ class Cost:
     def get_cost_schedule(cls, cost_schedule): pass
     def get_cost_value_attributes(cls): pass
     def get_cost_value_unit_component(cls): pass
-    def get_direct_cost_item_products(cls): pass
     def get_highlighted_cost_item(cls): pass
     def get_products(cls, related_object_type): pass
     def get_schedule_cost_items(cls, cost_schedule): pass
@@ -355,6 +354,8 @@ class Drawing:
     def enable_editing_schedules(cls): pass
     def enable_editing_sheets(cls): pass
     def enable_editing_text(cls, obj): pass
+    def ensure_drawings_parent_document(cls): pass
+    def ensure_drawings_parent_group(cls): pass
     def ensure_unique_drawing_name(cls, name): pass
     def ensure_unique_identification(cls, identification): pass
     def export_font_size(cls, obj): pass
@@ -804,7 +805,7 @@ class Profile:
 
 @interface
 class Parametric:
-    def get_geom_generation(cls) -> int: pass
+    def get_geom_generation(cls): pass
     def refresh_post_commit(cls, operator) -> None: pass
 
 
@@ -1170,8 +1171,6 @@ class Style:
 @interface
 class Surveyor:
     def get_absolute_matrix(cls, obj): pass
-    def get_z_rotation(cls, obj): pass
-    def set_z_rotation(cls, obj, z): pass
 
 
 @interface
@@ -1208,6 +1207,7 @@ class Type:
     def get_representation_context(cls, representation): pass
     def get_type_occurrences(cls, element_type): pass
     def has_material_usage(cls, element): pass
+    def is_relating_type_compatible(cls, occurrence, relating_type): pass
     def record_material_usage_attributes(cls, element): pass
     def restore_material_usage_attributes(cls, element, usage_attributes): pass
     def run_geometry_add_representation(cls, obj=None, context=None, ifc_representation_class=None, profile_set_usage=None): pass

src/bonsai/bonsai/tool/__init__.py

@@ -80,3 +80,6 @@ from bonsai.tool.type import Type
 from bonsai.tool.unit import Unit
 from bonsai.tool.wall import Wall
 from bonsai.tool.web import Web
+
+# Have to move after import of tool.drawing
+from bonsai.tool.autosave import Autosave  # isort: skip

src/bonsai/bonsai/tool/array.py

@@ -178,6 +178,25 @@ class Array(bonsai.core.tool.Array):
         element_root = cls.get_array_root_guid(element)
         return [o for o in occurrences if cls.get_array_root_guid(o) == element_root]
 
+    @classmethod
+    def select_only_parent(cls, parent_obj: bpy.types.Object, context: bpy.types.Context) -> None:
+        """Post-condition for the user-facing regenerate and finish-edit paths:
+        only ``parent_obj`` is selected + active. Grow and shrink otherwise
+        diverge on which objects stay selected, surfacing an inconsistency."""
+        tool.Blender.select_and_activate_single_object(context, parent_obj)
+
+    @classmethod
+    def is_array_child(cls, element: entity_instance) -> bool:
+        """True when ``element`` is a child of a parametric array — has a
+        BBIM_Array pset whose Parent GUID points to a different element.
+        Lighter than ``get_child_layer_index`` (no ``by_guid`` lookup, no
+        Data parse); suitable for per-element checks in draw handlers."""
+        pset = ifcopenshell.util.element.get_pset(element, "BBIM_Array")
+        if not pset:
+            return False
+        parent_guid = pset.get("Parent")
+        return bool(parent_guid) and parent_guid != element.GlobalId
+
     @classmethod
     def get_child_layer_index(cls, child_element: entity_instance) -> int | None:
         """Index of the layer that produced ``child_element``, or ``None``

src/bonsai/bonsai/tool/autosave.py

@@ -0,0 +1,194 @@
+# Bonsai - OpenBIM Blender Add-on
+# Copyright (C) 2026
+#
+# This file is part of Bonsai.
+#
+# Bonsai is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# Bonsai is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with Bonsai.  If not, see <http://www.gnu.org/licenses/>.
+#
+# This file was generated with the assistance of an AI coding tool.
+
+from __future__ import annotations
+
+import atexit
+import logging
+import os
+from collections.abc import Callable
+from pathlib import Path
+from typing import Union
+
+import bpy
+
+import bonsai.tool as tool
+from bonsai.bim import export_ifc
+from bonsai.bim.module.model import preview_base
+
+AUTOSAVING_SUFFIX = "_autosaving.ifc"
+AUTOSAVED_SUFFIX = "_autosaved.ifc"
+
+_timer_callback: Union[Callable[[], None], None] = None
+# See cleanup_stale_autosave() for why this is a cached plain string rather
+# than looked up live.
+_active_ifc_path_cache: Union[str, None] = None
+
+
+class Autosave:
+    @classmethod
+    def get_paths(cls, ifc_path: Union[str, Path]) -> tuple[Path, Path, Path]:
+        path = Path(ifc_path)
+        stem = path.stem if path.suffix.lower() == ".ifc" else path.name
+        parent = path.parent
+        main_path = path if path.suffix.lower() == ".ifc" else parent / f"{stem}.ifc"
+        autosaving_path = parent / f"{stem}{AUTOSAVING_SUFFIX}"
+        autosaved_path = parent / f"{stem}{AUTOSAVED_SUFFIX}"
+        return main_path, autosaving_path, autosaved_path
+
+    @classmethod
+    def get_active_ifc_path(cls) -> Union[Path, None]:
+        props = tool.Blender.get_bim_props()
+        if not props.ifc_file:
+            return None
+        path = tool.Blender.ensure_blender_path_is_abs(Path(props.ifc_file))
+        if path.suffix.lower() != ".ifc":
+            return None
+        return path
+
+    @classmethod
+    def _update_active_ifc_path_cache(cls) -> None:
+        global _active_ifc_path_cache
+        ifc_path = cls.get_active_ifc_path()
+        _active_ifc_path_cache = ifc_path.as_posix() if ifc_path is not None else None
+
+    @classmethod
+    def is_enabled(cls) -> bool:
+        return bool(tool.Blender.get_addon_preferences().autosave_enabled)
+
+    @classmethod
+    def get_interval_seconds(cls) -> float:
+        minutes = tool.Blender.get_addon_preferences().autosave_interval_minutes
+        return max(1.0, float(minutes) * 60.0)
+
+    @classmethod
+    def is_eligible(cls) -> bool:
+        return cls.is_enabled() and tool.Ifc.get() is not None and cls.get_active_ifc_path() is not None
+
+    @classmethod
+    def cancel_timer(cls) -> None:
+        global _timer_callback
+        if _timer_callback is not None and bpy.app.timers.is_registered(_timer_callback):
+            bpy.app.timers.unregister(_timer_callback)
+        _timer_callback = None
+
+    @classmethod
+    def reset_timer(cls) -> None:
+        cls.cancel_timer()
+        cls._update_active_ifc_path_cache()
+        if not cls.is_eligible():
+            return
+
+        def on_timer() -> Union[float, None]:
+            cls._on_timer_expired()
+            # Reschedule by returning the next interval rather than calling
+            # reset_timer(), which would unregister this timer from within
+            # its own callback. Blender frees the timer's internal registry
+            # entry on that manual unregister, then frees it again when the
+            # callback returns - a double free that corrupts the heap and
+            # crashes Blender shortly after (e.g. when the prompt dialog
+            # spawned below is next interacted with).
+            return cls.get_interval_seconds() if cls.is_eligible() else None
+
+        global _timer_callback
+        _timer_callback = on_timer
+        bpy.app.timers.register(on_timer, first_interval=cls.get_interval_seconds())
+
+    @classmethod
+    def _on_timer_expired(cls) -> None:
+        if not cls.is_eligible():
+            return
+
+        prefs = tool.Blender.get_addon_preferences()
+        bim_props = tool.Blender.get_bim_props()
+
+        if bim_props.is_dirty:
+            if prefs.autosave_mode == "PROMPT":
+                bpy.ops.bim.autosave_prompt("INVOKE_DEFAULT")
+            elif prefs.autosave_mode == "BACKUP":
+                try:
+                    cls.perform_backup(bpy.context)
+                except Exception as error:
+                    print(f"Bonsai: autosave backup failed: {error}")
+
+    @classmethod
+    def perform_backup(cls, context: bpy.types.Context) -> None:
+        ifc_path = cls.get_active_ifc_path()
+        if ifc_path is None:
+            return
+
+        _, autosaving_path, autosaved_path = cls.get_paths(ifc_path)
+        autosaving_path.parent.mkdir(parents=True, exist_ok=True)
+
+        tool.Parametric.commit_pending_edits()
+        preview_base.discard_pending_previews(context.scene)
+
+        logger = logging.getLogger("ExportIFC")
+        output_file = autosaving_path.as_posix().replace("\\", "/")
+        settings = export_ifc.IfcExportSettings.factory(context, output_file, logger)
+        export_ifc.IfcExporter(settings).export()
+
+        try:
+            os.replace(autosaving_path, autosaved_path)
+        except OSError:
+            if autosaving_path.is_file():
+                autosaving_path.unlink(missing_ok=True)
+            raise
+
+    @classmethod
+    def get_newer_autosaved_path(cls, ifc_path: Union[str, Path]) -> Union[str, None]:
+        path = Path(ifc_path)
+        if path.suffix.lower() != ".ifc" or not path.is_file():
+            return None
+
+        _, _, autosaved_path = cls.get_paths(path)
+        if not autosaved_path.is_file():
+            return None
+        if autosaved_path.stat().st_mtime > path.stat().st_mtime:
+            return autosaved_path.as_posix().replace("\\", "/")
+        return None
+
+    @classmethod
+    def cleanup_stale_autosave(cls) -> None:
+        """Remove the active IFC's autosave file(s) on a graceful shutdown.
+
+        Registered via `atexit`, which only runs on a normal interpreter
+        shutdown - never on an actual crash. So a deliberate quit (whether
+        the user saved or chose "don't save") clears the recovery file and
+        won't prompt on next startup, while a genuine crash leaves it in
+        place for recovery, since no atexit callbacks fire then.
+
+        Deliberately reads only `_active_ifc_path_cache` - a plain string
+        kept up to date by `reset_timer()` - rather than touching `bpy` here.
+        By the time `atexit` fires, Blender's own C++ side is torn down far
+        enough that even reading `bpy.context.scene` aborts the process
+        (std::bad_optional_access) instead of raising a catchable exception.
+        """
+        if _active_ifc_path_cache is None:
+            return
+        try:
+            _, autosaving_path, autosaved_path = cls.get_paths(_active_ifc_path_cache)
+            autosaving_path.unlink(missing_ok=True)
+            autosaved_path.unlink(missing_ok=True)
+        except Exception:
+            pass
+
+
+atexit.register(Autosave.cleanup_stale_autosave)

src/bonsai/bonsai/tool/blender.py

@@ -538,6 +538,19 @@ class Blender(bonsai.core.tool.Blender):
             cls.handlers.clear()
             cls.is_installed = False
 
+        def draw_batch(self, shader_type, content_pos, color, indices=None):
+            """Submit a GPU batch through ``self.line_shader`` (for ``"LINES"``)
+            or ``self.shader`` (for any other primitive). Skips empty batches
+            via ``validate_shader_batch_data`` so Blender 4.4+ doesn't crash on
+            empty ``indices``. Subclasses bind both shaders in their draw method
+            before calling this helper."""
+            if not Blender.validate_shader_batch_data(content_pos, indices):
+                return
+            shader = self.line_shader if shader_type == "LINES" else self.shader
+            batch = batch_for_shader(shader, shader_type, {"pos": content_pos}, indices=indices)
+            shader.uniform_float("color", color)
+            batch.draw(shader)
+
         @staticmethod
         def _lookup_active_instance(gizmo_cls: type, context: bpy.types.Context) -> Optional[Any]:
             """Return the live ``GizmoGroup`` instance registered under
@@ -1524,6 +1537,10 @@ class Blender(bonsai.core.tool.Blender):
                 bpy.ops.bim.enable_editing_railing_path()
             elif feature := tool.Parametric.is_object_editing(obj):
                 tool.Parametric.run_bim_op(feature.finish_op)
+            elif tool.Parametric.is_wall(element):
+                # Placed after the generic finish dispatch so the TAB toggle splits:
+                # wall already editing → finish above; wall not editing → enter here.
+                bpy.ops.bim.enable_editing_wall()
             else:
                 return False
             return True
@@ -2387,6 +2404,13 @@ class Blender(bonsai.core.tool.Blender):
             return False
         return True
 
+    @staticmethod
+    def transparent_color(color: Iterable[float], alpha: float = 0.1) -> list[float]:
+        """Copy an RGBA color with its alpha channel overridden."""
+        out = [c for c in color]
+        out[3] = alpha
+        return out
+
     @classmethod
     def draw_bmesh_face_tris(
         cls,

src/bonsai/bonsai/tool/brick.py

@@ -192,10 +192,9 @@ class Brick(bonsai.core.tool.Brick):
     def get_brick(cls, element: ifcopenshell.entity_instance) -> Union[str, None]:
         for rel in element.HasAssociations:
             if rel.is_a("IfcRelAssociatesLibrary"):
-                if tool.Ifc.get_schema() == "IFC2X3" and "#" in rel.RelatingLibrary.ItemReference:
-                    return rel.RelatingLibrary.ItemReference
-                if tool.Ifc.get_schema() != "IFC2X3" and "#" in rel.RelatingLibrary.Identification:
-                    return rel.RelatingLibrary.Identification
+                identification = tool.Document.get_external_reference_id(rel.RelatingLibrary)
+                if identification and "#" in identification:
+                    return identification
 
     @classmethod
     def get_brick_class(cls, element: ifcopenshell.entity_instance) -> Union[str, None]:

src/bonsai/bonsai/tool/clip_box.py

@@ -86,7 +86,19 @@ class ClipBox:
     # aligned to the prior view and the edit-mode picker rejects verts
     # inside the current clip_planes after orbit/pan/zoom.
     _view_matrix_at_arm: dict[int, tuple] = {}
-    _refresh_pending: bool = False
+    _pending_refresh: Optional[Callable[[], None]] = None
+    # True from load_pre until the first on_pre_view tick of the new file
+    # (first paint = GPU contexts wired). Suppresses schedule_refresh and
+    # short-circuits on_depsgraph_update so neither path can drive
+    # RegionView3D.update() against regions whose GL state is not yet
+    # initialised — that crash inside GPU_matrix_ortho_set is a CTD, not
+    # catchable from Python. load_post fires before the first paint, so it
+    # CANNOT be the gate-clear point.
+    _file_loading: bool = False
+    # Edge-trigger consumed by on_pre_view: clears _file_loading on the
+    # first frame after load and kicks a refresh so the new file's clip
+    # box arms against now-safe regions.
+    _post_load_paint_pending: bool = False
     _last_seen_ifc_id: int = 0
     # Tracks the last matrix we persisted to the pset, keyed by Blender
     # object name. Lets the depsgraph handler detect committed transform
@@ -318,19 +330,32 @@ class ClipBox:
         from within a property write disrupts gizmo modal accounting and
         can leave the operator stack inconsistent. Deferring via a 0-delay
         timer hands the refresh to Blender's main loop, where operators are
-        legal. Debounced: a flag suppresses repeats while one is pending.
+        legal. Debounced: a pending handle suppresses repeats while one is
+        in flight, and lets the file-load gate tear it down cleanly so the
+        timer can't fire against not-yet-realised regions.
         """
-        if cls._refresh_pending:
+        if cls._file_loading:
+            return
+        if cls._pending_refresh is not None:
             return
-        cls._refresh_pending = True
 
         def _do_refresh():
-            cls._refresh_pending = False
+            cls._pending_refresh = None
             cls.refresh()
             return None
 
+        cls._pending_refresh = _do_refresh
         bpy.app.timers.register(_do_refresh, first_interval=0.0)
 
+    @classmethod
+    def _cancel_pending_refresh(cls) -> None:
+        """Cancel any pending debounced refresh. Idempotent; safe to call
+        when none is registered (e.g. on addon unregister)."""
+        pending = cls._pending_refresh
+        if pending is not None and bpy.app.timers.is_registered(pending):
+            bpy.app.timers.unregister(pending)
+        cls._pending_refresh = None
+
     @classmethod
     def reset_ownership(cls) -> None:
         """Drop the ownership table without touching any region. Used on register/reload."""
@@ -594,6 +619,13 @@ class ClipBox:
           so this branch fires once per commit — exactly the cadence the
           user expects for "save my latest transform".
         """
+        # During the file-load danger window (load_pre → first paint of the
+        # new file) the screen exists but its regions' GPU contexts are not
+        # yet wired; calling apply_clip_planes_direct here drives
+        # RegionView3D.update() into a CTD inside GPU_matrix_ortho_set.
+        # on_pre_view will reopen this gate on first paint.
+        if cls._file_loading:
+            return
         if getattr(bpy.context, "screen", None) is None:
             return
         if cls._active_scene_props(scene) is None:
@@ -662,6 +694,15 @@ class ClipBox:
         handler's job (it fires on transform commit and writes through
         the operator transaction path).
         """
+        # First paint after a file load is the GPU-ready signal: open the
+        # _file_loading gate and kick a refresh so the new file's clip box
+        # arms against now-safe regions. Runs BEFORE the active-clip-box
+        # check so the gate clears even when the new file has no clip box
+        # (otherwise the gate would deadlock until the next file load).
+        if cls._post_load_paint_pending:
+            cls._post_load_paint_pending = False
+            cls._file_loading = False
+            cls.schedule_refresh()
         if cls._active_scene_props() is None:
             return
         obj = cls.get_active_clip_box()

src/bonsai/bonsai/tool/connection.py

@@ -18,25 +18,33 @@
 #
 # This file was generated with the assistance of an AI coding tool.
 
-"""Generic discovery of the relation linking two IFC elements.
+"""Generic discovery of the connection linking two IFC elements.
 
 Used by ``bim.disconnect_elements`` so the operator surface is one operator
 per disconnect intent (active vs. partner, identified by GlobalId) rather
-than one per rel class. The kind label returned alongside the rel lets the
-operator dispatch the right post-disconnect cleanup:
+than one per rel class. Each lookup returns ``(subject, kind)`` tuples where
+``subject`` is the entity whose teardown effects the disconnect:
 
-- ``"path"`` for ``IfcRelConnectsPathElements`` (wall-wall, wall-roof, etc.)
-- ``"element-top"`` for ``IfcRelConnectsElements`` with ``Description=="TOP"``
-  (the rel kind ``extend_walls_to_underside`` creates)
-- ``"element"`` for any other ``IfcRelConnectsElements``
+- ``"path"`` — ``IfcRelConnectsPathElements`` (wall-wall, wall-roof, etc.).
+  ``subject`` is the rel; removing it disconnects.
+- ``"element-top"`` — ``IfcRelConnectsElements`` with ``Description=="TOP"``
+  (created by ``extend_walls_to_underside``). ``subject`` is the rel.
+- ``"element"`` — any other ``IfcRelConnectsElements``. ``subject`` is the rel.
+- ``"mep-pair-fitting"`` — two MEP elements joined via ``IfcRelConnectsPorts``
+  through a single bridging ``IfcFlowFitting``. ``subject`` is the fitting
+  itself; removing it disconnects. ``OBSTRUCTION`` fittings are excluded
+  here; those go through ``bim.mep_add_obstruction(mode=REMOVE)``.
 
-Add new rel kinds by extending :py:meth:`Connection.find_rel`. The disconnect
-operator's cleanup switch maps each kind to the right post-mutation calls."""
+Add new kinds by extending :py:meth:`Connection.find_rels`. The dispatch in
+``bonsai.core.connection.disconnect_rel`` maps each kind to the right
+post-mutation cleanup; the AST forward-compat guard enforces coverage."""
 
 from __future__ import annotations
 
 from typing import TYPE_CHECKING
 
+import bonsai.tool as tool
+
 if TYPE_CHECKING:
     import ifcopenshell
 
@@ -45,16 +53,16 @@ class Connection:
     @classmethod
     def find_rels(
         cls,
-        elem_a: "ifcopenshell.entity_instance",
-        elem_b: "ifcopenshell.entity_instance",
-    ) -> "list[tuple[ifcopenshell.entity_instance, str]]":
-        """Return every supported rel linking ``elem_a`` to ``elem_b`` as a
-        list of ``(rel, kind)`` tuples. Walks both ``ConnectedTo`` and
-        ``ConnectedFrom`` because either side of the rel can be the relating
-        element, and the same pair may carry rels authored with opposite
-        orientations (``disconnect_path``'s ``(relating, related)`` mode only
-        inspects ``relating.ConnectedTo``, so a single call would miss the
-        opposite-orientation rel)."""
+        elem_a: ifcopenshell.entity_instance,
+        elem_b: ifcopenshell.entity_instance,
+    ) -> list[tuple[ifcopenshell.entity_instance, str]]:
+        """Return every supported connection linking ``elem_a`` to ``elem_b``
+        as a list of ``(subject, kind)`` tuples — ``subject`` is the entity
+        whose teardown effects the disconnect (the rel itself for
+        relationship-kinds, the bridging fitting for ``"mep-pair-fitting"``).
+        Walks both ``ConnectedTo`` and ``ConnectedFrom`` because either side
+        of a rel can be the relating element, and the same pair may carry
+        rels authored with opposite orientations."""
         rels: list[tuple[ifcopenshell.entity_instance, str]] = []
         seen: set[int] = set()
 
@@ -79,16 +87,20 @@ class Connection:
                 kind = "element-top" if getattr(rel, "Description", None) == "TOP" else "element"
                 _record(rel, kind)
 
+        fitting = tool.System.find_bridging_fitting(elem_a, elem_b)
+        if fitting is not None:
+            _record(fitting, "mep-pair-fitting")
+
         return rels
 
     @classmethod
     def find_rel(
         cls,
-        elem_a: "ifcopenshell.entity_instance",
-        elem_b: "ifcopenshell.entity_instance",
-    ) -> "tuple[ifcopenshell.entity_instance | None, str | None]":
-        """Return the first ``(rel, kind)`` or ``(None, None)``. Cheaper than
-        ``find_rels`` when callers only need to know whether a connection
+        elem_a: ifcopenshell.entity_instance,
+        elem_b: ifcopenshell.entity_instance,
+    ) -> tuple[ifcopenshell.entity_instance | None, str | None]:
+        """Return the first ``(subject, kind)`` or ``(None, None)``. Cheaper
+        than ``find_rels`` when callers only need to know whether a connection
         exists or what kind it is."""
         rels = cls.find_rels(elem_a, elem_b)
         return rels[0] if rels else (None, None)
@@ -96,17 +108,23 @@ class Connection:
     @classmethod
     def find_rels_for_element(
         cls,
-        elem: "ifcopenshell.entity_instance",
-    ) -> "list[tuple[ifcopenshell.entity_instance, str, ifcopenshell.entity_instance]]":
-        """Return every supported rel touching ``elem`` as ``(rel, kind, partner)``
-        triples. ``partner`` is the *other* element on the rel — the side cascade
-        cleanup must operate on when ``elem`` is being deleted.
+        elem: ifcopenshell.entity_instance,
+    ) -> list[tuple[ifcopenshell.entity_instance, str, ifcopenshell.entity_instance]]:
+        """Return every supported connection touching ``elem`` as
+        ``(subject, kind, partner)`` triples. ``partner`` is the *other*
+        element on the connection — the side cascade cleanup must operate on
+        when ``elem`` is being deleted.
 
-        Mirrors :py:meth:`find_rels`'s kind taxonomy. The single-element entry
-        point lets the cascade-on-delete in ``tool.Geometry.delete_ifc_object``
-        enumerate everything the disconnect operator would handle pairwise.
+        Mirrors :py:meth:`find_rels`'s relationship-kind taxonomy. Notably
+        does NOT emit ``"mep-pair-fitting"`` triples: ``IfcRelConnectsPorts``
+        cleanup is owned by ``tool.Geometry.delete_ifc_object``'s
+        ``remove_port`` loop, which runs unconditionally on any IFC root
+        deletion. Including MEP here would cause the cascade to also remove
+        the bridging fitting when one of its connected segments is deleted —
+        a policy choice (fitting may still join other live segments) that's
+        better left to the user via the explicit disconnect operator.
         """
-        result: list[tuple["ifcopenshell.entity_instance", str, "ifcopenshell.entity_instance"]] = []
+        result: list[tuple[ifcopenshell.entity_instance, str, ifcopenshell.entity_instance]] = []
         seen: set[int] = set()
 
         def _record(rel, kind, partner):
@@ -133,10 +151,10 @@ class Connection:
     @classmethod
     def orient_element_top(
         cls,
-        rel: "ifcopenshell.entity_instance",
-        elem_a: "ifcopenshell.entity_instance",
-        elem_b: "ifcopenshell.entity_instance",
-    ) -> "tuple[ifcopenshell.entity_instance, ifcopenshell.entity_instance]":
+        rel: ifcopenshell.entity_instance,
+        elem_a: ifcopenshell.entity_instance,
+        elem_b: ifcopenshell.entity_instance,
+    ) -> tuple[ifcopenshell.entity_instance, ifcopenshell.entity_instance]:
         """Return ``(wall, slab)`` for an ``IfcRelConnectsElements(TOP)`` rel.
 
         The ``extend_walls_to_underside`` flow stores slab as the relating

src/bonsai/bonsai/tool/document.py

@@ -261,7 +261,8 @@ class Document(bonsai.core.tool.Document):
     def get_reference_document(cls, reference: ifcopenshell.entity_instance) -> ifcopenshell.entity_instance | None:
         # TODO: migrate to util.document and replace all instances
         if reference.file.schema == "IFC2X3":
-            return (reference.ReferenceToDocument or (None))[0]
+            reference_to_document = reference.ReferenceToDocument
+            return reference_to_document[0] if reference_to_document else None
         return reference.ReferencedDocument
 
     @classmethod

src/bonsai/bonsai/tool/drawing.py

@@ -38,6 +38,7 @@ import ifcopenshell.api.context
 import ifcopenshell.api.document
 import ifcopenshell.api.drawing
 import ifcopenshell.api.geometry
+import ifcopenshell.api.group
 import ifcopenshell.api.pset
 import ifcopenshell.api.root
 import ifcopenshell.geom
@@ -78,6 +79,7 @@ if TYPE_CHECKING:
 
 class Drawing(bonsai.core.tool.Drawing):
     ANNOTATION_DATA_TYPE = Literal["empty", "curve", "mesh"]
+    PERSPECTIVE_CAMERA_SHIFT_PROPERTIES = ("PerspectiveShiftX", "PerspectiveShiftY")
     DOCUMENT_TYPE = Literal["SCHEDULE", "REFERENCE"]
     LocationHintLiteral = Literal["PERSPECTIVE", "ORTHOGRAPHIC", "NORTH", "SOUTH", "EAST", "WEST"]
     LOCATION_HINT_LITERALS = ("PERSPECTIVE", "ORTHOGRAPHIC", "NORTH", "SOUTH", "EAST", "WEST")
@@ -453,6 +455,41 @@ class Drawing(bonsai.core.tool.Drawing):
         camera.matrix_world = matrix
         return camera
 
+    @classmethod
+    def get_perspective_camera_shifts(cls, drawing: ifcopenshell.entity_instance) -> dict[str, float]:
+        pset = ifcopenshell.util.element.get_pset(drawing, "EPset_Drawing") or {}
+        shift_x_prop, shift_y_prop = cls.PERSPECTIVE_CAMERA_SHIFT_PROPERTIES
+        return {
+            "shift_x": float(pset.get(shift_x_prop, 0.0) or 0.0),
+            "shift_y": float(pset.get(shift_y_prop, 0.0) or 0.0),
+        }
+
+    @classmethod
+    def sync_perspective_camera_shifts(cls, drawing: ifcopenshell.entity_instance, camera: bpy.types.Camera) -> None:
+        if camera.type != "PERSP":
+            return
+
+        shift_x_prop, shift_y_prop = cls.PERSPECTIVE_CAMERA_SHIFT_PROPERTIES
+        current_shifts = cls.get_perspective_camera_shifts(drawing)
+        new_shifts = {"shift_x": float(camera.shift_x or 0.0), "shift_y": float(camera.shift_y or 0.0)}
+        if tool.Cad.is_x(current_shifts["shift_x"], new_shifts["shift_x"]) and tool.Cad.is_x(
+            current_shifts["shift_y"], new_shifts["shift_y"]
+        ):
+            return
+
+        ifc_file = tool.Ifc.get()
+        pset = tool.Pset.get_element_pset(drawing, "EPset_Drawing")
+        if not pset:
+            pset = ifcopenshell.api.pset.add_pset(ifc_file, product=drawing, name="EPset_Drawing")
+        ifcopenshell.api.pset.edit_pset(
+            ifc_file,
+            pset=pset,
+            properties={
+                shift_x_prop: new_shifts["shift_x"],
+                shift_y_prop: new_shifts["shift_y"],
+            },
+        )
+
     @classmethod
     def create_svg_schedule(cls, schedule: ifcopenshell.entity_instance) -> None:
         import bonsai.bim.module.drawing.scheduler as scheduler
@@ -737,6 +774,32 @@ class Drawing(bonsai.core.tool.Drawing):
     def get_drawing_target_view(cls, drawing: ifcopenshell.entity_instance) -> str:
         return ifcopenshell.util.element.get_psets(drawing).get("EPset_Drawing", {}).get("TargetView", "MODEL_VIEW")
 
+    @classmethod
+    def ensure_drawings_parent_document(cls) -> ifcopenshell.entity_instance:
+        ifc_file = tool.Ifc.get()
+        for document in ifc_file.by_type("IfcDocumentInformation"):
+            if document.Name == "DRAWINGS" and document.Scope == "DRAWINGS":
+                return document
+        document = ifcopenshell.api.document.add_information(ifc_file)
+        if ifc_file.schema == "IFC2X3":
+            attributes = {"DocumentId": "DRAWINGS", "Name": "DRAWINGS", "Scope": "DRAWINGS"}
+        else:
+            attributes = {"Identification": "DRAWINGS", "Name": "DRAWINGS", "Scope": "DRAWINGS"}
+        ifcopenshell.api.document.edit_information(ifc_file, information=document, attributes=attributes)
+        return document
+
+    @classmethod
+    def ensure_drawings_parent_group(cls) -> ifcopenshell.entity_instance:
+        ifc_file = tool.Ifc.get()
+        for group in ifc_file.by_type("IfcGroup"):
+            if group.Name == "DRAWINGS" and group.ObjectType == "DRAWINGS":
+                return group
+        group = ifcopenshell.api.group.add_group(ifc_file)
+        ifcopenshell.api.group.edit_group(
+            ifc_file, group=group, attributes={"Name": "DRAWINGS", "ObjectType": "DRAWINGS"}
+        )
+        return group
+
     @classmethod
     def get_group_elements(cls, group: ifcopenshell.entity_instance) -> list[ifcopenshell.entity_instance]:
         for rel in group.IsGroupedBy or []:
@@ -1009,6 +1072,8 @@ class Drawing(bonsai.core.tool.Drawing):
         camera_props.has_annotation = True
         camera_props.target_view = "PLAN_VIEW"
         camera_props.is_nts = False
+        camera.shift_x = 0.0
+        camera.shift_y = 0.0
 
         pset = ifcopenshell.util.element.get_pset(drawing, "EPset_Drawing")
         if pset:
@@ -1044,6 +1109,10 @@ class Drawing(bonsai.core.tool.Drawing):
                 camera_props.fill_mode = str(pset["FillMode"])
             if "CutMode" in pset:
                 camera_props.cut_mode = str(pset["CutMode"])
+            if camera.type == "PERSP":
+                shifts = cls.get_perspective_camera_shifts(drawing)
+                camera.shift_x = shifts["shift_x"]
+                camera.shift_y = shifts["shift_y"]
 
         camera_props.update_props = update_props
 
@@ -1098,10 +1167,7 @@ class Drawing(bonsai.core.tool.Drawing):
             new = documents_collection.add()
             new.ifc_definition_id = schedule.id()
             new.name = schedule.Name or "Unnamed"
-            if tool.Ifc.get_schema() == "IFC2X3":
-                new.identification = schedule.DocumentId
-            else:
-                new.identification = schedule.Identification
+            new.identification = tool.Document.get_document_information_id(schedule) or ""
 
     @classmethod
     def get_sheet_identification(cls, sheet: ifcopenshell.entity_instance) -> str:
@@ -1142,10 +1208,7 @@ class Drawing(bonsai.core.tool.Drawing):
                 new.ifc_definition_id = reference.id()
                 new.is_sheet = False
 
-                if tool.Ifc.get_schema() == "IFC2X3":
-                    new.identification = reference.ItemReference or ""
-                else:
-                    new.identification = reference.Identification or ""
+                new.identification = tool.Document.get_external_reference_id(reference) or ""
 
                 new.name = os.path.basename(reference.Location)
                 new.reference_type = reference_description
@@ -2267,14 +2330,19 @@ class Drawing(bonsai.core.tool.Drawing):
         cls, drawing: ifcopenshell.entity_instance, ifc_file: Optional[ifcopenshell.file] = None
     ) -> set[ifcopenshell.entity_instance]:
         """returns a set of elements that are included in the drawing"""
-        if ifc_file is None:
+        param_was_none = ifc_file is None
+        if param_was_none:
             ifc_file = tool.Ifc.get()
-            elements = cls.get_elements_in_camera_view(tool.Ifc.get_object(drawing), bpy.data.objects)
-        else:
-            # This can probably be smarter
-            elements = set(ifc_file.by_type("IfcElement"))
         pset = ifcopenshell.util.element.get_psets(drawing).get("EPset_Drawing", {})
         include = pset.get("Include", None)
+
+        # Only the active IFC file has Blender objects we can test against the
+        # camera's view frustum, which lets us drop elements - including those
+        # picked by an Include filter - that fall outside the drawing boundary.
+        camera_view_elements = None
+        if (param_was_none or include) and ifc_file is tool.Ifc.get():
+            camera_view_elements = cls.get_elements_in_camera_view(tool.Ifc.get_object(drawing), bpy.data.objects)
+
         if include:
             try:
                 data = json.loads(include)
@@ -2286,7 +2354,16 @@ class Drawing(bonsai.core.tool.Drawing):
                     elements = ifcopenshell.util.selector.filter_elements(ifc_file, include)
             except (json.JSONDecodeError, ValueError):
                 elements = ifcopenshell.util.selector.filter_elements(ifc_file, include)
+            # The Include filter chooses which elements may appear, but they must
+            # still fall within the drawing's camera boundary.
+            if camera_view_elements is not None:
+                elements &= camera_view_elements
         else:
+            if param_was_none:
+                elements = camera_view_elements
+            else:
+                # This can probably be smarter
+                elements = set(ifc_file.by_type("IfcElement"))
             if ifc_file.schema == "IFC2X3":
                 base_elements = set(ifc_file.by_type("IfcElement") + ifc_file.by_type("IfcSpatialStructureElement"))
             else:
@@ -2367,9 +2444,8 @@ class Drawing(bonsai.core.tool.Drawing):
     def get_reference_document(
         cls, reference: ifcopenshell.entity_instance
     ) -> Union[ifcopenshell.entity_instance, None]:
-        if tool.Ifc.get_schema() == "IFC2X3":
-            return reference.ReferenceToDocument[0]
-        return reference.ReferencedDocument
+        # TODO: migrate to document.get_reference_document.
+        return tool.Document.get_reference_document(reference)
 
     @classmethod
     def select_assigned_product(cls, context: bpy.types.Context) -> None:
@@ -2384,13 +2460,13 @@ class Drawing(bonsai.core.tool.Drawing):
     @classmethod
     def is_drawing_active(cls) -> bool:
         camera = bpy.context.scene.camera
-        area = tool.Blender.get_view3d_area()
-        return bool(
-            camera is not None
-            and camera.type == "CAMERA"
-            and tool.Blender.get_ifc_definition_id(camera)
-            and area is not None
-        )
+        if not (camera is not None and camera.type == "CAMERA" and tool.Blender.get_ifc_definition_id(camera)):
+            return False
+        # A VIEW_3D area is meaningless (and unobtainable) in background
+        # mode, but isn't otherwise required to generate a drawing.
+        if bpy.app.background:
+            return True
+        return tool.Blender.get_view3d_area() is not None
 
     @classmethod
     def is_camera_orthographic(cls) -> bool:
@@ -2521,10 +2597,19 @@ class Drawing(bonsai.core.tool.Drawing):
                     has_context = True
                     break
 
+        linked_handles: set[bpy.types.Object] = set()
+        for link in tool.Project.get_project_props().get_loaded_links_for_drawings():
+            try:
+                handle = tool.Project.get_link_empty_handle(link)
+            except Exception:
+                continue
+            if handle:
+                linked_handles.add(handle)
+
         visible_objects = []
         for obj in bpy.context.view_layer.objects:
             if element := tool.Ifc.get_entity(obj):
-                if element in filtered_elements:
+                if element in filtered_elements or obj in linked_handles:
                     visible_objects.append(obj)
             else:
                 if obj.hide_get() is False:

src/bonsai/bonsai/tool/duplicate.py

@@ -248,32 +248,30 @@ class Duplicate(bonsai.core.tool.Duplicate):
         old_to_new: dict[ifcopenshell.entity_instance, list[ifcopenshell.entity_instance]],
     ) -> None:
         for element, data in relationship.items():
-            try:
-                new_relating_element = old_to_new.get(data.relating_element)[0]
-                new_related_element = old_to_new.get(data.related_element)[0]
-            except (KeyError, IndexError, TypeError):
-                continue
-            new_rel = tool.Ifc.run(
-                "geometry.connect_path",
-                relating_element=new_relating_element,
-                related_element=new_related_element,
-                relating_connection=data.relating_connection_type,
-                related_connection=data.related_connection_type,
-            )
+            new_relating_elements = old_to_new.get(data.relating_element) or []
+            new_related_elements = old_to_new.get(data.related_element) or []
             # connect_path hardcodes priorities to []; restore them post-hoc.
             priority_attrs: dict[str, Any] = {}
             if data.relating_priorities:
                 priority_attrs["RelatingPriorities"] = data.relating_priorities
             if data.related_priorities:
                 priority_attrs["RelatedPriorities"] = data.related_priorities
-            if new_rel is not None and priority_attrs:
-                try:
-                    tool.Ifc.run("attribute.edit_attributes", product=new_rel, attributes=priority_attrs)
-                except (RuntimeError, ifcopenshell.Error) as e:
-                    cls._emit_warning(
-                        f"connection priority restore failed for {new_rel}; "
-                        f"duplicate has empty RelatingPriorities/RelatedPriorities: {e}"
-                    )
+            for new_relating_element, new_related_element in zip(new_relating_elements, new_related_elements):
+                new_rel = tool.Ifc.run(
+                    "geometry.connect_path",
+                    relating_element=new_relating_element,
+                    related_element=new_related_element,
+                    relating_connection=data.relating_connection_type,
+                    related_connection=data.related_connection_type,
+                )
+                if new_rel is not None and priority_attrs:
+                    try:
+                        tool.Ifc.run("attribute.edit_attributes", product=new_rel, attributes=priority_attrs)
+                    except (RuntimeError, ifcopenshell.Error) as e:
+                        cls._emit_warning(
+                            f"connection priority restore failed for {new_rel}; "
+                            f"duplicate has empty RelatingPriorities/RelatedPriorities: {e}"
+                        )
 
     @classmethod
     def recreate_port_connections(
@@ -283,46 +281,43 @@ class Duplicate(bonsai.core.tool.Duplicate):
     ) -> None:
         """Recreate ``IfcRelConnectsPorts`` between duplicates; skip records whose duplicate's port count diverges from the snapshot."""
         for relating_element, records in snapshot.by_element.items():
+            new_relatings = old_to_new.get(relating_element) or []
+            expected_relating = snapshot.port_counts.get(relating_element)
             for record in records:
                 related_element = record.related_element
-                try:
-                    new_relating = old_to_new[relating_element][0]
-                    new_related = old_to_new[related_element][0]
-                except (KeyError, IndexError):
-                    continue
-
-                new_relating_ports = tool.System.get_ports(new_relating)
-                new_related_ports = tool.System.get_ports(new_related)
-
-                expected_relating = snapshot.port_counts.get(relating_element)
-                if expected_relating is not None and len(new_relating_ports) != expected_relating:
-                    cls._emit_warning(
-                        f"port reconnect skipped — duplicate has {len(new_relating_ports)} ports, "
-                        f"snapshot had {expected_relating}"
-                    )
-                    continue
+                new_relateds = old_to_new.get(related_element) or []
                 expected_related = snapshot.port_counts.get(related_element)
-                if expected_related is not None and len(new_related_ports) != expected_related:
-                    cls._emit_warning(
-                        f"port reconnect skipped — duplicate has {len(new_related_ports)} ports, "
-                        f"snapshot had {expected_related}"
-                    )
-                    continue
+                for new_relating, new_related in zip(new_relatings, new_relateds):
+                    new_relating_ports = tool.System.get_ports(new_relating)
+                    new_related_ports = tool.System.get_ports(new_related)
 
-                try:
-                    new_port_a = new_relating_ports[record.relating_port_index]
-                    new_port_b = new_related_ports[record.related_port_index]
-                except IndexError:
-                    cls._emit_warning(
-                        f"port reconnect skipped — record references port index past the duplicate's port list"
-                    )
-                    continue
-                try:
-                    tool.Ifc.run(
-                        "system.connect_port",
-                        port1=new_port_a,
-                        port2=new_port_b,
-                        direction=record.direction or "NOTDEFINED",
-                    )
-                except (RuntimeError, ifcopenshell.Error) as e:
-                    cls._emit_warning(f"port reconnect failed between duplicates: {e}")
+                    if expected_relating is not None and len(new_relating_ports) != expected_relating:
+                        cls._emit_warning(
+                            f"port reconnect skipped — duplicate has {len(new_relating_ports)} ports, "
+                            f"snapshot had {expected_relating}"
+                        )
+                        continue
+                    if expected_related is not None and len(new_related_ports) != expected_related:
+                        cls._emit_warning(
+                            f"port reconnect skipped — duplicate has {len(new_related_ports)} ports, "
+                            f"snapshot had {expected_related}"
+                        )
+                        continue
+
+                    try:
+                        new_port_a = new_relating_ports[record.relating_port_index]
+                        new_port_b = new_related_ports[record.related_port_index]
+                    except IndexError:
+                        cls._emit_warning(
+                            f"port reconnect skipped — record references port index past the duplicate's port list"
+                        )
+                        continue
+                    try:
+                        tool.Ifc.run(
+                            "system.connect_port",
+                            port1=new_port_a,
+                            port2=new_port_b,
+                            direction=record.direction or "NOTDEFINED",
+                        )
+                    except (RuntimeError, ifcopenshell.Error) as e:
+                        cls._emit_warning(f"port reconnect failed between duplicates: {e}")

src/bonsai/bonsai/tool/geometry.py

@@ -24,6 +24,7 @@ import multiprocessing
 import struct
 from collections import defaultdict
 from collections.abc import Generator, Iterable, Iterator
+from contextlib import contextmanager
 from math import pi, radians
 from typing import (
     TYPE_CHECKING,
@@ -32,7 +33,6 @@ from typing import (
     Optional,
     TypeGuard,
     Union,
-    cast,
     get_args,
 )
 
@@ -130,6 +130,85 @@ class Geometry(bonsai.core.tool.Geometry):
         if cache and hasattr(element, "GlobalId"):
             cache.remove(element.GlobalId)
 
+    # Per-host work coalesced by `batch_host_recut`. Keys are voided element ifc ids;
+    # dict insertion preserves call ordering. Recut values store the representation at
+    # enqueue time, but the drain re-reads `get_active_representation` so the recut
+    # always reflects current IFC state.
+    _host_batch_depth: int = 0
+    _host_recut_queue: dict[int, tuple[bpy.types.Object, ifcopenshell.entity_instance]] = {}
+    _host_update_queue: dict[int, bpy.types.Object] = {}
+
+    @classmethod
+    @contextmanager
+    def batch_host_recut(cls) -> Generator[None, None, None]:
+        """Coalesce host body work — `recut_host` and `update_host_representation`
+        calls inside the with-block enqueue by voided element id. On the outermost
+        exit: every host's `update_representation` runs first (writes Blender mesh
+        back to IFC), then every host's `switch_representation` runs (reads IFC +
+        openings → Blender mesh). The two-phase order matters: a recut that ran
+        before the matching update_representation would re-tessellate against stale
+        IFC, losing the user's edits.
+
+        Nests safely — only the outermost exit drains. The depth counter and queues
+        are reset on exit even if the body raises."""
+        cls._host_batch_depth += 1
+        try:
+            yield
+        finally:
+            cls._host_batch_depth -= 1
+            if cls._host_batch_depth == 0:
+                update_queue = cls._host_update_queue
+                recut_queue = cls._host_recut_queue
+                cls._host_update_queue = {}
+                cls._host_recut_queue = {}
+                for voided_obj in update_queue.values():
+                    try:
+                        if not voided_obj or not voided_obj.data:
+                            continue
+                    except ReferenceError:
+                        # Blender object was deleted while the batch was open
+                        # (e.g. user removed it via the outliner mid-op).
+                        continue
+                    if tool.Ifc.get_entity(voided_obj) is None:
+                        continue
+                    bpy.ops.bim.update_representation(obj=voided_obj.name)
+                for voided_obj, _ in recut_queue.values():
+                    try:
+                        if not voided_obj or not voided_obj.data:
+                            continue
+                    except ReferenceError:
+                        continue
+                    if tool.Ifc.get_entity(voided_obj) is None:
+                        continue
+                    current_rep = cls.get_active_representation(voided_obj)
+                    if current_rep is None:
+                        continue
+                    bonsai.core.geometry.switch_representation(
+                        tool.Ifc, cls, obj=voided_obj, representation=current_rep
+                    )
+
+    @classmethod
+    def recut_host(cls, voided_obj: bpy.types.Object, representation: ifcopenshell.entity_instance) -> None:
+        """Recut a host's body representation. Inside `batch_host_recut`, enqueues
+        by voided element id; outside, fires `switch_representation` directly."""
+        if cls._host_batch_depth > 0:
+            element = tool.Ifc.get_entity(voided_obj)
+            if element is not None:
+                cls._host_recut_queue[element.id()] = (voided_obj, representation)
+            return
+        bonsai.core.geometry.switch_representation(tool.Ifc, cls, obj=voided_obj, representation=representation)
+
+    @classmethod
+    def update_host_representation(cls, voided_obj: bpy.types.Object) -> None:
+        """Run `bim.update_representation` on a host. Inside `batch_host_recut`,
+        enqueues by voided element id; outside, fires the operator directly."""
+        if cls._host_batch_depth > 0:
+            element = tool.Ifc.get_entity(voided_obj)
+            if element is not None:
+                cls._host_update_queue[element.id()] = voided_obj
+            return
+        bpy.ops.bim.update_representation(obj=voided_obj.name)
+
     @classmethod
     def has_axis_representation(cls, element: ifcopenshell.entity_instance) -> bool:
         """True if the element carries a shape representation whose
@@ -396,13 +475,13 @@ class Geometry(bonsai.core.tool.Geometry):
         # same OverrideDelete batch.
         if element.is_a("IfcRoot"):
             skip_ids = batch_being_deleted_ids or set()
-            for rel, kind, partner in tool.Connection.find_rels_for_element(element):
+            for subject, kind, partner in tool.Connection.find_rels_for_element(element):
                 bonsai.core.connection.disconnect_rel(
                     tool.Ifc,
                     tool.Geometry,
                     tool.Model,
                     tool.Connection,
-                    rel=rel,
+                    subject=subject,
                     kind=kind,
                     elem=element,
                     partner=partner,
@@ -2107,7 +2186,7 @@ class Geometry(bonsai.core.tool.Geometry):
             setattr(item, attribute.name, attribute.get_value())
 
         if item.is_a("IfcSweptAreaSolid"):
-            item_profile = cast(str, props.item_profile)
+            item_profile = props.item_profile
             profile = item.SweptArea
             profile_name: Union[str, None] = profile.ProfileName
             if item_profile == "-":
@@ -2409,99 +2488,16 @@ class Geometry(bonsai.core.tool.Geometry):
         old_obj_name_to_new_obj_name: dict[str, str] = {}
 
         for obj in objects_to_duplicate:
-            element = tool.Ifc.get_entity(obj)
-            if element:
-                if element.is_a("IfcAnnotation") and element.ObjectType == "DRAWING":
-                    tool.Blender.deselect_object(obj)
-                    continue  # For now, don't copy drawings until we stabilise a bit more. It's tricky.
-                elif tool.Geometry.is_locked(element):
-                    tool.Blender.deselect_object(obj)
-                    continue
-            elif tool.Geometry.is_representation_item(obj):
-                cls.duplicate_ifc_item(obj)
-                continue
-
-            tracked_opening_type = tool.Model.get_tracked_opening_type(obj)
-            is_tracked_opening = bool(tracked_opening_type)
-            keep_data_linked = linked and not element and not is_tracked_opening
-
-            # Prior to duplicating, sync the object placement to make decomposition recreation more stable.
-            cls.commit_placement_if_moved(obj, apply_scale=False)
-
-            new_obj = obj.copy()
-            temp_data = None
-
-            # Currently for optimization we do not apply pending changes (scale or changed .data)
-            # to the original and duplicated objects.
-            # Keep new object edited if original is.
-            if tool.Ifc.is_edited(obj, ignore_scale=True):
-                tool.Ifc.edit(new_obj)
-
-            if obj.data and not keep_data_linked:
-                # assure root.copy_class won't replace the previous mesh globally
-                temp_data = obj.data.copy()
-                new_obj.data = temp_data
-
-                # Unlink from previous boolean element
-                # and keep object tracked for decorations.
-                if is_tracked_opening:
-                    mprops = tool.Geometry.get_mesh_props(new_obj.data)
-                    mprops.ifc_boolean_id = 0
-                    tool.Root.add_tracked_opening(new_obj, tracked_opening_type)
-
-            if obj == active_object:
-                new_active_obj = new_obj
-            for collection in obj.users_collection:
-                collection.objects.link(new_obj)
-            obj.select_set(False)
-            new_obj.select_set(True)
-            old_obj_name_to_new_obj_name[obj.name] = new_obj.name
-
-            if not element:
-                continue
-
-            # clear object's collection so it will be able to have it's own
-            tool.Blender.get_object_bim_props(new_obj).collection = None
-            # copy the actual class
-            new = bonsai.core.root.copy_class(tool.Ifc, tool.Collector, tool.Geometry, tool.Root, obj=new_obj)
-
-            # clean up the orphaned mesh with ifc id of the original object to avoid confusion
-            # IfcGridAxis keeps the same mesh data (it's pointing to ifc id 0, so it's not a problem)
-            if new and temp_data and not new.is_a("IfcGridAxis"):
-                if new.is_a("IfcRelSpaceBoundary"):
-                    surface = new.ConnectionGeometry.SurfaceOnRelatingElement
-                    temp_data.name = f"0/{surface.id()}"
-                    tool.Ifc.link(surface, temp_data)
-                else:
-                    tool.Blender.remove_data_block(temp_data)
-
-            if new:
-                # TODO: handle array data for other cases of duplication
-                array_data = arrays_to_duplicate.get(obj, None)
-                tool.Model.handle_array_on_copied_element(new, array_data)
-                if array_data:
-                    for child in tool.Array.get_all_children_objects(new):
-                        child.select_set(True)
-
-                # TODO: add new array children to recreate their decomposition too
-                old_to_new[element] = [new]
-                if new.is_a("IfcRelSpaceBoundary"):
-                    tool.Boundary.decorate_boundary(new_obj)
-                # Slab-trim booleans (from extend_walls_to_underside) belong to
-                # the source wall's connection, not the copy. Strip them so the
-                # duplicate reverts to its pre-clip extrusion — mirrors the way
-                # filling rels are dropped while manual booleans persist on copy.
-                # Reload the body when something was stripped so the viewport
-                # immediately shows the unclipped geometry; otherwise the user
-                # sees a stale mesh until they Shift+G, which is easy to miss.
-                if new.is_a("IfcWall"):
-                    if tool.Model.strip_underside_booleans(new):
-                        tool.Model.reload_body_representation(new_obj)
-                    # HasOpenings rels don't follow object duplication, so
-                    # the duplicate's body must rebuild to match its current
-                    # opening set.
-                    else:
-                        tool.Model.regenerate_wall(new_obj)
+            new_active = cls._duplicate_ifc_object_once(
+                obj,
+                active_object,
+                linked,
+                arrays_to_duplicate,
+                old_to_new,
+                old_obj_name_to_new_obj_name,
+            )
+            if new_active is not None:
+                new_active_obj = new_active
 
         # Remap Blender parent relationships for duplicated objects
         for old_obj_name, new_obj_name in old_obj_name_to_new_obj_name.items():
@@ -2529,10 +2525,211 @@ class Geometry(bonsai.core.tool.Geometry):
         # Recreate decompositions
         tool.Duplicate.recreate_decompositions(decomposition_relationships, old_to_new)
         cls.remove_linked_aggregate_data(old_to_new)
+
+        # In-loop regenerate_wall runs before recreate_connections, so any new
+        # walls that just received an IfcRelConnectsPathElements have stale
+        # junction geometry — recalculate them now that their connection graph
+        # is complete.
+        cls._recalculate_walls_with_new_connections(old_to_new)
+
         bonsai.bim.handler.refresh_ui_data()
         tool.Root.reload_grid_decorator()
         return old_to_new, new_active_obj or active_object
 
+    @classmethod
+    def duplicate_ifc_object_n_times(
+        cls, source: bpy.types.Object, count: int
+    ) -> dict[ifcopenshell.entity_instance, list[ifcopenshell.entity_instance]]:
+        """N-way duplicate of a single source.
+
+        Same per-copy semantics as duplicate_ifc_objects (IFC class copy,
+        decomposition + connection recreation, body regen for walls), but
+        bypasses the set() dedupe and the arrays_to_duplicate pre-scan so
+        callers building a fresh array don't pay per-call overhead N times.
+        Returns the same old_to_new dict shape, with the source element
+        mapping to the N new entities."""
+        if count <= 0:
+            return {}
+
+        sources = {source}
+        decomposition_relationships = tool.Duplicate.get_decomposition_relationships(sources)
+        connection_relationships = tool.Duplicate.get_connection_relationships(sources)
+        port_connection_snapshot = tool.Duplicate.get_port_connection_relationships(sources)
+        old_to_new: dict[ifcopenshell.entity_instance, list[ifcopenshell.entity_instance]] = {}
+        old_obj_name_to_new_obj_name: dict[str, str] = {}
+
+        for _ in range(count):
+            cls._duplicate_ifc_object_once(
+                source,
+                None,
+                False,
+                {},
+                old_to_new,
+                old_obj_name_to_new_obj_name,
+                keep_source_selected=True,
+            )
+
+        for old_obj_name, new_obj_name in old_obj_name_to_new_obj_name.items():
+            new_obj = bpy.data.objects.get(new_obj_name)
+            if new_obj and new_obj.parent and new_obj.parent.name in old_obj_name_to_new_obj_name:
+                world_matrix = new_obj.matrix_world.copy()
+                new_parent_name = old_obj_name_to_new_obj_name[new_obj.parent.name]
+                new_parent = bpy.data.objects.get(new_parent_name)
+                if new_parent:
+                    new_obj.parent = new_parent
+                    new_obj.matrix_world = world_matrix
+
+        for old in old_to_new.keys():
+            if old.is_a("IfcElementAssembly"):
+                tool.Root.recreate_aggregate(old_to_new)
+
+        cls.remove_old_connections(old_to_new)
+        tool.Duplicate.recreate_connections(connection_relationships, old_to_new)
+        tool.Duplicate.recreate_port_connections(port_connection_snapshot, old_to_new)
+        tool.Duplicate.recreate_decompositions(decomposition_relationships, old_to_new)
+        cls.remove_linked_aggregate_data(old_to_new)
+        cls._recalculate_walls_with_new_connections(old_to_new)
+        bonsai.bim.handler.refresh_ui_data()
+        tool.Root.reload_grid_decorator()
+        return old_to_new
+
+    @classmethod
+    def _duplicate_ifc_object_once(
+        cls,
+        obj: bpy.types.Object,
+        active_object: Optional[bpy.types.Object],
+        linked: bool,
+        arrays_to_duplicate: dict[bpy.types.Object, Any],
+        old_to_new: dict[ifcopenshell.entity_instance, list[ifcopenshell.entity_instance]],
+        old_obj_name_to_new_obj_name: dict[str, str],
+        keep_source_selected: bool = False,
+    ) -> Optional[bpy.types.Object]:
+        """Per-source body of the duplicate flow. Mutates old_to_new and
+        old_obj_name_to_new_obj_name in place. Returns new_obj when obj is
+        the active_object, else None.
+
+        keep_source_selected: when True, skip the source deselect so batched
+        callers can run N iterations without N×2 select flips and without
+        needing a post-loop restore on the source."""
+        new_active_obj: Optional[bpy.types.Object] = None
+        element = tool.Ifc.get_entity(obj)
+        if element:
+            if element.is_a("IfcAnnotation") and element.ObjectType == "DRAWING":
+                tool.Blender.deselect_object(obj)
+                return None  # For now, don't copy drawings until we stabilise a bit more. It's tricky.
+            elif tool.Geometry.is_locked(element):
+                tool.Blender.deselect_object(obj)
+                return None
+        elif tool.Geometry.is_representation_item(obj):
+            cls.duplicate_ifc_item(obj)
+            return None
+
+        tracked_opening_type = tool.Model.get_tracked_opening_type(obj)
+        is_tracked_opening = bool(tracked_opening_type)
+        keep_data_linked = linked and not element and not is_tracked_opening
+
+        # Prior to duplicating, sync the object placement to make decomposition recreation more stable.
+        cls.commit_placement_if_moved(obj, apply_scale=False)
+
+        new_obj = obj.copy()
+        temp_data = None
+
+        # Currently for optimization we do not apply pending changes (scale or changed .data)
+        # to the original and duplicated objects.
+        # Keep new object edited if original is.
+        if tool.Ifc.is_edited(obj, ignore_scale=True):
+            tool.Ifc.edit(new_obj)
+
+        if obj.data and not keep_data_linked:
+            # assure root.copy_class won't replace the previous mesh globally
+            temp_data = obj.data.copy()
+            new_obj.data = temp_data
+
+            # Unlink from previous boolean element
+            # and keep object tracked for decorations.
+            if is_tracked_opening:
+                mprops = tool.Geometry.get_mesh_props(new_obj.data)
+                mprops.ifc_boolean_id = 0
+                tool.Root.add_tracked_opening(new_obj, tracked_opening_type)
+
+        if obj == active_object:
+            new_active_obj = new_obj
+        for collection in obj.users_collection:
+            collection.objects.link(new_obj)
+        if not keep_source_selected:
+            obj.select_set(False)
+        new_obj.select_set(True)
+        old_obj_name_to_new_obj_name[obj.name] = new_obj.name
+
+        if not element:
+            return new_active_obj
+
+        # clear object's collection so it will be able to have it's own
+        tool.Blender.get_object_bim_props(new_obj).collection = None
+        # copy the actual class
+        new = bonsai.core.root.copy_class(tool.Ifc, tool.Collector, tool.Geometry, tool.Root, obj=new_obj)
+
+        # clean up the orphaned mesh with ifc id of the original object to avoid confusion
+        # IfcGridAxis keeps the same mesh data (it's pointing to ifc id 0, so it's not a problem)
+        if new and temp_data and not new.is_a("IfcGridAxis"):
+            if new.is_a("IfcRelSpaceBoundary"):
+                surface = new.ConnectionGeometry.SurfaceOnRelatingElement
+                temp_data.name = f"0/{surface.id()}"
+                tool.Ifc.link(surface, temp_data)
+            else:
+                tool.Blender.remove_data_block(temp_data)
+
+        if new:
+            # TODO: handle array data for other cases of duplication
+            array_data = arrays_to_duplicate.get(obj, None)
+            tool.Model.handle_array_on_copied_element(new, array_data)
+            if array_data:
+                for child in tool.Array.get_all_children_objects(new):
+                    child.select_set(True)
+
+            # TODO: add new array children to recreate their decomposition too
+            old_to_new.setdefault(element, []).append(new)
+            if new.is_a("IfcRelSpaceBoundary"):
+                tool.Boundary.decorate_boundary(new_obj)
+            # Slab-trim booleans (from extend_walls_to_underside) belong to
+            # the source wall's connection, not the copy. Strip them so the
+            # duplicate reverts to its pre-clip extrusion — mirrors the way
+            # filling rels are dropped while manual booleans persist on copy.
+            # Reload the body when something was stripped so the viewport
+            # immediately shows the unclipped geometry; otherwise the user
+            # sees a stale mesh until they Shift+G, which is easy to miss.
+            if new.is_a("IfcWall"):
+                if tool.Model.strip_underside_booleans(new):
+                    tool.Model.reload_body_representation(new_obj)
+                # HasOpenings rels don't follow object duplication, so
+                # the duplicate's body must rebuild to match its current
+                # opening set.
+                else:
+                    tool.Model.regenerate_wall(new_obj)
+
+        return new_active_obj
+
+    @classmethod
+    def _recalculate_walls_with_new_connections(
+        cls, old_to_new: dict[ifcopenshell.entity_instance, list[ifcopenshell.entity_instance]]
+    ) -> None:
+        """Recalculate new IfcWall duplicates that just received an
+        ``IfcRelConnectsPathElements``. The in-loop ``regenerate_wall`` runs
+        before ``recreate_connections``, so wall body geometry doesn't reflect
+        the junction until this second pass."""
+        walls_to_recalc: list[bpy.types.Object] = []
+        for new_list in old_to_new.values():
+            for new_entity in new_list:
+                if not new_entity.is_a("IfcWall"):
+                    continue
+                if not (getattr(new_entity, "ConnectedTo", None) or getattr(new_entity, "ConnectedFrom", None)):
+                    continue
+                new_obj = tool.Ifc.get_object(new_entity)
+                if new_obj is not None:
+                    walls_to_recalc.append(new_obj)
+        if walls_to_recalc:
+            tool.Model.recalculate_walls(walls_to_recalc)
+
     @classmethod
     def duplicate_ifc_item(cls, obj: bpy.types.Object) -> None:
         props = tool.Geometry.get_geometry_props()

src/bonsai/bonsai/tool/ifcgit.py

@@ -29,6 +29,7 @@ from typing import TYPE_CHECKING, Any, Union
 
 import bpy
 
+import bonsai.core.tool
 import bonsai.tool as tool
 from bonsai.bim import import_ifc
 from bonsai.bim.ifc import IfcStore
@@ -50,7 +51,7 @@ if TYPE_CHECKING:
     from bonsai.bim.module.ifcgit.prop import IfcGitProperties
 
 
-class IfcGit:
+class IfcGit(bonsai.core.tool.IfcGit):
     STEP_IDS = dict[str, set[int]]
 
     @classmethod

src/bonsai/bonsai/tool/loader.py

@@ -189,7 +189,7 @@ class Loader(bonsai.core.tool.Loader):
                 uv_mode = "Generated"
             elif coordinates.is_a("IfcTextureCoordinateGenerator") and coordinates.Mode == "COORD-EYE":
                 uv_mode = "Camera"
-        surface_texture["uv_mode"] = uv_mode or "Generated"
+        surface_texture["uv_mode"] = uv_mode or "UV"
         return surface_texture
 
     @classmethod
@@ -197,7 +197,6 @@ class Loader(bonsai.core.tool.Loader):
         cls, blender_material: bpy.types.Material, surface_style: ifcopenshell.entity_instance
     ) -> None:
         surface_style = cls.surface_style_to_dict(surface_style)
-        surface_style: dict[str, Any]
 
         cls.create_surface_style_shading(blender_material, surface_style)
 
@@ -315,7 +314,7 @@ class Loader(bonsai.core.tool.Loader):
                     image_url = str(image_url)
                     if is_relative and bpy.data.filepath:
                         image_url = bpy.path.relpath(image_url)
-                    return bpy.data.images.load(image_url)
+                    return bpy.data.images.load(image_url, check_existing=True)
 
                 elif texture["type"] == "IfcBlobTexture":
                     # https://blender.stackexchange.com/questions/173206/how-to-efficiently-convert-a-pil-image-to-bpy-types-image
@@ -472,12 +471,23 @@ class Loader(bonsai.core.tool.Loader):
                         print(f"{mode} Mode texture will be skipped.")
                     continue
 
-                if (image := get_image) is None:
+                if (image := get_image()) is None:
                     continue
 
-                # remove RGB node from `create_surface_style_rendering`
-                prev_node = bsdf.inputs[2].links[0].from_node
-                blender_material.node_tree.nodes.remove(prev_node)
+                # Replace whatever currently feeds the FLAT color input (RGB or previous texture chain).
+                for link in list(bsdf.inputs[2].links):
+                    prev_node = link.from_node
+                    blender_material.node_tree.links.remove(link)
+                    if prev_node.type == "TEX_IMAGE":
+                        # Remove linked texture coordinate node if it's no longer used.
+                        for vec_link in list(prev_node.inputs["Vector"].links):
+                            coord_node = vec_link.from_node
+                            blender_material.node_tree.links.remove(vec_link)
+                            if coord_node.type == "TEX_COORD" and not any(o.links for o in coord_node.outputs):
+                                blender_material.node_tree.nodes.remove(coord_node)
+                        blender_material.node_tree.nodes.remove(prev_node)
+                    elif prev_node.type == "RGB":
+                        blender_material.node_tree.nodes.remove(prev_node)
 
                 node = blender_material.node_tree.nodes.new(type="ShaderNodeTexImage")
                 node.location = bsdf.location - Vector((200, 250))

src/bonsai/bonsai/tool/misc.py

@@ -112,10 +112,14 @@ class Misc(bonsai.core.tool.Misc):
         reading data and never writing, to avoid the possibility of corrupting user preferences.
         """
 
+        # Byte offset of UserDef.user_menus within the UserDef C struct, per (major, minor)
+        # Blender version. Shifts whenever UserDef's fields change, so must be re-derived
+        # per version (e.g. from that Blender build's SDNA).
         OFFSET_USER_MENUS: dict[tuple[int, int], int] = {
             (4, 5): 10032,
             (5, 0): 10032,
             (5, 1): 10032,
+            (5, 2): 10800,
         }
 
         @classmethod

src/bonsai/bonsai/tool/model.py

@@ -59,6 +59,7 @@ from ifcopenshell.util.shape_builder import ShapeBuilder, np_to_3d
 from mathutils import Matrix, Vector
 
 import bonsai.core.geometry
+import bonsai.core.model
 import bonsai.core.tool
 import bonsai.tool as tool
 from bonsai.bim import import_ifc
@@ -1244,6 +1245,42 @@ class Model(bonsai.core.tool.Model):
         cls, parent_obj: bpy.types.Object, data: list[dict[str, Any]], array_layers_to_apply: Iterable[int] = tuple()
     ) -> None:
         """`array_layers_to_apply` - list of array layer indices to apply"""
+        with tool.Geometry.batch_host_recut():
+            cls._regenerate_array_body(parent_obj, data, array_layers_to_apply)
+
+    @classmethod
+    def _prune_orphan_array_children(cls, array: dict[str, Any]) -> None:
+        """Drop GUIDs from ``array['children']`` whose IFC entity or Blender
+        object is no longer alive, and cascade-remove the orphan IFC entity
+        if it still exists. Outliner / keyboard delete of a Bonsai-managed
+        object bypasses ``bim.delete``'s cascade, leaving dangling opening
+        and filling references that later confuse regen and crash the
+        ``batch_host_recut`` drain."""
+        live_guids: list[str] = []
+        ifc_file = tool.Ifc.get()
+        for guid in array["children"]:
+            try:
+                element = ifc_file.by_guid(guid)
+            except RuntimeError:
+                continue
+            obj = tool.Ifc.get_object(element)
+            try:
+                is_live = obj is not None and obj.data is not None
+            except ReferenceError:
+                is_live = False
+            if is_live:
+                live_guids.append(guid)
+                continue
+            try:
+                ifcopenshell.api.root.remove_product(ifc_file, product=element)
+            except (RuntimeError, ifcopenshell.Error):
+                pass
+        array["children"] = live_guids
+
+    @classmethod
+    def _regenerate_array_body(
+        cls, parent_obj: bpy.types.Object, data: list[dict[str, Any]], array_layers_to_apply: Iterable[int]
+    ) -> None:
         parent_element = tool.Ifc.get_entity(parent_obj)
 
         if pset := ifcopenshell.util.element.get_pset(parent_element, "BBIM_Array"):
@@ -1255,6 +1292,7 @@ class Model(bonsai.core.tool.Model):
         obj_stack = [parent_obj]
 
         for array_i, array in enumerate(data):
+            cls._prune_orphan_array_children(array)
             child_i = 0
             existing_children = set(array["children"])
             total_existing_children = len(array["children"])
@@ -1268,6 +1306,14 @@ class Model(bonsai.core.tool.Model):
             else:
                 base_offset = Vector([array["x"], array["y"], array["z"]]) * unit_scale
 
+            target_new_in_this_layer = (array["count"] - 1) * len(obj_stack)
+            missing_count = max(0, target_new_in_this_layer - total_existing_children)
+            new_entities_pool: list[ifcopenshell.entity_instance] = []
+            if missing_count > 0:
+                batch_old_to_new = tool.Geometry.duplicate_ifc_object_n_times(parent_obj, missing_count)
+                new_entities_pool = batch_old_to_new.get(parent_element, [])
+            new_entities_iter = iter(new_entities_pool)
+
             for i in range(array["count"]):
                 if i == 0:
                     continue
@@ -1285,8 +1331,13 @@ class Model(bonsai.core.tool.Model):
                         child_obj = tool.Ifc.get_object(child_element)
                         assert child_obj
                     except (IndexError, RuntimeError, AssertionError):
-                        old_to_new, _ = tool.Geometry.duplicate_ifc_objects([parent_obj])
-                        child_element = next(iter(old_to_new.values()))[0]
+                        try:
+                            child_element = next(new_entities_iter)
+                        except StopIteration:
+                            # Stale-GUID mid-list left the pool exhausted; fall back
+                            # to a one-off duplicate so the layer can still complete.
+                            old_to_new, _ = tool.Geometry.duplicate_ifc_objects([parent_obj])
+                            child_element = next(iter(old_to_new.values()))[0]
                         child_obj = tool.Ifc.get_object(child_element)
 
                     # add child pset
@@ -1354,14 +1405,7 @@ class Model(bonsai.core.tool.Model):
             tool.Ifc.get(), pset=pset, properties={"Data": json_data, "Parent": parent_element.GlobalId}
         )
 
-        # Post-condition: parent is selected on return. duplicate_ifc_objects
-        # deselects the source on every call inside the regen loop; without
-        # this restore, callers get a deselected parent for arrays with N >= 2.
-        # TODO: batch the per-child duplicate_ifc_objects([parent]) calls into
-        # a single N-way duplicate — N depsgraph churns + N select/deselect
-        # flips is wasteful, and a batched duplicate would also remove the
-        # need for this restore.
-        parent_obj.select_set(True)
+        tool.Blender.set_object_selection(parent_obj, True)
 
     @classmethod
     def mirror_parent_void_fillings_to_children(
@@ -1442,9 +1486,7 @@ class Model(bonsai.core.tool.Model):
             representation = tool.Geometry.get_representation_by_context(voided_element, context)
             if representation is None:
                 continue
-            bonsai.core.geometry.switch_representation(
-                tool.Ifc, tool.Geometry, obj=voided_obj, representation=representation
-            )
+            tool.Geometry.recut_host(voided_obj, representation)
 
     @classmethod
     def unshare_opening_representation(cls, filling: ifcopenshell.entity_instance) -> None:
@@ -2055,47 +2097,86 @@ class Model(bonsai.core.tool.Model):
         return (vertices, edges, faces)
 
     @classmethod
-    def update_simple_openings(cls, element: ifcopenshell.entity_instance) -> None:
+    def regenerate_filling_opening_body(cls, filling: ifcopenshell.entity_instance) -> Optional[bpy.types.Object]:
+        """Regenerate only the mapped source used by ``filling``'s opening so
+        it matches ``filling``'s current parametric dimensions.
+
+        Returns the voided host Blender object so the caller can recut it,
+        or ``None`` if ``filling`` has no opening to refresh or the host is
+        an aggregate (no mesh data to recut against)."""
         from bonsai.bim.module.model.opening import FilledOpeningGenerator
 
-        ifc_file = tool.Ifc.get()
-        fillings = {e: tool.Ifc.get_object(e) for e in tool.Array.get_parametric_propagation_targets(element)}
+        if not filling.FillsVoids:
+            return None
 
-        voided_objs = set()
-        has_replaced_opening_representation = False
+        ifc_file = tool.Ifc.get()
+        opening = filling.FillsVoids[0].RelatingOpeningElement
+        voided_obj = tool.Ifc.get_object(opening.VoidsElements[0].RelatingBuildingElement)
+        if voided_obj is None or voided_obj.data is None:
+            return None
+
+        old_representation = tool.Geometry.get_body_representation(opening)
+        if old_representation is None:
+            return voided_obj
+        old_representation = tool.Geometry.resolve_mapped_representation(old_representation)
+
+        ifcopenshell.api.geometry.unassign_representation(ifc_file, product=opening, representation=old_representation)
+
+        filling_obj = tool.Ifc.get_object(filling)
+        new_representation = FilledOpeningGenerator().generate_opening_from_filling(
+            filling, filling_obj, voided_obj.dimensions[1]
+        )
+
+        for inverse in ifc_file.get_inverse(old_representation):
+            ifcopenshell.util.element.replace_attribute(inverse, old_representation, new_representation)
+
+        ifcopenshell.api.geometry.remove_representation(ifc_file, representation=old_representation)
+
+        return voided_obj
+
+    @classmethod
+    def regenerate_simple_opening_bodies(cls, element: ifcopenshell.entity_instance) -> set:
+        """Regenerate every distinct mapped opening source within ``element``'s
+        type-occurrence family so each one matches the family's current
+        parametric dimensions.
+
+        Most occurrences share a single mapped source — refreshing it once
+        propagates to every filling via inverse-substitution. Some families,
+        especially those imported from foreign authoring tools, fragment into
+        several mapped sources for the same type; dedup is by source id so
+        every distinct source gets one refresh. Returns the set of Blender
+        objects whose host representation needs a viewport-level recut
+        (callers handle the recut themselves)."""
+        ifc_file = tool.Ifc.get()
+        fillings = list(tool.Array.get_parametric_propagation_targets(element))
+
+        voided_objs: set = set()
+        seen_source_ids: set[int] = set()
         for filling in fillings:
             if not filling.FillsVoids:
                 continue
 
             opening = filling.FillsVoids[0].RelatingOpeningElement
             voided_obj = tool.Ifc.get_object(opening.VoidsElements[0].RelatingBuildingElement)
-            voided_objs.add(voided_obj)
+            if voided_obj is not None:
+                voided_objs.add(voided_obj)
 
-            # We assume all occurrences of the same element type (e.g. a window)
-            # will use openings of the same thickness.
-            # Generator we use by default will create a really thick opening representation
-            # to make sure it will fit for walls with different thickness.
-            if has_replaced_opening_representation:
+            body = tool.Geometry.get_body_representation(opening)
+            if body is None:
                 continue
+            source = tool.Geometry.resolve_mapped_representation(body)
+            if source.id() in seen_source_ids:
+                continue
+            seen_source_ids.add(source.id())
 
-            old_representation = ifcopenshell.util.representation.get_representation(
-                opening, "Model", "Body", "MODEL_VIEW"
-            )
-            old_representation = tool.Geometry.resolve_mapped_representation(old_representation)
-            ifcopenshell.api.geometry.unassign_representation(
-                ifc_file, product=opening, representation=old_representation
-            )
+            cls.regenerate_filling_opening_body(filling)
 
-            new_representation = FilledOpeningGenerator().generate_opening_from_filling(
-                filling, fillings[filling], voided_obj.dimensions[1]
-            )
+        return voided_objs
 
-            for inverse in ifc_file.get_inverse(old_representation):
-                ifcopenshell.util.element.replace_attribute(inverse, old_representation, new_representation)
-
-            ifcopenshell.api.geometry.remove_representation(ifc_file, representation=old_representation)
-
-            has_replaced_opening_representation = True
+    @classmethod
+    def update_simple_openings(cls, element: ifcopenshell.entity_instance) -> None:
+        voided_objs = cls.regenerate_simple_opening_bodies(element)
+        fillings = {e: tool.Ifc.get_object(e) for e in tool.Array.get_parametric_propagation_targets(element)}
 
         tool.Model.reload_body_representation(voided_objs)
         if fillings:
@@ -3058,6 +3139,9 @@ class Model(bonsai.core.tool.Model):
             regenerate_fillet_corner_wall(element, obj)
             return
         rep = ifcopenshell.api.geometry.regenerate_wall_representation(tool.Ifc.get(), element)
+        if rep is None:
+            # Wall has no IfcMaterialLayerSet — layer-set rebuild not applicable.
+            return
         bonsai.core.geometry.switch_representation(
             tool.Ifc,
             tool.Geometry,
@@ -3100,6 +3184,26 @@ class Model(bonsai.core.tool.Model):
                 obj = tool.Ifc.get_object(rel.RelatingElement)
                 tool.Geometry.commit_placement_if_moved(obj)
                 queue.add((rel.RelatingElement, obj))
+
+        # Sync filling and opening placements so subsequent wall recuts
+        # operate on the up-to-date opening positions — a filling moved
+        # along the wall's reference line otherwise stays cut at its old
+        # spot.
+        for element, wall in queue:
+            if not wall:
+                continue
+            for rel in getattr(element, "HasOpenings", []) or []:
+                opening = rel.RelatedOpeningElement
+                for fill_rel in getattr(opening, "HasFillings", []) or []:
+                    filling = fill_rel.RelatedBuildingElement
+                    filling_obj = tool.Ifc.get_object(filling)
+                    if filling_obj is None or not tool.Ifc.is_moved(filling_obj):
+                        continue
+                    bonsai.core.geometry.edit_object_placement(tool.Ifc, tool.Geometry, tool.Surveyor, obj=filling_obj)
+                    ifcopenshell.api.geometry.edit_object_placement(
+                        tool.Ifc.get(), product=opening, matrix=filling_obj.matrix_world
+                    )
+
         for element, wall in queue:
             if not wall:
                 continue

src/bonsai/bonsai/tool/parametric.py

@@ -81,11 +81,19 @@ class ParametricObject:
     ``_cancel_targets``) and that therefore wire their operators through
     ``build_edit_lifecycle``. Entries with bespoke edit lifecycles (per-attribute
     diff dispatch, layer-stack editing, mid-spline gizmo drag) leave this
-    False and declare their operator classes directly."""
+    False and declare their operator classes directly.
+
+    ``has_default_parameters`` marks entries whose ``BIM<Name>Properties``
+    class exposes ``get_general_kwargs`` / ``copy_to`` and a matching
+    ``draw_<name>_properties`` UI helper, so the addon-preferences panel can
+    surface a per-type defaults section and the create operator can seed new
+    instances from the preset. Entries without that machinery leave this False
+    and don't appear in the preferences ``Default Parameters`` panel."""
 
     name: str
     has_non_editable_path: bool = False
     supports_build_edit_lifecycle: bool = False
+    has_default_parameters: bool = False
 
     def __post_init__(self) -> None:
         if not _VALID_NAME_RE.match(self.name):
@@ -148,11 +156,17 @@ class Parametric(bonsai.core.tool.Parametric):
             self._gen = None
 
     EDIT_TYPES: list[ParametricObject] = [
-        ParametricObject("door", has_non_editable_path=True, supports_build_edit_lifecycle=True),
-        ParametricObject("window", has_non_editable_path=True, supports_build_edit_lifecycle=True),
-        ParametricObject("stair", has_non_editable_path=True, supports_build_edit_lifecycle=True),
-        ParametricObject("railing", supports_build_edit_lifecycle=True),
-        ParametricObject("roof", supports_build_edit_lifecycle=True),
+        ParametricObject(
+            "door", has_non_editable_path=True, supports_build_edit_lifecycle=True, has_default_parameters=True
+        ),
+        ParametricObject(
+            "window", has_non_editable_path=True, supports_build_edit_lifecycle=True, has_default_parameters=True
+        ),
+        ParametricObject(
+            "stair", has_non_editable_path=True, supports_build_edit_lifecycle=True, has_default_parameters=True
+        ),
+        ParametricObject("railing", supports_build_edit_lifecycle=True, has_default_parameters=True),
+        ParametricObject("roof", supports_build_edit_lifecycle=True, has_default_parameters=True),
         ParametricObject("array", supports_build_edit_lifecycle=True),
         ParametricObject("pipe_segment", supports_build_edit_lifecycle=True),
         ParametricObject("duct_segment", supports_build_edit_lifecycle=True),

src/bonsai/bonsai/tool/patch.py

@@ -18,18 +18,33 @@
 
 from __future__ import annotations
 
+import re
 from typing import TYPE_CHECKING, Any
 
 import bpy
 import ifcopenshell
+import ifcopenshell.util.schema
 import ifcpatch
 
 import bonsai.core.tool
+import bonsai.tool
 
 if TYPE_CHECKING:
     from bonsai.bim.module.patch.prop import BIMPatchProperties
 
 
+# Lower index = older schema. Used to detect downgrades vs upgrades.
+_SCHEMA_AGE = {"IFC2X3": 0, "IFC4": 1, "IFC4X3": 2}
+
+# Pretty-printed argument name for the ``Migrate`` recipe's schema parameter
+# (see UpdateIfcPatchArguments.pretty_arg_name in bim/module/patch/operator.py).
+_MIGRATE_SCHEMA_ARG_NAME = "Schema"
+
+# Match a STEP-encoded FILE_SCHEMA header: ``FILE_SCHEMA(('IFC4'));`` and the
+# IFC4X3_ADD2 / IFC2X3_TC1 variants. Captures the bare schema identifier.
+_IFC_FILE_SCHEMA_RE = re.compile(r"FILE_SCHEMA\s*\(\s*\(\s*'([^']+)'", re.IGNORECASE)
+
+
 class Patch(bonsai.core.tool.Patch):
     @classmethod
     def get_patch_props(cls) -> BIMPatchProperties:
@@ -54,6 +69,63 @@ class Patch(bonsai.core.tool.Patch):
             "SplitByBuildingStorey",
         )
 
+    @classmethod
+    def get_preset_subdir(cls) -> str:
+        """Resolve the preset subdirectory for the currently selected recipe.
+
+        Returns a stable string for the ``-`` placeholder so the menu and save
+        operator remain usable when no real recipe has been picked yet."""
+        recipe = cls.get_patch_props().ifc_patch_recipes or "-"
+        return f"bonsai/ifc_patch/{recipe}"
+
+    @classmethod
+    def migration_is_lossy_downgrade(cls) -> bool:
+        """``True`` when the currently configured patch is the ``Migrate``
+        recipe targeting an older schema than the input file. Used to gate
+        the destructive-migration confirmation dialog."""
+        props = cls.get_patch_props()
+        if props.ifc_patch_recipes != "Migrate":
+            return False
+        target_schema = next(
+            (arg.get_value() for arg in props.ifc_patch_args_attr if arg.name == _MIGRATE_SCHEMA_ARG_NAME),
+            None,
+        )
+        if not target_schema:
+            return False
+        source_schema = cls._patch_source_schema()
+        if not source_schema:
+            return False
+        return _SCHEMA_AGE.get(target_schema, -1) < _SCHEMA_AGE.get(source_schema, -1)
+
+    @classmethod
+    def _patch_source_schema(cls) -> str:
+        """Resolve the IFC schema of the configured input without parsing the
+        full file. For loaded-from-memory the schema is in the entity_instance
+        wrapper; for disk paths we read only the STEP file header (first ~2KB)
+        rather than ``ifcopenshell.open`` which parses the whole file."""
+        props = cls.get_patch_props()
+        if props.should_load_from_memory:
+            ifc_file = bonsai.tool.Ifc.get()
+            return ifc_file.schema if ifc_file else ""
+        if not props.ifc_patch_input:
+            return ""
+        try:
+            with open(props.ifc_patch_input, "rb") as f:
+                header = f.read(2048).decode("utf-8", errors="ignore")
+        except OSError:
+            return ""
+        match = _IFC_FILE_SCHEMA_RE.search(header)
+        if not match:
+            return ""
+        # Collapse IFC4X3_ADD2 / IFC2X3_TC1 / IFC4_ADD2 / IFC4X1 etc. to their
+        # base via the canonical normaliser — handles longest-prefix-first
+        # ordering correctly (IFC4X3 before IFC4) so we don't misclassify
+        # IFC4X3 files as IFC4.
+        try:
+            return ifcopenshell.util.schema.get_fallback_schema(match.group(1).upper())
+        except AssertionError:
+            return ""
+
     @classmethod
     def post_process_patch_arguments(cls, recipe: str, args: list[Any]) -> list[Any]:
         if recipe == "ExtractElements":

src/bonsai/bonsai/tool/project.py

@@ -334,6 +334,14 @@ class Project(bonsai.core.tool.Project):
                 if reference[1]:
                     m = np.fromstring(reference[1], sep=",", dtype=np.float64).reshape(4, 4)
                     link.has_transformation = not np.allclose(m, np.eye(4))
+                # The selector query used at link time is persisted only in the
+                # sidecar cache JSON; restore it so Reload/Load replay the filter.
+                json_filepath = Path(tool.Ifc.resolve_uri(filepath)).with_suffix(".ifc.cache.json")
+                if json_filepath.exists():
+                    try:
+                        link.query = json.loads(json_filepath.read_text()).get("query", "")
+                    except (OSError, json.JSONDecodeError):
+                        pass
 
     @classmethod
     def get_project_library_elements(

src/bonsai/bonsai/tool/raycast.py

@@ -232,7 +232,7 @@ class Raycast(bonsai.core.tool.Raycast):
         return final_2d, v2
 
     @classmethod
-    def intersect_mouse_2d_bounding_box(cls, mouse_pos: tuple[int, int], bbox: list[float, float, float, float]):
+    def intersect_mouse_2d_bounding_box(cls, mouse_pos: tuple[int, int], bbox: list[float]):
         x, y = mouse_pos
         xmin, xmax, ymin, ymax = bbox
 

src/bonsai/bonsai/tool/root.py

@@ -373,35 +373,37 @@ class Root(bonsai.core.tool.Root):
                 try:
                     new_aggregate = old_to_new[old_aggregate]
                 except:
-                    bonsai.core.aggregate.unassign_object(
-                        tool.Ifc,
-                        tool.Aggregate,
-                        tool.Collector,
-                        relating_obj=tool.Ifc.get_object(old_aggregate),
-                        related_obj=tool.Ifc.get_object(new[0]),
-                    )
-                    continue
-
-                bonsai.core.aggregate.assign_object(
-                    tool.Ifc,
-                    tool.Aggregate,
-                    tool.Collector,
-                    relating_obj=tool.Ifc.get_object(new_aggregate[0]),
-                    related_obj=tool.Ifc.get_object(new[0]),
-                )
-
-                # Make sure that the array children also get reassigned to the correct aggregate
-                pset = ifcopenshell.util.element.get_pset(new[0], "BBIM_Array")
-                if pset:
-                    array_children = tool.Array.get_all_children_objects(new[0])
-                    for obj in array_children:
-                        bonsai.core.aggregate.assign_object(
+                    for new_entity in new:
+                        bonsai.core.aggregate.unassign_object(
                             tool.Ifc,
                             tool.Aggregate,
                             tool.Collector,
-                            relating_obj=tool.Ifc.get_object(new_aggregate[0]),
-                            related_obj=tool.Ifc.get_object(tool.Ifc.get_entity(obj)),
+                            relating_obj=tool.Ifc.get_object(old_aggregate),
+                            related_obj=tool.Ifc.get_object(new_entity),
                         )
+                    continue
+
+                for new_entity in new:
+                    bonsai.core.aggregate.assign_object(
+                        tool.Ifc,
+                        tool.Aggregate,
+                        tool.Collector,
+                        relating_obj=tool.Ifc.get_object(new_aggregate[0]),
+                        related_obj=tool.Ifc.get_object(new_entity),
+                    )
+
+                    # Make sure that the array children also get reassigned to the correct aggregate
+                    pset = ifcopenshell.util.element.get_pset(new_entity, "BBIM_Array")
+                    if pset:
+                        array_children = tool.Array.get_all_children_objects(new_entity)
+                        for obj in array_children:
+                            bonsai.core.aggregate.assign_object(
+                                tool.Ifc,
+                                tool.Aggregate,
+                                tool.Collector,
+                                relating_obj=tool.Ifc.get_object(new_aggregate[0]),
+                                related_obj=tool.Ifc.get_object(tool.Ifc.get_entity(obj)),
+                            )
 
         if new_aggregate is None:
             return

src/bonsai/bonsai/tool/system.py

@@ -357,6 +357,13 @@ class System(bonsai.core.tool.System):
             if not cls.is_mep_element(element):
                 continue
 
+            # Array children inherit port topology from their parent's IFC
+            # entity, but their positions are derived — drawing ports on every
+            # copy of an arrayed segment doubles up markers and misleads the
+            # user into thinking each copy has its own port network.
+            if tool.Array.is_array_child(element):
+                continue
+
             selected_element = element in connected_elements
             verts_pos = []
 
@@ -488,6 +495,69 @@ class System(bonsai.core.tool.System):
     def is_mep_element(cls, element: ifcopenshell.entity_instance) -> bool:
         return element.is_a("IfcFlowSegment") or element.is_a("IfcFlowFitting")
 
+    @classmethod
+    def is_disconnectable_fitting(cls, element: ifcopenshell.entity_instance) -> bool:
+        """A fitting whose deletion is the supported teardown for one of
+        its port connections. ``OBSTRUCTION`` fittings are excluded — they
+        have a dedicated grow/shrink flow (``bim.mep_add_obstruction``
+        with ``mode=REMOVE``) that absorbs the freed segment length."""
+        if not element.is_a("IfcFlowFitting"):
+            return False
+        return getattr(element, "PredefinedType", None) != "OBSTRUCTION"
+
+    @classmethod
+    def neighbours_at_ports(cls, element: ifcopenshell.entity_instance) -> list[ifcopenshell.entity_instance]:
+        """Entities reachable from ``element``'s ports via a single
+        ``IfcRelConnectsPorts`` hop, deduped by IFC id."""
+        neighbours: list[ifcopenshell.entity_instance] = []
+        seen: set[int] = set()
+        for port in cls.get_ports(element):
+            connected_port = cls.get_connected_port(port)
+            if connected_port is None:
+                continue
+            neighbour = ifcopenshell.util.system.get_port_element(connected_port)
+            if neighbour is None or neighbour.id() in seen:
+                continue
+            seen.add(neighbour.id())
+            neighbours.append(neighbour)
+        return neighbours
+
+    @classmethod
+    def find_bridging_fitting(
+        cls,
+        elem_a: ifcopenshell.entity_instance,
+        elem_b: ifcopenshell.entity_instance,
+    ) -> Union[ifcopenshell.entity_instance, None]:
+        """Return the disconnectable ``IfcFlowFitting`` whose removal
+        disconnects ``elem_a`` from ``elem_b``, or ``None``.
+
+        Two topologies are handled. (1) Direct port-to-port between a
+        segment/fitting and a disconnectable fitting: the fitting endpoint
+        is returned. (2) Two segments joined by a single bridging
+        disconnectable fitting: the bridging fitting is returned.
+        ``OBSTRUCTION`` fittings short-circuit to ``None``."""
+        if not (cls.is_mep_element(elem_a) and cls.is_mep_element(elem_b)):
+            return None
+
+        a_neighbours = cls.neighbours_at_ports(elem_a)
+        b_neighbours = cls.neighbours_at_ports(elem_b)
+        elem_a_id = elem_a.id()
+        elem_b_id = elem_b.id()
+
+        if cls.is_disconnectable_fitting(elem_a) and any(n.id() == elem_b_id for n in a_neighbours):
+            return elem_a
+        if cls.is_disconnectable_fitting(elem_b) and any(n.id() == elem_a_id for n in b_neighbours):
+            return elem_b
+
+        a_fittings = [n for n in a_neighbours if cls.is_disconnectable_fitting(n)]
+        if not a_fittings:
+            return None
+        b_fitting_ids = {n.id() for n in b_neighbours if cls.is_disconnectable_fitting(n)}
+        for fitting in a_fittings:
+            if fitting.id() in b_fitting_ids:
+                return fitting
+        return None
+
     @classmethod
     def has_parametric_body(cls, element: ifcopenshell.entity_instance) -> bool:
         """True when the MEP element's body representation is a profile sweep

src/bonsai/bonsai/tool/type.py

@@ -24,6 +24,7 @@ import bpy
 import ifcopenshell
 import ifcopenshell.util.element
 import ifcopenshell.util.representation
+import ifcopenshell.util.type
 
 import bonsai.core.geometry
 import bonsai.core.tool
@@ -96,6 +97,26 @@ class Type(bonsai.core.tool.Type):
     def get_type_occurrences(cls, element_type: ifcopenshell.entity_instance) -> list[ifcopenshell.entity_instance]:
         return ifcopenshell.util.element.get_types(element_type)
 
+    @classmethod
+    def is_relating_type_compatible(
+        cls,
+        occurrence: ifcopenshell.entity_instance,
+        relating_type: ifcopenshell.entity_instance,
+    ) -> bool:
+        # IFC's EXPRESS schema has no WHERE rule pairing IfcRelDefinesByType's
+        # RelatingType / RelatedObjects classes; the one-to-one class pairing
+        # is a buildingSMART implementer agreement, not file-validation.
+        schema = occurrence.file.schema
+        if relating_type.is_a() in ifcopenshell.util.type.get_applicable_types(occurrence.is_a(), schema=schema):
+            return True
+        # The implementer agreement map has no entry for the abstract
+        # IfcTypeProduct, which Bonsai uses for annotation types. The schema
+        # defines IfcTypeProduct.ApplicableOccurrence for exactly this purpose,
+        # so honor it. occurrence.is_a() handles subtypes and unknown tokens.
+        if applicable_occurrence := getattr(relating_type, "ApplicableOccurrence", None):
+            return occurrence.is_a(applicable_occurrence.split("/", 1)[0])
+        return False
+
     @classmethod
     def has_material_usage(cls, element: ifcopenshell.entity_instance) -> bool:
         material = ifcopenshell.util.element.get_material(element)