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+<!-- This file was generated with the assistance of an AI coding tool. -->
+
+# AGENTS.md
+
+Guidelines for AI coding agents contributing to IfcOpenShell. This file is
+intended to be read by all AI agents regardless of platform (Claude Code,
+Copilot, Cursor, etc.) in addition to any tool-specific configuration files.
+
+Human contributors using AI tools should also read this document carefully,
+as they are responsible for ensuring their contributions comply with these
+guidelines.
+
+## Project Overview
+
+IfcOpenShell is an open source library for working with Industry Foundation
+Classes (IFC). It provides C++ and Python APIs, geometry processing, and an
+ecosystem of tools including IfcConvert and the Bonsai Blender add-on.
+
+## Licensing
+
+All contributions must be compatible with the project's licensing:
+
+- **Library code** (everything except Bonsai): **LGPL-3.0-or-later**
+- **Bonsai** (`src/bonsai/`): **GPL-3.0-or-later**
+
+There is no Contributor License Agreement (CLA). By submitting a pull request,
+you agree that your contribution is licensed under the applicable license above.
+
+## Indicating AI-Generated Code
+
+Contributors must clearly indicate when code has been generated or
+substantially written by an AI tool.
+
+### Commits
+
+Commits that modify existing code must include a note in the **body** of the
+commit message (not the subject line) indicating that the change was
+AI-generated. For example:
+
+```
+Fix off-by-one error in element iteration
+
+The loop termination condition was incorrect when processing
+IfcRelAggregates relationships.
+
+Generated with the assistance of an AI coding tool.
+```
+
+### New Files
+
+New files that are AI-generated must include a comment near the top of the
+file indicating this. Use the appropriate comment syntax for the language:
+
+```python
+# This file was generated with the assistance of an AI coding tool.
+```
+
+```cpp
+// This file was generated with the assistance of an AI coding tool.
+```
+
+### Pull Requests
+
+Pull requests containing AI-generated code must indicate in the PR description
+which parts of the contribution are AI-generated. If the entire PR is
+AI-generated, state that clearly. If only specific commits or files are
+AI-generated, identify them.
+
+## Pull Request Guidelines
+
+### Scope and Size
+
+- Each pull request should address a **single issue or feature**.
+- Do not mix unrelated changes (e.g., bug fixes with refactoring or style
+  changes) in the same PR.
+- Large pull requests should be broken down into **multiple small, standalone
+  commits** that are each easy to review independently. Rewrite commit history
+  for this purpose if necessary.
+- PRs that are minimal, focused solutions to a specific problem are much more
+  likely to be accepted.
+
+### What to Avoid
+
+- **Over-engineering**: Do not add features, abstractions, or configurability
+  beyond what is needed to solve the immediate problem.
+- **Scope creep**: Do not make changes to files or code that are not directly
+  related to the task at hand.
+- **Unnecessary additions**: Do not add docstrings, comments, type annotations,
+  or error handling to code you did not otherwise need to change.
+- **Cosmetic changes**: Do not reformat, rename, or reorganize code that is
+  unrelated to your change.
+
+## Commit Messages
+
+- The **subject line** must be **50 characters or less**.
+- Use the **imperative mood** (e.g., "Fix crash in geometry kernel", not
+  "Fixed crash" or "Fixes crash").
+- A commit message can be a single line if the purpose is obvious from the
+  subject alone.
+- Otherwise, add a blank line after the subject followed by a short explanation
+  of a few lines in the body.
+
+## Code Style
+
+### Python
+
+- **Line length**: 120 characters
+- **Formatter**: black
+- **Linter**: ruff
+- Configuration is in `pyproject.toml`
+
+### C++
+
+- **Standard**: C++17 minimum
+- **Formatter**: clang-format (configuration in `.clang-format`)
+- **Linter**: clang-tidy (configuration in `.clang-tidy`)
+
+Run linters and formatters **before submitting** your pull request. Do not rely
+on CI to catch formatting issues.
+
+## Testing
+
+- Pull requests with test coverage are **much more likely to be merged**.
+- If tests are appropriate and feasible for your change, they should be
+  included.
+- Tests are not required for every change (e.g., documentation-only changes),
+  but the expectation is that testable code changes come with tests.
+- Python tests use **pytest** and are located in `test/` or `tests/` directories
+  within each package under `src/`.
+- Run the existing test suite for the package you modified before submitting.
+
+## Architecture Quick Reference
+
+### Directory Structure
+
+- `src/ifcparse/` — C++ IFC file parsing
+- `src/ifcgeom/` — C++ geometry processing (OpenCASCADE and CGAL kernels)
+- `src/serializers/` — Output format serializers (glTF, Collada, SVG, etc.)
+- `src/ifcwrap/` — SWIG Python bindings
+- `src/ifcconvert/` — CLI conversion tool
+- `src/ifcopenshell-python/` — Python API (`ifcopenshell` package)
+- `src/bonsai/` — Blender add-on (GPL-3.0-or-later)
+- `src/ifctester/` — IDS model auditing
+- `src/ifcpatch/` — IFC file manipulation scripts
+- `src/ifcdiff/` — IFC model comparison
+- `src/ifcclash/` — Clash detection
+- `src/ifccsv/` — Schedule import/export
+
+### IFC Schema Versions
+
+The library supports IFC2x3 TC1, IFC4 Add2 TC1, IFC4x1, IFC4x2, and
+IFC4x3 Add2. Schema-specific code is compiled conditionally. Be aware of
+which schema versions your change affects.