diff --git a/src/ifcmcp/README.md b/src/ifcmcp/README.md
new file mode 100644
index 0000000000..d930820e70
--- /dev/null
+++ b/src/ifcmcp/README.md
@@ -0,0 +1,221 @@
+# ifcmcp
+
+An MCP (Model Context Protocol) server that wraps `ifcquery` and `ifcedit`,
+holding the IFC model in memory across tool calls for fast interactive editing
+sessions.
+
+## Installation
+
+```bash
+pip install ifcmcp
+```
+
+Requires `ifcopenshell`, `ifcquery`, `ifcedit`, and `mcp`.
+
+## Running the server
+
+```bash
+python3 -m ifcmcp
+```
+
+This starts the server on stdio transport, suitable for use with Claude Code
+or any MCP client.
+
+### Claude Code configuration
+
+Use the `claude mcp add` command:
+
+```bash
+claude mcp add --transport stdio ifc -- python3 -m ifcmcp
+```
+
+Or create a `.mcp.json` file in your project root:
+
+```json
+{
+  "mcpServers": {
+    "ifc": {
+      "type": "stdio",
+      "command": "python3",
+      "args": ["-m", "ifcmcp"]
+    }
+  }
+}
+```
+
+After adding the server, restart Claude Code for the tools to become available.
+Then load a model by asking Claude to use `ifc_load`:
+
+```
+load model.ifc using ifc_load
+```
+
+## Tools
+
+### Session
+
+#### ifc_load
+
+Open an IFC file into memory.
+
+```
+ifc_load(path="/path/to/model.ifc")
+-> "Loaded /path/to/model.ifc: schema IFC4, 1847 entities"
+```
+
+#### ifc_save
+
+Write the in-memory model to disk. Empty path overwrites the original file.
+
+```
+ifc_save()
+ifc_save(path="/path/to/output.ifc")
+```
+
+### Query tools
+
+All query tools require a model to be loaded first via `ifc_load`.
+
+#### ifc_summary
+
+Model overview: schema, entity counts, project info.
+
+```json
+{
+  "schema": "IFC4",
+  "total_entities": 1847,
+  "project": {"id": 1, "name": "Office Building"},
+  "types": {"IfcWall": 42, "IfcSlab": 12, "IfcWindow": 36}
+}
+```
+
+#### ifc_tree
+
+Full spatial hierarchy from IfcProject down through sites, buildings, storeys,
+and contained elements.
+
+```json
+{
+  "id": 1,
+  "type": "IfcProject",
+  "name": "Office Building",
+  "children": [
+    {
+      "id": 2,
+      "type": "IfcSite",
+      "children": [{"id": 3, "type": "IfcBuilding", "children": ["..."]}]
+    }
+  ]
+}
+```
+
+#### ifc_info
+
+Deep inspection of an entity by step ID: attributes, property sets, type,
+material, container, and 4x4 placement matrix.
+
+```
+ifc_info(element_id=10)
+```
+
+#### ifc_select
+
+Filter elements using ifcopenshell selector syntax.
+
+```
+ifc_select(query="IfcWall")
+ifc_select(query="IfcWindow")
+```
+
+Returns a sorted list of `{"id", "type", "name"}` references.
+
+#### ifc_relations
+
+Show all relationships for an element: hierarchy, children, type, groups,
+systems, material, connections.
+
+```
+ifc_relations(element_id=10)
+ifc_relations(element_id=10, traverse="up")
+```
+
+With `traverse="up"`, walks the hierarchy from element up to IfcProject.
+
+#### ifc_clash
+
+Check an element for geometric intersections and clearance violations.
+
+```
+ifc_clash(element_id=10)
+ifc_clash(element_id=10, clearance=0.5, scope="all")
+```
+
+Parameters:
+
+- `clearance` -- minimum clearance distance in meters (0.0 = no clearance check)
+- `tolerance` -- intersection tolerance in meters (default: 0.002)
+- `scope` -- `"storey"` or `"all"` (default: `"storey"`)
+
+### Edit discovery tools
+
+#### ifc_list
+
+List all API modules, or functions within a specific module.
+
+```
+ifc_list()              # all modules
+ifc_list(module="root") # functions in the root module
+```
+
+#### ifc_docs
+
+Show full documentation for an API function including parameters, types,
+defaults, and descriptions.
+
+```
+ifc_docs(function_path="root.create_entity")
+```
+
+### Edit execution
+
+#### ifc_edit
+
+Execute an `ifcopenshell.api` mutation function. Parameters are passed as a
+JSON string with string values that get coerced by ifcedit's type system.
+
+```
+ifc_edit(
+    function_path="root.create_entity",
+    params='{"ifc_class": "IfcWall", "name": "My Wall"}'
+)
+```
+
+Returns `{"ok": true, "result": ...}` or `{"ok": false, "error": "..."}`.
+
+Does NOT auto-save -- call `ifc_save()` when ready to write changes to disk.
+
+**Parameter coercion:**
+
+| Type | JSON value | Python value |
+|------|------------|--------------|
+| `entity_instance` | `"42"` | resolved from model by step ID |
+| `list[entity_instance]` | `"5,6,7"` | list of resolved entities |
+| `dict` | `'{"key": "val"}'` | parsed JSON object |
+| `bool` | `"true"` | `True` |
+| `Optional[X]` | `"none"` | `None` |
+
+## Typical workflow
+
+1. **Load** a model: `ifc_load`
+2. **Inspect** with query tools: `ifc_summary`, `ifc_tree`, `ifc_select`, `ifc_info`, `ifc_relations`
+3. **Find** the right API function: `ifc_list`, `ifc_docs`
+4. **Edit** the model: `ifc_edit`
+5. **Verify** changes with query tools
+6. **Save** when satisfied: `ifc_save`
+
+The model stays in memory across all calls, so multi-step editing sessions
+are fast -- no file I/O between operations.
+
+## License
+
+LGPLv3+ -- see the IfcOpenShell project license.
diff --git a/src/ifcmcp/ifcmcp/__init__.py b/src/ifcmcp/ifcmcp/__init__.py
new file mode 100644
index 0000000000..9d42a08c1d
--- /dev/null
+++ b/src/ifcmcp/ifcmcp/__init__.py
@@ -0,0 +1,19 @@
+# IfcMCP - MCP server for IFC building models
+# Copyright (C) 2025 Bruno Postle <bruno@postle.net>
+#
+# This file is part of IfcMCP.
+#
+# IfcMCP is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# IfcMCP 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 Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with IfcMCP.  If not, see <http://www.gnu.org/licenses/>.
+
+__version__ = version = "0.0.0"
diff --git a/src/ifcmcp/ifcmcp/__main__.py b/src/ifcmcp/ifcmcp/__main__.py
new file mode 100644
index 0000000000..a6ea60e469
--- /dev/null
+++ b/src/ifcmcp/ifcmcp/__main__.py
@@ -0,0 +1,3 @@
+from ifcmcp.server import server
+
+server.run(transport="stdio")
diff --git a/src/ifcmcp/ifcmcp/server.py b/src/ifcmcp/ifcmcp/server.py
new file mode 100644
index 0000000000..834d63eed0
--- /dev/null
+++ b/src/ifcmcp/ifcmcp/server.py
@@ -0,0 +1,142 @@
+from __future__ import annotations
+
+import json
+from typing import Any
+
+import ifcopenshell
+
+from ifcquery import clash as clash_mod
+from ifcquery import info, relations, select, summary, tree
+from ifcedit.discover import function_docs, list_functions, list_modules
+from ifcedit.run import run_api
+from mcp.server.fastmcp import FastMCP
+
+server = FastMCP(
+    name="ifc-mcp",
+    instructions="MCP server for querying and editing IFC building models. "
+    "Load a file first with ifc_load, then use query/edit tools. "
+    "Save changes with ifc_save.",
+)
+
+_model: ifcopenshell.file | None = None
+_model_path: str | None = None
+
+
+def _require_model() -> ifcopenshell.file:
+    if _model is None:
+        raise ValueError("No model loaded. Call ifc_load first.")
+    return _model
+
+
+# -- Session tools --
+
+
+@server.tool()
+def ifc_load(path: str) -> str:
+    """Open an IFC file into memory. Returns confirmation with schema and entity count."""
+    global _model, _model_path
+    _model = ifcopenshell.open(path)
+    _model_path = path
+    count = sum(1 for _ in _model)
+    return f"Loaded {path}: schema {_model.schema}, {count} entities"
+
+
+@server.tool()
+def ifc_save(path: str = "") -> str:
+    """Write the in-memory model to disk. Empty path overwrites the original file."""
+    model = _require_model()
+    target = path if path else _model_path
+    if not target:
+        raise ValueError("No path specified and no original path available.")
+    model.write(target)
+    return f"Saved to {target}"
+
+
+# -- Query tools --
+
+
+@server.tool()
+def ifc_summary() -> dict[str, Any]:
+    """Model overview: schema, entity counts, project info."""
+    return summary.summary(_require_model())
+
+
+@server.tool()
+def ifc_tree() -> dict[str, Any] | list[dict[str, Any]]:
+    """Full spatial hierarchy tree (Project -> Site -> Building -> Storeys -> Elements)."""
+    return tree.tree(_require_model())
+
+
+@server.tool()
+def ifc_info(element_id: int) -> dict[str, Any]:
+    """Deep inspection of an entity by step ID (attributes, psets, placement, type, material)."""
+    model = _require_model()
+    element = model.by_id(element_id)
+    return info.info(model, element)
+
+
+@server.tool()
+def ifc_select(query: str) -> list[dict[str, Any]]:
+    """Filter elements using ifcopenshell selector syntax (e.g. 'IfcWall', 'IfcWindow')."""
+    return select.select(_require_model(), query)
+
+
+@server.tool()
+def ifc_relations(element_id: int, traverse: str = "") -> dict[str, Any] | list[dict[str, Any]]:
+    """Show relationships for an element. Set traverse='up' to walk hierarchy to IfcProject."""
+    model = _require_model()
+    element = model.by_id(element_id)
+    return relations.relations(model, element, traverse=traverse if traverse else None)
+
+
+@server.tool()
+def ifc_clash(
+    element_id: int,
+    clearance: float = 0.0,
+    tolerance: float = 0.002,
+    scope: str = "storey",
+) -> dict[str, Any]:
+    """Check element for geometric clashes. clearance=0.0 means no clearance check."""
+    model = _require_model()
+    element = model.by_id(element_id)
+    return clash_mod.clash(
+        model,
+        element,
+        clearance=clearance if clearance > 0.0 else None,
+        tolerance=tolerance,
+        scope=scope,
+    )
+
+
+# -- Edit discovery tools --
+
+
+@server.tool()
+def ifc_list(module: str = "") -> list[dict]:
+    """List all API modules, or functions within a module. Empty module = all modules."""
+    if module:
+        return list_functions(module)
+    return list_modules()
+
+
+@server.tool()
+def ifc_docs(function_path: str) -> dict:
+    """Show full documentation for an API function. Input format: 'module.function'."""
+    module, function = function_path.split(".", 1)
+    return function_docs(module, function)
+
+
+# -- Edit execution tool --
+
+
+@server.tool()
+def ifc_edit(function_path: str, params: str = "{}") -> dict:
+    """Execute an ifcopenshell.api mutation. params is a JSON string of {"param": "value"} pairs.
+
+    Values are strings coerced by ifcedit's type system (entity IDs as "123",
+    dicts as JSON strings, etc). Does NOT auto-save; call ifc_save() after edits.
+    """
+    model = _require_model()
+    module, function = function_path.split(".", 1)
+    raw_kwargs = json.loads(params)
+    return run_api(model, module, function, raw_kwargs)
diff --git a/src/ifcmcp/pyproject.toml b/src/ifcmcp/pyproject.toml
new file mode 100644
index 0000000000..c3729db421
--- /dev/null
+++ b/src/ifcmcp/pyproject.toml
@@ -0,0 +1,29 @@
+[build-system]
+requires = ["setuptools>=61.0"]
+build-backend = "setuptools.build_meta"
+
+[project]
+name = "ifcmcp"
+version = "0.0.0"
+authors = [
+  { name="Bruno Postle", email="bruno@postle.net" },
+]
+description = "MCP server for querying and editing IFC building models"
+keywords = ["IFC", "BIM", "MCP"]
+classifiers = [
+    "Programming Language :: Python :: 3",
+    "License :: OSI Approved :: GNU Lesser General Public License v3 or later (LGPLv3+)",
+]
+dependencies = ["ifcopenshell", "ifcquery", "ifcedit", "mcp"]
+
+[project.urls]
+Homepage = "http://ifcopenshell.org"
+Documentation = "https://docs.ifcopenshell.org"
+Issues = "https://github.com/IfcOpenShell/IfcOpenShell/issues"
+
+[tool.setuptools.packages.find]
+include = ["ifcmcp*"]
+exclude = ["test*"]
+
+[tool.ruff]
+extend = "../../pyproject.toml"
diff --git a/src/ifcmcp/tests/__init__.py b/src/ifcmcp/tests/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/src/ifcmcp/tests/conftest.py b/src/ifcmcp/tests/conftest.py
new file mode 100644
index 0000000000..095a43d587
--- /dev/null
+++ b/src/ifcmcp/tests/conftest.py
@@ -0,0 +1,64 @@
+import pytest
+
+import ifcopenshell
+import ifcopenshell.api.aggregate
+import ifcopenshell.api.owner.settings
+import ifcopenshell.api.project
+import ifcopenshell.api.root
+import ifcopenshell.api.spatial
+import ifcopenshell.api.unit
+
+import ifcmcp.server as server_mod
+
+
+@pytest.fixture
+def model():
+    """Create an IFC4 model with a spatial hierarchy, a wall, and a slab."""
+    f = ifcopenshell.api.project.create_file()
+    ifcopenshell.api.owner.settings.get_user = lambda ifc: (ifc.by_type("IfcPersonAndOrganization") or [None])[0]
+    ifcopenshell.api.owner.settings.get_application = lambda ifc: (ifc.by_type("IfcApplication") or [None])[0]
+
+    project = ifcopenshell.api.root.create_entity(f, ifc_class="IfcProject", name="TestProject")
+    ifcopenshell.api.unit.assign_unit(f)
+
+    site = ifcopenshell.api.root.create_entity(f, ifc_class="IfcSite", name="TestSite")
+    building = ifcopenshell.api.root.create_entity(f, ifc_class="IfcBuilding", name="TestBuilding")
+    storey = ifcopenshell.api.root.create_entity(f, ifc_class="IfcBuildingStorey", name="Ground Floor")
+
+    ifcopenshell.api.aggregate.assign_object(f, products=[site], relating_object=project)
+    ifcopenshell.api.aggregate.assign_object(f, products=[building], relating_object=site)
+    ifcopenshell.api.aggregate.assign_object(f, products=[storey], relating_object=building)
+
+    wall = ifcopenshell.api.root.create_entity(f, ifc_class="IfcWall", name="Wall001")
+    ifcopenshell.api.spatial.assign_container(f, products=[wall], relating_structure=storey)
+
+    slab = ifcopenshell.api.root.create_entity(f, ifc_class="IfcSlab", name="Slab001")
+    ifcopenshell.api.spatial.assign_container(f, products=[slab], relating_structure=storey)
+
+    return f
+
+
+@pytest.fixture
+def model_file(model, tmp_path):
+    """Write the model fixture to a temp file and return the path."""
+    path = tmp_path / "test.ifc"
+    model.write(str(path))
+    return str(path)
+
+
+@pytest.fixture(autouse=True)
+def reset_server_state():
+    """Reset module-level state before each test."""
+    server_mod._model = None
+    server_mod._model_path = None
+    yield
+    server_mod._model = None
+    server_mod._model_path = None
+
+
+@pytest.fixture
+def loaded_model(model):
+    """Set the server module state to an in-memory model (no file path)."""
+    server_mod._model = model
+    server_mod._model_path = None
+    return model
diff --git a/src/ifcmcp/tests/test_edit.py b/src/ifcmcp/tests/test_edit.py
new file mode 100644
index 0000000000..69ff74ec9d
--- /dev/null
+++ b/src/ifcmcp/tests/test_edit.py
@@ -0,0 +1,99 @@
+import json
+
+import pytest
+
+from ifcmcp.server import ifc_docs, ifc_edit, ifc_list
+
+
+class TestNoModel:
+    def test_edit_no_model(self):
+        with pytest.raises(ValueError, match="No model loaded"):
+            ifc_edit("root.create_entity")
+
+
+class TestList:
+    def test_list_all_modules(self, loaded_model):
+        result = ifc_list()
+        assert isinstance(result, list)
+        assert len(result) > 0
+        modules = [m["module"] for m in result]
+        assert "root" in modules
+        assert "spatial" in modules
+
+    def test_list_module_functions(self, loaded_model):
+        result = ifc_list(module="root")
+        assert isinstance(result, list)
+        names = [f["name"] for f in result]
+        assert "create_entity" in names
+
+    def test_list_empty_string_returns_modules(self, loaded_model):
+        result = ifc_list(module="")
+        assert isinstance(result, list)
+        assert any(m["module"] == "root" for m in result)
+
+
+class TestDocs:
+    def test_docs_create_entity(self, loaded_model):
+        result = ifc_docs("root.create_entity")
+        assert result["module"] == "root"
+        assert result["function"] == "create_entity"
+        assert "params" in result
+
+    def test_docs_bad_format(self, loaded_model):
+        with pytest.raises(ValueError):
+            ifc_docs("no_dot_here")
+
+
+class TestEdit:
+    def test_create_entity(self, loaded_model):
+        result = ifc_edit("root.create_entity", json.dumps({"ifc_class": "IfcWall", "name": "NewWall"}))
+        assert result["ok"] is True
+        assert result["result"]["type"] == "IfcWall"
+        assert result["result"]["name"] == "NewWall"
+
+    def test_create_entity_default_params(self, loaded_model):
+        result = ifc_edit("root.create_entity", "{}")
+        assert result["ok"] is True
+
+    def test_unknown_function(self, loaded_model):
+        result = ifc_edit("root.nonexistent", "{}")
+        assert result["ok"] is False
+        assert "Cannot find" in result["error"]
+
+    def test_unknown_parameter(self, loaded_model):
+        result = ifc_edit("root.create_entity", json.dumps({"bogus": "value"}))
+        assert result["ok"] is False
+        assert "Unknown parameter" in result["error"]
+
+    def test_bad_json(self, loaded_model):
+        with pytest.raises(json.JSONDecodeError):
+            ifc_edit("root.create_entity", "not json")
+
+    def test_edit_does_not_save(self, loaded_model, tmp_path):
+        """Verify that ifc_edit mutates the in-memory model but does not write to disk."""
+        import ifcmcp.server as server_mod
+
+        path = str(tmp_path / "test.ifc")
+        loaded_model.write(path)
+        server_mod._model_path = path
+
+        before_count = sum(1 for _ in loaded_model)
+        ifc_edit("root.create_entity", json.dumps({"ifc_class": "IfcWall", "name": "Unsaved"}))
+        after_count = sum(1 for _ in loaded_model)
+        assert after_count == before_count + 1
+
+        # Re-read the file — it should not have the new entity
+        import ifcopenshell
+
+        on_disk = ifcopenshell.open(path)
+        disk_count = sum(1 for _ in on_disk)
+        assert disk_count == before_count
+
+    def test_assign_container(self, loaded_model):
+        wall = loaded_model.by_type("IfcWall")[0]
+        storey = loaded_model.by_type("IfcBuildingStorey")[0]
+        result = ifc_edit(
+            "spatial.assign_container",
+            json.dumps({"products": str(wall.id()), "relating_structure": str(storey.id())}),
+        )
+        assert result["ok"] is True
diff --git a/src/ifcmcp/tests/test_query.py b/src/ifcmcp/tests/test_query.py
new file mode 100644
index 0000000000..515528cffc
--- /dev/null
+++ b/src/ifcmcp/tests/test_query.py
@@ -0,0 +1,112 @@
+import pytest
+
+from ifcmcp.server import ifc_info, ifc_relations, ifc_select, ifc_summary, ifc_tree
+
+
+class TestNoModel:
+    """All query tools should fail when no model is loaded."""
+
+    def test_summary_no_model(self):
+        with pytest.raises(ValueError, match="No model loaded"):
+            ifc_summary()
+
+    def test_tree_no_model(self):
+        with pytest.raises(ValueError, match="No model loaded"):
+            ifc_tree()
+
+    def test_info_no_model(self):
+        with pytest.raises(ValueError, match="No model loaded"):
+            ifc_info(1)
+
+    def test_select_no_model(self):
+        with pytest.raises(ValueError, match="No model loaded"):
+            ifc_select("IfcWall")
+
+    def test_relations_no_model(self):
+        with pytest.raises(ValueError, match="No model loaded"):
+            ifc_relations(1)
+
+
+class TestSummary:
+    def test_schema(self, loaded_model):
+        result = ifc_summary()
+        assert result["schema"] == "IFC4"
+
+    def test_total_entities(self, loaded_model):
+        result = ifc_summary()
+        assert result["total_entities"] > 0
+
+    def test_project_name(self, loaded_model):
+        result = ifc_summary()
+        assert result["project"]["name"] == "TestProject"
+
+    def test_type_counts(self, loaded_model):
+        result = ifc_summary()
+        assert result["types"]["IfcWall"] == 1
+        assert result["types"]["IfcSlab"] == 1
+
+
+class TestTree:
+    def test_root_is_project(self, loaded_model):
+        result = ifc_tree()
+        assert result["type"] == "IfcProject"
+        assert result["name"] == "TestProject"
+
+    def test_hierarchy_depth(self, loaded_model):
+        result = ifc_tree()
+        site = result["children"][0]
+        assert site["type"] == "IfcSite"
+        building = site["children"][0]
+        assert building["type"] == "IfcBuilding"
+        storey = building["children"][0]
+        assert storey["type"] == "IfcBuildingStorey"
+
+
+class TestInfo:
+    def test_wall_info(self, loaded_model):
+        wall = loaded_model.by_type("IfcWall")[0]
+        result = ifc_info(wall.id())
+        assert result["id"] == wall.id()
+        assert result["type"] == "IfcWall"
+
+    def test_invalid_id(self, loaded_model):
+        with pytest.raises(Exception):
+            ifc_info(999999)
+
+
+class TestSelect:
+    def test_select_walls(self, loaded_model):
+        result = ifc_select("IfcWall")
+        assert len(result) == 1
+        assert result[0]["type"] == "IfcWall"
+        assert result[0]["name"] == "Wall001"
+
+    def test_select_slabs(self, loaded_model):
+        result = ifc_select("IfcSlab")
+        assert len(result) == 1
+        assert result[0]["name"] == "Slab001"
+
+    def test_select_no_match(self, loaded_model):
+        result = ifc_select("IfcWindow")
+        assert result == []
+
+
+class TestRelations:
+    def test_wall_relations(self, loaded_model):
+        wall = loaded_model.by_type("IfcWall")[0]
+        result = ifc_relations(wall.id())
+        assert result["id"] == wall.id()
+        assert result["type"] == "IfcWall"
+        assert "hierarchy" in result
+
+    def test_traverse_up(self, loaded_model):
+        wall = loaded_model.by_type("IfcWall")[0]
+        result = ifc_relations(wall.id(), traverse="up")
+        assert isinstance(result, list)
+        assert result[0]["type"] == "IfcWall"
+        assert result[-1]["type"] == "IfcProject"
+
+    def test_traverse_empty_string_means_no_traverse(self, loaded_model):
+        wall = loaded_model.by_type("IfcWall")[0]
+        result = ifc_relations(wall.id(), traverse="")
+        assert isinstance(result, dict)
diff --git a/src/ifcmcp/tests/test_server.py b/src/ifcmcp/tests/test_server.py
new file mode 100644
index 0000000000..38ddd4260c
--- /dev/null
+++ b/src/ifcmcp/tests/test_server.py
@@ -0,0 +1,28 @@
+from ifcmcp.server import server
+
+
+class TestServerRegistration:
+    def test_server_name(self):
+        assert server.name == "ifc-mcp"
+
+    def test_all_tools_registered(self):
+        tools = [t.name for t in server._tool_manager.list_tools()]
+        expected = [
+            "ifc_load",
+            "ifc_save",
+            "ifc_summary",
+            "ifc_tree",
+            "ifc_info",
+            "ifc_select",
+            "ifc_relations",
+            "ifc_clash",
+            "ifc_list",
+            "ifc_docs",
+            "ifc_edit",
+        ]
+        for name in expected:
+            assert name in tools, f"Tool {name} not registered"
+
+    def test_tool_count(self):
+        tools = server._tool_manager.list_tools()
+        assert len(tools) == 11
diff --git a/src/ifcmcp/tests/test_session.py b/src/ifcmcp/tests/test_session.py
new file mode 100644
index 0000000000..0bb5a09d92
--- /dev/null
+++ b/src/ifcmcp/tests/test_session.py
@@ -0,0 +1,45 @@
+import pytest
+
+import ifcmcp.server as server_mod
+from ifcmcp.server import ifc_load, ifc_save
+
+
+class TestLoad:
+    def test_load_file(self, model_file):
+        result = ifc_load(model_file)
+        assert "IFC4" in result
+        assert server_mod._model is not None
+        assert server_mod._model_path == model_file
+
+    def test_load_sets_entity_count(self, model_file):
+        result = ifc_load(model_file)
+        assert "entities" in result
+
+    def test_load_nonexistent_file(self):
+        with pytest.raises(Exception):
+            ifc_load("/nonexistent/path/model.ifc")
+
+
+class TestSave:
+    def test_save_no_model(self):
+        with pytest.raises(ValueError, match="No model loaded"):
+            ifc_save()
+
+    def test_save_overwrites_original(self, model_file):
+        ifc_load(model_file)
+        result = ifc_save()
+        assert model_file in result
+
+    def test_save_to_new_path(self, model_file, tmp_path):
+        ifc_load(model_file)
+        new_path = str(tmp_path / "output.ifc")
+        result = ifc_save(new_path)
+        assert new_path in result
+        import ifcopenshell
+
+        reloaded = ifcopenshell.open(new_path)
+        assert reloaded.schema == "IFC4"
+
+    def test_save_no_path_no_original(self, loaded_model):
+        with pytest.raises(ValueError, match="No path specified"):
+            ifc_save()