AnkusDrive

A CLI + MCP server that drives FreeCAD through its Python API so LLMs (and humans at a terminal) can design mechanical parts and run FEM simulations without clicking through the GUI.

Why

FreeCAD exposes almost everything it does through a Python API — create documents, build sketches, extrude solids, mesh them, run CalculiX/Elmer FEM solves, read back stress/displacement fields. But that API lives inside FreeCAD's embedded Python (freecadcmd), which is awkward to call from anywhere else. AnkusDrive wraps it behind two surfaces:

• CLI — one-shot commands (ankusdrive run script.py, ankusdrive box --w 10 --d 20 --h 5 -o part.FCStd) for scripts, CI, and quick iteration.
• MCP server — 280+ structured tools (new_document, add_primitive, boolean_op, pad, add_gear, fem_new_analysis, fem_run, fem_results) so an LLM agent can model, inspect, and simulate iteratively. Beyond core CAD/FEM this now spans a broad simulation surface (thermal, CFD/CHT, EM, acoustics, FSI, injection molding, granular/DEM, optics, multibody) and a design-control layer (item/part numbers, recipes, variant families, lifecycle/revision, ECO change orders, versioned interfaces).
• Multi-agent orchestration — a host-side reference layer that lets a team of agents partition one product into components, build them in parallel, and merge the pieces back together with the joints actually fitting (see Multi-agent design).

Target environment

• FreeCAD 1.1.x. The freecadcmd binary is auto-discovered per-OS (macOS .app bundle, Linux /usr/bin etc., Windows C:\Program Files\FreeCAD 1.1\bin\freecadcmd.exe — version-globbed); override via $ANKUSDRIVE_FREECADCMD or rely on PATH. Run ankusdrive doctor to see exactly what resolved.
• Bundled Python, ccx (CalculiX), and gmsh already ship inside every FreeCAD install — the macOS .app, the Linux package, and the Windows bin\ — so core CAD + structural FEM work on all three with no extra install.
• Host-side rendering needs Pillow and numpy; both are installed by AnkusDrive as regular pip deps.
• One optional exception: drawing PDF/SVG export (export_drawing) renders inside FreeCAD's bundled Python, so it needs reportlab + svglib installed there — see Drawing export (PDF/SVG). DXF export and everything else leave FreeCAD's Python untouched.

Setup

AnkusDrive is a pip-installable package; FreeCAD itself is the only thing you install separately. The host-side dependencies (mcp, Pillow, numpy) come along with the install. freecadcmd is launched as a subprocess and uses its own bundled Python — AnkusDrive doesn't touch it.

# 1. Install FreeCAD 1.1.x from https://www.freecad.org/
#    (macOS: drag to /Applications; Linux: distro package or AppImage;
#     Windows: run the installer — default C:\Program Files\FreeCAD 1.1)

# 2. Install AnkusDrive. Pick one:
pipx install ankusdrive                                       # from PyPI — isolated app, `ankusdrive` on PATH
pip install ankusdrive                                        # or into an env you manage yourself
# unreleased main, or for development from a clone:
pipx install git+https://github.com/gchen19/AnkusDrive.git
git clone https://github.com/gchen19/AnkusDrive.git && cd AnkusDrive
python3 -m venv .venv && .venv/bin/pip install -e .         # `.venv/bin/ankusdrive`

# 3. Smoke-test that the worker can reach FreeCAD, and see the full setup report
ankusdrive ping        # → ping=pong freecad=1.1.1
ankusdrive doctor      # per-item FreeCAD + solver checklist with the exact fix each

Windows (PowerShell): the clone path is py -m venv .venv then .venv\Scripts\pip install -e ., and the resulting entry point is .venv\Scripts\ankusdrive.exe. FreeCAD's own freecadcmd.exe needs nothing on PATH — AnkusDrive globs C:\Program Files\FreeCAD *\bin\ automatically. Everything in step 3 works from a stock FreeCAD 1.1 install (verified: core CAD + a CalculiX cantilever solve via the bundled ccx.exe).

AnkusDrive is published on PyPI at pypi.org/project/ankusdrive; the distribution roadmap beyond it (marketplace listings, hosted transport) is tracked in docs/PUBLISHING_PLAN.md.

Telling AnkusDrive where FreeCAD lives

AnkusDrive auto-discovers freecadcmd in this order: $ANKUSDRIVE_FREECADCMD, then shutil.which(...) on PATH (trying freecadcmd, FreeCADCmd, and freecad.cmd), then a per-OS list of standard install locations:

So a stock installer on any of the three needs no configuration. For a non-default install, point AnkusDrive at the binary directly:

export ANKUSDRIVE_FREECADCMD=/path/to/freecadcmd            # macOS/Linux

$env:ANKUSDRIVE_FREECADCMD = "D:\Apps\FreeCAD\bin\freecadcmd.exe"   # Windows

ankusdrive doctor prints which of the three layers (env / PATH / auto) actually resolved FreeCAD, plus every candidate it checked — the fastest way to debug a "FreeCAD not found" on a new box.

Drawing export (PDF/SVG)

export_drawing builds 2-D mechanical drawings (multi-view PDF/SVG/DXF with dimensions) entirely headless. DXF uses FreeCAD's own writer and needs nothing extra. PDF and SVG are composed and rasterised with reportlab + svglib, and because that runs inside the worker — FreeCAD's bundled Python, not the host venv — the two packages must be installed into FreeCAD's Python:

# Resolve FreeCAD's bundled Python from freecadcmd itself (portable across the
# macOS .app, a Linux distro package, and an extracted AppImage). freecadcmd
# prints a startup banner after the script output, so match a marker line
# rather than taking the last line:
printf 'import sys; print("DPREFIX="+sys.prefix)\n' > /tmp/_fcprefix.py
FREECAD_PREFIX="$(freecadcmd /tmp/_fcprefix.py 2>/dev/null | sed -n 's/^DPREFIX=//p')"
FREECAD_PY="$FREECAD_PREFIX/bin/python"      # some builds: $FREECAD_PREFIX/bin/python3

# Pin svglib<1.6 — newer svglib pulls rlPyCairo -> pycairo, a native build we
# don't use (our drawings are line art, no gradients).
"$FREECAD_PY" -m pip install reportlab "svglib<1.6"

# Verify:
"$FREECAD_PY" -c "import reportlab, svglib; print('drawing export ready')"

Without this, export_drawing still produces .dxf; .pdf/.svg raise a clear ModuleNotFoundError. FreeCAD already bundles Pillow (reportlab needs it), so no separate install is required.

Wiring it into an MCP host

The MCP server speaks stdio. Point your host at the ankusdrive binary and let it run the mcp subcommand.

Claude Desktop — add to ~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or %APPDATA%\Claude\claude_desktop_config.json (Windows):

{
  "mcpServers": {
    "ankusdrive": {
      "command": "ankusdrive",
      "args": ["mcp"]
    }
  }
}

If ankusdrive isn't on the host process's PATH, use an absolute path — e.g. /Users/<you>/.local/bin/ankusdrive (pipx default) or /absolute/path/to/AnkusDrive/.venv/bin/ankusdrive (clone+venv).

Claude Code — register once:

claude mcp add ankusdrive -- ankusdrive mcp

Other hosts (Cursor, Continue, custom MCP clients) — same shape: stdio transport, command = ankusdrive, args = ["mcp"].

After restarting the host, you should see 280+ ankusdrive__* tools become available. If startup hangs or the host reports a closed connection, run ankusdrive ping directly — that exercises the same worker boot path with cleaner error messages.

Simulation solvers & review-video demos

The base install (FreeCAD + pip install ankusdrive) covers geometry, the analytic oracles, and the MCP surface. The heavy simulation families each shell out to an external solver, discovered at runtime by ankusdrive/solvers.py ($ANKUSDRIVE_<SOLVER>_PATH → PATH → standard install dirs). A family whose solver is absent degrades to a clean {ok: false, reason, install} dict instead of crashing — check what currently resolves with ankusdrive doctor (cross-platform, no server boot needed), the solve_capabilities MCP tool, or the install script's list. The install script installs the pip-wheel solvers and provisions the native ones — scripts/install-solvers.sh on Linux/macOS (apt/conda + source builds), and scripts/install-solvers.ps1 on Windows (pip extras + portable SU2/Elmer/PrusaSlicer downloads; CalculiX auto-detected from FreeCAD's bundle).

Persistent config: every ANKUSDRIVE_* path can instead live in ~/.config/ankusdrive/config.toml (%APPDATA%\ankusdrive\config.toml on Windows; ANKUSDRIVE_CONFIG overrides): freecadcmd = "..." at top level, one lowercased key per solver var under [solvers] (su2_path, elmer_path, openfoam_bashrc, ...). Env vars still win when set; the file is the layer that survives an MCP host's minimal launch environment. ankusdrive doctor reports the file and which layer resolved each value.

Platform note: the solver discovery layer is fully cross-platform (per-OS install dirs, Windows PATHEXT/.exe, env overrides), so ankusdrive doctor gives an honest report on macOS/Linux/Windows. The pip-wheel families (MBD, topology, optics, fluids) install identically everywhere. The native-binary families differ by OS — CalculiX ships inside every FreeCAD install; SU2 and PrusaSlicer have good Windows/macOS binaries; Elmer has a portable Windows zip but no macOS binaries; the OpenFOAM-backed families (CFD, FSI, injection molding) still rely on a Linux shell + linker glue and are Linux/WSL/Docker for now. See docs/WINDOWS.md and docs/MACOS.md for the full per-solver reality and setup on each OS.

The review-video demos under scratch/ turn a solver result into a GIF a human can watch — the real exported geometry in motion with the matching oracle overlaid on the frame (written to artifacts/). Each needs its family's solver plus matplotlib, and the CFD one needs meshio (on top of the base numpy/Pillow):

pip install matplotlib meshio        # frame rendering + reading OpenFOAM's VTK output

All of them also use FreeCAD for the geometry/meshing, so run each with the same interpreter that launches the worker — e.g. .venv/bin/python3 scratch/cfd_field_video.py.

Optics

Two optics engines sit behind the MCP surface, in two licensing/runtime lanes:

The sequential engines import in-process, so install the optics extra into the same interpreter that launches the worker (like the other wheels). The non-sequential engine is GPL-3.0 and is therefore never imported by AnkusDrive — it runs in a separate subprocess (ankusdrive/optics_gpl_runner.py), the same arm's-length boundary used for the GPL Elmer/OpenFOAM binaries. The worker locates a Python that can import KrakenOS automatically (from where the wheel is installed); override with ANKUSDRIVE_OPTICS_GPL_PYTHON=/path/to/python. Because of that isolation the GPL extra is opt-in: the no-argument install-solvers.sh run installs only the permissive extras and prints how to add optics_gpl. Rendered examples for both lanes (lens layout, spot diagram, optimization, prism TIR, and a ball-lens spherical-aberration study) live in examples/optics_gallery/ — regenerate with .venv/bin/python examples/optics_gallery.py (and …_3d.py, optics_ball_lens.py), or bootstrap everything in one shot (installs both lanes, then renders every figure):

scripts/install-solvers.sh --optics-gallery

Architecture sketch

 ┌────────────┐      ┌────────────┐      ┌──────────────────────┐
 │  MCP host  │ ───► │ AnkusDrive   │ ───► │  freecadcmd worker   │
 │  (Claude)  │      │ (Python)   │ IPC  │  (long-lived Python) │
 └────────────┘      └────────────┘      └──────────────────────┘
       ▲                    ▲                        │
       │                    │                        ▼
       └── CLI user ────────┘               .FCStd / .inp / .vtk

Key decision: long-lived worker with JSON-over-stdin/stdout, not subprocess-per-call. FreeCAD startup is ~1–2s; re-paying that per tool call is unacceptable for an interactive agent. The worker is a small Python loop launched under freecadcmd, reading commands, dispatching to handlers, returning structured results (including object IDs so follow-up calls can reference created geometry).

FreeCAD API surface we care about

Notes gathered from the scripting docs and the FEM Python tutorial:

Core (App):

• App.newDocument(name) / App.ActiveDocument / doc.recompute() / doc.save(path)
• doc.addObject("Part::Box", "name") — typed object creation; properties set after (box.Height = 5)
• doc.supportedTypes() for introspection; obj.TypeId, obj.isDerivedFrom("Part::Feature")

Modeling:

• Part — makeBox, makeCylinder, makeSphere, boolean cut/common/fuse, fillets, lofts (OpenCASCADE under the hood)
• Draft — 2D primitives, move, arrays
• Sketcher + PartDesign — parametric sketch-driven solids (most "real" mechanical design happens here)
• FreeCAD.Vector, Placement for positioning

FEM (ObjectsFem + femtools):

• ObjectsFem.makeAnalysis(doc, "Analysis") — container
• makeSolverCalculixCcxTools / makeSolverElmer — solver objects with tunables (GeometricalNonlinearity, ThermoMechSteadyState, …)
• makeMaterialSolid — assign YoungsModulus, PoissonRatio, Density
• Constraints: makeConstraintFixed, makeConstraintForce, makeConstraintPressure, makeConstraintDisplacement, contact/tie/spring, thermal
• Mesh: makeMeshGmsh + femmesh.gmshtools.GmshTools(...).create_mesh() (or Netgen)
• Run: femtools.ccxtools.FemToolsCcx().run()
• Results: iterate analysis.Group for Fem::FemResultObject; read .DisplacementVectors, stress fields

Headless invocation:

• freecadcmd script.py — runs script then exits
• freecadcmd with no args — interactive Python REPL (what the worker will drive)
• --console, -M <moddir>, -P <pypath>, --pass <args>, FreeCAD.ConfigGet(...) for env info
• FreeCADGui is not available headless — keep design logic in App/Part/Fem only

How an agent reaches FreeCAD: three layers

AnkusDrive exposes FreeCAD through three layers, each with a different audience and a different cost-of-use. Knowing which layer a feature lives in tells you how to invoke it.

Layer 1 — typed MCP tools (the agent surface)

280+ first-class MCP tools span the core mechanical-design surface, a broad engineering-analysis / simulation surface, and a design-control (PLM) layer. They have validated parameters, structured returns, and stable handles for chaining. This is the happy path — what an agent uses for things people do every day.

All tools return JSON; geometry-creating tools return a handle (e.g. pad_1) that subsequent calls reference. The heavy simulation families return a {ok: false, reason, install} dict (rather than crashing) when their solver isn't installed — see Simulation solvers.

Layer 2 — generic property reflection

For the long tail of "I just need to tweak this one property" without a dedicated tool:

• get_object(handle) — dump every entry in obj.PropertiesList with Quantities → float (mm/deg), Vectors → list, Placements → dict.
• set_property(handle, name, value) — set any single property by name.

Use this when a typed tool exists for the object kind but doesn't expose the exact property you need (e.g. Refine on a Pad, Sections ordering on a Loft, internal tunables on a CCX solver).

Layer 3 — run_script (the universal escape hatch)

For features that have no first-class MCP tool at all — e.g. Path workbench (CAM toolpaths), Surface workbench, Arch/BIM, Spreadsheet, TechDraw dimensions, contact/spring FEM constraints, B-spline sketcher operations, expression-engine bindings, anything in a workbench AnkusDrive doesn't wrap.

run_script(code='''
import Path
job = Path.Job.Create("Job", [_resolve("pad_1")])
__result__ = {"job_name": job.Name}
''')

Inside the script, the worker pre-injects: App / FreeCAD, Part, ObjectsFem, plus _register(prefix, obj) / _resolve(handle) / _handles so scripts can register new objects into the same handle registry that typed tools use. Set __result__ = ... to a JSON-serializable value to return data; print statements go to /dev/null.

The escape hatch costs more (the agent has to write FreeCAD Python) but makes the entire FreeCAD API reachable. The Phase 2 plan's "After Phase 2" section calls out which run_script patterns deserve promotion to typed tools — that's how the surface grows over time.

What the CLI is (and isn't)

The CLI is not the agent surface — it's a human-debugging + transport tool. Seven subcommands:

Agents do not invoke the CLI. They speak MCP via stdio after the host has launched ankusdrive mcp. The CLI's job is (a) to start that server and (b) to give a human a way to poke at the worker without writing an MCP client.

Decision rule

Multi-agent design

The roadmap above is about deepening what one agent can do. The orchestration/ layer is about many agents sharing the work: split a product into components and subassemblies, build those in parallel (each agent cold, seeing only its own contract slice), then merge the whole back up with the joints actually fitting. The design is written up in docs/MULTI_AGENT.md; it targets partition + merge, not shared co-editing of one live document (a single worker = one App.ActiveDocument, so concurrent mutation is a non-goal for now).

Concurrent agents on one MCP server — workspaces. FastMCP runs sync tools in a thread pool, so a host can have several tool calls in flight at once. The server keeps a pool of named workspaces, each its own freecadcmd process with its own App.ActiveDocument and handle registry. Each concurrent agent claims its own workspace with use_workspace(name) at the start of its session; handles and documents do not cross workspaces. A client that never calls use_workspace sees the historical single-worker behavior byte-for-byte (everything routes to the default workspace). Worker.call() is internally serialized so two threads can never interleave the stdin/stdout protocol on one process. The pool is capped (ANKUSDRIVE_MAX_WORKSPACES, default 4) and idle workspaces are reaped (ANKUSDRIVE_WORKSPACE_IDLE_S, default 900s) so abandoned sessions don't leak processes; list_workspaces / close_workspace manage it.

The split of responsibilities is deliberate:

• AnkusDrive ships the thin, tool-agnostic primitives that make a merge verifiable — publish_interface (declare a component's mating frames), merge_assembly (combine component files into one assembly), and the gates that decide whether a merge is sound: interface_align_check (do published frames line up?), interference_check (do solids collide?), envelope_check (does it fit its bounding budget?), plus an assembly_lock / assembly_lock_check contract lockfile. These are real MCP tools usable by any host.
• orchestration/ is the host-side reference coordinator — explicitly not part of the ankusdrive package. Given a free-text brief it decomposes it into a validated manifest, fans out one builder agent per component, merge_assemblys them, reads the gates, and on failure renegotiates — re-dispatching only the components implicated by the failing gate — up to a round budget. It runs against a real Anthropic client or a scripted stub (ScriptedClient) for free dry runs; the merge and gates are real worker calls either way. Any host (Claude, another tool, a human) can use it, replace it, or ignore it — the only contract that matters is the manifest + the component files on disk.

How well partition+merge holds up is measured by a dedicated eval ladder (tests/test_multiagent_m1.py / _m2.py, runnable in CI) with hard-oracle merge gates and a single-agent baseline — see tests/MULTI_AGENT_EVAL.md. Early experiments have partition performing at or above the single-agent baseline on the harder toys.

Designs, not just parts — the design-control layer

Multi-agent orchestration partitions one product across a team. A separate axis makes a design (not just a part) something you can parameterize, vary, and evolve under control — the mechanisms a PLM/PDM workflow expects, mapped onto AnkusDrive's deterministic, headless, git-diffable grain. The keystone insight: the build recipe is the feature tree; the parameters are its inputs; regeneration is re-running the recipe — so AnkusDrive gets parametric regen and family tables without a live in-file expression engine. The full scoping and rationale is in docs/DESIGN_HIERARCHY.md; the agent-facing judgment lives in the design-modularly skill.

• Parametric hierarchy — recipes (recipe, recipe_validate) are named, declared-input build templates (AnkusDrive's PowerCopy/UDF and its intra-part parametric model); a relations DAG drives driven dimensions from master parameters by formula (pitch_d = module * teeth, arithmetic only — no iterative solve, no double-driving); feature templates (feature_instantiate) graft reusable features onto reference geometry by name; the typed units layer rejects dimensionally-wrong inputs at the door ("5 N" for a length is an error, not a silent mis-scale).
• Variant families — family_materialize expands a row × column design table into a set of variants deterministically, running the recipe per row and allocating part numbers in table order.
• Identity & lifecycle — items (items_new) give a part a stable part-number identity decoupled from its file path; a lifecycle state machine (lifecycle_transition: in_work → in_review → released → obsolete) enforces released-immutability, and a Form/Fit/Function predicate decides revision bump vs. new part number on a change.
• Change control — ECOs (eco_create) are first-class change records; where_used / change_impact compute blast radius over the dependency graph before you commit; baseline_create / baseline_verify pin reproducible snapshots.
• Versioned interfaces — an interface-type registry (get_interface, nema17_face@1-style named/versioned types) plus a Liskov substitutability_check gate enforce Form/Fit/Function compatibility as code, so a swapped part is verified to actually mate.
• Projects — scaffold_project + project_validate / project_check_references promote the multi-agent directory convention to a first-class project.json (manifest-of-manifests) with a master/skeleton single-source-of-truth slot and reference-integrity guards.

Like the merge gates, these are thin, deterministic, mostly FreeCAD-free primitives — the logic layers import and test without launching a worker.

Status

Phase 3 closed 2026-05-10 (v0.3.0). The core mechanical-design surface from Phase 2 (2026-04-25) is intact; Phase 3 layered intent-encoding APIs on top of it. Since then the tool surface has grown from ~100 to 280+ tools across several waves: a command-tier expansion (parametric components + direct feature ops + metrology), the multi-agent orchestration layer, a broad engineering-analysis + external-solver simulation surface (thermal/CFD/CHT/ EM/acoustics/FSI/molding/granular/optics/multibody), and a design-control (PLM) layer (items, recipes, variant families, lifecycle, ECO/change, versioned interfaces, projects).

• Worker + transport — long-lived freecadcmd worker, newline-JSON over stdio with stdio hygiene (FreeCAD C++ chatter redirected off the protocol fd).
• CLI — ping, version, box, cylinder, export, run, mcp, fem cantilever, plus top-level --version.
• MCP server — FastMCP over stdio, 280+ typed tools across document lifecycle, primitives, selection (face/edge tags), full PartDesign (sketcher + pad/pocket/revolve/hole/loft/sweep/helix/fillet/chamfer/pattern/mirror/thickness/draft), direct-modeling feature ops, parametric components, metrology/inspection, generic property reflection, mass properties, assembly + interface gates, TechDraw (incl. headless PDF/SVG/DXF export, dimensions, gates), multi-view + photoreal rendering, FEM (static + modal + buckling + thermal + nonlinear + result-probe), the engineering-analysis oracles and external-solver simulation families (sync + async *_submit/job_*), the materials/fluids corpora, Design-for-X / manufacturing checks, the design-control (PLM) layer, and transactions.
• Command tiers 1–3 — 21 new tools: parametric components (add_gear, add_rack, add_sprocket, add_pulley, add_spring, add_fastener, add_bearing, add_thread), direct feature ops (fillet_edges, chamfer_edges, shell_solid, add_rib, engrave_text, oring_groove, transform, scale_shape, copy_shape), and metrology/inspection (measure_distance, measure_angle, bounding_box, check_shape, section_view, min_clearance).
• Multi-agent orchestration — AnkusDrive ships the thin merge primitives + gates (publish_interface, merge_assembly, interface_align_check, envelope_check, assembly_lock/_check); the host-side reference coordinator (orchestration/) decomposes a brief, fans out per-component builders, merges, gates, and renegotiates. See Multi-agent design and docs/MULTI_AGENT.md.
• Phase 3 intent-encoding additions — direction='into_body'|'away_from_body' and through='wall'|'body' on pocket/hole (ray-cast wall depth handles hollow shells correctly); intended_for='print'|'machine'|'drawing' on hole drives ModelThread; verify_feature diffs actual-vs-expected volume change to catch silent failures; visibility hygiene at save hides consumed inputs; register_handle + run_script auto_register close the escape-hatch one-way trapdoor; list_thread_options surfaces the coupled ThreadType/ThreadSize enums dynamically; revolve has an OCCT pre-check that flags axis-coincident edges with an actionable error.
• Selection layer — list_faces / list_edges / query_faces / resolve_* produce stable geometric tags that survive edits; FEM constraints take tags directly.
• Rendering — host-side software rasterizer (ankusdrive/render.py) with per-pixel z-buffer (render_view / render_views return PNGs as MCP ImageContent), plus photoreal render_photoreal via the FreeCAD Render addon + an external renderer (POV-Ray / LuxCore / Appleseed / Cycles / OSPRay / PBRT). Support matrix, install, and limitations: docs/RENDERING.md.
• Simulation surface — engineering-analysis oracles (machine elements, structural, durability, thermal, tolerance/GD&T) plus external-solver families that shell out to OpenFOAM / Elmer / CalculiX / openEMS / YADE / KrakenOS, discovered at runtime by ankusdrive/solvers.py and degrading cleanly when absent. Long solves use an async submit→poll job pattern (*_submit + job_status/job_result/job_list). Catalog and result schemas: docs/SIMULATION_TOOLS.md; proof harness: docs/SIMULATION_EXAMPLES.md. Materials/fluids back these via material_* and fluid_props (mechanical-property / molding / CoolProp corpora).
• Design-control (PLM) layer — recipes + a relations DAG (parametric regen), feature templates, variant families from a design table, item/part-number identity, a lifecycle/revision state machine, ECO change records with where-used/impact + baselines, a versioned interface registry + Liskov substitutability gate, and project containers with reference-integrity guards. Scoping + rationale: docs/DESIGN_HIERARCHY.md. See Designs, not just parts.
• Tests — ~980 test functions across ~90 files (worker / MCP / CLI / render / determinism / edit stability / negative paths / perf / multi-agent / simulation families / molding / PLM layer), runnable via tests/run_all.sh (Linux/macOS) or tests/run_all.ps1 (Windows — single-interpreter, skips the Linux-only solver families; see docs/WINDOWS.md). Reliability harness (Layer A classification, B diff-detection, C agent-loop closure) is gated behind RUN_RELIABILITY=1; see tests/RELIABILITY.md.

See docs/ROADMAP.md for the per-slice changelog and remaining backlog (FEM contact/spring/tie refinements, fully async fem_run, feature_tree introspection, deeper external-solver integrations).

Open questions

• Error model: FreeCAD raises plain Python exceptions from C++; worker catches and serializes them, but stack context across the JSON boundary is still lossy.
• Async / concurrency: multi-doc shipped (list_documents / set_active_document / close_document), and the long-running external solvers run off the channel via the *_submit + job_* pattern, but the in-worker fem_run itself is still synchronous and blocks the MCP channel for the duration of a CalculiX/Elmer solve.
• macOS Gatekeeper / sandboxing: freecadcmd launched from a non-interactive context may hit quarantine issues — still worth verifying under MCP-host launch paths.

License

Licensed under the Apache License, Version 2.0. Contributions submitted to this project are licensed under the same terms (Apache 2.0 §5: inbound = outbound), which means contributors retain copyright but grant the project — and everyone downstream — a perpetual, irrevocable license to use their work, including a patent grant. The intent is to keep the project welcoming to contributors while ensuring nobody can later re-proprietize what they contributed.

The code is Apache-2.0; the name is not. Apache-2.0 §6 grants no trademark rights, so the AnkusDrive word mark and the brand assets in logo/ are covered separately — see TRADEMARKS.md for what you may do without asking (referring to the project, compatibility claims, redistribution, packaging, and forking all qualify) and NOTICE for the attribution a redistributor must carry.

References

• FreeCAD Scripting Basics
• Python scripting tutorial
• Start up and Configuration
• FEM Workbench
• FEM Tutorial Python — full cantilever example
• Model Context Protocol