radia-mcp 0.29.0

MCP servers for the Radia CAE ecosystem. 0.27.0: cubit_mesh_race_review (wait-all + shortlist sorted by min-Jacobian + persisted history) + cubit_mesh_apply_choice (human picks from shortlist) + quality_summary probe. Pivots from auto-commit to human-decides. 0.26.0 base: cubit_mesh_race_smart auto-generates N candidates from geometry.

radia-mcp

First-and-only public Model Context Protocol (MCP) server suite for Coreform Cubit, Gmsh, build123d, and the Radia CAE ecosystem. Pioneering MCP territory for mesh generators worldwide.

Authored by the Sugawara Lab (菅原研究室), Kindai University — where the lab-standard primary pair is build123d (CAD authoring) + Cubit (hex meshing), with Gmsh as the post-processing workhorse.

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Why this exists

radia-mcp lets an AI assistant drive a real CAE pipeline end-to-end:

build123d script  →  STEP  →  Cubit hex mesh  →  .msh v4.1 / .vol  →  ngsolve / radia
        ↑                            ↓
   AI authors                   AI iterates safely
   (Builder API)                 (auto-checkpoint
                                  + batch dry-run
                                  + live GUI replay)

What makes it different from typical CAD-MCP servers (FreeCAD, OpenSCAD, Blender):

• Test-then-reflect safety pattern: every risky operation auto-checkpoints to .cub5, runs in a disposable batch Cubit first, reflects to the live GUI only when batch passes cleanly. The user watches success paths, not failures.
• Scheme ladder with geometry split: cubit_mesh_auto walks auto → sweep → polyhedron → tetmesh, auto-detects compound bodies (volume/surface ratio heuristic) and auto-webcuts before retrying.
• Universal mesh backend for the CAD-MCP ecosystem: any_step_to_cubit_hex accepts STEP from any upstream MCP (FreeCAD-MCP / OpenSCAD-MCP / cadquery-mcp / Blender-MCP / Onshape-MCP / KiCad-MCP) and dispatches to the same hex-mesh backend.
• Deeply scraped knowledge (≈800 lab files + 65 build123d examples
  • 15 bd_warehouse + GitHub issues + GitLab issues + StackOverflow + YouTube tutorial transcripts + Coreform training pack), all searchable via tf-idf with heading boost.

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Demo (placeholder — recordings to be added)

build123d_to_cubit_hex(script=generate_build123d_script("helix_coil")["script"], target_size=1.0) in one call:

1. build123d Builder API: 4-turn helix + 2 radial leads (3 prismatic bodies)
2. STEP export → /tmp/coil.step
3. cubit_batch_try (headless): scheme ladder
   ├─ auto → 1668 hex / 0 tet ✓ WIN
   └─ (sweep / polyhedron / tetmesh skipped)
4. live Cubit GUI replay → user sees the winning recipe execute
5. .cub5 checkpoint preserved for rollback

Total time: ~30 s on a 4-core laptop. AI watches state delta, applies hint heuristics on failure, and never leaves a half-broken mesh in the user's window.

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Install

pip install radia-mcp                 # core (Cubit + build123d + gmsh-post + interop)
pip install radia-mcp[build123d]      # adds build123d itself
pip install radia-mcp[cadquery]       # adds CadQuery (interop with cadquery-mcp)
pip install radia-mcp[gmsh]           # adds gmsh Python bindings (gmsh_post operations)
pip install radia-mcp[youtube]        # adds youtube-transcript-api (tutorial scrape)
pip install radia-mcp[radia]          # adds Radia core (radia-coupled servers)
pip install radia-mcp[full]           # everything above

Requires Python ≥ 3.10. Coreform Cubit is auto-discovered from standard install paths; set CUBIT_BIN_DIR env var if installed non-standard.

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The four MCP servers

Server	Entry point	Tools	Highlights
Cubit	mcp-server-cubit	52	cubit_mesh_auto, cubit_exec_safely, cubit_ask, scheme ladder + geometry split, .cub5 checkpoint/restore, scrape index over Coreform forum + S:\CoreformCubit lab archive (787 files) + YouTube + Coreform training
build123d	mcp-server-build123d	37	build123d_to_cubit_hex, lint_build123d_script (7 rules), build123d_try (subprocess isolation), build123d_inspect_step, build123d_heal, build123d_api, 13 Radia/general templates (magnet_ring, c_core, racetrack_coil, …), CadQuery + bd_warehouse interop
gmsh-post	mcp-server-gmsh-post	21	gmsh_post_inspect/validate/convert (MSH v4.1 only), gmsh_post_quality, gmsh_post_extract_physical, gmsh_post_boundary, gmsh_post_add_view_from_csv, scrape over GitLab issues + StackOverflow + YouTube
radia-interop	mcp-server-radia-interop	4	any_step_to_cubit_hex (any source) + freecad_to_cubit_hex (FreeCADCmd subprocess) + openscad_to_cubit_hex (OpenSCAD CLI) + list_cad_mcp_interop

pip install radia-mcp[radia] additionally enables the radia-coupled servers (radia-ngsolve / ih / electromagnet / peec / gmsh authoring / elf), which depend on the Radia core.

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Claude Code / Desktop configuration

Add to your MCP client config (Claude Desktop, Claude Code, Cursor, Continue, …):

{
  "mcpServers": {
    "cubit":         {"command": "mcp-server-cubit"},
    "build123d":     {"command": "mcp-server-build123d"},
    "gmsh-post":     {"command": "mcp-server-gmsh-post"},
    "radia-interop": {"command": "mcp-server-radia-interop"}
  }
}

For local development from a checkout (no install needed):

{
  "mcpServers": {
    "cubit": {
      "command": "python",
      "args": ["-m", "radia_mcp.cubit.server"]
    }
  }
}

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Knowledge bases shipped (offline)

Server	Bundled knowledge	Lines
Cubit	cubit_api_reference.py (600+ functions) + scripting + forum tips + netgen workflow + export rules + panels	≈ 29 000
build123d	Auto-generated API reference (inspect.getmembers, 142 classes / 65 functions) + 18 curated topics (Plane/Axis/Location cookbook, Builder ↔ Algebra rosetta, joints, assemblies, CAE workflow, …)	1 673
gmsh-post	Auto-generated API reference (651 entries across gmsh.model, .view, .option, .fltk, …) + MSH v4.1 spec + view_data + physical_groups cookbooks	2 008

Plus persistent failure log per kind, fed into every *_lookup / *_ask retrieval so past mistakes are searchable next session.

Live-scraped knowledge (cached 7 days)

Source	Kind	Volume
Coreform forum (Discourse)	cubit_examples	full archive walk, ≈ 60 code-bearing posts
S:\CoreformCubit + Radia/01_GitHub/examples	cubit_examples	787 .jou / .py files (lab archive + Coreform training pack)
Cubit YouTube tutorials	cubit_examples	5 transcripts
GitHub .jou code search (PAT)	cubit_examples	15 files
gumyr/build123d/examples	build123d_examples	65 scripts
gumyr/bd_warehouse	build123d_examples	15 modules
gumyr/build123d Issues + GraphQL Discussions	build123d_examples	60 + 50
build123d YouTube	build123d_examples	4 transcripts
gitlab.onelab.info/gmsh/gmsh issues	gmsh_examples	walking 3000+
StackOverflow / SciComp.SE [gmsh]	gmsh_examples	30 votes-sorted
gmsh YouTube	gmsh_examples	5 transcripts

{cubit,build123d,gmsh}_examples_refresh() re-scrapes anytime; otherwise cache TTL is 7 days.

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Lab stance (Sugawara Lab, 菅原研究室)

Tool	Position
build123d	主力 (push) — new lab work is authored here
Cubit	主力 (push) — hex mesh + visualization
FreeCAD	応援 (friendly) — first-class interop, not first-class authoring; lab respects the FreeCAD community
CadQuery	interop / compat — OCCT sibling
OpenSCAD	interop / compat — legacy scripts

The MCP-tool layer encodes this stance: list_cad_mcp_interop reports primary_pair: "build123d (CAD authoring) + Cubit (hex mesh)" and flags FreeCAD as friendly, others as compat.

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Design pattern: Checkpoint-Batch-Commit-Race (CBCR)

The signature workflow cubit_mesh_race_with_human realizes a publishable design pattern we call CBCR: the user and N AI agents race the same starting state; first-to-finish wins; the human's in-progress work is never silently overwritten.

Full design document (defensive prior-art publication, BSD-3-Clause): docs/design/checkpoint_batch_commit_race.md.

Architecture (Plan A)

The Cubit server uses Plan A: launch coreform_cubit.exe -nojournal cubit_bootstrap.py, which installs a PyQt5 QTimer (200 ms poll) inside Cubit's Qt event loop. The MCP side drops *.req.json into a temp directory; the bootstrap polls, runs cubit.cmd() on the Qt main thread, and writes out/*.resp.json back. No sockets, no pipes — just atomically-renamed JSON files.

This sidesteps every ABI / event-loop / GIL issue the COMSOL-style "external Python + library load" approach hits.

cubit_exec_safely adds a second safety layer on top:

1. Auto-save as the live GUI state to ~/.cubit_viewer/checkpoints/autosafe_<ts>.cub5.
2. Spawn a fresh batch Cubit, open the checkpoint, run candidate commands.
3. If batch passes (and cubit.get_error_count() didn't tick up — silent-error guard), replay on the live GUI.
4. Otherwise: live GUI untouched, checkpoint label returned for cubit_restore.

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Quickstart

build123d → Cubit hex mesh, one call

build123d_to_cubit_hex(
    script=generate_build123d_script("helix_coil")["script"],
    target_size=1.0,
    prefer="hex",
    commit_to_gui=True,
)
# ⇒ STEP exported → batch ladder picks scheme auto → live Cubit GUI
#   shows 1668 hex / 0 tet / 3780 nodes

Safe Cubit live edit

cubit_exec_safely(commands=[
    "volume all size 1.0",
    "volume all scheme tetmesh",
    "mesh volume all",
])
# ⇒ auto-checkpoint → batch dry-run → only on pass: live GUI mesh
#   if dry-run fails, GUI is untouched + rollback label returned

Search any layer of knowledge

cubit_ask("hex meshing tutorial")
# ⇒ unioned ranked hits across bundled KB + lab archive (787 files)
#   + Coreform forum + YouTube transcripts

Convert + post-process a Cubit-exported mesh

gmsh_post_convert("/tmp/cubit_export.msh", "/tmp/v41.msh")  # any → v4.1
gmsh_post_validate("/tmp/v41.msh")                          # spec compliance
gmsh_post_quality("/tmp/v41.msh")                           # min Jacobian etc.
gmsh_post_add_view_from_csv(
    msh_path="/tmp/v41.msh",
    csv_path="/tmp/B_field.csv",
    out_path="/tmp/v41_with_B.msh",
    view_name="B_magnitude",
)

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Contributing

Bug reports + PRs welcome — particularly for:

• New CAD-MCP adapters in radia_mcp.interop.server (Blender, Onshape, KiCad, AutoCAD via any_step_to_cubit_hex plumbing).
• Additional scrape sub-sources under radia_mcp.common.examples (mailing list archives, more YouTube channels, blog posts).
• Cookbook topics for build123d_usage / gmsh_post_spec — worked-example knowledge fragments are always welcome.

See CONTRIBUTING.md for the lightweight workflow. History of every release is in CHANGELOG.md.

License

BSD-3-Clause — see LICENSE.

Acknowledgments

• Coreform for Cubit and the open Discourse forum that we scrape with appreciation.
• Roger Maitland (gumyr) for build123d and bd_warehouse — the lab-standard upstream CAD.
• Christophe Geuzaine for Gmsh and the open issue tracker on gitlab.onelab.info.
• MCP / Anthropic for the protocol that made AI-driven CAE practical.