@forgent3d/cad-build

The portable CAD build capability a coding agent (Claude Code / Codex) drives to author a Forgent3D model.py. It bundles the same engine the product runs — @forgent3d/build-service's buildOne / probeOne over @forgent3d/cad-engine's wasm — so rebuild and run-python return byte-for-byte what the in-product CAD agent sees. No monorepo, no python, no OCCT install: the wasm + cadkit assets ship inside this package.

This is the engine behind the forgent3d skill; the skill's scripts shell out to npx @forgent3d/cad-build … (with a local-path fallback for unpublished use).

Commands

cad-build rebuild    [model.py]                 # build-check + dimension report
cad-build run-python [model.py] --code '…'      # measure geometry after the build
cad-build run-python --code-stdin < snippet.py  # large snippet via stdin
cad-build recipe     <assembly|selectors|outline>
cad-build export     [model.py] --format step   # step | stl | glb | obj | 3mf
cad-build preview    [model.py]                 # → shareable read-only 3D link

model.py defaults to ./model.py; its directory is the project root (so relative refs resolve exactly like the product's per-project workspace).

• rebuild — mirrors the product's rebuild_model: ok + overall bbox + per-body world bboxes + cylindrical-face census + diagnostics, or the first actionable build error.
• run-python — mirrors run_python: runs an ephemeral dialect snippet in model.py's namespace after it builds and prints what you print(). Nothing is persisted — real changes go in model.py.
• recipe — prints a focused CAD recipe (bundled from the production *.recipe.ts, single source of truth).
• export — writes the built model as STEP/STL/GLB/OBJ/3MF next to the source (--out to place it elsewhere). Entirely local; talks to no server.
• preview — builds the BREP locally, then uploads model.py and that geometry to the anonymous preview endpoint and prints a share link. The link opens read-only for anyone, signed in or not — nothing is rebuilt server-side, and it becomes editable only when someone remixes it into their own account. The secret that lets a later preview update the same link lives in .forgent3d-preview.json. Override the endpoint with FORGENT3D_PREVIEW_ENDPOINT.

Build

pnpm --filter @forgent3d/cad-build build   # esbuild bundle + copy assets + gen recipes.json
pnpm --filter @forgent3d/cad-build smoke   # offline smoke: rebuild / run-python / recipe in an os-temp dir

scripts/build.mjs bundles src/cli.ts → dist/cli.mjs (keeping web-tree-sitter external), copies the runtime assets into dist/assets/ (tree-sitter*.wasm, occt-import-js.cjs + .wasm, cadkit-snapshot.json), and generates recipes.json. bin/cad-build.mjs points the engine at those assets via CAD_ENGINE_ASSETS_DIR / OCCT_WASM_JS / CAD_BUILD_ASSETS_DIR before loading the bundle.

Keep in sync

• src/format.ts's formatRebuild / formatProbe mirror cf-sandbox's formatRebuildModel / formatProbeResult (packages/cf-sandbox/src/lib/agent-tools.ts).
• recipes.json regenerates from packages/cloud/lib/aicad-agent/recipes/*.recipe.ts.

Relationship to the forgent3d skill

The skill (github.com/forgent3d/forgent3d-skills, mounted here as the forgent3d-skills submodule) is maintained independently — its SKILL.md is hand-written and evolves on its own, no longer generated from the in-product agent-boot.ts prompt. The only contract between the two lines is this CLI: the skill shells out to cad-build <cmd>, so the subcommand names, flags and output shape above are what must stay stable. Changing them is a breaking change for the skill.