--- name: cad-router description: Route natural-language or image-guided CAD generation and modification, plus uploaded STEP/STP reconstruction and modification, across text-to-cad and SimpleCADAPI. Use unified executable DesignIR 3.0 in semantic-feature mode for authored models and SurfaceIR mode for uploaded STEP reconstruction, without teacher geometry dependencies, with independent validation and CAD Viewer review. --- # CAD Router Choose a backend before modeling, keep its source as the editable authority, and normalize every result into one handoff contract. Use two projects by role: text-to-cad owns orchestration, general CAD, refinement, validation, repair, and viewing; SimpleCADAPI owns specialized mechanical families. ## Required workflow 1. Convert the natural-language or image-guided request into a brief: part type, dimensions, units, assembly relationships, editability, and validation targets. Every model uses DesignIR 3.0 plus STEP geometry. New text/image models use `fully_semantic_parametric`; uploaded STEP reconstruction uses `surface_parametric`. A generated semantic model may include a compiled SurfaceIR snapshot and then uses `hybrid_semantic_surface_parametric`, while its semantic layer remains authoritative. Never treat a teacher STEP or a single-case DesignIR as experience. Batch case JSON belongs to the separate CAD Experience plugin. Generation may consume only its promoted schema `2.0` generalized library. Never read `cad-experience-plugin/parser/input`, `parser/output`, or private case JSON during creation, modification, or reconstruction. 2. Run the deterministic router from this skill directory: ```bash python3 scripts/route.py "" --explain ``` Add explicit signals when known: `--edit-source path/to/source`, `--existing-model`, or `--assembly`. The router auto-discovers the workspace `cad-experience-library/library.json`, infers an experience family and feature roles from the request, and emits a backend-neutral `design_plan`. When promoted `reconstruction_grammar` records match, instantiate their symbolic parameter roles, datum roles, canonical stages, and validation roles in the new part's DesignIR; fill values from explicit user dimensions first and dimensionless distributions second. Use `--experience-library`, `--experience-family`, or repeated `--experience-feature` only to override those defaults. For one uploaded STEP, execute the route rather than stopping after the routing decision: ```bash ../../.venv/bin/python scripts/route.py \ "重建上传的 STEP，并返回可修改参数" \ --edit-source /absolute/path/to/upload.step \ --task-dir /absolute/path/to/task \ --execute ``` This command must finish extraction, source-independent reconstruction, geometry acceptance, parameter perturbation acceptance, and artifact publication. A route decision alone is not a completed reconstruction. 3. Follow the selected route unless a hard environmental constraint makes it unavailable. If overriding it, record the reason in the task manifest. 4. Load only the selected backend reference from `references/capabilities.md` and the matching installed Skill: - `build123d`: use `$cad`; this is the default for general STEP-first mechanical parts, assemblies, and existing STEP modification. - `simplecadapi`: use an installed SimpleCADAPI Skill/runtime; prefer it for gears, racks, ring gears, bearings, cycloidal parts, reducers, replayable graphs, and semantic tags. 5. When the route reports `requirement_refinement` or `visual_repair`, refine the brief, generate, execute, inspect multiple views, and repair no more than three visual mismatch rounds before asking the user. 6. Generate into a task-owned directory and start CAD Viewer with that task directory as `--dir`; do not expose the repository-wide fixture library for a task review. Write one DesignIR 3.0 `*.designir.json` per part and treat it as the editable geometry contract; keep `cad-task.json` as the execution record. Read `references/designir-3.0.md` for both semantic authoring and uploaded STEP reconstruction. `references/designir-2.0.md` is migration-only. Never change backend during an edit unless conversion is explicitly requested; modify the recorded authoritative layer. For a supplied STEP/STP, use `scripts/route.py --execute`; do not manually approximate the model when the executable adapter is available. The deterministic ingestion service extracts private teacher evidence into DesignIR 3.0. The independent rebuild subprocess receives the DesignIR and output path, never the STEP path. The acceptance stage alone receives both teacher and reconstruction. The DesignIR and generator must not import STEP, embed B-Rep or meshes, retain face references, or use the source model as a base feature. The acceptance agent alone compares the teacher and reconstructed STEP. Only expose parameters listed by `parameters.json`; every listed parameter has passed an isolated perturbation test. Other inferred names remain evidence, not a promised edit interface. 7. Validate against the brief. Run STEP geometry inspection and snapshot review. For experience-informed generation, record which generalized methods were applied, including the reconstruction grammar ID and instantiated symbolic roles. Validate against the user's brief and held-out targets, never against parameters exposed from the same source case. 8. Write a `cad-task.json` manifest using the contract in `references/backend-contract.md`. Hand the STEP artifact to `$cad-viewer` and return its live link. ## Routing rules - Prefer an explicit user backend when it can produce the editable STEP contract. - Prefer SimpleCADAPI when a supported standard mechanical factory or replay/semantic requirement materially reduces custom modeling. - Prefer build123d for general machined parts such as brackets, connecting rods, housings, shafts, flanges, fixtures, and source-driven assemblies. - Prefer source quality and future modification over the shortest first generation. ## V1 boundaries - Do not promise lossless conversion of feature history between backends. - Do not claim engineering certification, tolerance analysis, FEA, CAM toolpaths, or manufacturability without separate checks. ## References - Read `references/capabilities.md` when comparing or invoking backends. - Read `references/backend-contract.md` before writing a task manifest or adding another backend. - Read `references/designir-3.0.md` for semantic authoring, uploaded STEP reconstruction, and edits. - Read `references/designir-2.0.md` only when migrating legacy artifacts. - `scripts/capabilities.json` is the machine-readable V1 registry used by `scripts/route.py`.