name	synthcad-cad-authoring
description	Build, modify, and validate SynthCAD build123d CAD projects, including project-local tests and generated review artifacts.

SynthCAD CAD Authoring

Use this skill when working in the SynthCAD repository on CAD projects, exports, inspection, project-local tests, or URDF handoff.

Operating Rules

Use millimeters for all CAD dimensions.
Discover the active project and target before editing. Use the build registry or user request as the source of truth.
Prefer small parameterized changes in the target's existing source module.
Preserve real component interfaces first: hole patterns, shafts, registers, fastener clearances, mounting faces, service access, cable/connector access, and other constraints documented by the current project.
Do not hand-edit generated STEP, STL, GLB, URDF, inspection, or BREP files.
Keep each project's source references, docs, tests, and generated artifacts inside projects/<project-slug>/.
Put project-specific tests under projects/<project-slug>/tests/. Reserve root tests/ for reusable framework, CLI, registry, and library behavior.
When creating a new project or build target, add or update tests for its geometry invariants, critical component interfaces, source refs/docs metadata, and expected assembly interferences.
If a drawing or component constraint is incomplete, record the assumption in the project's own docs/ directory.

Commands

Set these from the current repo and request:

uv run synthcad-build --list
PROJECT=<project-slug>
TARGET=<changed-build-target>
ASSEMBLY_TARGET=<assembly-target-to-review>
URDF_TARGET=<urdf-target-or-empty>

Use the variables consistently:

uv run synthcad-build --project "$PROJECT"
uv run synthcad-probe --target "$TARGET" --children
uv run synthcad-inspect --target "$ASSEMBLY_TARGET"
uv run show-interference --target "$ASSEMBLY_TARGET"
uv run synthcad-report --project "$PROJECT"
test -z "$URDF_TARGET" || uv run synthcad-urdf --target "$URDF_TARGET"
uv run pytest
uv run pytest "projects/$PROJECT/tests"

Use synthcad-probe before writing throwaway geometry scripts. It reports target bounds, child labels, and inspection model structure quickly.

Done Criteria

A CAD change is done when:

the changed target imports and builds without errors;
relevant project-local tests are added/updated and pass;
exports regenerate for the affected project or target;
inspection artifacts are generated for the changed target or assembly;
unexpected interferences are fixed or documented as intentional; and
project-specific assumptions or validation notes are updated.

Reference

Open references/project-workflow.md for the generic project workflow and test expectations.

Robotics Robustness Extension

For robotics parts/assemblies, pair this skill with:

references/robotics-robustness-prompt.md for a reusable prompt add-on.
docs/robotics-design-guidelines.md for design guardrails and tooling roadmap.

When outputs include rotating shafts, bearing supports, or structural load paths, require explicit rationale and fail the task if support topology is unsafe or insufficiently specified.

SynthCAD CAD Authoring

Use this skill when working in the SynthCAD repository on CAD projects, exports, inspection, project-local tests, or URDF handoff.

Operating Rules

Use millimeters for all CAD dimensions.

Discover the active project and target before editing. Use the build registry or user request as the source of truth.

Prefer small parameterized changes in the target's existing source module.

Preserve real component interfaces first: hole patterns, shafts, registers, fastener clearances, mounting faces, service access, cable/connector access, and other constraints documented by the current project.

Do not hand-edit generated STEP, STL, GLB, URDF, inspection, or BREP files.

Keep each project's source references, docs, tests, and generated artifacts inside projects/<project-slug>/.

Put project-specific tests under projects/<project-slug>/tests/. Reserve root tests/ for reusable framework, CLI, registry, and library behavior.

When creating a new project or build target, add or update tests for its geometry invariants, critical component interfaces, source refs/docs metadata, and expected assembly interferences.

If a drawing or component constraint is incomplete, record the assumption in the project's own docs/ directory.

Commands

Set these from the current repo and request:

uv run synthcad-build --list PROJECT=<project-slug> TARGET=<changed-build-target> ASSEMBLY_TARGET=<assembly-target-to-review> URDF_TARGET=<urdf-target-or-empty>

Use the variables consistently:

uv run synthcad-build --project "$PROJECT" uv run synthcad-probe --target "$TARGET" --children uv run synthcad-inspect --target "$ASSEMBLY_TARGET" uv run show-interference --target "$ASSEMBLY_TARGET" uv run synthcad-report --project "$PROJECT" test -z "$URDF_TARGET" || uv run synthcad-urdf --target "$URDF_TARGET" uv run pytest uv run pytest "projects/$PROJECT/tests"

Use synthcad-probe before writing throwaway geometry scripts. It reports target bounds, child labels, and inspection model structure quickly.

Done Criteria

A CAD change is done when:

the changed target imports and builds without errors;

relevant project-local tests are added/updated and pass;

exports regenerate for the affected project or target;

inspection artifacts are generated for the changed target or assembly;

unexpected interferences are fixed or documented as intentional; and

project-specific assumptions or validation notes are updated.

Reference

Open references/project-workflow.md for the generic project workflow and test expectations.

Robotics Robustness Extension

For robotics parts/assemblies, pair this skill with:

references/robotics-robustness-prompt.md for a reusable prompt add-on.

docs/robotics-design-guidelines.md for design guardrails and tooling roadmap.

When outputs include rotating shafts, bearing supports, or structural load paths, require explicit rationale and fail the task if support topology is unsafe or insufficiently specified.

synthcad-cad-authoring