capwitf/mechanical-cad-skills/cad-evidence-ledger

CAD Evidence Ledger

Overview

A CAD result is not ready because the final answer says it is ready. Create an evidence ledger that records the actual files, source of truth, checks, and claim status behind the delivery.

Core Rule

Before final CAD reporting, produce or update an evidence ledger when files are delivered, external tooling was used, or the task has had quality complaints. The ledger must make stale files, missing formats, unchecked geometry, and overclaims visible.

Use scripts/cad_evidence_manifest.py to generate a JSON manifest for final files. The script records file existence, size, modified time, SHA256, source provenance, recorded checks, and claim categories. It does not execute external commands.

Evidence Manifest

Record these fields:

Script Usage

python .\.codex\skills\cad-evidence-ledger\scripts\cad_evidence_manifest.py `
  --root . `
  --source .\models\bracket.py `
  --toolchain "FreeCAD export" `
  --check "Rendered PDF page 1 nonblank" `
  --verified "Final STEP exists and hash recorded" `
  --unverified "Strength not calculated; loads missing" `
  --output .\deliverables\cad-evidence.json `
  .\deliverables\bracket.step .\deliverables\bracket.pdf

If any final file is missing and --allow-missing was not used, the script exits nonzero. Missing files in a manifest are failure evidence, not acceptable delivery.

Claim Categories

• Verified: directly checked from the final file, rebuilt source, open/render log, measurement, hash, screenshot, or script output.
• Inferred: plausible from source or tool behavior, but not directly checked in the final file.
• Unverified: not checked, blocked, missing data, missing tool, or requires human engineering judgement.

Do not bury Unverified items under a success summary. If strength, fit, layout, or native SolidWorks quality was not directly checked, say so.

Required Evidence by Deliverable

Handoff

Use with:

• cad-final-verification before claiming delivery is ready.
• cad-artifact-inspection to generate read-only parser evidence for STEP/STL/DXF/DWG/PDF artifacts.
• cad-toolchain-preflight to record local tool proof.
• cad-engineering-sanity to label mechanical claims.
• cad-visual-layout and cad-design-richness to record subjective gates separately from file evidence.

Common Mistakes

• Reporting paths without checking the files exist.
• Mixing old exports with new source.
• Recording commands that were planned but not run.
• Treating hash/mtime as proof of geometry correctness.
• Marking human judgement items as Verified.