opencad

Bake-off

One contract, four CAD backends

Each entry is the same design contract authored by Astra (gpt-6-astra, fast tier) on CadQuery, build123d, FreeCAD and Zoo KCL, then gated by the same OpenCascade evaluator. Codex USD comes from the pinned price card; local kernels cost nothing to run, and the Zoo API column is the prepaid balance drop for that cell. Newest first.

python -m opencad.bakeoff report appends an entry once every backend has a gate verdict, Astra turns on its tag, no fallback to another worker, and every turn metered from a single exec (sum or rollout). Runs with a re-billed resumed thread or a voided Zoo cell stay in docs/bake-off-experiments.md and off this page. A published entry is not rewritten.

2026-10-17tag bakeoff-astra

3DBenchy

All 4 backends pass every applicable gate.

BackendGatesCodex USDZoo APIInput tokensTurnsWall
CadQueryPASS 11/11$15.95—3.8M213m 41s
build123d lowest CodexPASS 11/11$14.27—3.2M212m 52s
FreeCADPASS 11/11$34.87—10.2M325m 10s
Zoo KCLPASS 11/11$32.17479 credits, $3.988.9M339m 06s
2026-10-16tag bakeoff-astra

Aleph stack case

Every backend fails features.

BackendGatesCodex USDZoo APIInput tokensTurnsWall
CadQuery lowest CodexFAIL 10/11$71.39—16.6M112h 25m
build123dFAIL 10/11$86.47—18.2M132h 50m
FreeCADFAIL 10/11$107.67—24.9M123h 21m
Zoo KCLFAIL 10/11$115.89512 credits, $4.2530.9M112h 33m
2026-10-14tag bakeoff-astra

Bracket

All 4 backends pass every applicable gate. Zoo credits for this cell were not kept (a later run on the same part replaced its cost.json); docs/bake-off-experiments.md records 97 credits, $0.80.

BackendGatesCodex USDZoo APIInput tokensTurnsWall
CadQueryPASS 11/11$4.53—1.1M24m 07s
build123dPASS 11/11$5.10—1.1M23m 55s
FreeCAD lowest CodexPASS 11/11$3.58—0.8M23m 26s
Zoo KCLPASS 11/11$9.06—2.6M27m 03s