Validation & grades

Validation is not a stage of this engine; it is the engine’s spine. Every claim the pipeline makes — “this feature is built”, “this forbidden form is absent”, “these parts fit” — is backed by a named check that actually ran and PASSed on measured geometry.

The honesty rule

Three commitments, enforced structurally rather than by convention:

1. A feature is only claimed after its validators PASS. built can only be written when every check in the feature’s verified_by list has PASSed — and the schema itself enforces built ⊆ supported, so an unsupported feature literally cannot serialize as built.
2. An unknown name is a load error, never a silent skip. Every check name, recipe op and joint type binds against its registry at catalog load. A typo is a CatalogError before any geometry exists.
3. A check whose implementation is unavailable honestly does not run. It is reported as an ENGINE GAP finding and any feature it verifies stays honestly un-built — never a silent no-op that still claims its features.

Check levels

Check names follow <level>.<check>; the level tells you where the measurement happens:

Level	Measured on	Critical?
form.*	the Form IR — analytically, zero CAD, no tolerance fuzz	per-finding
interface.*	datums and port frames on the IR; mates in the assembled pose	per-finding
topology.*	the compiled solid, via geometry probes	yes
region.*	the compiled solid, restricted to declared semantic regions	yes
manufacturing.*	the solid / exported mesh, against printer constraints	caps the grade
assembly.*	cross-part checks in the assembled pose	yes
quality.*	shape-quality scoring; WARN-oriented	no

The same physical property is often checked twice, once per side of the CAD boundary: form.mouth_opens_sideways reads tagged profile segments on the IR; topology.mouth_opens_sideways probes the actual void through the compiled solid. The form check gates cheaply and early; the topology probe verifies the compiler kept the promise.

Which checks run is archetype-driven: a handful of universal form checks always run; the rest come from the archetype’s own validators: list — one product family is never judged by another family’s checks. Browse all registered checks in the registry.

forge validate vs forge build

forge validate is the pre-CAD golden gate — it writes nothing, never imports cadquery, and exits non-zero on critical failure. forge build refuses to compile a form that failed its own IR checks, then measures the compiled solid and finalizes two reports:

• the honesty report — requested / supported / PROVEN-built / missing features, which forbidden forms were checked and with what verdict (absent / present / unchecked), and which gaps the engine admits to;
• the score — a numeric grade with a hard gate: a critical FAIL at contract / topology / region level forces status FAIL and grade F no matter how good the numbers look.

The findings model

Every validator, reviewer and repair rule speaks one result shape:

Field	Meaning
check	the registered check name
status	pass / warn / fail — a report’s status is the worst finding
level	which validation level produced it
critical	a critical FAIL forces overall FAIL regardless of score
measured / limit / unit	the actual number vs the threshold — findings carry evidence, not just verdicts
suggestion	an actionable hint; feeds the deterministic repair rules

report.passed(check) is true only if the check ran and its worst finding is PASS — absence of evidence is never evidence of absence.

Forbidden forms

An archetype’s contract names what the product must contain and what it must not degenerate into. Forbidden form ids bind at load time to the check whose failure means the form is present (e.g. closed_ring is detected by form.mouth_opens_sideways failing). A detected forbidden form is a critical contract FAIL; an unchecked one is reported as unchecked in the honesty report — never assumed absent.