XZBT/docs/evidence/phase0/2026-09-05-gc2-format-contracts.md

Phase 0 GC2 Format Contract Completeness Evidence

Gate: GC2 / Format contract completeness
Result: Passed for shared format contracts, schema validation, semantic validation, and diagnostic error generation.
Date: 2026-09-05T18:33:45Z
Tooling: Zero-dependency Node.js validator (tools/validate-exhibit.mjs), JSON Schema Draft-07 (schema/xzbt-0.1.schema.json), and automated test suite (test/gc2-runner.test.mjs).

Specification & Implementation Summary

1. Normative Specification: Updated XZBT_0-1_Format_Specification.md (Revision 0.2) defining document structure, metadata, primitive type system with strict coercion ban, ValueSpec 5-form grammar and operator arity table, ConditionSpec comparisons and logical composition with edge-trigger re-arming, DurationSpec literals, and standard error codes.
2. Structural JSON Schema: Authoritative schema authored at schema/xzbt-0.1.schema.json.
3. Semantic Validator: Standalone CLI engine authored at tools/validate-exhibit.mjs.

Automated Conformance Test Matrix Results

The automated test runner executed 12 tests covering valid exhibits and deliberate fault injections:

Fixture	Classification	Expected Outcome	Actual Result	Status
test/fixtures/gc2/valid-minimal.xzbt	Minimal Exhibit	Valid (0 errors)	Valid (0 errors)	PASS
test/fixtures/gc2/valid-full-feature.xzbt	Full Feature Exhibit	Valid (0 errors)	Valid (0 errors)	PASS
prototypes/phase0/fixtures/amber-study.xzbt	Prototype Baseline	Valid (0 errors)	Valid (0 errors)	PASS
prototypes/phase0/fixtures/blue-study.xzbt	Prototype Baseline	Valid (0 errors)	Valid (0 errors)	PASS
test/fixtures/gc2/invalid-unknown-field.xzbt	Fault Injection	ERR_UNKNOWN_FIELD	ERR_UNKNOWN_FIELD	PASS
test/fixtures/gc2/invalid-unsupported-version.xzbt	Fault Injection	ERR_UNSUPPORTED_VERSION	ERR_UNSUPPORTED_VERSION	PASS
test/fixtures/gc2/invalid-id-syntax.xzbt	Fault Injection	ERR_INVALID_ID	ERR_INVALID_ID	PASS
test/fixtures/gc2/invalid-reference-missing.xzbt	Fault Injection	ERR_INVALID_REFERENCE	ERR_INVALID_REFERENCE	PASS
test/fixtures/gc2/invalid-type-mismatch.xzbt	Fault Injection	ERR_TYPE_MISMATCH	ERR_TYPE_MISMATCH	PASS
test/fixtures/gc2/invalid-cyclic-bindings.xzbt	Fault Injection	ERR_CYCLIC_DEPENDENCY	ERR_CYCLIC_DEPENDENCY	PASS
test/fixtures/gc2/invalid-out-of-bounds.xzbt	Fault Injection	ERR_OUT_OF_BOUNDS	ERR_OUT_OF_BOUNDS	PASS
test/fixtures/gc2/invalid-operator-arity.xzbt	Fault Injection	ERR_INVALID_ARITY	ERR_INVALID_ARITY	PASS

Gate Conclusion

The shared contracts portion of GC2: Format Contract Completeness is satisfied. The schema, validator, and test suite provide a deterministic foundation for Phase 1 runtime loading and validation. Subsystem-specific schemas and contracts (audio graphs, visual systems, scenarios) will be filled in dependency order alongside their respective phases.

Revision 0.3 reconciliation addendum

GC3 review found that the draft BindingSpec used from/to/transform, conflicting with the PRD's canonical source/target/scale/offset/clamp fields. Revision 0.3 corrected the schema, validator, and affected fixtures to the PRD vocabulary and added when plus exact smoothing semantics. The same 12-case GC2 matrix was rerun as part of the 27-test combined Phase 0 suite and still passed with zero failures. See the GC3–GC5 evidence for the reconciliation rationale and combined command.