Why: recording checks in a frozen task card can change the candidate and invalidate current-head CI.
Evidence: SELF fixed-candidate capture regression and all 33 evidence tests passed; actual output and object digests are preserved by make evidence.
Impact: document preparation, external receipts and post-phase import using existing schema 1; no filesystem freeze or trust upgrade is introduced.
Refs: U3; policy/governance.md; .task/feature-merge-queue-policy-draft.md