ADR-0154 - Spec-backed tasks and review closure

Context

Task CI evidence, blocker-list parsing, task authority, and review acceptance each had more than one plausible representation. That ambiguity let valid packets fail and invalid terminal states pass.

Decision

1. C023 CI evidence is visibly labeled. A task's CI evidence is a URL following CI: or CI link:. An unlabeled URL is not C023 evidence.
2. C024 recognizes Markdown list forms. Canonical blocker labels are recognized after unordered and ordered list markers. none and n/a remain resolved values.
3. Every task is spec-backed. The source spec owns scoped requirements. A change plan may add wave and preservation context but cannot replace the spec in a task or review.
4. Review structure stays deterministic and unnumbered. Review ID and Requirement coverage are non-empty; decision and assessment values use their declared enums; waivers appear only on accepted reviews and exactly cover Unsupported and Unverified requirement rows; accepted reviews contain no non-empty Open decisions section or Blocked assessment. Blocked cannot be waived.
5. The checks contract remains 0.18.0. No C-code is added, removed, renamed, or reused.

Narrowed decisions

• ADR-0151: task packets remain part of the small artifact set and now always retain one governing requirement authority.
• ADR-0152: C023, C024, task source authority, and unnumbered review structure use the exact forms above without changing the C-code catalog or contract version.

Consequences

• Task CI and blocker evidence parse consistently with their fixtures.
• Change-plan tasks and reviews retain one requirement authority.
• Accepted review state has one mechanically reconcilable waiver and decision shape.

Status

Accepted (2026-07-13).