ADR-0152 - Deterministic contract tightening

Context

The checker inferred missing types, accepted frontmatter through several partial parsers, left task shape as prose-only rules, and published C014 even though no deterministic checker could compute it. Those gaps made malformed artifacts look valid and made the machine contract overstate its reach.

Decision

1. The checks contract is version 0.18.0. Artifact checking requires an explicit recognized type:. Missing and unknown types are blocking usage errors.
2. The recognized types are closed. spec, task, review, and change-plan have deterministic checker faces. inventory, audit, research, and inspection are recognized and return checked: false until a deterministic contract exists for them.
3. Frontmatter uses one strict subset. It accepts an optional UTF-8 BOM, top-level keys, plain or balanced quoted string scalars, flat inline string lists, flat block string lists, and comments outside quotes. It preserves scalar text without boolean, number, or null coercion. Duplicate keys, malformed delimiters, nesting, maps, multiline scalars, anchors, aliases, tags, empty list heads, and field-shape mismatches are blocking parse errors.
4. C014 retires. Its identifier is never reused. Comparing a live diff with Do not change remains reviewer work, not a deterministic contract claim.
5. New checks are stable. C021 intent-present requires a non-empty spec ## Intent. C022 task-shape validates task type, non-empty ID/source/scope, field shapes, status, and exactly-once required sections. C023 task-evidence does not run at ready or running; at review-ready or closed, it requires a numeric exit plus non-empty fenced raw output, a CI link, or justified n/a. Bare claims and visible placeholders fail. C024 closed-task-resolved rejects unresolved markers and non-empty canonical blocker labels in a closed task; none and n/a are resolved values.

Narrowed decisions

• ADR-0059: type: is mandatory and unknown values are rejected.
• ADR-0066 and ADR-0086: the deterministic catalog contains only checks the reference implementation computes.
• ADR-0097: retired and reserved identifiers remain unavailable for reuse.

Consequences

• One parser owns every frontmatter read.
• Task files can be checked directly.
• Unsupported syntax fails visibly instead of being guessed or coerced.
• The checks contract states exactly what the CLI can enforce.

Status

Accepted (2026-07-13).