One canonical YAML scalar resolver: frontmatter exports the single null/bool/quote resolution helper and the capture, lint, lifeboat, and memory decoders all delegate to it, so a cross-package verdict split on any scalar axis becomes unrepresentable

Press Release

Alice writes impact: NULL in an issue record and every abcd surface reads it the same way: capture accepts what lint accepts, the release cut diagnoses what lint diagnoses, and the lifeboat graveyard sees the same null the memory dumper writes. There is exactly one place in the codebase that knows what a YAML scalar means — an exported resolution helper in internal/core/frontmatter covering nulls, booleans, and quoting — and the capture, lint, lifeboat, and memory decoders all delegate to it. When Bob extends the scalar rules (a new spelling, whitespace trimming), they edit one function and every consumer moves together; the class of bug where two hand-synced copies drift apart is no longer expressible.

Why This Matters

The uppercase-null bug (iss-287) happened because a widening landed in some predicate copies and not others; its fix (PR #294) widened two of four independent scalar decoders and left the quoting axis split (iss-285) and the boolean axis untouched (memory/parseScalar accepts true/True/TRUE while memory/vintage.go tests == "true" exactly). Each remaining asymmetry is a future issue of the same shape. This is the one-canonical-primitive principle applied to scalar resolution: fix the class, not the instance. Evidence: .abcd/work/reviews/2026-08-19-pr-294-null-predicate/ (F6).

Acceptance Criteria

• Given a YAML scalar value, When any of the capture, lint, lifeboat, or memory decoders resolves its null/bool/quoting meaning, Then the answer comes from one exported frontmatter helper and no package-local literal set or hand-synced copy remains (grep proves zero duplicate null/bool tables outside the helper and its tests).
• Given the frontmatter package, When its scalar rules are widened in one edit, Then an equivalence/consumer test suite proves every delegating package observes the change without further edits.
• Given a record carrying a quoted null (impact: "NULL"), When capture validation and record-lint both judge it, Then their verdicts agree (closes iss-285), and the two currently-contradictory tests (frontmatter_test.go vs graveyard_abandoned_test.go) are reconciled to the same stance.

Open Questions

• Where does quoting normalisation live — inside the shared helper (callers pass raw bytes) or as a documented pre-step every caller must apply? The helper-owns-it answer makes the drift unrepresentable; the pre-step answer preserves callers that need the raw form (lint's "not a record handle" message wants the original bytes).
• Does the write path (memory/yaml.go dumper's own null-literal list) fold into the same helper, or is emit a separate concern?

Audit Notes

Empty. Populated by intent-fidelity-reviewer when intent moves to shipped/.