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type: adr id: adr-0090 status: accepted created: 2026-06-20 updated: 2026-06-20

ADR-0090 — C015 tier-checks stay deferred: no high-precision form exists pre-measurement; the Rejected case is already covered by an invariant

Context

ADR-0087 minted C015 citation-resolves (v0: a [[KEY]] that resolves to no <a id="KEY"> anchor in sources.md is surfaced) and deferred the tier checks to a separate v1 decision — a [[KEY]] citing a Caveated or Rejected entry, where the discipline is "Caveated entries MUST NOT carry a MUST-level claim; Rejected entries MUST NOT be cited at all." This ADR makes that v1 decision after investigating the implementation surface.

The investigation found that neither deferred case has a clean, high-precision implementation today:

• The Rejected case is already covered. The ## Rejected — DO NOT CITE tier is a prose table; its entries carry no <a id> anchors (verified: zero anchors under the Rejected heading). So a [[KEY]] citing a rejected claim already dangles and is already surfaced by C015 v0 — just with a generic "resolves to no anchor" message. There is no new detection to add, only a cosmetic message tweak, which does not earn a contract change.
• The Caveated case is fuzzy. A Caveated entry has an anchor, so it passes v0. Flagging "a MUST-level claim cites a Caveated entry" requires a MUST-claim detector — a natural-language classification over the sentence around each citation. That is precisely the low-precision surface the effective-false-positive discipline (≤10% effective FP, [GOOGLESA]) says not to ship unmeasured; an over-firing tier check gets --no-verify'd like any other.

Decision

1. Do not build C015 tier-checks now; keep C015 at v0 (dangling-anchor only). Level: convention / decision (ADR-0063) — no check minted, no checks.yaml row, no contract-version bump. Honors ADR-0077 Decision 8 (don't ship a noisy fact) and the measure-first gate (0086 Decision 3): a check ships only once its precision is measured.

2. Cover the Rejected case with an invariant, not a check. Record that a Rejected entry MUST NOT carry an <a id> anchor — which is already true. Because rejected entries are anchor-less by construction, any [[KEY]] citing one dangles and C015 v0 surfaces it. This is a high-precision safeguard with zero new code; the invariant is noted in sources.md so it stays true (a future editor who anchors a rejected entry would silently defeat the check).

3. The trigger to revisit the Caveated case. Fold citation cases into the corpus-bench corpus and measure a candidate MUST-detector's effective-FP before minting anything. Only a structural, high-precision signal earns a check — e.g. a controlled RFC-2119 MUST marker adjacent to a [[KEY]] whose anchor sits under the Caveated tier — and only after the benchmark shows it clears the ≤10% bar. Until then, the Caveated-MUST discipline stays a review checklist item, not a tool.

Alternatives considered

Alternative	Why weaker
Build the Caveated-MUST detector now	Needs fuzzy NL MUST-claim detection; likely exceeds the ≤10% effective-FP bar [GOOGLESA]; violates the measure-first gate. Ship it and it gets --no-verify'd.
Add a Rejected-citation message variant to C015	The Rejected case is already surfaced by v0 (anchor-less → dangles); a sharper message needs the resolver to parse the Rejected table for tiers — real complexity for a cosmetic gain.
Mint a new check id (C016)	Premature — there is no new high-precision fact to mint. The Rejected case is covered; the Caveated case is unmeasured.
Promote the discipline to a hard rule with no tool	The honesty framework forbids enforcement-sounding claims without a level; the Caveated-MUST rule stays an explicit checklist item until a measured check exists.

Consequences

C015 stays v0 (dangling-anchor only). The Rejected-citation case is covered for free by the anchor-less invariant — now documented in sources.md so it does not silently rot. The Caveated-MUST case defers to a measured future ADR, remaining a review-checklist item meanwhile. No contract change, no version bump, no new check. Refines ADR-0087 Decision 4 (resolves the deferred v1 question) and honors ADR-0063 (no enforcement without a level) + ADR-0086 Decision 3 (measure before shipping a check).

Propagation

docs/adrs/0090-c015-tier-checks-deferred.md (this record) · docs/adrs/README.md (index row) · docs/research/sources.md (the "Rejected entries carry no <a id> anchor" invariant note in the Rejected section). No corpus-cli / checks.yaml change. Refines 0087 Decision 4.