[observation] ADR-0058 expression-surface ratchet discovers surfaces by schema-name text — any slot narrowed onto its own schema silently drops out of the scan

[os-zhuang]

Observation-class record from #7327's implementation (PR #7387), filed by the dispatching PM so it is not lost to session memory. The dev's own words carry the finding; this card records it for triage grading.

The fragility

packages/qa/dogfood/test/expression-conformance.test.ts (the ADR-0058 expression-surface ratchet) discovers governed surfaces by textually matching <key>: ExpressionInputSchema in schema sources. Consequence, measured live on PR #7387's first push: narrowing settings-manifest.zod.ts's two visible slots onto their own module-private schema (SettingsVisibilityInputSchema) made them drop out of discovery entirely — a live predicate surface silently leaving the ledger, i.e. the #1887 class that ledger exists to catch. Caught only because the stale ledger entry turned Dogfood Regression Gate (3/3) red.

Mitigation already landed (PR #7387)

Discovery now reads a registered schema-name list instead of one hardcoded name, and the trap is written down in both the test and the ledger header. That converts the failure from "silent drop" to "remember to register" — better, still fragile by construction: any future slot narrowed onto its own schema stays invisible unless someone registers it, and nothing fails if they don't (the stale-cover check fires only when an EXISTING entry goes stale, not when a surface never enters).

The structural fix (not attempted — larger than #7327's card)

Discover by resolved type rather than by identifier text — e.g. walk the exported schemas and detect "accepts the ExpressionInput envelope shape (or a narrowing of it)" structurally. That makes registration automatic and the ratchet complete by construction.

Refs

• PR feat(spec): declare the settings visible grammar the evaluator actually implements (#7327) #7387 (the mitigation + trap documentation; commit 60b3120 is the CI-forced fix)
• Narrow the settings-manifest visible declaration to the grammar the save-time evaluator actually implements (#7169 alignment half, measured 1-vs-93) #7327 / OS-DEV-REPORT comment 5238208223 (the dev's full account, "open_questions" section)
• The settings-visibility ledger row + ExprDialect member added there

Filed unlabeled and unassigned for triage per the filing discipline. Dedup: open-issue search for expression-conformance discovery / ADR-0058 ratchet / ExpressionInputSchema textual returns nothing covering the discovery mechanism itself.

[claude]

Triage: finding + domain:cli (held, not queued).

• Classification: observation-class, exactly as self-filed — a structural fragility in gate discovery, with nothing dropped on main today. One factual correction to the card: PR feat(spec): declare the settings visible grammar the evaluator actually implements (#7327) #7387 is still open at triage time (not merged), so the "mitigation already landed" section is in-flight, not on origin/main. Verified on b948a41: packages/qa/dogfood/test/expression-conformance.test.ts:37 still discovers surfaces by the single hardcoded textual match (<key>: ExpressionInputSchema), and SettingsVisibilityInputSchema does not exist in packages/spec/src yet — both the narrowing that triggers the drop and the registered-list mitigation arrive with that PR. Re-verify this card's premises at the merged ref once feat(spec): declare the settings visible grammar the evaluator actually implements (#7327) #7387 lands (the unlock-moment rule: the merge that changes this file face is exactly the one to re-read).
• Residual after feat(spec): declare the settings visible grammar the evaluator actually implements (#7327) #7387: "remember to register" — a future slot narrowed onto its own schema stays invisible unless registered, and nothing fails when it isn't (the stale-cover check fires only for existing entries). The structural fix (discover by resolved type / envelope shape) is real work larger than Narrow the settings-manifest visible declaration to the grammar the save-time evaluator actually implements (#7169 alignment half, measured 1-vs-93) #7327's card, correctly not attempted there.
• Routing: the ratchet lives in packages/qa ⇒ domain:cli (qa is a cli-row package).
• Dedup: the filer's three-query search corroborated; Narrow the settings-manifest visible declaration to the grammar the save-time evaluator actually implements (#7169 alignment half, measured 1-vs-93) #7327 (parent card, PR feat(spec): declare the settings visible grammar the evaluator actually implements (#7327) #7387 in flight) covers the mitigation, not the discovery mechanism. Clean.
• Promotion triggers: a second silent-drop event, or maintainer appetite for the resolved-type discovery rewrite.

本评论来自分诊座位 Routine（#5474 试点），不构成认领。

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