CARD: scaffold-f-structured-diagnostics — Structured, Requirement-Citing Diagnostics (TypeScript)

Band 1 — Identity & Recognition

02Classification: layer=E (verification) + C (meta); mechanism=scaffold F.

03Intent: Engineer linter/checker output as agent input — stable, structured, citing the violated requirement and the fix surface — because error text is the highest-leverage prompt in the loop.

04Also Known As: actionable diagnostics; SARIF output; fix-it hints; structured errors; machine-readable lint; ESLint messageId.

05Applicability / Recognition: Apply when — a custom @typescript-eslint rule (or a thrown domain error) emits free text; an error states what failed but not which REQ or where to fix; tool output is unstable across runs. Detector seed: a custom eslint/check message or a domain error without a spec:// REQ URI and a fix-surface hint → recognition fires (tool output is the agent's percept, R3-011). Note: tsc's own diagnostics (TS2322 etc.) are already coded — wrap them with REQ context, do not replace them.

Band 2 — Justification & Tradeoffs

06Motivation: A weak agent sees Type 'string' is not assignable to type 'never' from a satisfies never exhaustiveness check — true but opaque. With the custom rule emitting violates REQ spec://errors/r6: error union not exhaustively handled; fix surface: add a case for variant 'Timeout' before assertNever, the agent acts directly. The strong author's "what to do when this fails" is materialized in the message.

07Structure & Participants: Diagnostic (an eslint report with a stable messageId) · REQ citation (spec:// URI) · Fix-surface hint (where/what) · Stable format (SARIF / fixed grammar).

08Collaborations: Carries failures from Classes C/D/E and the §8 bans; feeds the agent loop's next prompt; in raids, structured diagnostics let the orchestrator triage misfires.

09Goals / Non-Goals: Goals: every custom check is agent-actionable. Non-Goals: NOT rewriting tsc's own diagnostics (already good — wrap them); does NOT replace the contract that defines correctness.

10Consequences: (+) iterations-to-green drop, more for weaker models; (+) diagnostics double as a navigable requirement map. (−) message authoring cost; (−) verbosity vs token budget — keep a compact grammar.

11Alternatives: free-text errors (wasted conditioning); silent failure (worst). Neither acceptable for an agent loop.

12Risks & Assumptions: assumes a stable REQ namespace exists (it does — specmap, guide §9). Sunset: none material.

13Evidence & Transfer-strength: R3-011 (tool output is highest-leverage prompt, theory), R2C-004 (agent conditions on tool text, benchmark). Class: benchmark + theory. Tag: [E-mid].

Band 3 — Operation

trigger: WHEN a custom eslint/check message or a domain error lacks a spec:// REQ URI + fix-surface hint THEN apply
mode: inline
routine:
  1. Add the violated REQ's spec:// URI to the message.
  2. Add a one-line fix surface: where to change and what.
  3. Emit in a stable structured form (eslint `messageId` + SARIF; fixed grammar for domain errors).
  4. Keep it compact (one line of why + one of where).
checker: `diagnostic-cites-req` in the flat-config plugin `@org.vibevm/eslint-plugin-ai-native` (rule key `ai-native/diagnostic-cites-req`; source `typescript-ai-native-lang/v1.0.0/tools/eslint-plugin-ai-native/`) — custom messages must match the grammar `violates REQ <uri>: <why>; fix surface: <where>`; wired via the project's own eslint config (demo: `research/ts-demo/eslint.config.js` at `error`)
raid_role: layer=tooling; order=after:none; batch=package
budget: active_rules=1; first_signal=lint pass (<60s)