New stage

Scaffold a new pipeline stage named $1 (kebab-case → src/$1.ts), following the conventions from global_ignore/skl-skill-analysis-plan.md §2–§3 and .claude/rules/testing.md. Any further arguments are diagnostic codes the stage will emit.

Preconditions — verify before doing anything

1. src/schema.ts, src/diagnostics.ts, and src/analyze.ts exist (P0 has landed). If not, STOP and tell the user this skill needs the P0 skeleton first.
2. src/$1.ts does not already exist. If it does, STOP — this skill scaffolds, it does not overwrite.

Steps

1. Create src/$1.ts — a pure function module:

   • One exported function taking plain inputs (never a SkillSource — IO stays in analyze.ts) and returning { <result fields>, diagnostics: Diagnostic[] }.
   • No clock, no randomness, no locale-dependent calls, no node: imports.
   • Any array it returns must have a fixed, documented sort order.
   • Match the style of the closest existing stage module.

2. Register diagnostic codes — for each code passed as an argument, add an entry to the registry in src/diagnostics.ts: code, default severity (error | warning), message template, optional hint. Codes are kebab-case, no E_/W_ prefixes (e.g. readme-missing).

3. Create tests/$1.test.ts — mirrored test file:

   • Table-driven unit tests over the pure function: happy path, empty input, and one case per diagnostic code (the vocabulary meta-test in tests/contract.test.ts fails CI if a registered code has no fixture).
   • Zero mocks. Use plain values or the fromFiles memory source via tests/helpers.ts for full-pipeline cases.

4. Wire into the pipeline — call the stage from src/analyze.ts at the right point in the flow (see the pipeline order in global_ignore/skl-skill-analysis-flow.md §1, or the stage sequence already in analyze.ts). If the stage adds output fields, update SkillAnalysisSchema in src/schema.ts in this same change and extend the full-output fixtures.

5. Run the gate — npm run lint && npm run typecheck && npm test. All green, including the contract meta-tests (determinism, schema conformance, diagnostic coverage).

6. Report — list created/modified files, the registered codes, and remind the user this should be committed per .claude/rules/commit-message.md (scope = the stage name; arch type if the schema changed, otherwise feat).

Stay within the current build-plan phase: if $1 belongs to a later phase than the one in progress, point that out and ask before proceeding.