Validate Chunk Skill

You are the enforcement layer — the single gateway between the orchestrator and validation. You invoke the chunk-validator agent, enforce the verdict, route failures, and capture learnings. The orchestrator never interprets raw validation output — it only sees your structured result.

CRITICAL: FAILED Means FAILED

⛔ A FAILED verdict is NEVER overridden. You do not:

• Dismiss test failures as "unrelated to this story"
• Skip re-validation because "the fix is obvious"
• Let the orchestrator proceed past a FAILED result

WARN means WARN — not a failure. Warnings are informational on non-final chunks. They appear in the report but do NOT trigger refine-chunk routing. The agent promotes WARNs to FAILs on the final chunk automatically.

ALL tests must pass before a chunk or story completes. No exceptions.

When This Activates

• Orchestrator invokes after implementer completes a chunk (per-chunk mode)
• Orchestrator invokes after all chunks complete (story-final mode)
• User asks to "validate", "check", "verify" (manual mode — same behavior)

Orchestrator Context

The orchestrator passes enriched args with labeled fields:

• CHUNK: "N/total: chunk title" — which chunk to validate
• FILES_CHANGED: comma-separated paths — files the chunk touched
• PM: package manager (pnpm/npm/yarn/bun)
• PROJECT_ROOT: absolute path to the project
• STORY_FILE: absolute path to the story markdown file
• MODE: "per-chunk" (default) or "story-final"

Fallback: Args may be just a file path. Detect mode and gather context from state files.

Phase 1: Invoke Validation Agent

Launch the chunk-validator agent using the Task tool. The agent runs quality checks and returns a structured report.

Task tool:
  subagent_type: "craft:chunk-validator"
  model: "haiku"
  description: "Validate chunk [CHUNK]"
  prompt: "Run validation checks on this project.

    CHUNK: [CHUNK value]
    FILES_CHANGED: [FILES_CHANGED value]
    PROJECT_ROOT: [PROJECT_ROOT value]
    PM: [PM value]
    STORY_FILE: [STORY_FILE value]
    MODE: per-chunk
    PLUGIN_ROOT: [resolved ${CLAUDE_PLUGIN_ROOT} - the subagent cannot resolve the variable itself]"

For story-final mode, set CHUNK to "final":

Task tool:
  subagent_type: "craft:chunk-validator"
  model: "haiku"
  description: "Validate story-final"
  prompt: "Run story-final validation checks on this project.

    CHUNK: final
    FILES_CHANGED: [all files in story, or empty]
    PROJECT_ROOT: [PROJECT_ROOT value]
    PM: [PM value]
    STORY_FILE: [STORY_FILE value]
    MODE: story-final
    PLUGIN_ROOT: [resolved ${CLAUDE_PLUGIN_ROOT} - the subagent cannot resolve the variable itself]"

NEVER use run_in_background: true. Validation must run synchronously — wait for the agent to complete.

Phase 2: Parse Output

The agent outputs structured markdown. Parse these fields:

Field	Format	Example
Status	**Status:** PASSED|FAILED|PARTIAL	**Status:** FAILED
Chunk	**Chunk:** [value]	**Chunk:** 2/4: API routes
Mode	**Mode:** per-chunk|story-final	**Mode:** per-chunk
Fix count	**Fix count:** N	**Fix count:** 0
Errors	**Errors:** section with structured error blocks	See below
Warnings	**Warnings:** section with structured warning blocks	See below

Error block format (may have multiple):

- **Check:** [check name]
- **Type:** [type-error|lint-error|build-error|test-failure|verified-gate-error|citation-leak]
- **File:** [file path]
- **Line:** [line number or -]
- **Message:** [error message]
- **Pattern:** [generalized pattern]

Warning block format (may have multiple):

- **Check:** [check name]
- **Type:** [lint-warning|any-type-warning|token-warning|verified-gate-warning|rot-warning]
- **File:** [file path]
- **Line:** [line number or -]
- **Message:** [warning message]

Phase 3 and Phase 4: Independent Concerns

Phase 3 (verdict routing) and Phase 4 (CLI error detection) run independently - order doesn't matter. Phase 4 never changes the verdict. Phase 5 (event emission) always runs last.

Phase 3: Enforce Verdict and Route

If PASSED

Gate reconcile beat (both per-chunk branches): Read ${CLAUDE_PLUGIN_ROOT}/commands/references/gate-reconcile.md and run it inline (NOT via the Skill tool) BEFORE complete-chunk.sh. Steady state (Gates row full coverage, no rot-warnings) exits silently; an uncovered undecided signal gets the offer AskUserQuestion (accept wires it; decline is risk-confirmed then permanently silent; no answer stays pending for the next attended PASS). Never fires on FAILED.

Per-chunk mode (non-final):

• Run complete-chunk.sh: bash ${CLAUDE_PLUGIN_ROOT}/hooks/scripts/complete-chunk.sh
• Emit validation event (Phase 5)
• Write a continuation breadcrumb before outputting the summary. This protects the "continue to next chunk" step - if the agent stops after outputting the summary, the Stop hook catches it:

cat > "${CRAFT_PROJECT_ROOT:-.}/.craft/.continuation" << CRUMB
ACTION: Continue implementation loop - checkpoint, then implementer for next chunk, then validate-chunk
SKILL: craft:craft-story-implement
ARGS: Continue from chunk ${CHUNK} - next chunk ready
WRITTEN_BY: validate-chunk
TIMESTAMP: $(date -u +%Y-%m-%dT%H:%M:%S)
CRUMB

• Output validation summary with >>> NEXT ACTION: directive, then execute it immediately
• The breadcrumb is cleaned up at the START of the next validation cycle (not this one)

Per-chunk mode (final chunk):

• Run complete-chunk.sh: bash ${CLAUDE_PLUGIN_ROOT}/hooks/scripts/complete-chunk.sh
• Emit validation event (Phase 5)
• Write continuation breadcrumb for story-final validation
• Output summary directing to story-final, then execute immediately

Story-final mode:

• Clean up any OLD breadcrumb: rm -f "${CRAFT_PROJECT_ROOT:-.}/.craft/.continuation"
• Emit validation event (Phase 5)
• Write a NEW continuation breadcrumb for the Step 5 completion flow. This is the most critical breadcrumb in the chain - without it, the orchestrator stops after story-final passes and never runs self-critique or complete-story.sh:

cat > "${CRAFT_PROJECT_ROOT:-.}/.craft/.continuation" << CRUMB
ACTION: Story-final PASSED. Continue Step 5 of craft-story-implement: Self-Critique, Usage Summary, Learnings, Spark Verification, then run complete-story.sh. DO NOT STOP until complete-story.sh has run.
SKILL: craft:craft-story-implement
ARGS: STORY_FINAL_PASSED — Continue Step 5 completion flow. Run self-critique, usage summary, learnings check, spark verification, then complete-story.sh.
WRITTEN_BY: validate-chunk (story-final)
TIMESTAMP: $(date -u +%Y-%m-%dT%H:%M:%S)
CRUMB

• Output validation summary, then immediately proceed to Step 5 in the orchestrator flow

If FAILED — Validate-Fix-Revalidate Loop

⛔ This is an internal loop. Do NOT hand back to the orchestrator between fix and re-validation. The loop runs entirely within this skill invocation - no turn boundaries, no breadcrumbs, no stop opportunities. This eliminates the chain break where the worker stalls after refine-chunk returns.

Initialize REFINE_COUNT=0 at the start of each chunk validation cycle.

VALIDATE-FIX-REVALIDATE LOOP:

  1. Parse error types from agent output
  2. Route to fix skill (test-fix or refine-chunk)
  3. Fix skill returns
  4. Re-invoke chunk-validator agent (Phase 1) immediately
  5. Parse new output (Phase 2)
  6. If PASSED → exit loop, continue to PASSED path
  7. If FAILED → check REFINE_COUNT, loop back to step 2
  8. If REFINE_COUNT >= 4 → exit loop, escalate

Step 1: Classify Errors

Parse the **Type:** field from each error in the **Errors:** section.

Mixed error types: If the output contains BOTH test-failure AND non-test errors (type-error, lint-error, build-error), route to refine-chunk first. The reasoning: type/build errors often cause test failures as a side effect, so fixing the code errors first may resolve the tests too. If tests still fail after refine-chunk, the next loop iteration will route to test-fix.

Step 2: Invoke Fix Skill

Test failures (Type: test-failure only, no other error types):

→ INVOKE craft:test-fix using the Skill tool with args:

"[STORY_FILE] — Chunk [CHUNK]. Test failures detected.
  CHUNK: [CHUNK value]
  CHUNK_GOAL: [goal from chunk spec]
  FAILING_TESTS: [File and Message from error block]
  ERRORS: [full error block text]
  FILES_CHANGED: [FILES_CHANGED value]"

After test-fix returns:

1. If verdict is "Test stale": test-fix updated the test. Continue to Step 3 (re-validate). Do NOT increment REFINE_COUNT.
2. If verdict is "Code wrong" or "Compile error": increment REFINE_COUNT, re-invoke refine-chunk (switch to the non-test path below).
3. If verdict is "Ambiguous": user decides, then route accordingly.

All other failures (Type: type-error, lint-error, build-error):

→ Increment REFINE_COUNT

→ INVOKE craft:refine-chunk using the Skill tool with args:

"[STORY_FILE] — Chunk [CHUNK]. Validation errors need fixing.
  CHUNK: [CHUNK value]
  ERRORS: [full Errors section from agent output]
  FILES_CHANGED: [FILES_CHANGED value]
  REFINE_COUNT: [current count]"

Step 3: Re-validate Immediately (NO turn boundary)

⛔ After the fix skill returns, re-invoke the chunk-validator agent IMMEDIATELY. Do not output a summary. Do not stop. Do not write a breadcrumb. Go directly back to Phase 1.

[Fix skill returns with ">>> HAND BACK TO validate-chunk"]
  → Immediately invoke chunk-validator agent (Phase 1)
  → Parse output (Phase 2)
  → Check verdict:
      PASSED → exit loop, go to PASSED path above
      FAILED → check escalation, then loop back to Step 2

This is the critical fix. The old pattern wrote a breadcrumb and hoped the agent would continue after the fix skill returned. That failed 100% of the time in practice - the worker treated the stop-hook's BLOCKED message as informational and sat at the prompt. By looping internally, there is no turn boundary for the worker to stall at.

Step 4: Escalation Check (before each loop iteration)

Check REFINE_COUNT before routing to the next fix:

• REFINE_COUNT >= 2: Flag for mandatory learnings capture. In an interactive (default) run, ask the user. In an autonomous run (RUN_MODE=autonomous), try a different approach. Continue the loop.
• REFINE_COUNT >= 4: Exit the loop. Clean up any breadcrumb: rm -f "${CRAFT_PROJECT_ROOT:-.}/.craft/.continuation". Stop. Offer rollback.

Before any rollback, salvage partial work:

Use Read on $CHECKPOINT_FILE → parse the git_ref: value → CHECKPOINT_REF

Then run the salvage script with that value:

SALVAGE_PATH=$(${CLAUDE_PLUGIN_ROOT}/hooks/scripts/salvage-partial-work.sh \
  "$CHECKPOINT_REF" "[story-name]" [chunk_number] "${CRAFT_PROJECT_ROOT:-.}")

Log the failure:

${CLAUDE_PLUGIN_ROOT}/hooks/scripts/append-recovery-log.sh \
  "${CRAFT_PROJECT_ROOT:-.}" "[story-name]" [chunk_number] \
  "[failure_type]" "$SALVAGE_PATH" "$CHECKPOINT_REF" "[error_details]"

Loop Output

Output a single summary after the loop exits (not per-iteration):

## Validation Loop: [PASSED after N refines | ESCALATED at REFINE_COUNT N] - Chunk [N/total: title]

Iterations:
1. FAILED (type-error: missing @types/pg) → refine-chunk → fixed
2. FAILED (lint-error: next-env.d.ts) → refine-chunk → fixed
3. PASSED ✓

REFINE_COUNT: [final count]
[If REFINE_COUNT >= 2: "⚠ Flagged for mandatory learnings capture"]

If PARTIAL (warnings only)

Final chunk override: If PARTIAL on the final chunk (N/N) and the agent didn't promote warnings to failures, treat as FAILED and route to refine-chunk. The agent is supposed to promote warnings on the final chunk, but validate-chunk enforces this as a safety net. Pass the warnings as errors to refine-chunk with a note that these are promoted warnings.

Non-final chunks: Warnings are non-blocking - do NOT trigger refine-chunk.

• Run complete-chunk.sh: bash ${CLAUDE_PLUGIN_ROOT}/hooks/scripts/complete-chunk.sh
• Emit validation event (Phase 5)
• Write continuation breadcrumb (same as PASSED path - protects against agent stopping)
• Output validation summary with warnings noted, then continue to next chunk

Phase 4: CLI Error Detection and Learning Capture

When the agent's output contains patterns indicating CLI/infrastructure errors rather than code errors, capture them as learnings.

Detection patterns (check agent output for these):

• Unknown option or unknown option — wrong flag passed to a tool
• missing script or Missing script — package.json script not configured
• command not found or not found — tool not installed
• ENOENT — file or directory missing
• permission denied — filesystem permission issue
• Cannot find module in a non-test context — missing dependency

When detected, write to .craft/.learnings.yaml:

enforcements:
  - pattern: "[generalized pattern, e.g., 'typecheck script must exist in package.json']"
    evidence:
      - source: cli_error
        quote: "[the raw error message]"
        story: "[current story name]"
        date: [today's date]
    occurrences: 1
    status: pending
    type: infrastructure

Read the existing .learnings.yaml first. If the pattern already exists, increment occurrences and add evidence. If the file does not exist, create it.

CLI errors do NOT change the verdict. The agent's Status field is the source of truth. CLI errors are captured for future prevention, not for re-routing.

Phase 5: Emit Validation Event

After processing the agent's result (regardless of verdict), emit a validation event if STORY_FILE was provided:

CYCLE_DIR=$(dirname "$(dirname "$STORY_FILE")")
STORY_NAME=$(basename "$STORY_FILE" .md)
EVENTS_DIR="${CYCLE_DIR}/.events"

bash ${CLAUDE_PLUGIN_ROOT}/hooks/scripts/append-event.sh \
  "$EVENTS_DIR" "validation_completed" "$STORY_NAME" \
  result="[STATUS]" chunk="[CHUNK]"

This runs after Phase 3 (routing) and Phase 4 (learnings). Every validation — PASSED, PARTIAL, or FAILED — gets logged.

Output Format

Output a structured summary, then immediately execute the next action. You ARE the orchestrator - outputting a directive and stopping is the bug that breadcrumbs exist to catch.

Template (adapt header and NEXT ACTION based on context):

## Validation: [PASSED|PASSED (warnings)|FAILED] - [Chunk N/total: title | (story-final)]

[Table from agent output]
[If warnings: list them as "Warnings (non-blocking, enforced on final chunk): ..."]
[If FAILED: "Routing: [Type] -> invoking [test-fix|refine-chunk]"]

>>> NEXT ACTION: [see below]

NEXT ACTION by scenario:

• Per-chunk PASSED (not final): Continue Step 4 loop - checkpoint, implementer for chunk [N+1], validate-chunk
• Per-chunk PASSED (final chunk): Proceed to Step 5: Story Completion - invoke story-final validation
• Story-final PASSED: Continue Step 5 - Self-Critique, Usage Summary, complete-story.sh
• FAILED: Invoke [test-fix|refine-chunk], then re-validate this chunk
• Escalation (REFINE_COUNT >= 4): No NEXT ACTION - stop, salvage, offer rollback

Remember

• FAILED means FAILED. No overrides. No dismissals.
• WARN means WARN. Non-blocking on non-final chunks. The agent promotes to FAIL on final chunk.
• Route, don't fix. Parse errors, invoke the right skill. Don't attempt fixes yourself.
• The fix loop is internal. After refine-chunk or test-fix returns, re-invoke the validator agent immediately within this skill. No turn boundaries, no breadcrumbs, no hand-back. The loop exits on PASS or REFINE_COUNT >= 4.
• REFINE_COUNT persists across the loop. It is initialized once at the start and incremented each iteration. It never resets within a chunk validation cycle.
• Always continue. After outputting the summary, execute the next action. Breadcrumbs protect the PASSED path (continue to next chunk), not the fix loop.