1. CHECKPOINT
   - Run: git add -A && git commit -m "checkpoint before run" && git push
   - Store the commit hash (git rev-parse HEAD)
   - This commits everything including _step2_plan.md — the safety net

2. LOAD
   - Read _step2_plan.md, verify marker <!-- @plan: /step2 ... -->
   - Parse phases overview table (deps, groups, titles)

3. EXECUTE LOOP
   While phases remain:
   a. Find ready phases (deps satisfied, not done)
   b. Batch by parallel group:
      - All ready in same group → ONE message with MULTIPLE Task calls (parallel)
      - NEVER mix different groups in parallel
   c. Dispatch subagent(s) — one Task call per phase
   d. On ANY failure: STOP, jump to FAILURE
   e. Log: "✓ Phase N: [title]"

4. ON SUCCESS
   - Delete _step2_plan.md
   - Run: git add -A && git commit -m "run complete: [Goal field from _step2_plan.md]" && git push
   - Store the final commit hash
   - Report: "Run complete. N/N phases succeeded. Committed & pushed: <short-hash>"

5. ON FAILURE — see Failure Protocol below

╔══════════════════════════════════════════════════════════════════╗
║  PLAN FAILED — RESET TO CHECKPOINT RECOMMENDED                 ║
║                                                                 ║
║  Checkpoint: <hash> (committed at start of this session)        ║
║                                                                 ║
║  To recover:                                                    ║
║    git reset --hard <hash>                                      ║
║    git push --force                                             ║
║                                                                 ║
║  This discards ALL changes from this run and restores           ║
║  the codebase with _step2_plan.md intact for a clean re-run.    ║
╠══════════════════════════════════════════════════════════════════╣
║  Failed: Phase N — [error summary]                              ║
║  Completed before failure: Phases X, Y, Z                       ║
║  Not started: Phases A, B, C                                    ║
╚══════════════════════════════════════════════════════════════════╝

# Context
Goal: [1-2 sentences from _step2_plan.md Goal field]
Rationale: [from _step2_plan.md Rationale section]
Working directory: [absolute path]

# Your Assignment: Phase N
[EXACT phase section copied from _step2_plan.md]

# Instructions
1. Read the Reference files FIRST — understand patterns before writing code
2. Execute all tasks in order
3. RESPECT Guardrails — these are hard constraints, not suggestions
4. Stay within Modifies scope — do not touch files outside it
5. On failure: stop immediately, return error details
6. Return 1-2 sentence summary of what was done

# Context
Goal: [1-2 sentences from _step2_plan.md Goal field]
Working directory: [absolute path]
Follow patterns in CLAUDE.md and Reference files.

# Dependencies
[Verbatim dependency notes from _step2_plan.md, e.g.:]
- Depends: 2 (creates lib/core.py)

# Your Assignment: Phase N
[EXACT phase section copied from _step2_plan.md]

# Instructions
1. Read the Reference files FIRST — understand patterns before writing code
2. Execute all tasks in order
3. RESPECT Guardrails — these are hard constraints, not suggestions
4. Stay within Modifies scope — do not touch files outside it
5. On failure: stop immediately, return error details
6. Return 1-2 sentence summary of what was done

/step3

Checkpoint created: abc1234
Loading _step2_plan.md... N phases, M parallel groups

Group A:
  ✓ Phase 1: [title]

Group B (parallel):
  ✓ Phase 2: [title]
  ✓ Phase 3: [title]
Group C:
  ✓ Phase 4: [title]

Run complete. N/N phases succeeded. Committed & pushed: abc1235