agent-plan-act-reflect

Single-agent iterative self-correction loop. Composes existing
building blocks (task-splitter / shared-memory / acceptance-gate)
into one closed cycle.

This is the agent equivalent of test-driven development: write
spec, build, test, fail, revise, build again, until pass. Where
agent-debate is "2 agents disagree", PAR is "1 agent revises".

When to use

Good for:

• A single agent owns the task end-to-end, but the first attempt
  rarely lands clean (refactors, papers, optimizations, anything
  with > 3 quality dimensions to balance)
• The success criterion is automatically checkable (tests, eval, linter)
• Budget allows 2-5 iterations
• You want a paper trail of what was tried + why it failed

Not for:

• Single-shot tasks (overkill)
• Tasks where two agents should argue opposing designs (use agent-debate)
• Multi-agent coordination (use agent-task-splitter)
• Pure exploration / ideation (no test criterion to drive iteration)
• Tasks where a human is the final adjudicator (PAR can't replace human review for high-stakes decisions; run PAR, then present result to human)

Inputs

User must provide:

1. Goal — single sentence, with concrete acceptance criterion
   • Good: "Stage 6 §RAG section reads at < 10 grade-level + passes anchor strict"
   • Bad: "Make Stage 6 better"
2. Max iterations — default 3. After this many cycles without
   convergence, surface to user.
3. Critique source — what gives the "fail signal" each iteration:
   • Test results (preferred — most objective)
   • Subagent review (next-most objective)
   • Eval framework score (ragas / promptfoo / etc.)
   • Self-critique by the same agent (least reliable, only as fallback)
4. Optional: which delegate (Claude inline / Codex / Gemini). Default Claude inline.

Workflow

write plan ──► .coord/par_<topic>.yml
    │
    ▼
┌──────────────────────────────────────┐
│  Iteration loop (cap = max_iterations): │
│                                      │
│  Act    ─► delegate executes        │
│             writes result.md         │
│                                      │
│  Reflect ─► run critique source     │
│             (test / subagent /      │
│              eval / self)            │
│                                      │
│  Pass?   ─► YES → exit loop with PASS │
│            NO  → continue if N <    │
│                  max_iterations      │
│                                      │
│  N = max?─► YES → exit loop with    │
│                   `EXHAUSTED` —     │
│                   surface to user   │
│            NO  → continue           │
│                                      │
│  Revise  ─► update .coord/par_      │
│             <topic>.yml with        │
│             learned-from-failure    │
└──────────────────────────────────────┘
    │
    ▼
write final summary → .coord/par_<topic>_final.md
+ promote learned principles → .coord/memory.yml

Exit conditions (be explicit, prevents runaway loops):

• Verdict PASS at any iteration → exit immediately with status PASS
• N reaches max_iterations without PASS → exit with status EXHAUSTED, surface to user with summary of all failed attempts
• Any iteration fails with status error (test infrastructure crash, delegate timeout, etc.) → exit with status ERROR, do NOT continue

The loop NEVER continues past max_iterations. The anti-pattern says
"don't go past 5"; the workflow enforces this by failing closed.

Outputs

• .coord/par_<topic>.yml — running state (plan + iteration history)
• .coord/par_<topic>_final.md — final summary + lessons (≤ 500 words)
• Promoted principles → .coord/memory.yml (via agent-shared-memory)

par_.yml schema

goal: "Stage 6 §RAG passes plain-language test"
acceptance_criterion: "subagent code-reviewer scores >= 8/10 on clarity"
max_iterations: 3
critique_source: subagent
delegate: claude-inline

iterations:
  - n: 1
    plan_summary: "Drop encyclopedic table; replace with prose + 3 concrete examples"
    artifact: ".coord/par_rag_iter1.md"
    critique:
      score: 6
      issues:
        - "Examples still too abstract (no specific Yelp/database)"
        - "DSPy reference confuses scope"
      verdict: FAIL
    revise: "Add concrete Yelp example; drop DSPy until next iteration"

  - n: 2
    plan_summary: "Apply iter-1 revisions"
    artifact: ".coord/par_rag_iter2.md"
    critique:
      score: 8
      issues:
        - "Heading hierarchy still inconsistent"
      verdict: CONDITIONAL PASS
    revise: "Fix heading levels; minor polish"

  - n: 3
    plan_summary: "Final polish"
    artifact: ".coord/par_rag_iter3.md"
    critique:
      score: 9
      issues: []
      verdict: PASS

final_status: PASS
total_cost_usd: 0.45
elapsed_minutes: 22

Anti-patterns

• Don't loop more than 5 times. If after 5 the agent hasn't
  converged, the goal is probably mis-specified or the critique
  source is inconsistent. Surface to user, don't keep burning $.
• Don't use self-critique as the only critique source. The agent
  that wrote the code will mostly approve its own code. Bias is
  real and well-documented. Use external test / subagent / eval.
• Don't promote raw iteration content to memory. Only PROMOTE
  the learned principle (e.g., "DSPy belongs in §進階 RAG, not in
  intro") to .coord/memory.yml. Iteration artifacts stay in
  .coord/par_*.md and get archived after 14 days like other
  .ai/ files.
• Don't run PAR for trivial tasks. Single-shot is fine for
  typo fixes, sweep rules, single-file edits. PAR is for tasks
  where 1 iteration is reliably insufficient.

Subagent review (keep main session lean)

When: PAR loop enters iteration 3+, OR .coord/par_*.yml exceeds 8 KB.

Why: Main session that wrote the original plan + observed
iteration 1+2 results doesn't need to re-read all artifacts in
later iterations. A subagent can read the par_*.yml + recent
iteration artifact + return a structured "should we iterate again
or stop?" verdict.

Pattern:

Spawn `code-reviewer` subagent:
  - Read .coord/par_<topic>.yml in full
  - Read latest iteration artifact (.coord/par_<topic>_iterN.md)
  - Apply critique source (test results / preset / etc.)
  - Return: { verdict: PASS/CONDITIONAL/FAIL,
              top 3 issues: [...],
              recommend: continue/stop/escalate,
              estimated_iterations_remaining: N }

Main session reads only the verdict.

Commit Boundary

Every agent boundary is a commit boundary (see global rule:
~/.claude/CLAUDE.md → "Commit Discipline for Multi-Agent Work").

Specific to this skill: each iteration is its own commit with
message par(iter-N): <plan_summary>. The final PASS iteration
commit can be followed by a par(final): merge to main commit
that includes the principle promotion to .coord/memory.yml.

This makes the PAR loop a commit-by-commit replay: a future
maintainer can git log --grep "par(iter" to see the full
self-correction history.

Composes with

• agent-task-splitter — write the initial plan
• agent-shared-memory — promote learned principles after PAR converges
• agent-acceptance-gate — can be the critique source for an iteration
• agent-debate — different tool (multi-agent disagreement). Use PAR
  for single-agent self-correction; use debate for adjudicating between
  two equally-valid options.

Output to user (final message format)

[agent-plan-act-reflect]
  Goal: <one-line goal>
  Status: PASS after N iterations
  Final artifact: <path>
  Cost: ~$X.XX total
  Promoted to memory: <list of principles, if any>

  Iteration summary:
    iter 1: FAIL (score 6/10) → revised plan
    iter 2: CONDITIONAL (score 8/10) → minor polish
    iter 3: PASS (score 9/10)

  Time: ~N min wall-clock