Compound-Engineering Loop Protocol

MODE: LOOP runs an objective end to end as a series of gated phases, then loops to compound improvements until the objective is met or a stop condition fires. Each cycle reuses the existing mode skills (brainstorm, plan, critic-gate, execute, phase-wrap) and ends with a learning-capture step so the next cycle is cheaper — that is what makes the loop compounding rather than merely repeating.

This is a real implementation workflow: it delegates to the coder, declares scope, and mutates source code through the normal EXECUTE path. It is distinct from full-auto (a critic gate via the critic_oversight agent that intercepts phase completions and high-risk actions for review — full-auto never plans, delegates, or executes; the architect retains ALL delegation duty) and turbo (parallel lanes within a single phase). LOOP is a user-initiated, gated, sequential, compounding workflow.

The two design rules that everything below serves:

1. Separate the generator from the verifier. The context that writes a change must never be the only context that approves it. Implementation, independent review, and critic challenge live in separate delegated contexts. Review is report-only; a distinct fix step applies changes.
2. Stop on positive evidence or a budget — never on vibes. Every phase has an entry gate and an exit gate backed by concrete evidence, and the loop has layered stop conditions so it can never run away.

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Step 0 — Parse Header

Parse the [MODE: LOOP ...] header to extract:

• objective: the goal text after the header (the WHAT to achieve). Empty only when resume=true.
• max_cycles: integer 1..5 (default 3) — hard cap on outer improvement cycles.
• autonomy: auto (default) or checkpoint.
  • auto: proceed across gates without prompting, but still enforce every hard stop condition and the mandatory review/critic gates.
  • checkpoint: pause at each phase gate and wait for explicit user approval before continuing.
• depth: standard (default) or exhaustive (wider exploration in BRAINSTORM and PLAN: more candidate approaches, deeper localization).
• resume: true | false. When true, resume the existing run from durable state instead of starting a new objective.

If the header is malformed or required fields are missing, report the error and stop.

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Step 1 — Preconditions & Durable State

1. Working tree. Check git status. If the tree is dirty, surface the uncommitted changes and ask whether to proceed (checkpoint) or proceed only if the changes are clearly part of this objective (auto). Do not silently build on an unknown working state.
2. Run state directory. Loop state lives under .swarm/loop/<run-id>/ (containment invariant — never write loop state outside .swarm/).
   • New run (resume=false): allocate a run-id (short slug + timestamp), create .swarm/loop/<run-id>/state.json, and record the baseline: objective, parsed parameters, start HEAD commit, cycle: 0, phase: brainstorm, empty improvements and learnings lists.
   • Resume (resume=true): locate the most recent .swarm/loop/<run-id>/ with an unfinished state, read it, validate required fields (run_id, cycle, phase, done must all be present and have the correct types; if any are missing or malformed, report the corruption clearly and stop rather than continuing with undefined values), print a short progress summary (cycle N of max_cycles, current phase, last gate result), and continue from the recorded phase. If no resumable run exists, say so and stop.
   • Retention: On both new-run and resume entry, prune completed runs (.done === true) that exceed 10 in count — keep the 10 most recent by timestamp, remove the rest. This prevents unbounded state accumulation under .swarm/loop/.
3. State is derived, not authoritative for code. The durable state file tracks loop control (cycle counter, phase, gate outcomes, captured learnings, stop reason). Actual implementation progress is derived from git and the plan ledger (.swarm/plan-ledger.jsonl), never from conversation memory — so a killed/resumed session never loses or re-does work.

Write the state file after every gate transition. The on-disk state is the single source of truth for resumability.

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Step 2 — The Cycle

One cycle is five phases run in order: BRAINSTORM → PLAN → BUILD → REVIEW → IMPROVE. Do not skip or collapse phases. Each phase has an entry gate (precondition) and an exit gate (positive evidence required before the next phase begins). In checkpoint autonomy, pause at each gate for user approval.

When autonomy=auto, use the balanced-speed defaults instead of asking the user for execution preferences: reviewer ON, test_engineer ON, sme_enabled ON, critic_pre_plan ON, sast_enabled ON, drift_check ON, and council_mode, hallucination_guard, mutation_test, phase_council, final_council OFF. Keep commit frequency at phase-level only. During PLAN, choose the largest safe parallel coder count from dependency-ready, file-disjoint task groups, clamped to the configured limit (currently 6); if scopes overlap or are unknown, use 1. This does not weaken QA; it removes only the preference prompt.

On cycle 2+, BRAINSTORM is replaced by a lightweight refinement step: feed the prior cycle's captured improvements and residual findings into PLAN directly (skip full discovery dialogue) — the objective is already framed.

Phase 1 — BRAINSTORM (cycle 1 only)

• Entry gate: objective is non-empty; no approved plan already covers it.
• Action: Load file:.swarm/bundled-skills/brainstorm/SKILL.md and run it to produce .swarm/spec.md and a QA gate profile. With depth=exhaustive, require at least one non-obvious candidate approach.
• Exit gate: spec.md exists with explicit, testable success criteria and scope boundaries. Record the success criteria into loop state — they are the objective-met test used by the stop conditions. Checkpoint: confirm the spec with the user.

Phase 2 — PLAN

• Entry gate: a spec (or, on cycle 2+, the improvement directives) exists.
• Action:
  1. Load file:.swarm/bundled-skills/pre-phase-briefing/SKILL.md (required before planning, especially on cycle 2+: it reads the prior retrospective and verifies codebase reality so the new plan reflects what actually changed).
  2. Load file:.swarm/bundled-skills/swarm-plan/SKILL.md to decompose the work into tasks and call save_plan. With depth=exhaustive, prefer finer task granularity and deeper localization.
  3. Load file:.swarm/bundled-skills/critic-gate/SKILL.md to put the plan through an independent critic.
• Exit gate: critic verdict is APPROVED (NEEDS_REVISION → revise and re-submit, max 2 cycles per the critic-gate skill; REJECTED → stop and report to the user). Record the verdict in loop state.

Phase 3 — BUILD

• Entry gate: a critic-approved plan exists.
• Action: Load file:.swarm/bundled-skills/execute/SKILL.md and run the plan phase by phase. The coder implements each task; per-task QA gates (tests, lint, security, etc.) run as defined by the selected QA profile. The coder context is the generator — it does not get to declare its own work correct.
• Exit gate: all planned tasks for the cycle are implemented and their per-task QA gates pass with recorded evidence. NEVER weaken, mock, skip, or delete a failing test/assertion to make a gate pass — fix the root cause or stop and report.

Phase 4 — REVIEW (report-only) + FIX

This phase is the heart of the generator/verifier separation. It runs on the actual current diff, in contexts independent of the coder.

• Entry gate: BUILD exit gate passed; capture the current diff (git diff against the cycle's start commit).
• Action:
  1. Independent reviewer. Delegate the real diff and the QA evidence to a fresh reviewer context. It defaults to disbelief, looks for correctness bugs, regressions, security issues, missing edge cases, and claimed-vs-actual mismatches, and classifies each finding. The reviewer does not edit code — it reports.
  2. Critic challenge. Delegate the reviewer-approved diff and any HIGH/CRITICAL findings to a separate critic context that challenges weak evidence, overclaimed severity, and missing sibling-file checks. The critic may overturn the reviewer.
  3. Fix step. For every NEEDS_REVISION / REJECTED / BLOCKED item, return to the coder (generator) to fix it with code, tests, or evidence, then re-run the affected reviewer/critic gate. Any edit after approval invalidates that approval — re-review.
• Exit gate: reviewer approval AND critic approval on the latest diff, with the latest edit older than both approvals. Record the reviewer/critic verdicts durably alongside the phase evidence (the phase-wrap evidence manager writes retrospective and gate artifacts under .swarm/evidence/ — keep the review/critic outcomes with that phase's evidence so phase_complete and any later audit can read them). This satisfies the mandatory implementation closeout gate.

Phase 5 — IMPROVE (phase-wrap + compounding capture)

This is what makes the loop compound. Do not declare completion without it.

• Entry gate: REVIEW exit gate passed.
• Action:
  1. Load file:.swarm/bundled-skills/phase-wrap/SKILL.md and write the mandatory retrospective (the phase_complete gate blocks without a valid retro-N bundle). Rescan the codebase and update documentation exactly as the phase-wrap skill directs — that is, scoped to its authorized set (README.md / CONTRIBUTING.md / docs/ via the docs agent). Do NOT edit the governance contract files (AGENTS.md / CLAUDE.md); they constrain the loop and are out of scope for autonomous edits.
  2. Capture learnings durably. Distill what this cycle taught — recurring bug classes, surprising couplings, tooling gotchas, convention decisions — into the knowledge base (the knowledge_add tool / the memory tools when enabled) and/or a categorized note under .swarm/loop/<run-id>/learnings/.
  3. Make learnings discoverable. Ensure the next loop will actually read them: persist via knowledge_add (which knowledge_recall surfaces in later phases) rather than a write-only note nobody reads — capturing learnings nothing retrieves does not compound.
  4. Feed findings forward. Record any review/critic finding that recurred so it becomes an explicit check in the next cycle's reviewer prompt.
• Exit gate: retrospective written and accepted by phase_complete; learnings persisted; the cycle's improvements and residual findings recorded in loop state.

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Step 3 — Loop Decision (Stop Conditions)

After IMPROVE, evaluate the stop conditions in order. Use defense in depth: several overlapping conditions, not one. Record the chosen stop_reason in loop state.

1. Objective met (primary). The success criteria captured in Phase 1 are all satisfied AND the full validation suite / required QA gates are green. → STOP (success).
2. Cycle budget exhausted. cycle >= max_cycles. → STOP. Never exceed max_cycles.
3. No-progress / plateau. The just-finished cycle produced no qualifying improvement toward the objective (no new passing criteria, no accepted review fix that advanced the goal). → STOP and report the plateau; looping again would burn budget without progress.
4. Oscillation. The cycle reintroduced or reverted a change made in a prior cycle (the diff fingerprint repeats). → STOP and report; the loop is thrashing.
5. Unrecoverable error. A gate cannot pass for a reason outside this objective's scope (e.g., REJECTED plan, environment failure, a required external dependency is unavailable). → STOP and report.
6. Explicit user stop. The user asked to stop. → STOP immediately.

If none fire and budget remains: increment cycle, set the next cycle's input to the recorded improvement directives + residual findings, and return to Phase 2 (PLAN) (cycle 2+ skips full BRAINSTORM). In checkpoint autonomy, confirm "continue for another cycle?" with the user before looping.

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Step 4 — Completion

When a stop condition fires:

1. Mark loop state done with the stop_reason and final HEAD commit.

2. Present a human-readable summary:

   • Objective and whether it was met.
   • Baseline → final state (what changed, key files/tasks).
   • Cycles run (and why it stopped).
   • Tasks completed vs deferred; residual review findings and where they are recorded.
   • Learnings captured this run and where they live.
   • Suggested next steps (e.g., open a PR via /swarm pr-review or the commit-pr flow — do NOT open a PR unless the user asks).

3. Emit a completion marker on its own line to summarize terminal state for human readers:

   <loop-complete reason="objective-met|budget-exhausted|plateau|oscillation|unrecoverable-error|user-stop" cycles="N"/>

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Durable State Schema (.swarm/loop/<run-id>/state.json)

A minimal, append-friendly shape — extend as needed but keep these fields:

{
  "run_id": "rate-limit-20260618T0712Z",
  "objective": "add rate limiting to the public API",
  "params": { "max_cycles": 3, "autonomy": "checkpoint", "depth": "standard" },
  "start_commit": "<sha>",
  "cycle": 1,
  "phase": "review",
  "success_criteria": ["...", "..."],
  "gates": [
    { "cycle": 1, "phase": "plan", "result": "approved", "at": "<iso>" }
  ],
  "improvements": [],
  "learnings": [],
  "done": false,
  "stop_reason": null,
  "final_commit": null
}

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Autonomy Quick Reference

Behavior	auto (default)	checkpoint
Pause at phase gates	No	Yes — wait for user approval
Confirm before next cycle	No	Yes
Mandatory review + critic gates	Enforced	Enforced
Hard stop conditions (budget, plateau, oscillation, errors)	Enforced	Enforced
Weaken/mock/skip a failing test	Never	Never

auto reduces prompts; it never reduces verification.

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Anti-Patterns (do not do these)

• Letting the coder context approve its own diff. Review and critic must be independent contexts.
• Treating passing tests, explorer output, or self-review as the implementation closeout gate. They are not.
• Editing code after reviewer/critic approval and then declaring done without re-review. Any post-approval edit invalidates the approval.
• Looping "one more time" past max_cycles or after a plateau because it feels close. Stop and report.
• Skipping the IMPROVE/compound capture step to finish faster. The compounding step is the point of the loop.
• Storing loop progress only in conversation context. Persist to .swarm/loop/<run-id>/ so the loop survives interruption.
• Weakening, mocking, skipping, or deleting a failing assertion to turn a gate green. Fix the root cause or stop.