implement

name	implement
description	Autonomously plan and implement a task with external LLM review. Writes a behavioral spec, runs an evidence-gated plan review (premortem + independent alternative), applies feedback through a decision ledger, implements with a triggered debug loop, and finishes with an evidence-gated post-implementation verification review. No user interaction.
allowed-tools	Bash, Glob, Grep, Read, Edit, Write

End-to-end autonomous workflow: spec → plan → review → implement → verification review → summary. Reviewers must produce structured findings with concrete evidence; conflicts resolve through a written decision ledger, not silent agent judgment.

Load the consult-llm skill before proceeding - it defines the invocation contract. Do not call the CLI without loading it first.

Argument handling

Arguments: $ARGUMENTS

Reviewer flags: any --<selector> resolvable by consult-llm models selects a reviewer (e.g. --gemini, --openai). Repeat for multiple. Translate model flags and defaults according to the loaded consult-llm skill's model-selection rules.

Mode flags:

• --consult-first - gather independent reviewer proposals before writing the spec/plan, then synthesize into an Approach Decision Record. Use when scope is ambiguous, direction non-obvious, the change crosses module boundaries, or the repo is unfamiliar. Skip for typos, mechanical renames, exact bug fixes, or dependency bumps.
• --rounds N - repeat the review-refine cycle (Phases 3-4) up to N times. Default 1, max 3.
• --review full|standard|light|none - choose review depth. Default standard. full and standard run Phases 3, 4, and 6. light skips Phases 3 and 4 but keeps Phase 6. none skips Phases 3, 4, and 6.
• --no-review - alias for --review none. Compatible with --consult-first (proposal generation still runs; plan review and verification review do not).

Strip all flags from arguments to get the task description.

Phase 0: Snapshot state

Load consult-llm. Capture working-tree state for the Phase 6 diff base:

git rev-parse HEAD                    # store as START_HEAD
git status --short
git symbolic-ref --short HEAD

Halt conditions (do not auto-recover):

• Working tree shows changes outside expected files - user must clean or stash.
• No reviewer model resolves (unless --review none or --no-review is set and --consult-first is not).

Phase 1: Gather context

Use Glob, Grep, Read to research the task surface. Make reasonable assumptions; do not ask the user clarifying questions.

Before planning or consulting, do enough research to understand how the requested behavior actually works. Before starting, think about what resources would be useful to obtain first: relevant source files, tests, logs, generated files, config, examples, command output, external docs, or authoritative upstream source. Gather the cheapest useful evidence before forming a plan.

Do not stop at the first plausible file, definition, setting, or example. Follow references, callers, related tests, and runtime usage until you can explain the current behavior and the likely impact of changing it.

Before planning, ground the requested behavior in the real system, not just this repo. If the task depends on an external product, CLI, API, protocol, file format, or ecosystem convention, verify the relevant behavior using the cheapest authoritative evidence available: local binaries/flags, generated files, official docs, public source, package/library code, or web search. Capture only decision-relevant facts that affect scope, acceptance criteria, compatibility, or implementation constraints; do not create a separate research artifact unless the evidence materially changes the plan.

Capture:

• Files, modules, public interfaces, dependents, migration concerns.
• Existing patterns and conventions.
• External behavior facts that define requested semantics or constraints, with source/path/command evidence.
• Validation contract: how do tests/types/lints run? Look in CLAUDE.md, CLAUDE.local.md, justfile, Makefile, package.json, pyproject.toml. Record the canonical command (e.g. just check).

Select source files that let reviewers understand the behavior being changed and verify your assumptions. These are passed as shared -f <path> to every reviewer call.

Phase 2: Spec and plan

2A - Independent proposals (only if --consult-first)

Reviewers must see only the raw task and factual source context. Do not write inferred scope, assumptions, acceptance criteria, direction, or tasks before proposals are captured.

Save a context bundle to history/<YYYY-MM-DD>-context-<topic>.md. Include only:

• Raw task verbatim.
• Repo facts: branch, START_HEAD, validation command, test framework.
• Source inventory - files with factual reasons for inclusion only ("contains symbol X", "test file for Y"). No "likely needs change", no "probable approach".

Invoke consult-llm once with one -m <selector> per reviewer, -f <context bundle>, and -f <relevant source>. Capture [thread_id:group_xxx] from line 1 as CONSULT_THREAD_ID - it threads through 2A → 3 → 4 → 6. Synthesize the proposals directly into the ADR.

Prompt:

You are independently advising on how to implement the raw task using the attached source context.

You have NOT been given an agent-written spec, plan, architecture, or intended scope. Infer the most defensible scope and approach from the raw task and source evidence. Make assumptions explicit. Do not ask clarifying questions.

Output exactly these sections in this order:

## Scope Reading
- In scope:
- Out of scope:
- Assumptions:
- Ambiguities:
- Confidence: high | medium | low

## Recommended Approach
- Strategy (2-4 sentences):
- Files/modules likely touched:
- Implementation outline:
- Compatibility/migration impact:
- Complexity: low | medium | high

## Acceptance Criteria I Would Verify
Given/When/Then. Observable behavior only.

## Key Design Choices
For each: choice / rationale / tradeoff.

## Risks and Failure Modes
For each: risk / trigger / impact / mitigation_or_test.

## Alternative Worth Considering
- Strategy (materially different, not a minor variant):
- When it wins:
- Why not primary:

## Evidence To Check Before Planning

Ambiguity / groupthink handling:

• If two or more reviewers report Confidence: low and no proposal produces testable acceptance criteria, stop with an Ambiguity Blocker (record conflicting readings and required user decision in the ADR; do not implement).
• If proposals converge on one narrow strategy with no credible alternative on a high-risk or cross-module task, run one divergence-challenge consult on the same thread before synthesis.

Then write an Approach Decision Record at history/<YYYY-MM-DD>-adr-<topic>.md. Every proposal must be accepted, rejected, or watched-risk - no silent discard. Required sections:

• Scope Divergence Matrix - for each scope question: proposal readings / selected interpretation / rationale / risk.
• Proposal Summary - id / model / scope confidence / strategy / strengths / weaknesses / decision.
• Selected Approach - single coherent core architecture (data model, control flow, API boundary, ownership, persistence, concurrency must come from one proposal).
• Frankenstein Guard - if core choices mix across proposals, include an explicit compatibility proof. Otherwise the plan is invalid. Borrowing rejected proposals' tests, naming, validation, or error handling is fine.
• Rejected Alternatives - for each: reason / evidence / watched-risk?
• Watched Risks - risk / why accepted / what would change the call.
• Evidence Checks Required Before/During Implementation.

Scope-divergence rule: if divergence affects public API, data loss, security, or migration behavior and no reading is clearly supported, stop with an Ambiguity Blocker.

Tiebreakers: literal fit to raw task → safety/data integrity → acceptance criteria coverage → existing patterns → maintainability → testability → simplicity.

2B - Plan or implementation note

For --review standard and --review full, save history/<YYYY-MM-DD>-plan-<topic>.md. With --consult-first, link the context bundle and ADR at the top, and reflect the ADR in spec/criteria/tasks.

For --review light, do not write a review-grade plan artifact. Keep planning compact: write only history/<YYYY-MM-DD>-note-<topic>.md with the goal, assumptions, acceptance checks, validation command, and task checklist needed to implement safely. If the task comes from a larger workflow whose prompt already names a reviewed parent plan, cite that parent plan in the note instead of duplicating it. Use this note for implementation tracking and Phase 6 context.

For --review none or --no-review, write a compact note only if it is needed for implementation tracking, debugging, or the final summary.

# <Feature> Plan

**Goal:** <one sentence>
**Approach:** <2-3 sentences>
**Assumptions:** <list>
**Validation command:** `<e.g. just check>`

## Behavioral Spec

- **In scope:**
- **Out of scope:**
- **Acceptance criteria** (Given/When/Then):
- **Invariants** (must always hold):

## Test Matrix

| # | Scenario | Expected behavior | Test file/command | Required before implementation? |
| - | -------- | ----------------- | ----------------- | ------------------------------- |

## Rollback

Required only when the change touches schema, on-disk format, or a public API contract. Rollback steps / data compatibility / rollback window.

## Tasks

### Task 1 - <short description>
- **Files:** create/modify with exact paths (and line ranges for modify)
- **Steps:** specific actions
- **Code:**
  ```language
  // actual code, not placeholders
  ```
- **Verifies acceptance criteria:** #1, #3

Guidelines for standard and full: exact paths only, never "somewhere in src/". Each task small (2-5 minutes) and tied to acceptance criteria. DRY, YAGNI - only what the spec demands. Include the actual code to be written under Code: only when it clarifies a public interface, tricky algorithm, schema, migration, or non-obvious control flow. Otherwise include exact files, behavioral steps, and tests so reviewers can verify the intended behavior without reviewing speculative implementation code.

light note format:

# <Feature> Implementation Note

**Goal:** <one sentence>
**Reviewed parent plan:** <path, or n/a>
**Assumptions:** <short list>
**Acceptance checks:** <observable checks>
**Validation command:** `<e.g. just check>`

## Checklist
- <small implementation step>

Do not expand the light note into the full Behavioral Spec, Test Matrix, Rollback, and detailed task template unless the implementation discovers plan drift that needs durable tracking.

Phase 3: Plan review

Review runs for --review standard and --review full. Skip Phase 3 and Phase 4 for --review light, --review none, or --no-review. Do not skip plan review under standard or full because the task seems small, obvious, mechanical, or already validated locally. Reviewers receive the review-grade plan file and relevant source files; they must produce structured output.

Invoke consult-llm once with one -m <selector> per reviewer, -f <plan path>, -f <relevant source>. With --consult-first, continue from CONSULT_THREAD_ID via -t <id> and additionally attach -f <context bundle>, -f <ADR>. Use the same selector resolution for standard and full; full differs by intent and should be chosen when the caller wants no review shortcuts or reviewer count reductions from future policy changes.

Compose the prompt by including the ## ADR Check section if and only if --consult-first was used; otherwise include ## Independent Alternative. Send exactly one of these - do not include the bracket markers in the prompt sent to reviewers.

Capture the new [thread_id:group_xxx] for --rounds and Phase 6.

Review this implementation plan against the attached source context.

Output exactly these sections:

## Spec Check
List acceptance criteria that are missing, ambiguous, or untestable. Flag invariants the plan does not preserve. If sufficient, write "Spec sufficient."

## ADR Check (only when `--consult-first`)
- better_rejected_approach: <proposal id or "none">
- incompatible_merge_detected: yes | no
- selection_rationale_sufficient: yes | no
- required_change:

## Independent Alternative (only when not `--consult-first`)
In 3-5 sentences, the approach you would choose given the spec and source alone. Note any material divergence from the proposed plan.

## Premortem
Assume the plan ships and fails in production within six months. Top 3 failure modes. For each:
- failure_mode (concrete, with trigger):
- impact: low | medium | high
- probability: low | medium | high
- evidence (in plan or source):
- current_mitigation (quote plan or "none"):
- mitigation_sufficient: yes | no
- required_plan_change_or_test:

Only report failures with a concrete trigger and measurable impact.

## Plan Findings
For each issue:
- severity: must-fix | should-fix | optional
- issue_identity: <short kebab-case label>
- location_or_task: <plan section, task, or file:line>
- rationale:
- recommended_change:

Phase 4: Verify findings, update ledger

Skip this phase when Phase 3 was skipped.

Verify before adopting. Treat every reviewer finding (including must-fix) as an unverified claim. Reviewer severity is advisory. Deduplicate findings by issue identity before verification.

Verify all must-fix findings. Verify should-fix findings only when they affect correctness, compatibility, security, data integrity, or test adequacy. Record optional findings as notes unless they expose a concrete defect.

For each verified finding, record the title, claim, suggested fix, and file/line references when available. Then pick the cheapest method that proves or disproves the claim:

• Plan claims - re-read the cited plan section.
• Source claims - read the cited file against current code.
• Library/API claims - verify against library source or official docs. Use gh search code for usage patterns, Grep in node_modules/vendored deps, or a throwaway script in /tmp/.
• Premortem claims - confirm the trigger actually occurs in the planned design.

For each finding, report a verdict:

• CONFIRMED: The finding is accurate and is a real issue.
• NOT AN ISSUE: The finding is technically correct but does not matter in practice.
• INCORRECT: The finding is wrong; show disproof.
• UNABLE TO VERIFY: Cannot test this without external resources/setup.

Then assess the impact of the smallest plausible fix. Question the suggested fix, not just the finding.

• Likelihood: REGULAR | OCCASIONAL | RARE | COSMIC RAY | N/A
• Readability impact: IMPROVES | NEUTRAL | WORSENS | N/A
• Architecture impact: NONE | MINOR | MODERATE | MAJOR | N/A
• Recommendation: FIX | FIX (with care) | DISCUSS | SPIN-OFF | DROP

Recommendation rules:

• DROP: False/unverifiable, rare with no clarity gain, no practical impact, duplicate defense, or readability worsens without regular impact.
• DISCUSS: The real question is product behavior, policy, or user expectations rather than bug severity.
• SPIN-OFF: The issue is real and important but needs its own design or broader work.
• FIX (with care): Confirmed and impactful, but the fix has moderate or major structural reach.
• FIX: Confirmed and impactful with none or minor architecture cost.

Classify each finding for the ledger:

• FIX or FIX (with care) → accept if it is in scope for this implementation.
• DISCUSS or SPIN-OFF → record as Watched Risk unless it blocks the current spec.
• DROP → reject with evidence.

With --consult-first, findings claiming better_rejected_approach or incompatible_merge_detected: yes must be verified against the raw proposals and source before adoption.

Append a Feedback Ledger to the plan file:

## Feedback Ledger - Round N

- **finding-id:** <short kebab-case>
  - **reviewer(s):** <models>
  - **severity:** must-fix | should-fix | optional
  - **verdict:** confirmed | not-an-issue | incorrect | unable-to-verify
  - **likelihood:** regular | occasional | rare | cosmic-ray | n/a
  - **readability:** improves | neutral | worsens | n/a
  - **architecture:** none | minor | moderate | major | n/a
  - **recommendation:** fix | fix-with-care | discuss | spin-off | drop
  - **decision:** accepted | rejected | watched-risk
  - **rationale & evidence:** <proof from codebase/docs>
  - **plan/spec/test change:** <action or "none">

## Watched Risks
- **<label>:** why accepted; what would change the call.

## Premortem Mitigations Applied
- <failure mode> → <plan change>

Conflict tiebreakers (in order): security on safety conflicts → spec coverage → existing patterns → simplicity.

Any premortem finding rated mitigation_sufficient: no AND (probability: high OR impact: high) must be addressed before Phase 5 - change the plan, add a test-matrix row, or record explicitly in Watched Risks.

For every DISCUSS and SPIN-OFF recommendation, write 100-200 words in the ledger explaining the decision needed or the design work required.

Multiple rounds (--rounds N): for round 2+, reuse -m flags, pass -t <group_thread_id> and -f <updated plan>, and send: "Revision N. Were previous concerns addressed? New issues introduced? Same four sections, focus on what changed." Stop early if reviewers signal no further changes. Append a fresh ledger section per round.

Phase 5: Implement

Implement tasks in order. The validation command must pass at the end.

1. Spec-first per task - write or extend the test that proves the linked acceptance criterion before implementation. Confirm it fails. Write the code. Confirm it passes.
2. Plan drift halts. If implementation requires touching files outside the plan or note, or deviating from the agreed approach, stop. Update the plan or note with the deviation and a one-line reason, then continue.
3. Validation - run the validation command after every logical unit and again at the end. A task is done when (a) its tests pass, (b) its acceptance criteria are verified, and (c) validation is green for the touched scope.
4. Auto-commit at end - when all tasks are done and validation is green, create a single commit for all implementation changes. Lowercase imperative subject; body explaining the why per CLAUDE.md. Phase 6 fixes go in separate commits (see below).

Triggered debug protocol

Activate only when the same check fails twice, OR a fix would require changing the plan/spec, OR the failure cause is unclear. Do not formalize debugging for ordinary fixes.

For each blocked attempt, append to a scratch section at the bottom of the plan or note file (do not commit):

- failing command:
- exact error:
- recent relevant changes:
- hypothesis:
- evidence-gathering command (read-only):
- result:
- conclusion:
- fix or plan revision:

Cap: 3 hypotheses. If two have failed, consult reviewers with --task debug, the same selectors, and the latest [thread_id:group_xxx]:

We are blocked during Phase 5 implementation.

Task: <ref>
Failing command and full output:
<output>

Hypotheses already tried (and why they failed):
<list>

Relevant recent changes:
<diff or summary>

Give ranked hypotheses with concrete evidence checks. For each hypothesis, state the observation that would confirm or falsify it. Do not propose code changes until the falsification step is identified.

If the third hypothesis fails, stop. Record blocker, hypotheses, and unanswered evidence question in the Phase 7 summary. Do not loop.

Phase 6: Verification review

Verification review runs for --review standard, --review full, and --review light. Skip Phase 6 only for --review none or --no-review. Do not skip verification because the task seems small, because tests passed, or because the implementation appears low-risk. The only non-flag exception is a strictly mechanical diff: renames, version bumps, comment/string typo fixes, or formatting/whitespace only. If any executable behavior, tests, public contract, generated output, or control flow changed, run Phase 6. When using the mechanical exception, state the exact reason in the Phase 7 summary.

Re-list changed files against START_HEAD:

git diff --name-only --diff-filter=d <START_HEAD>
git ls-files --others --exclude-standard

If both empty, stop and report nothing implemented. Otherwise pass tracked files as --diff-files <path> and untracked as -f <path>. Skip binaries and lockfiles.

Invoke consult-llm with --task review, --diff-base <START_HEAD>, the file flags above, and -f <plan-or-note path>. In light mode, pass the compact note plus any reviewed parent plan named by the invoking prompt. By default, do not reuse the Phase 3/4 thread for verification review; the useful evidence is the spec or note, feedback ledger when present, and real diff. Continue the earlier thread only for --review full or when verifying whether specific prior concerns were addressed.

Verify this diff against the Behavioral Spec and Test Matrix in the plan file, or against the compact implementation note when running in `light` mode. You are a verifier, not an attacker - the goal is to confirm the implementation is correct, complete, and consistent with the recorded intent and the surrounding system. Do not manufacture threat models for code that has no relevant surface.

Apply these lenses in order. For each lens, either report findings or state it does not apply and why:

1. **Spec conformance** - every acceptance criterion satisfied; invariants preserved on every path; no silent deviation from the plan.
2. **Regression & compatibility** - existing callers, public APIs, output formats, ordering, error types, and performance characteristics unchanged unless the plan says so.
3. **Edge cases & invariants** - boundary inputs, empty/null/missing, large inputs, error paths, resource lifecycle, concurrent access where the code is actually concurrent.
4. **Test adequacy** - tests assert the important observable behavior, not just that code runs; acceptance criteria from the plan are covered.
5. **Implementation quality** - unnecessary complexity, dead code, duplicated logic, brittle coupling, naming/patterns inconsistent with the surrounding code, simpler alternatives.
6. **Security** (apply ONLY when the changed surface touches authn/authz, secrets, untrusted external input, parsing/serialization of untrusted data, file/path access, network boundaries, tenant isolation, crypto, dependency loading, or shared mutable state across trust boundaries) - auth bypass, injection, unsafe parsing, data exposure, race conditions with security impact.

A finding may be marked **Verified** only if it includes concrete evidence: a failing input, a failing or insufficient test, a diff/source citation showing a contract mismatch, or a minimal reproduction. Speculation goes under "Unverified Hypotheses" and may not be marked must-fix.

If no material issues are found across any applicable lens, say so explicitly under "No Issues Found" and still report which lenses you considered. A clean review is a valid result.

Output exactly:

## Lenses Considered
- applied: <list>
- skipped (with reason): <list>

## Verified Findings

### Finding N
- severity: must-fix | should-fix
- category: spec-drift | regression | edge-case | test-gap | compatibility | maintainability | security
- location: path:line
- spec_or_invariant_violated: <reference, or "none">
- evidence: <failing test, input, command output, or source/diff citation that demonstrates the issue>
- expected_behavior:
- actual_behavior:
- rationale:
- recommended_change:

## Unverified Hypotheses
- <bullet, or "none">

## Test Coverage Gaps
- <criterion or invariant the diff does not exercise, or "none">

## Maintainability Notes
- <non-blocking simplification or structural concern, or "none">

## No Issues Found
- <only if all sections above are empty: state this explicitly>

Verify each finding before fixing

The evidence is a claim - run or read it. For each finding, record the title, claim, suggested fix, and file/line references when available. Then report:

• Verdict: CONFIRMED | NOT AN ISSUE | INCORRECT | UNABLE TO VERIFY
• Likelihood: REGULAR | OCCASIONAL | RARE | COSMIC RAY | N/A
• Readability impact: IMPROVES | NEUTRAL | WORSENS | N/A
• Architecture impact: NONE | MINOR | MODERATE | MAJOR | N/A
• Recommendation: FIX | FIX (with care) | DISCUSS | SPIN-OFF | DROP

Recommendation rules are the same as Phase 4:

• DROP: False/unverifiable, rare with no clarity gain, no practical impact, duplicate defense, or readability worsens without regular impact.
• DISCUSS: The real question is product behavior, policy, or user expectations rather than bug severity.
• SPIN-OFF: The issue is real and important but needs its own design or broader work.
• FIX (with care): Confirmed and impactful, but the fix has moderate or major structural reach.
• FIX: Confirmed and impactful with none or minor architecture cost.

Apply these outcomes:

• Evidence reproduces, diff is responsible, recommendation is FIX → eligible to fix.
• Evidence reproduces, diff is responsible, recommendation is FIX (with care) → hand off unless the fix is localized and has one clear answer.
• Evidence reproduces, different code is responsible → re-target or note misattribution; do not silently fix the wrong place.
• Evidence does not reproduce or source citation is wrong → DROP. List under "rejected after verification" in the summary.
• Reproduces only via inputs no caller produces, impossible timing, DISCUSS, or SPIN-OFF → record as Watched Risk; do not fix.

Apply fixes

Apply only Verified Findings that survived verification, are must-fix, have recommendation FIX, and are localized (single hunk, single right answer, no interface changes). For each fix:

1. Re-read the file and apply the smallest correct change.
2. Run the validation command for the touched scope.
3. Commit each logical fix separately, one by one. Use a lowercase imperative subject and a body that names the failure mode prevented.

Do not auto-fix should-fix, Unverified Hypotheses, Test Coverage Gaps, or Maintainability Notes. List them in the Phase 7 summary.

If any must-fix cannot be fixed safely, stop and hand off - do not loop another review pass.

Phase 7: Summary

Print:

## Summary

**Implemented:** <one sentence>
**Consult-first:** yes | no
**Context bundle:** history/<date>-context-<topic>.md | n/a
**ADR:** history/<date>-adr-<topic>.md | n/a
**Plan or note:** history/<date>-plan-<topic>.md | history/<date>-note-<topic>.md | n/a
**Diff base:** <START_HEAD short sha>
**Review phases run:** Phase 3 [yes | skipped] · Phase 6 [yes | skipped]

**Plan review (Round N):**
- accepted: <count> (must-fix: X, should-fix: Y)
- rejected: <count>
- watched risks: <count>

**Implementation:**
- tasks completed: X / Y
- validation: passed | failed (<command>)
- plan deviations: <list, or "none">

**Verification review:**
- verified findings auto-fixed: <count>
- verified findings handed off: <list>
- rejected after verification: <count>
- unverified hypotheses: <count>
- test coverage gaps: <list, or "none">
- maintainability notes: <list, or "none">

**Blockers (if any):**
- <description, hypotheses tried, evidence question outstanding>

**Commits:**
- <sha> - <subject>