Codex Code Review

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Trigger

• Keywords: review, PR, code review, second opinion, audit, check

When NOT to Use

• Document review (use doc-review)
• Security-specific review (use security-review)
• Test coverage review (use test-review)
• Just want to understand code (use code-explore)

Variants

Variant	Command	Scope	Pre-checks
Fast	/codex-review-fast	Diff only	None
Full	/codex-review	Diff + local checks	lint:fix + build
Branch	/codex-review-branch	Full branch	None

Shared Workflow

Step 0 (PENDING) → Collect changes → [Pre-checks if Full] → Dual Review (Codex + Task) → Await Results → Aggregate → Emit Gate → Loop if Blocked

Step 0: Dual Review Init (Fail-closed)

Execute: bash scripts/emit-review-gate.sh PENDING

This sets review_mode=dual and aggregate_gate.executed=false in state file, ensuring fail-closed semantics — if the process crashes before Step 4.5, stop-guard blocks.

Step 1: Collect Change Metadata

Collect metadata only — Codex reads the actual diffs and file contents itself via sandbox access.

Variant	Collection Method
Fast	CHANGED_FILES: git diff --name-only HEAD + DIFF_STAT: git diff --stat HEAD
Full	Same as Fast
Branch	Same + CURRENT_BRANCH + BASE_BRANCH + COMMIT_COUNT

Codex independently reads full diffs and file contents via git diff HEAD -- <file> + cat (per research instructions).

Step 2: Pre-checks (Full variant only)

{LINT_FIX_COMMAND}
{BUILD_COMMAND}

These placeholders are resolved from the host project's CLAUDE.md or package.json scripts. Record results as LOCAL_CHECKS.

Step 3: Dual Review (Parallel Dispatch)

Case A: First review (no --continue)

Launch two reviewers in parallel (single message, multiple tool calls):

1. Codex MCP (primary): Use mcp__codex__codex with variant-specific prompt:

   Variant	Prompt Template
   Fast	references/codex-prompt-fast.md
   Full	references/codex-prompt-full.md
   Branch	references/codex-prompt-branch.md

   Config: sandbox: 'read-only', approval-policy: 'never'

   Save the returned threadId.

2. Secondary reviewer: Use Task tool with reviewer selection cascade:

   Priority	Reviewer	subagent_type	Condition
   1	pr-review-toolkit:code-reviewer	pr-review-toolkit:code-reviewer	Default choice
   2	strict-reviewer	strict-reviewer	Priority 1 fails/times out
   3	Codex-only (degraded)	—	Both unavailable

   Selection: Try priority 1 first. If Task fails or times out (30s), try priority 2. If both unavailable, fall back to Codex-only (degraded mode — proceed with Codex results only, apply degradation matrix from references/review-common.md).

   Task prompt (provide changed file list + diff stats, request P0/P1/P2/Nit findings in standard output format):

   Review the code changes for correctness, security, performance, and maintainability issues.
   
   ## Changed Files
   <git diff --name-only output>
   
   ## Diff Stats
   <git diff --stat output>
   
   Read the actual diffs and file contents yourself to perform the review.
   
   Output findings in this format:
   - [P0/P1/P2/Nit] file:line issue description → fix recommendation
   
   Group by severity. Include a final gate: ✅ Ready (no P0/P1) or ⛔ Blocked (has P0/P1).
   

Case B: Loop review (has --continue)

• Codex: Use mcp__codex__codex-reply with re-review template from references/review-common.md
• Secondary: Re-dispatch in parallel (same mechanism as first pass, fresh context). Always dispatched in v1 — no skip exception. Cycle resets on any code edit.

Step 3.5: Await Codex + Reconcile Secondary

Codex is the blocking reviewer — await its result for the initial gate. Secondary runs in background (run_in_background: true) and is non-blocking:

Secondary Status	Action
Completed before Codex	Include in aggregation (Step 4)
Completed after Codex, before precommit	Reconcile at pre-precommit checkpoint
Still running at precommit	Proceed with Codex gate (authoritative); if late result has P0/P1, re-open fix→re-review loop
Failed/timed out	Apply degradation matrix per references/review-common.md § Dual Reviewer Aggregation

Step 4: Consolidate Output (Dual Mode)

1. Normalize both sets of findings to unified format: [severity] file:line description → fix

   • Codex findings: already in standard format
   • toolkit findings: apply Severity Mapping (see references/review-common.md § Severity Mapping)
   • strict-reviewer findings: already use P0/P1/P2/Nit

2. Deduplicate using key = file + canonical_issue_text (ignore line ±5 difference)

   • Same key → keep highest severity (P0 > P1 > P2 > Nit)

3. Tag source: source = codex | toolkit | both

4. Sort: P0 → P1 → P2 → Nit

5. Gate decision: any P0/P1 → BLOCKED; else → READY

Output format includes source tag:

- [P0] file:line issue → fix [source: both]
- [P1] file:line issue → fix [source: codex]

Step 4.5: Emit Review Gate

Execute: bash scripts/emit-review-gate.sh READY or bash scripts/emit-review-gate.sh BLOCKED

This updates aggregate_gate.executed=true and aggregate_gate.gate in the state file.

Then output the standard gate sentinel:

• ✅ Ready — if READY (no P0/P1)
• ⛔ Blocked — if BLOCKED (has P0/P1)

Shared Definitions

See references/review-common.md for:

• Severity levels (P0/P1/P2/Nit)
• Review dimensions
• Merge gate definitions
• Re-review prompt template
• Gate sentinels (hook + behavior-layer)
• Dual Reviewer Aggregation (severity mapping, deduplication, degradation matrix, source attribution)

Review Loop

⚠️ @CLAUDE.md auto-loop: fix → re-review → ... → ✅ PASS ⚠️

Blocked → fix P0/P1 → /codex-review-fast --continue <threadId> → repeat until Ready. Ready + P2/Nit → batch fix → 1 Codex --continue verify → evaluate (see rules/auto-loop.md P2/Nit Quality Sweep).

3 rounds on same issue → report blocker, request intervention.

Dual Mode Loop Behavior

Reviewer	Loop Behavior
Codex MCP	Stateful → mcp__codex__codex-reply(threadId) continues context
Secondary	Re-dispatched every iteration (fresh context). Always dispatched in v1 (no skip exception).

Codex gate is authoritative for timing. Secondary runs non-blocking in background. Aggregation reconciled at pre-precommit checkpoint. Any code edit resets the review cycle — both reviewers must re-run.

Pre-precommit Checkpoint

Before triggering /precommit-fast, reconcile any pending secondary result:

Condition	Action
Task completed + has P0/P1	Re-emit BLOCKED → fix → re-review (Codex --continue + Secondary fresh)
Task completed + no P0/P1	Union aggregate → proceed to precommit
Task still running	Proceed with Codex gate (authoritative); if late result has P0/P1, re-open fix→re-review loop

Verification

• Each issue tagged with severity (P0/P1/P2/Nit)
• Gate is clear (✅ Ready / ⛔ Blocked)
• Issues include: file:line, description, fix suggestion
• Codex performed independent project research
• Branch variant: dimension rating table included

References

• Shared definitions: references/review-common.md
• Fast prompt: references/codex-prompt-fast.md
• Full prompt: references/codex-prompt-full.md
• Branch prompt: references/codex-prompt-branch.md
• Research instructions: references/codex-research-instructions.md

Examples

Input: /codex-review-fast
Action: emit PENDING → git diff → Codex + Task(code-reviewer) parallel → aggregate → emit gate → P0/P1/P2/Nit + Gate

Input: /codex-review --focus "auth"
Action: emit PENDING → lint:fix → build → git diff → Codex + Task parallel (focus: auth) → aggregate → emit gate

Input: /codex-review-branch origin/develop
Action: emit PENDING → branch diff + history → Codex + Task parallel → aggregate → emit gate → Rating table + Findings + Gate

Input: /codex-review-fast (Codex unavailable)
Action: emit PENDING → git diff → Task(code-reviewer) only → degraded aggregate → emit gate + ⚠️ warning