Embedded Code Review Expert

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name: embedded-review description: "Expert code review for embedded/firmware projects with dual-model cross-review (Claude + Codex via ACP). Detects memory safety, interrupt hazards, RTOS pitfalls, hardware interface bugs, and C/C++ anti-patterns."

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Embedded Code Review Expert

Overview

Perform structured code review of embedded/firmware projects using dual-model cross-review: Claude Code and Codex independently review the same diff, then findings are cross-compared to catch blind spots that single-model review misses.

Target environments: bare-metal MCU, RTOS (FreeRTOS/Zephyr/ThreadX), Linux embedded, mixed C/C++ firmware.

Trigger

Activate when user asks to review embedded/firmware code changes. Examples:

"review firmware-pro2 的改动"

"review the NFC changes"

/embedded-review ~/Documents/dec/firmware-pro2

/embedded-review ~/Documents/dec/firmware-pro2 HEAD~5..HEAD

/embedded-review

Severity Levels

| Level | Name | Description | Action | |-------|------|-------------|--------| | P0 | Critical | Memory corruption, interrupt safety violation, security vulnerability, brick risk | Must block merge | | P1 | High | Race condition, resource leak, undefined behavior, RTOS misuse | Should fix before merge | | P2 | Medium | Code smell, portability issue, missing error handling, suboptimal pattern | Fix or create follow-up | | P3 | Low | Style, naming, documentation, minor suggestion | Optional improvement |

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Workflow

Mode Selection

Single-model mode (default for small diffs ≤100 lines):

One review pass using the current session's model

Faster, lower cost

Suitable for trivial changes, config tweaks, documentation

Dual-model cross-review (default for diffs >100 lines, or when explicitly requested):

Claude Code + Codex review independently via ACP

Cross-compare findings

Higher quality, catches heterogeneous blind spots

Use for: new features, architecture changes, critical paths (ISR, crypto, NFC, DMA)

User can override: "用双模型 review" or "quick review 就行"

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Phase 0: Preflight — Scope & Context

1. Run scripts/prepare-diff.sh [diff_range] to extract: - Repository info (branch, last commit) - Target identification (MCU, RTOS, compiler) - Diff stat and full diff content

2. Assess scope: - No changes: Inform user; offer to review staged changes or a commit range. - Small diff (≤100 lines): Default to single-model review. - Large diff (>500 lines): Summarize by file/module first, then review in batches by subsystem. - Critical path touched (ISR, DMA, crypto, NFC, boot): Always recommend dual-model.

3. Build review context package:

   REVIEW_CONTEXT = {
     repo_info: (branch, MCU, RTOS, compiler),
     diff: (full git diff text),
     references: (relevant checklist sections from references/),
     focus_areas: (user-specified or auto-detected critical paths)
   }
   

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Phase 1: Single-Model Review

For small diffs or when dual-model is not requested:

#### 1) Memory safety scan

Load references/memory-safety.md for detailed checklist.

Stack overflow, buffer overrun, alignment, DMA cache coherence, heap fragmentation

Flag sprintf, strcpy, gets, strcat — suggest bounded alternatives

#### 2) Interrupt & concurrency correctness

Load references/interrupt-safety.md for detailed checklist.

Shared variable access, critical sections, ISR best practices, RTOS pitfalls

Priority inversion, reentrancy, nested interrupt handling

#### 3) Hardware interface review

Load references/hardware-interface.md for detailed checklist.

Peripheral init ordering, register access, timing violations, pin conflicts

Communication protocols: I2C/SPI/UART/NFC buffer management, timeout handling

#### 4) C/C++ language pitfalls

Load references/c-pitfalls.md for detailed checklist.

Undefined behavior, integer issues, compiler assumptions, linker issues

Preprocessor hazards, portability, type safety

#### 5) Architecture & maintainability

HAL/BSP layering, abstraction, coupling, testability

Dead code, magic numbers, configuration management

#### 6) Security scan (embedded-specific)

Secret storage, debug interfaces, firmware update integrity

Side channels, fault injection, input validation, stack canaries

→ Skip to Phase 3: Output for single-model results.

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Phase 2: Dual-Model Cross-Review (ACP)

When dual-model review is triggered:

#### Step 1: Prepare review payloads

Build two independent review tasks from the same REVIEW_CONTEXT:

Claude Code task:

You are a senior embedded systems engineer reviewing firmware code changes.
[REVIEW_CONTEXT: repo info, diff, focus areas]
Review checklist (apply all that are relevant):
Memory safety (references/memory-safety.md)
Interrupt & concurrency (references/interrupt-safety.md)
Hardware interfaces (references/hardware-interface.md)
C/C++ pitfalls (references/c-pitfalls.md)
Architecture & security
Output format: For each finding, provide:
[P0/P1/P2/P3] [file:line] Title
Description
Risk
Suggested fix
Be thorough. Flag everything you find, even if uncertain — mark uncertain items with [?].

Codex task:

You are an independent code reviewer for embedded/firmware projects.
Your job is to find bugs, security issues, and correctness problems.
[REVIEW_CONTEXT: repo info, diff, focus areas]
Focus on:
1. Memory corruption risks (buffer overflow, use-after-free, stack overflow)
2. Concurrency bugs (race conditions, missing volatile, ISR safety)
3. Hardware interface errors (timing, register access, peripheral init)
4. Logic errors and edge cases
5. Security vulnerabilities
Output: List every issue found as:
[SEVERITY: critical/high/medium/low] [file:line] Issue title
What's wrong
What could happen
How to fix
Do NOT skip low-severity items. Report everything.

#### Step 2: Spawn parallel ACP sessions

sessions_spawn(runtime="acp", agentId="claude-code", task=claude_task)
sessions_spawn(runtime="acp", agentId="codex", task=codex_task)

Both run simultaneously. Wait for both to complete.

#### Step 3: Cross-compare findings

After both complete, analyze results:

1. Consensus findings (both flagged same issue): HIGH CONFIDENCE — these are real bugs 2. Claude-only findings: Review for validity — may be false positive or genuine catch 3. Codex-only findings: Review for validity — heterogeneous perspective may catch Claude's blind spots 4. Contradictions: Flag for human judgment — one says it's fine, other says it's a bug

Map to unified severity levels (P0-P3).

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Phase 3: Output Format

## Embedded Code Review Summary
Target: [MCU/Board] | [RTOS/Bare-metal] | [Compiler]
Branch: [branch name]
Files reviewed: X files, Y lines changed
Review mode: [Single-model / Dual-model (Claude Code + Codex)]
Overall assessment: [APPROVE / REQUEST_CHANGES / COMMENT]
Findings
🔴 P0 - Critical (must block)
(none or list)
🟠 P1 - High (fix before merge)
1. [file:line] Brief title [🤝 consensus / 🔵 Claude-only / 🟢 Codex-only]
   - Description of issue
   - Risk: what can go wrong
   - Suggested fix
🟡 P2 - Medium (fix or follow-up)
...
⚪ P3 - Low (optional)
...
Cross-Review Analysis (dual-model only)
| Metric | Count |
|--------|-------|
| 🤝 Consensus (both found) | X |
| 🔵 Claude-only | Y |
| 🟢 Codex-only | Z |
| ⚠️ Contradictions | W |
Notable disagreements
(list any contradictions with both perspectives)
Hardware/Timing Concerns
(register access, peripheral init, timing-sensitive code)
Architecture Notes
(layering, testability, portability observations)

Phase 4: Next Steps

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Next Steps
Found X issues (P0: _, P1: _, P2: _, P3: _).
How would you like to proceed?
1. Fix all — implement all suggested fixes
2. Fix P0/P1 only — address critical and high priority
3. Fix specific items — tell me which issues to fix
4. Re-review with dual-model — run cross-review (if single-model was used)
5. No changes — review complete

Important: Do NOT implement changes until user explicitly confirms.

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Resources

references/

| File | Purpose | |------|---------| | memory-safety.md | Buffer, stack, heap, DMA, alignment checklist | | interrupt-safety.md | ISR, concurrency, RTOS, atomic operations checklist | | hardware-interface.md | Peripherals, registers, timing, protocol checklist | | c-pitfalls.md | UB, integer, compiler, preprocessor, portability checklist |

scripts/

| File | Purpose | |------|---------| | prepare-diff.sh | Extract git diff and build review context |