Gemini Dual Code Review Skill

Before Reviewing

1. Check Gemini availability — Run test -n "$GEMINI_API_KEY" via Bash to verify the API key is configured. If it fails, inform the user and fall back to a Claude-only review using the code-reviewer skill.
2. Gather context — Read related files to understand existing patterns, naming conventions, and architectural decisions.
3. Collect the diff — Use the same scope resolution as code-reviewer:
   • 1 → Uncommitted changes (git diff + git diff --cached)
   • 2 → Last local commit (git show HEAD)
   • 3 → Unpushed local commits (git diff @{upstream}..HEAD)
   • PR# → GitHub PR diff (gh pr diff <number>)

Dual Review Process

Step 1: Send to Gemini

Pipe the diff to Gemini via Bash:

echo "<diff content>" | node {pluginDir}/dist/gemini/cli.js --prompt "Review this diff for:
1. Logic bugs, incorrect assumptions, unhandled edge cases
2. Security vulnerabilities (injection, auth, data exposure)
3. Performance issues (N+1 queries, unnecessary allocations)
4. Maintainability concerns (naming, complexity, duplication)
5. Missing test coverage

Format your response as:
## Summary
Brief overview of change quality.

## Findings
- **Critical** — Must fix (security, data loss, crashes)
- **Major** — Should fix (quality/maintainability impact)
- **Minor** — Nice to fix (lower priority improvements)

Include file:line references where possible.
Be specific and actionable. Do NOT flag pre-existing issues." --system "You are a senior code reviewer. Be thorough, specific, and actionable."

Capture Gemini's full response from the JSON output's output field.

Step 2: Claude Review

Independently review the same diff using the code-reviewer skill evaluation criteria. Do NOT look at Gemini's output first — form your own assessment.

Step 3: Synthesis

Compare both reviews and present a unified report:

Output Format

Dual Code Review

Scope: [description of what was reviewed]

Claude's Review

[Claude's independent findings using code-reviewer format]

Gemini's Review

[Gemini's response, formatted cleanly]

Synthesis

Agreements

Findings both reviewers identified (highest confidence).

Unique to Claude

Findings only Claude caught.

Unique to Gemini

Findings only Gemini caught.

Verdict

Overall assessment combining both perspectives. Note where reviewers disagree and which assessment seems more accurate based on the code.

Fallback Behavior

If Gemini API key is not configured or the call fails:

1. Inform the user: "Gemini API key not configured — running Claude-only review."
2. Proceed with a standard code-reviewer skill review.
3. Do NOT block the review because of Gemini unavailability.

Guidelines

• Both reviews must be independent — do not let one influence the other.
• Present Gemini's output faithfully; do not rewrite or suppress its findings.
• If Gemini produces low-quality output, note it but still include it.
• The synthesis should add value, not just repeat findings.

When to Use This Skill

Use gemini-reviewer for structured dual code reviews with synthesis (agreements, unique findings, verdict). Use gemini-advisor (/ask-gemini) for general second opinions on any topic, file, or question — not limited to code review.

Pre-Delivery Checklist

Before presenting a dual review, verify:

• Claude's review was completed independently before reading Gemini's
• Gemini's output is presented faithfully without rewriting
• Synthesis contains all 3 sections: Agreements, Unique to Claude, Unique to Gemini
• Verdict addresses any disagreements between reviewers
• Fallback behavior was followed if Gemini was unavailable

CLI Reference

If unsure about Gemini CLI flags, run:

node {pluginDir}/dist/gemini/cli.js --help