gco-review

GCO Review

Code review via GitHub Copilot CLI, synthesized by Claude Code.

Process

Step 0: Pre-flight Rate Limit Check

Before doing anything, check if Copilot is currently in degraded mode:

RATE_CHECK=$(node $HOME/.claude/scripts/gco-rate-limit.js check 2>&1)

If the output starts with degraded:, notify the user that Copilot is in low-cost mode (auto-downgraded model, free for Pro users) but proceed with Copilot anyway — it is still usable. Do NOT skip or fall back.

Step 1: Determine Base Branch

BRANCH=$(git branch --show-current)
BASE=$(gh pr view --json baseRefName -q '.baseRefName' 2>/dev/null)

If no PR, use default branch:

BASE=$(git remote show origin | grep 'HEAD branch' | awk '{print $NF}')

Step 2: Build Review Prompt

Generate the diff and build a review prompt:

DIFF=$(git diff "$BASE"...HEAD)

Construct the prompt:

Review the following code changes (diff against $BASE branch).

Focus on:
1. Bugs, logic errors, and potential runtime failures
2. Security vulnerabilities (injection, XSS, auth issues)
3. Performance problems
4. Missing error handling at system boundaries
5. Breaking changes or regressions

For each finding, provide:
- File and approximate location
- Severity (high/medium/low)
- What the issue is and why it matters
- Suggested fix

Be concise. If the code looks good, say so briefly — don't invent problems.

Diff:
<the diff content>

Step 3: Run Copilot

LOGDIR=$(node $HOME/.claude/scripts/get-logdir.js)
mkdir -p "$LOGDIR"
DATETIME=$(date +%Y%m%d_%H%M%S)

bash $HOME/.claude/skills/gco/scripts/gco-run.sh \
  "<prompt>" \
  "$LOGDIR/${DATETIME}-gco-review.md" \
  "$LOGDIR/${DATETIME}-gco-review-stderr.log"

Run as a background Bash task with 15-minute timeout.

Step 4: Collect Results and Check for Quota Fallback

After Copilot completes (or times out):

1. Check for quota fallback — grep the stderr log for GCO_USED_FALLBACK=:

   grep '^GCO_USED_FALLBACK=' "$LOGDIR/${DATETIME}-gco-review-stderr.log"
   

   If found, gco-run.sh auto-retried with gpt-4.1 because the primary model was out of quota. Notify the user with one line: "Used gpt-4.1 instead of claude-opus-4.6 because of no quota." Proceed — the output is still valid.

2. Read the output file ($LOGDIR/${DATETIME}-gco-review.md)

3. If empty or missing, check stderr log for errors

4. If Copilot failed or timed out, jump to Fallback

Step 5: Fallback

If Copilot timed out, produced no usable output, or is not installed:

• Notify the user about the fallback
• Spawn 2 code-reviewer subagents in parallel (like /light-review) to review the diff against $BASE
• Continue as if /light-review was invoked
• Note: Quota exhaustion alone is NOT a fallback trigger — gco-run.sh auto-retries with gpt-4.1 (free) and produces valid output

Step 6: Synthesize and Report

1. Read output and organize findings
2. Categorize by priority (high / medium / low)
3. Present a clear summary
4. Include log file paths for reference

Step 7: Apply Fixes

• High priority: Implement automatically
• Medium priority: Implement if clearly safe, otherwise ask
• Low priority: Ask user

Step 8: Commit Changes

If fixes were applied, commit with a descriptive message.

Important Notes

• Copilot cannot modify files — all writes done by Claude Code
• NEVER use ~ in paths — use $HOME
• Output files: $LOGDIR/${DATETIME}-gco-review.md (timestamped)
• Quota fallback policy: When the primary model returns HTTP 402 no-quota, gco-run.sh automatically retries with gpt-4.1 (free zero-multiplier model on the Pro plan) and writes GCO_USED_FALLBACK=gpt-4.1 ... to the stderr file. Claude MUST check stderr for this marker and tell the user "Used gpt-4.1 instead of claude-opus-4.6 because of no quota." Output is still valid — do not fall back to 2-reviewer Claude Code unless Copilot actually fails (timeout, no output, not installed)
• Cheap variant: Use /gcoc-review to skip opus entirely and run gpt-4.1 from the start