Build a performance bot with Sentry + Claude

const prompt = `
You are a performance engineer reviewing a slow request.

Sentry trace: ${traceUrl}
Endpoint: ${endpoint}
P95 latency: ${p95ms}ms  |  Threshold: ${THRESHOLD_MS}ms

Using the Sentry MCP tool, pull the full trace details. Then:
1. Name the specific span responsible for the slowdown
2. Propose 1–3 code changes that would fix it
3. Return each fix as a unified diff

Respond ONLY with valid JSON:
{
  "root_cause": "string",
  "changes": [{ "file": "string", "diff": "string", "summary": "string" }],
  "risk_notes": "string"
}
`;

const res = await fetch('https://api.anthropic.com/v1/messages', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({
    model: 'claude-sonnet-4-6',
    max_tokens: 4000,
    mcp_servers: [{ type: 'url', url: 'https://mcp.sentry.dev/mcp', name: 'sentry' }],
    messages: [{ role: 'user', content: prompt }]
  })
});

const analysis = JSON.parse(res.content[0].text);

const { root_cause, changes, risk_notes } = analysis;

for (const change of changes) {
  const file = await octokit.repos.getContent({ owner, repo, path: change.file });
  const updated = applyPatch(atob(file.data.content), change.diff);

  await octokit.git.createRef({ owner, repo,
    ref: `refs/heads/perf/${traceId}`, sha: baseSha });

  await octokit.repos.createOrUpdateFileContents({
    owner, repo, path: change.file,
    message: `perf: ${root_cause}`,
    content: btoa(updated), branch: `perf/${traceId}`
  });

  await octokit.pulls.create({
    owner, repo,
    head: `perf/${traceId}`, base: 'main',
    title: `[Perf] ${root_cause}`,
    body: buildPRBody(analysis, traceUrl)
  });
}

# .github/workflows/perf-bot.yml
name: performance-bot

on:
  schedule:
    - cron: '0 9 * * 1'  # Every Monday at 9am UTC
  workflow_dispatch:

jobs:
  analyze:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with: { node-version: '20' }
      - run: npm install
      - run: node scripts/perf-bot.js
        env:
          SENTRY_AUTH_TOKEN: ${{ secrets.SENTRY_AUTH_TOKEN }}
          ANTHROPIC_API_KEY: ${{ secrets.ANTHROPIC_API_KEY }}
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}