Individual skill
perf-audit
Audit frontend bundle size and Core Web Vitals risks. Use when asked to "audit performance", "analyze bundle", "check bundle size", "check Core Web Vitals", or find frontend bottlenecks. Don't use for backend performance, database queries, or diagnosing a specific slowdown (/debug).
skills/perf-audit/SKILL.md
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- Not checked yet
- Last checked
- Nov 7, 2026
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- Repository last updated
- Oct 26, 2026
- License
- MIT
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# Performance Audit
## Workflow
1. Detect build tool from `package.json` (vite, webpack, next, rollup)
2. Run the production build via the project's task runner (auto-detect from package.json).
3. Analyze the build output — non-interactive only. Never launch a browser or a long-running server in an audit; those hang an automated run. Prefer, in order:
- **Measure the emitted files directly**: for each file in the output dir (e.g. `dist/assets/*.js`), report raw + gzipped size — `gzip -c <file> | wc -c`. This always works and needs no extra tooling.
- **Per-module breakdown, as a static artifact** (not a server), written under `$TMPDIR` (else `/tmp`) and never the working tree, where the next `commit` would sweep it in. Print the path:
- Vite/Rollup: `npx source-map-explorer 'dist/assets/*.js'`, or add `rollup-plugin-visualizer` configured to emit JSON/HTML to a file
- webpack/Next.js: `npx webpack-bundle-analyzer -m static -r "${TMPDIR:-/tmp}/report.html" <stats-file>` (writes a file; do **not** use the default server mode)
- `npx vite-bundle-visualizer` opens a browser and blocks — only suggest it to the user for manual exploration; do not run it here.
4. Check `package.json` for known heavy packages