build— agent skill

Execute all three phases in order.

Phase 1 — Bottleneck

Analyze whichever config file applies:

• Dockerfile
• webpack.config.js / vite.config.ts
• .github/workflows/*.yml

Identify the single step that consumes the most wall-clock time.

Phase 2 — Fix

Docker:

• Reorder layers: least-changing first (OS deps, runtime), most-changing last (app code).
• Use multi-stage builds: compile in a full image, copy only the output artifact into a minimal runtime image (e.g. alpine).

Webpack / Vite:

• Enable code splitting and tree-shaking.
• Enable TerserPlugin with parallel: true.
• Set cache: { type: 'filesystem' } for persistent build caching.

GitHub Actions:

• Cache node_modules using actions/cache keyed on the hash of package-lock.json.
• Cache pip packages keyed on the hash of requirements.txt.
• Add concurrency: groups to cancel in-progress runs on force-push.

Phase 3 — Report

State: "This change will save approximately X minutes per PR run" with explicit reasoning.