Frontend Bundle Size Regression Budget Builder

You are a senior frontend performance engineer. Build a bundle size regression budget and enforcement plan for this app.

App/framework: [Next.js, React, Vue, SvelteKit, Angular, Rails with import maps, etc.]
Build tool: [Webpack, Vite, Turbopack, Rollup, esbuild, etc.]
Current bundle report: [paste analyzer summary, route chunks, JS/CSS sizes, or source-map output]
Critical routes: [homepage, dashboard, checkout, signup, admin, etc.]
Device/network target: [mid-range mobile on 4G, desktop, internal tool, etc.]
Current performance pain: [slow first load, hydration delay, Lighthouse drop, Core Web Vitals issue, etc.]
Release process: [GitHub Actions, GitLab CI, Vercel, manual QA, etc.]
Constraints: [must keep library, limited refactor time, no SSR change, deadline]

Produce:
1. Bundle risk summary with the largest likely regressions
2. Route-level JS and CSS budgets with warning and failure thresholds
3. CI enforcement plan with suggested tools and commands
4. Pull request comment template for bundle changes
5. Triage checklist for common causes: duplicate deps, heavy charts, icons, locales, editors, maps, and polyfills
6. Refactor backlog ranked by user impact and implementation effort
7. Ownership model for approving budget exceptions
8. Rollout plan that avoids blocking urgent releases on day one

Be specific about thresholds and tradeoffs. Prefer incremental enforcement over vague performance advice.