Built-in Bundle Tree View & Size-Budget Alerts

[Livog]

Goals

1. Surface bundle-size regressions quicker.
2. Help developers improve Core Web Vitals more easily.

Non-Goals

No response

Background

next build shows a flat list:

/                         151 kB
/bundles/ui/antd/anchor    136 kB
/bundles/ui/antd/avatar    177 kB

Great for totals, useless for “what blew this up?”
When a page drifts past 500 kB you still need a plug-in, another build, and manual spelunking through component trees.

Proposal

1. --bundle-tree output or adding a "next.config.ts option"

   • Hierarchical view per route with gz/Brotli sizes.

   • Example:

     / (151 kB)
     ├─ shadcn/select (36 kB)   ← culprit
     └─ …
     

2. Size-budget warnings

   • Defaults: import > 30 kB or page > 250 kB (override in next.config.js).
   • Be able to add fails to CI when limits are exceeded.

3. --json for CI/dashboards

   • Same tree as machine-readable JSON.