The performance report measured nothing. It only read `entryJSFiles` from
each route's client-reference manifest, a field Turbopack emits and webpack
does not. When the build moved to webpack (3d828a61) every route fell
through to the "unavailable" branch, and because the report is informational
and exits 0 on an unavailable metric, nothing failed and the budgets quietly
stopped being enforced.
Derive the envelope from clientModules[*].chunks when entryJSFiles is
absent, which is the same source Next's own static-routes-info uses for
webpack builds. Webpack interleaves numeric chunk ids with file names in
those arrays, so ids are skipped by shape while a malformed chunk path still
throws — otherwise a broken manifest would quietly under-report a route.
entryJSFiles still wins when present, since it is per-segment and therefore
the tighter envelope, and the per-chunk origin label is shared rather than
the absolute node_modules path webpack records, which would otherwise bloat
report.json.
Six tests cover the webpack layout: id filtering, deduplication of a chunk
reached by several client modules, the origin label, the malformed-path
rejection, the no-chunks-at-all case, and entryJSFiles taking precedence.
Re-measured on the current build, all six routes are inside their budgets
again. Note /admin/studio/furni now sits at ~98% of its gzip limit, so one
more dependency on that route will trip it; docs/performance-budgets.md
records the webpack baseline numbers and how to recalibrate.
Verified: 3385 tests, typecheck and biome clean, and the report now emits
measured rows instead of six unavailable ones.
openhands
Simo