[DO NOT MERGE] Enable server HMR by default for testing by wbinnssmith · Pull Request #90389 · vercel/next.js

wbinnssmith · 2026-02-23T18:36:02Z

Do not merge this. This PR currently exists only so that we can run the e2e test suite with server hmr applied.

vercel

Additional Suggestion:

Test file uses removed --experimental-server-fast-refresh CLI flag and asserts on removed feature.experimentalServerFastRefresh trace tag, causing test failure.

nextjs-bot · 2026-02-23T18:41:58Z

Failing test suites

Commit: de01a81 | About building and testing Next.js

pnpm test-start test/e2e/app-dir/navigation/navigation.test.ts (job)

app dir - navigation > hash > should scroll to the specified hash (DD)

Expand output

● app dir - navigation › hash › should scroll to the specified hash

expect(received).toBe(expected) // Object.is equality

Expected: false
Received: true

  199 |           url.includes('with-query-param')
  200 |         )
> 201 |         expect(hasQueryParamRscRequest).toBe(false)
      |                                         ^
  202 |       }
  203 |
  204 |       await checkLink('query-param', 2284)

  at Object.toBe (e2e/app-dir/navigation/navigation.test.ts:201:41)

pnpm test-start-turbo test/production/deterministic-build/deployment-id.test.ts (turbopack) (job)

deterministic build - changing deployment id > build output API - builder > should produce identical build outputs even when changing deployment id (DD)

Expand output

● deterministic build - changing deployment id › build output API - builder › should produce identical build outputs even when changing deployment id

thrown: "Exceeded timeout of 60000 ms for a test.
Add a timeout value to this test to increase the timeout, if this is a long-running test. See https://jestjs.io/docs/api#testname-fn-timeout."

  50 |       }
  51 |
> 52 |       const result = Reflect.apply(target, thisArg, args)
     |                              ^
  53 |       return typeof result === 'function' ? wrapJestTestFn(result) : result
  54 |     },
  55 |     get(target, prop, receiver) {

  at Object.apply (lib/e2e-utils/index.ts:52:30)
  at it (production/deterministic-build/deployment-id.test.ts:245:7)
      at Array.forEach (<anonymous>)
  at production/deterministic-build/deployment-id.test.ts:217:41
  at Object.<anonymous> (production/deterministic-build/deployment-id.test.ts:197:58)

nextjs-bot · 2026-02-23T18:55:37Z

Stats from current PR

✅ No significant changes detected

📊 All Metrics

📖 Metrics Glossary

Dev Server Metrics:

Listen = TCP port starts accepting connections
First Request = HTTP server returns successful response
Cold = Fresh build (no cache)
Warm = With cached build artifacts

Build Metrics:

Fresh = Clean build (no .next directory)
Cached = With existing .next directory

Change Thresholds:

Time: Changes < 50ms AND < 10%, OR < 2% are insignificant
Size: Changes < 1KB AND < 1% are insignificant
All other changes are flagged to catch regressions

⚡ Dev Server

Metric	Canary	PR	Change	Trend
Cold (Listen)	457ms	507ms	✓	▁▁█▁▁
Cold (Ready in log)	459ms	461ms	✓	▁▁█▂▂
Cold (First Request)	942ms	909ms	✓	▁▁█▄▄
Warm (Listen)	457ms	457ms	✓	▁▁█▁▁
Warm (Ready in log)	454ms	458ms	✓	▁▁█▁▁
Warm (First Request)	370ms	373ms	✓	▁▁█▂▁

⚡ Production Builds

Metric	Canary	PR	Change	Trend
Fresh Build	4.296s	4.343s	✓	▁▁█▁▁
Cached Build	4.359s	4.305s	✓	▁▁█▁▁

📦 Production Builds (Webpack) (Legacy)

📦 Production Builds (Webpack)

Metric	Canary	PR	Change	Trend
node_modules Size	475 MB	475 MB	✓	▁▁▁▁▁

📦 Bundle Sizes

Bundle Sizes

⚡ Turbopack

Client

Main Bundles: **400 kB** → **400 kB** ✅ -13 B

80 files with content-based hashes (individual files not comparable between builds)

Server

Middleware

	Canary	PR	Change
middleware-b..fest.js gzip	764 B	764 B	✓
Total	764 B	764 B	✓

Build Details

Build Manifests

	Canary	PR	Change
_buildManifest.js gzip	451 B	452 B	✓
Total	451 B	452 B	⚠️ +1 B

🔄 Shared (bundler-independent)

Runtimes

	Canary	PR	Change
app-page-exp...dev.js gzip	320 kB	320 kB	✓
app-page-exp..prod.js gzip	170 kB	170 kB	✓
app-page-tur...dev.js gzip	319 kB	319 kB	✓
app-page-tur..prod.js gzip	169 kB	169 kB	✓
app-page-tur...dev.js gzip	316 kB	316 kB	✓
app-page-tur..prod.js gzip	168 kB	168 kB	✓
app-page.run...dev.js gzip	316 kB	316 kB	✓
app-page.run..prod.js gzip	168 kB	168 kB	✓
app-route-ex...dev.js gzip	70.8 kB	70.8 kB	✓
app-route-ex..prod.js gzip	49.2 kB	49.2 kB	✓
app-route-tu...dev.js gzip	70.8 kB	70.8 kB	✓
app-route-tu..prod.js gzip	49.2 kB	49.2 kB	✓
app-route-tu...dev.js gzip	70.4 kB	70.4 kB	✓
app-route-tu..prod.js gzip	49 kB	49 kB	✓
app-route.ru...dev.js gzip	70.4 kB	70.4 kB	✓
app-route.ru..prod.js gzip	49 kB	49 kB	✓
dist_client_...dev.js gzip	324 B	324 B	✓
dist_client_...dev.js gzip	326 B	326 B	✓
dist_client_...dev.js gzip	318 B	318 B	✓
dist_client_...dev.js gzip	317 B	317 B	✓
pages-api-tu...dev.js gzip	43.2 kB	43.2 kB	✓
pages-api-tu..prod.js gzip	32.9 kB	32.9 kB	✓
pages-api.ru...dev.js gzip	43.2 kB	43.2 kB	✓
pages-api.ru..prod.js gzip	32.8 kB	32.8 kB	✓
pages-turbo....dev.js gzip	52.5 kB	52.5 kB	✓
pages-turbo...prod.js gzip	38.5 kB	38.5 kB	✓
pages.runtim...dev.js gzip	52.5 kB	52.5 kB	✓
pages.runtim..prod.js gzip	38.4 kB	38.4 kB	✓
server.runti..prod.js gzip	62 kB	62 kB	✓
Total	2.82 MB	2.82 MB	⚠️ +1 B

📎 Tarball URL

next@https://vercel-packages.vercel.app/next/prs/90389/next

This is cherry-picked from #90389, which also serves as a test case for server hmr being enabled by default. This fixes a number of issues with server hmr, most notably that pages router updates weren’t reflected: 1. **Pages Router pages weren't clearing the chunk cache** — the old condition (which just checked the cli flag) meant the chunk cache was only cleared when server HMR was entirely absent. Once server HMR was enabled, Pages Router pages (which don't use the Turbopack module registry) got stale. 2. **`deleteCache` was skipped for files with server HMR subscriptions** — this left stale entries in `evalManifest`'s `sharedCache`, causing "Could not find module in React Client Manifest" errors when new `'use client'` components were added. 3. **`clearModuleContext` was skipped for middleware and edge routes** — server HMR subscriptions include edge runtime chunks, but `__turbopack_server_hmr_apply__` can't reach those sandboxes. They need `clearModuleContext` called explicitly. 4. **Chunk cache wasn't cleared for `.env`/config changes** — when `force: true` (no code change), module-level env captures stayed stale. Now `__next__clear_chunk_cache__()` is called unconditionally when `force` is set.

codspeed-hq · 2026-02-25T07:19:27Z

Merging this PR will not alter performance

✅ 17 untouched benchmarks
⏩ 3 skipped benchmarks¹

_{Comparing server-hmr-default (5e1b2ff) with canary (34647db)}

3 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

vercel · 2026-02-25T16:44:17Z

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
next-js	Error		Feb 25, 2026 4:47pm

This adds and calls \`maybeInlineSourcemap()\` to the Turbopack Node.js HMR runtime that appends \`//# sourceURL\` and \`//# sourceMappingURL\` (base64-encoded) to each `eval`ed module entry Test Plan: CI for #90389

wbinnssmith · 2026-02-26T06:19:40Z

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

This stack of pull requests is managed by Graphite. Learn more about stacking.

Do not merge this. This PR currently exists only so that we can run the e2e test suite with server hmr applied.

nextjs-bot added created-by: Turbopack team PRs by the Turbopack team. tests type: next labels Feb 23, 2026

vercel bot reviewed Feb 23, 2026

View reviewed changes

wbinnssmith force-pushed the server-hmr-default branch 2 times, most recently from ff2f17a to 4c3a0f3 Compare February 23, 2026 23:56

wbinnssmith mentioned this pull request Feb 24, 2026

Turbopack: Fix experimental server hmr for pages router #90398

Merged

wbinnssmith force-pushed the server-hmr-default branch from 4c3a0f3 to 52cd1eb Compare February 24, 2026 01:02

wbinnssmith force-pushed the server-hmr-default branch from 2d9a5e5 to d83b366 Compare February 24, 2026 01:48

wbinnssmith force-pushed the server-hmr-default branch from 7b18f67 to 0421f64 Compare February 24, 2026 01:56

wbinnssmith force-pushed the server-hmr-default branch 3 times, most recently from 7b9b517 to 57713d3 Compare February 24, 2026 23:07

nextjs-bot added the Turbopack Related to Turbopack with Next.js. label Feb 25, 2026

wbinnssmith force-pushed the server-hmr-default branch from bff7767 to 1306418 Compare February 25, 2026 07:55

vercel bot had a problem deploying to Preview February 25, 2026 16:47 Failure

wbinnssmith force-pushed the server-hmr-default branch 3 times, most recently from 23737d8 to 556f1b2 Compare February 26, 2026 03:41

wbinnssmith mentioned this pull request Feb 26, 2026

Turbopack server hmr: Implement restart event #90550

Open

wbinnssmith force-pushed the server-hmr-default branch from 556f1b2 to 5e1b2ff Compare February 26, 2026 04:13

wbinnssmith mentioned this pull request Feb 26, 2026

Turbopack server HMR: inline source maps for evaled modules #90561

Open

wbinnssmith changed the base branch from canary to graphite-base/90389 February 26, 2026 06:19

wbinnssmith force-pushed the server-hmr-default branch from 5e1b2ff to 1190e3a Compare February 26, 2026 06:19

wbinnssmith force-pushed the graphite-base/90389 branch from 34647db to 8cd12ca Compare February 26, 2026 06:19

wbinnssmith changed the base branch from graphite-base/90389 to server-hmr-sourcemaps February 26, 2026 06:19

wbinnssmith force-pushed the server-hmr-default branch from 1190e3a to f781f5c Compare February 26, 2026 06:23

wbinnssmith force-pushed the server-hmr-sourcemaps branch from 8cd12ca to 3c19fa8 Compare February 26, 2026 06:43

wbinnssmith force-pushed the server-hmr-default branch from f781f5c to c137904 Compare February 26, 2026 06:43

wbinnssmith added 2 commits February 25, 2026 23:01

[DO NOT MERGE] Enable server HMR by default for testing

1a3cea5

Do not merge this. This PR currently exists only so that we can run the e2e test suite with server hmr applied.

remove the flag from test for now

de01a81

wbinnssmith force-pushed the server-hmr-default branch from c137904 to de01a81 Compare February 26, 2026 07:01

wbinnssmith force-pushed the server-hmr-sourcemaps branch from 3c19fa8 to 65345c7 Compare February 26, 2026 07:01

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[DO NOT MERGE] Enable server HMR by default for testing#90389

[DO NOT MERGE] Enable server HMR by default for testing#90389
wbinnssmith wants to merge 2 commits intoserver-hmr-sourcemapsfrom
server-hmr-default

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Stats from current PR

✅ No significant changes detected

⚡ Dev Server

⚡ Production Builds

📦 Production Builds (Webpack)

Bundle Sizes

⚡ Turbopack

🔄 Shared (bundler-independent)

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Merging this PR will not alter performance

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