Fix preview version in `window.next.version` for PR builds by unstubbable · Pull Request #90937 · vercel/next.js

unstubbable · 2026-03-05T16:57:03Z

Preview builds served via vercel-packages.vercel.app were showing the published canary version instead of the PR-specific preview version. This happened because create-preview-tarballs.js updated package.json after the build, but the version was already baked into the compiled dist/ files by setNextVersion in taskfile-swc.js.

This extracts the version computation from create-preview-tarballs.js into a new set-preview-version.js script that runs before pnpm run build, so the compiled output naturally includes the correct version. create-preview-tarballs.js now reads the version from packages/next/package.json instead of computing it independently.

Test Plan

Create a new app: pnpm create next-app@canary
Install the preview build from this PR: pnpm i https://vercel-packages.vercel.app/next/commits/06681c21e886a97e39d277808780884151c00318/next
Run pnpm dev and inspect next.version in DevTools — should show 16.2.0-preview-06681c21-20260306 instead of the canary version

Preview builds served via `vercel-packages.vercel.app` were showing the published canary version instead of the PR-specific preview version. This happened because `create-preview-tarballs.js` updated `package.json` after the build, but the version was already baked into the compiled `dist/` files by `setNextVersion` in `taskfile-swc.js`. This extracts the version computation from `create-preview-tarballs.js` into a new `set-preview-version.js` script that runs before `pnpm run build`, so the compiled output naturally includes the correct version. `create-preview-tarballs.js` now reads the version from `packages/next/package.json` instead of computing it independently.

nextjs-bot · 2026-03-05T17:48:03Z

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)	456ms	456ms	✓	▅█▁▁▁
Cold (Ready in log)	439ms	440ms	✓	▄█▁▁▁
Cold (First Request)	1.215s	1.243s	✓	▃█▁▁▁
Warm (Listen)	456ms	457ms	✓	▅█▁▁▁
Warm (Ready in log)	444ms	445ms	✓	▃█▁▁▁
Warm (First Request)	356ms	355ms	✓	▃█▁▁▁

📦 Dev Server (Webpack) (Legacy)

📦 Dev Server (Webpack)

Metric	Canary	PR	Change	Trend
Cold (Listen)	455ms	456ms	✓	█▁▁▁▁
Cold (Ready in log)	437ms	437ms	✓	█▁▄▆▅
Cold (First Request)	1.938s	1.920s	✓	█▁▃▄▃
Warm (Listen)	455ms	457ms	✓	█▁▁▁▁
Warm (Ready in log)	437ms	437ms	✓	█▁▅▄▃
Warm (First Request)	1.951s	1.942s	✓	█▁▃▃▃

⚡ Production Builds

Metric	Canary	PR	Change	Trend
Fresh Build	3.851s	3.848s	✓	▃█▁▁▁
Cached Build	3.784s	3.771s	✓	▃█▁▁▁

📦 Production Builds (Webpack) (Legacy)

📦 Production Builds (Webpack)

Metric	Canary	PR	Change	Trend
Fresh Build	14.044s	14.122s	✓	█▁▁▁▁
Cached Build	14.188s	14.111s	✓	█▁▁▁▁
node_modules Size	477 MB	477 MB	✓	██▁▁▁

📦 Bundle Sizes

Bundle Sizes

⚡ Turbopack

Client

Main Bundles: **402 kB** → **402 kB** ⚠️ +31 B

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

Server

Middleware

	Canary	PR	Change
middleware-b..fest.js gzip	766 B	767 B	✓
Total	766 B	767 B	⚠️ +1 B

Build Details

Build Manifests

	Canary	PR	Change
_buildManifest.js gzip	446 B	450 B	✓
Total	446 B	450 B	⚠️ +4 B

📦 Webpack

Client

Main Bundles

	Canary	PR	Change
5528-HASH.js gzip	5.54 kB	N/A	-
6280-HASH.js gzip	59.4 kB	N/A	-
6335.HASH.js gzip	169 B	N/A	-
912-HASH.js gzip	4.59 kB	N/A	-
e8aec2e4-HASH.js gzip	62.6 kB	N/A	-
framework-HASH.js gzip	59.7 kB	59.7 kB	✓
main-app-HASH.js gzip	256 B	254 B	✓
main-HASH.js gzip	39.1 kB	39.1 kB	✓
webpack-HASH.js gzip	1.68 kB	1.68 kB	✓
262-HASH.js gzip	N/A	4.59 kB	-
2889.HASH.js gzip	N/A	169 B	-
5602-HASH.js gzip	N/A	5.55 kB	-
6948ada0-HASH.js gzip	N/A	62.6 kB	-
9544-HASH.js gzip	N/A	60.2 kB	-
Total	233 kB	234 kB	⚠️ +733 B

Polyfills

	Canary	PR	Change
polyfills-HASH.js gzip	39.4 kB	39.4 kB	✓
Total	39.4 kB	39.4 kB	✓

Pages

	Canary	PR	Change
_app-HASH.js gzip	194 B	194 B	✓
_error-HASH.js gzip	183 B	180 B	🟢 3 B (-2%)
css-HASH.js gzip	331 B	330 B	✓
dynamic-HASH.js gzip	1.81 kB	1.81 kB	✓
edge-ssr-HASH.js gzip	256 B	256 B	✓
head-HASH.js gzip	351 B	352 B	✓
hooks-HASH.js gzip	384 B	383 B	✓
image-HASH.js gzip	580 B	581 B	✓
index-HASH.js gzip	260 B	260 B	✓
link-HASH.js gzip	2.51 kB	2.51 kB	✓
routerDirect..HASH.js gzip	320 B	319 B	✓
script-HASH.js gzip	386 B	386 B	✓
withRouter-HASH.js gzip	315 B	315 B	✓
1afbb74e6ecf..834.css gzip	106 B	106 B	✓
Total	7.98 kB	7.98 kB	✅ -1 B

Server

Edge SSR

	Canary	PR	Change
edge-ssr.js gzip	125 kB	125 kB	✓
page.js gzip	256 kB	256 kB	✓
Total	380 kB	381 kB	⚠️ +910 B

Middleware

	Canary	PR	Change
middleware-b..fest.js gzip	618 B	615 B	✓
middleware-r..fest.js gzip	156 B	155 B	✓
middleware.js gzip	43.9 kB	43.7 kB	✓
edge-runtime..pack.js gzip	842 B	842 B	✓
Total	45.5 kB	45.3 kB	✅ -239 B

Build Details

Build Manifests

	Canary	PR	Change
_buildManifest.js gzip	715 B	718 B	✓
Total	715 B	718 B	⚠️ +3 B

Build Cache

	Canary	PR	Change
0.pack gzip	4.06 MB	4.07 MB	🔴 +7.1 kB (+0%)
index.pack gzip	103 kB	103 kB	✓
index.pack.old gzip	103 kB	104 kB	✓
Total	4.27 MB	4.28 MB	⚠️ +8.2 kB

🔄 Shared (bundler-independent)

Runtimes

	Canary	PR	Change
app-page-exp...dev.js gzip	322 kB	322 kB	✓
app-page-exp..prod.js gzip	171 kB	171 kB	✓
app-page-tur...dev.js gzip	322 kB	322 kB	✓
app-page-tur..prod.js gzip	171 kB	171 kB	✓
app-page-tur...dev.js gzip	318 kB	318 kB	✓
app-page-tur..prod.js gzip	169 kB	169 kB	✓
app-page.run...dev.js gzip	319 kB	319 kB	✓
app-page.run..prod.js gzip	169 kB	169 kB	✓
app-route-ex...dev.js gzip	70.9 kB	70.9 kB	✓
app-route-ex..prod.js gzip	49.3 kB	49.3 kB	✓
app-route-tu...dev.js gzip	70.9 kB	70.9 kB	✓
app-route-tu..prod.js gzip	49.3 kB	49.3 kB	✓
app-route-tu...dev.js gzip	70.5 kB	70.5 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	32.9 kB	32.9 kB	✓
pages-turbo....dev.js gzip	52.6 kB	52.6 kB	✓
pages-turbo...prod.js gzip	38.5 kB	38.5 kB	✓
pages.runtim...dev.js gzip	52.6 kB	52.6 kB	✓
pages.runtim..prod.js gzip	38.5 kB	38.5 kB	✓
server.runti..prod.js gzip	62 kB	62 kB	✓
Total	2.84 MB	2.84 MB	✓

📎 Tarball URL

https://vercel-packages.vercel.app/next/commits/06681c21e886a97e39d277808780884151c00318/next

nextjs-bot · 2026-03-05T18:51:11Z

Tests Passed

.github/workflows/build_and_deploy.yml

scripts/set-preview-version.js

Made possible by patching `allowBranch`.

Preview builds served via `vercel-packages.vercel.app` were showing the published canary version instead of the PR-specific preview version. This happened because `create-preview-tarballs.js` updated `package.json` after the build, but the version was already baked into the compiled `dist/` files by `setNextVersion` in `taskfile-swc.js`. This extracts the version computation from `create-preview-tarballs.js` into a new `set-preview-version.js` script that runs before `pnpm run build`, so the compiled output naturally includes the correct version. `create-preview-tarballs.js` now reads the version from `packages/next/package.json` instead of computing it independently. ## Test Plan 1. Create a new app: `pnpm create next-app@canary` 2. Install the preview build from this PR: `pnpm i https://vercel-packages.vercel.app/next/commits/06681c21e886a97e39d277808780884151c00318/next` 3. Run `pnpm dev` and inspect `next.version` in DevTools — should show `16.2.0-preview-06681c21-20260306` instead of the canary version

nextjs-bot added the created-by: Next.js team PRs by the Next.js team. label Mar 5, 2026

unstubbable force-pushed the hl/fix-embedded-preview-version branch from 8984eda to f750b0c Compare March 5, 2026 17:36

unstubbable added 3 commits March 5, 2026 19:01

Run pnpm install again after changing the version

39a6421

Let lerna set the version for the workspace

008bc9e

Allow versioning on branch

faa9994

unstubbable added 2 commits March 6, 2026 08:51

Set version manually for all packages

da64245

Install without frozen lockfile

f74fa45

unstubbable marked this pull request as ready for review March 6, 2026 09:43

unstubbable requested a review from eps1lon March 6, 2026 09:43

eps1lon reviewed Mar 6, 2026

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.github/workflows/build_and_deploy.yml Outdated Show resolved Hide resolved

eps1lon reviewed Mar 6, 2026

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scripts/set-preview-version.js Outdated Show resolved Hide resolved

unstubbable force-pushed the hl/fix-embedded-preview-version branch from ef3968f to b25058f Compare March 6, 2026 10:05

unstubbable added 2 commits March 6, 2026 11:16

Use lerna again for versioning

44a430d

Made possible by patching `allowBranch`.

Fix preview version step condition

06681c2

unstubbable force-pushed the hl/fix-embedded-preview-version branch from b25058f to 06681c2 Compare March 6, 2026 10:16

unstubbable requested a review from eps1lon March 6, 2026 10:25

eps1lon approved these changes Mar 6, 2026

View reviewed changes

unstubbable merged commit 87a8fb2 into canary Mar 6, 2026
287 of 291 checks passed

unstubbable deleted the hl/fix-embedded-preview-version branch March 6, 2026 11:30

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Fix preview version in `window.next.version` for PR builds#90937

Fix preview version in `window.next.version` for PR builds#90937
unstubbable merged 8 commits intocanaryfrom
hl/fix-embedded-preview-version

unstubbable commented Mar 5, 2026 •

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