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
Disclaimer: This PR is entirely claude+opencode generated.
- Crate name said `next-swc-napi`, which was confusing, because this has a lot more than swc bindings nowdays.
- The crate name didn't match the directory name, which often confused agents.
This does not change the npm package name, as that would likely have a much larger blast radius, and could break more things, to a point where it may not be worth it.
This updates our workflow for testing new tests against deploy mode to
allow running against forks as we don't want to introduce flakey tests
in this mode even if opened from forks.
Sebastian "Sebbie" Silbermann