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fix: yield to allow prerender updates to be visible - #16748

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Rich-Harris merged 4 commits into
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fix-prerender-logging
Aug 12, 2026
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fix: yield to allow prerender updates to be visible#16748
Rich-Harris merged 4 commits into
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fix-prerender-logging

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follow-up to #16744 — turns out we need this or stdout can buffer updates for long enough that progress appears stalled.

before:

logging-before.mov

after:

logging-after.mov

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Install the latest version of @sveltejs/kit from fc53a3f:

pnpm add https://pkg.svelte.dev/@sveltejs/kit/c/fc53a3f683f403388167257784b0ee16986119c3

Open in pkg.svelte.dev: https://pkg.svelte.dev/repos/kit/pr/16748

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🦋 Changeset detected

Latest commit: fc53a3f

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package
Name Type
@sveltejs/kit Patch

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Click here if you're a maintainer who wants to add another changeset to this PR

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@Nic-Polumeyv Nic-Polumeyv left a comment

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separately: nothing clears the last rendering /x line after q.done(), so the build still ends looking stuck through the manifest/adapter steps

Comment thread packages/kit/src/core/postbuild/prerender.js Outdated
Comment thread packages/kit/src/core/postbuild/prerender.js Outdated
Rich-Harris and others added 3 commits August 12, 2026 09:07
Co-authored-by: Nic Polumeyv <nicolas.polum@outlook.com>
@Rich-Harris
Rich-Harris merged commit 1e0fcc9 into version-3 Aug 12, 2026
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@Rich-Harris
Rich-Harris deleted the fix-prerender-logging branch August 12, 2026 14:06
Rich-Harris pushed a commit that referenced this pull request Aug 12, 2026
…s line (#16750)

If app code writes to stdout without a trailing newline during
prerendering on a TTY, the next progress line lands on the same row and
the update after that clears the row:

```
rendering /partial...
rendering /dynamic/foo...   <- app output destroyed
```

The write proxies now track whether the last chunk ended mid-line, and
the progress line starts a fresh row instead:

```
rendering /partial...
IMPORTANT APP OUTPUT (no newline)
rendering /dynamic/foo...
```

surfaced while reviewing #16748
Rich-Harris pushed a commit that referenced this pull request Aug 12, 2026
This PR was opened by the [Changesets
release](https://github.com/changesets/action) GitHub action. When
you're ready to do a release, you can merge this and the packages will
be published to npm automatically. If you're not ready to do a release
yet, that's fine, whenever you add more changesets to version-3, this PR
will be updated.

⚠️⚠️⚠️⚠️⚠️⚠️

`version-3` is currently in **pre mode** so this branch has prereleases
rather than normal releases. If you want to exit prereleases, run
`changeset pre exit` on `version-3`.

⚠️⚠️⚠️⚠️⚠️⚠️

# Releases
## @sveltejs/kit@3.0.0-next.21

### Major Changes

- breaking: move remote function types and `isValidationError` to
`@sveltejs/kit/remote`
([#16764](#16764))

- breaking: move `RequestEvent` and `Cookies` to `$app/server`
([#16751](#16751))

### Patch Changes

- fix: correctly implement Vite plugin hook filters
([#16760](#16760))

- fix: yield to allow prerender updates to be visible
([#16748](#16748))

- fix: don't destroy partial-line app output with the prerender progress
line ([#16750](#16750))
## @sveltejs/package@3.0.0-next.7

### Patch Changes

- chore: bump `svelte2tsx` to 0.7.60
([#16745](#16745))

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
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3 participants