fix: prerender pages adjacent to endpoints by aenriii · Pull Request #15621 · sveltejs/kit

aenriii · 2026-03-30T15:38:25Z

This PR addresses #15620, and adds tests for any possible regressions as a result of the implemented fix. (edit: seems to also fix #10735)

Changes:

modified kit/src/core/postbuild/analyse.js to add additional metadata fields to route metadata, page.prerender and api.prerender, which pass on the page and endpoint prerender fields. this prevents a regression which forces all parts of a route to prerender even if only one part requests it.
modified kit/src/core/postbuild/prerender.js to check if page.prerender and api.prerender is true, and enqueue prerendering if so. uses \x00page as a postfix to page keys within the preexisting seen set to differentiate between api endpoints and pages.
modified kit/src/core/postbuild/prerender.js, added and documented expect_html parameter in visit() and enqueue() to specify that the Accept: text/html header should be sent to the internal server when prerendering a page.
implemented two tests in prerendering/basics, one which tests the fix itself (see prerender-with-server-endpoint) and one which confirms the non-existence of a possible regression (see linked-api). both tests pass with flying colors :D

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changeset-bot · 2026-03-30T15:38:30Z

🦋 Changeset detected

Latest commit: 116467f

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svelte-docs-bot · 2026-04-05T01:17:09Z

Preview: https://svelte-dev-git-preview-kit-15621-svelte.vercel.app/

aenriii · 2026-04-05T02:55:18Z

regressions fixed, should also close #10735

teemingc · 2026-05-17T16:19:19Z

+	assert.isTrue(fs.existsSync(`${build}/get-and-post.html`));
+});
+
+test('prerendering a page with a linked GET server endpoint processes properly', () => {


This test passes even without the PR's fix. Do we really need it? Even if the endpoint wasn't discovered while crawling the page, the prerenderer would prerender the endpoint because it detects the exported prerender page option during analysis.

I mean I see no harm done in keeping it, I put it there in part because I knew my code changed the behavior there and I wanted to be sure that there was no regression happening on my behalf. Fully up to yall.

teemingc

Thanks! This is looking good. I just have two concerns which I've outlined in the files changed.

…mes to conform

…eeded to be truthy

suggested change by sveltekit contributors! Co-authored-by: Tee Ming <chewteeming01@gmail.com>

Co-authored-by: Tee Ming <chewteeming01@gmail.com>

aenriii · 2026-05-26T11:44:59Z

hit the big "rebase to sveltejs:main" button and nothing broke, supposedly looks good?

Routes with content negotiation cannot be prerendered. This may potentially be fixed by sveltejs/kit#15621

Rich-Harris · 2026-06-17T22:51:56Z

This doesn't seem right to me. Surely if a route has both a +page and a +server prerendering just should fail outright?

teemingc · 2026-06-18T06:24:23Z

Closing in favour of #16075

…erenderable (#16075) I'm pretty sure this, and not #15621, is the desired behaviour. Closes #15620 --- ### Please don't delete this checklist! Before submitting the PR, please make sure you do the following: - [x] It's really useful if your PR references an issue where it is discussed ahead of time. In many cases, features are absent for a reason. For large changes, please create an RFC: https://github.com/sveltejs/rfcs - [x] This message body should clearly illustrate what problems it solves. - [ ] Ideally, include a test that fails without this PR but passes with it. ### Tests - [x] Run the tests with `pnpm test` and lint the project with `pnpm lint` and `pnpm check` ### Changesets - [x] If your PR makes a change that should be noted in one or more packages' changelogs, generate a changeset by running `pnpm changeset` and following the prompts. Changesets that add features should be `minor` and those that fix bugs should be `patch`. Please prefix changeset messages with `feat:`, `fix:`, or `chore:`. ### Edits - [x] Please ensure that 'Allow edits from maintainers' is checked. PRs without this option may be closed.

aenriii changed the title ~~fix: prerender no longer silently fails pertinent to #15620~~ fix: prerender no longer silently ignores webpages pertinent to #15620 Mar 30, 2026

aenriii added a commit to lvehrt/openrx.info that referenced this pull request Apr 1, 2026

patchwork solution until sveltejs/kit#15621 is merged

fca9025

aenriii mentioned this pull request Apr 5, 2026

Prerendering ignores webpages if a +server file exists in the same route, regardless of who exports prerender = true #15620

Closed

teemingc changed the title ~~fix: prerender no longer silently ignores webpages pertinent to #15620~~ fix: prerender pages adjacent to endpoints without exported GET May 6, 2026

teemingc reviewed May 6, 2026

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