feat: Cloudflare Vite plugin integration by teemingc · Pull Request #15627 · sveltejs/kit

teemingc · 2026-03-31T17:22:05Z

closes #10496
closes #13692
closes #1712
closes #2963
closes #13300
closes #1519

This PR removes support for Cloudflare Pages and integrates with the Cloudflare Vite plugin. Users can now:

Use runtime APIs and bindings locally/remotely during build and preview.
Deploy apps unbundled by default (bundling is no longer required; saving a build artifact works again)
Write a custom worker entrypoint

TODOs

export a fetch handler for adapter-cloudflare
analysis in workerd
prerender in workerd
think about what tests are needed
split the PR up into removing Cloudflare Pages support and adding the Cloudflare Vite plugin

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This reverts commit eaffa39.

changeset-bot · 2026-03-31T17:22:10Z

🦋 Changeset detected

Latest commit: 8970286

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

This PR includes changesets to release 1 package

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@sveltejs/adapter-cloudflare	Major

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svelte-docs-bot · 2026-03-31T17:22:38Z

Preview: https://svelte-dev-git-preview-kit-15627-svelte.vercel.app/

rdlogout · 2026-05-18T04:45:02Z

Do we have any timeline on this one?
2 week passed

teemingc · 2026-05-18T05:09:04Z

The team is currently focusing on Svelte async bugs, regressions, security fixes, and remote functions. Even if this were merged, it would have to wait until the whole of SvelteKit 3 is ready before release

teemingc · 2026-05-19T09:21:53Z

+	await expect(page.locator('#var')).toHaveText(`Var: ${prod_string}VAR`);
+});
+
+test('serves static assets with assets path prefix', async ({ page, request }) => {


Not really sure how to get this test passing in the Cloudflare environment. Vite doesn't enforce consumers to allow us to run arbitrary code during preview so an alternative might be to have process.env.SVELTEKIT_ASSETS as an override which we set before anything else starts?

…1 (steps 1-3) Steps 1-3 of docs/jazz-to-cloudflare-migration.md: - Provision D1 + per-show ShowRoom and singleton ShowDirectory Durable Object bindings in wrangler.jsonc; generate binding types (pnpm cf:types). - Switch SvelteKit to @sveltejs/adapter-cloudflare. Because the released adapter (pre sveltejs/kit#15627) writes its worker to wrangler's `main`, a second config (wrangler.adapter.jsonc) drives the adapter's output while the real wrangler.jsonc `main` is src/worker.ts — a custom entry that imports the built SvelteKit worker, re-exports the Durable Objects, and wraps fetch with @sentry/cloudflare. - Port server Sentry to @sentry/cloudflare; delete instrumentation.server.ts and the adapter-node tracing/instrumentation settings. - Move Better Auth off jazzAdapter to a per-request createAuth(env) factory using the Drizzle / drizzle-orm/d1 adapter. Hand-authored D1 schema (auth tables + registry: shows/showHosts/hostLinks) with a partial unique index enforcing one live show. drizzle-kit migrations applied to local D1. - DEV_AUTH-gated dev-auth bypass (/dev-login) seeding an admin and a viewer, minting real JWKS-signed JWTs (verified: admin is_admin:true, viewer false). - Repoint auth:schema/db:reset; drop auth:validate. Add cf:types/db:* scripts. Deviations (documented): raw Durable Objects + WebSocket Hibernation API instead of PartyServer; wrangler dev against the build is the DO-capable runtime loop instead of @cloudflare/vite-plugin's vite dev, which cannot run a custom DO-exporting worker entry with the current SvelteKit adapter. Jazz data path goes dark mid-migration (single branch, no dual-path), restored on the new stack in steps 4-5. check/lint/build all green; app + auth verified under wrangler dev via Chrome DevTools. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Links the two live upstream tracks: sveltejs/kit#15627 (adapter-cloudflare adopting @cloudflare/vite-plugin) and the Durable Object / Workflow export gap in cloudflare/workers-sdk#14013. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

badreddinesaadioui · 2026-06-10T13:13:44Z

tested this PR against a real production app: SvelteKit + a Durable Object (voice agent) exported from the same Worker, WebSockets, Workers AI with remote: true bindings, R2, and a handful of +server.ts endpoints. Today we use @oselvar/sveltekit-add-worker-exports to work around #1712, so this PR is exactly what we've been waiting for. Sharing results in case real-world feedback is useful at this stage.

Setup: installed via pkg.pr.new/@sveltejs/kit@15627 and pkg.pr.new/@sveltejs/adapter-cloudflare@15627, with vite@8.0.16, svelte@5.56.3, @sveltejs/vite-plugin-svelte@7, @cloudflare/vite-plugin@1.x, Node 22. Custom entrypoint per the new docs: main pointing at our own src/worker/index.ts that does import { fetch } from '@sveltejs/adapter-cloudflare/worker', re-exports the DO class, and export default { fetch }.

Findings, in the order we hit them:

vite build fails during the analysis phase:
```
Cannot find module 'SERVER' imported from node_modules/.vite-analyse/deps_ssr/@sveltejs_adapter-cloudflare_worker.js
```
Same error reported above by another tester. Root cause appears to be that when the custom entrypoint imports @sveltejs/adapter-cloudflare/worker, Vite's dep optimizer pre-bundles that module, and the adapter's resolver for the virtual SERVER/MANIFEST ids never runs against the optimized copy. Adding optimizeDeps.exclude: ['@sveltejs/adapter-cloudflare/worker'] in user config (both top-level and ssr) did not help; the analysis server seems to spin up its own config. Maybe the adapter should exclude its own /worker subpath from dep optimization. This currently blocks the custom-entrypoint flow entirely, and since a DO class can only be exported from main, it blocks every Durable Object use case, which is the headline feature for us.
vite dev fails before that with:
```
The following environment options are incompatible with the Cloudflare Vite plugin:
	- "ssr" environment: `resolve.external`: ["@floating-ui/dom","@iconify/types"]
```
We never set resolve.external; vite-plugin-svelte auto-externalizes those (transitive deps of common Svelte UI libs, @iconify/svelte and svooltip in our case). So dev fails out of the box for apps using ordinary component libraries. Workaround: adding them to ssr.noExternal, after which we hit ReferenceError: exports is not defined from the runner, presumably a CJS dep now being executed raw in workerd. We stopped there.
pkce-challenge (transitive dep of Cloudflare's own agents SDK via the MCP SDK) fails to resolve in the worker build: its exports map only has browser and node conditions, no default, so the workerd-conditions resolve finds nothing. Worked around with a resolve.alias to its browser build. Probably an ecosystem problem rather than this PR's, but anyone building a voice/agents app on Workers will hit it immediately.
Minor setup friction worth documenting for testers: the preview kit imports rolldown at config-load time but doesn't ship it, so on a fresh install the build dies with ERR_MODULE_NOT_FOUND: rolldown until you install it manually. And with Vite 7 still installed (peer range is ^8.0.0, npm only warns with --legacy-peer-deps), the failure mode is a confusing Could not find file "src/routes/.../+server.ts" in Vite manifest for every endpoint rather than a version error.

Happy to re-test on this app as the PR evolves; it exercises pretty much everything at once (DO + WebSockets + remote AI bindings + custom entrypoint), so it's a decent canary.

teemingc added 2 commits March 25, 2026 02:52

split cloudflare changes

eaffa39

Revert "split cloudflare changes"

32054c0

This reverts commit eaffa39.

teemingc added the pkg:adapter-cloudflare label Mar 31, 2026

teemingc added 2 commits April 1, 2026 04:58

Merge branch 'fetchable-dev-environment' into cloudflare-vite-plugin

85ec266

wip

f3ee124

This was referenced Apr 5, 2026

feat: Vite environment API #14008

Closed

feature request: vite plugin with sveltekit cloudflare/workers-sdk#8922

Closed

teemingc added 6 commits April 6, 2026 18:12

fix

7e69296

Merge branch 'fetchable-dev-environment' into cloudflare-vite-plugin

83c5f60

fix

b202c77

wip

499a5c6

Merge branch 'fetchable-dev-environment' into cloudflare-vite-plugin

8696080

Merge branch 'fetchable-dev-environment' into cloudflare-vite-plugin

bf45653

teemingc added 6 commits April 8, 2026 02:49

docs

49b5bb6

wip

261a46a

bump cloudflare plugin

f181570

fix style inlining in workerd

3edc662

format

192dfe6

migration docs

79d04d5

teemingc added the breaking change label Apr 13, 2026

teemingc added 2 commits April 15, 2026 01:42

wip

8c990a2

i think its done now i just need to test

e1d7ea7

teemingc added 6 commits May 8, 2026 00:56

fix test

29e1666

Merge branch 'fetchable-dev-environment' into cloudflare-vite-plugin

305ddba

fix prerendering

3fed050

dedupe

42943b3

add todo

acb4167

don't need this now that we have an assets only test app

0665a78

teemingc added 5 commits May 19, 2026 14:58

add tests

9f21291

Merge branch 'fetchable-dev-environment' into cloudflare-vite-plugin

df106c9

add paths.assets

0fbf415

don't need service worker test

4a8670d

bump

57b2e70

teemingc commented May 19, 2026

View reviewed changes

teemingc added 4 commits May 19, 2026 17:28

Merge branch 'fetchable-dev-environment' into cloudflare-vite-plugin

ca9e964

changeset

b7686c1

changeset

f4b1d3c

Merge branch 'fetchable-dev-environment' into cloudflare-vite-plugin

30d1cda

teemingc linked an issue May 22, 2026 that may be closed by this pull request

adapter-cloudflare: wrangler.json vars not available via $env/dynamic/private during dev #15736

Open

teemingc added 3 commits May 25, 2026 03:20

Merge branch 'fetchable-dev-environment' into cloudflare-vite-plugin

3062a74

Merge branch 'fetchable-dev-environment' into cloudflare-vite-plugin

012a59a

Merge branch 'fetchable-dev-environment' into cloudflare-vite-plugin

f99a1cf

teemingc added 2 commits May 29, 2026 02:44

Merge branch 'fetchable-dev-environment' into cloudflare-vite-plugin

dbd7d03

Merge branch 'fetchable-dev-environment' into cloudflare-vite-plugin

8970286

basuke mentioned this pull request Jun 5, 2026

adapter-cloudflare on Vite 8 (Rolldown): worker fails to start with createRequire(import.meta.url) when a CJS dep uses a Node builtin #15960

Open

teemingc linked an issue Jun 6, 2026 that may be closed by this pull request

adapter-cloudflare on Vite 8 (Rolldown): worker fails to start with createRequire(import.meta.url) when a CJS dep uses a Node builtin #15960

Open

teemingc linked an issue Jun 15, 2026 that may be closed by this pull request

Add a boolean to mark prerenderable routes #14493

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