[wrangler] Support named-only module Workers in dev

[taylorlee]

The middleware facade only wraps the default entrypoint and re-exports named entrypoints unchanged, so skipping it for named-only modules preserves existing behavior while avoiding an invalid default import.

The regression test waits for the Worker runtime to reload and fails on build errors because worker.ready only indicates that the proxy server started and can resolve after a recoverable bundling failure.

Followup to #15518

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• Tests
  • Tests included/updated
  • Automated tests not possible - manual testing has been completed as follows:
  • Additional testing not necessary because:
• Public documentation
  • Cloudflare docs PR(s):
  • Documentation not necessary because: I have a docs pr drafted but wanted to fix any known issues in tooling here first. Docs will also only simplify the superfluous default exports for entrypoint examples, nothing needed to document for this to start working.

A picture of a cute animal (not mandatory, but encouraged)

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[changeset-bot]

🦋 Changeset detected

Latest commit: 226a196

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

This PR includes changesets to release 3 packages

Name	Type
wrangler	Patch
@cloudflare/vite-plugin	Patch
@cloudflare/vitest-plugin	Patch

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[workers-devprod]

Codeowners approval required for this PR:

• @cloudflare/wrangler

Show detailed file reviewers

• .changeset/calm-counters-develop.md: [@cloudflare/wrangler]
• packages/wrangler/e2e/multiworker-dev.test.ts: [@cloudflare/wrangler]
• packages/wrangler/src/tests/middleware.test.ts: [@cloudflare/wrangler]
• packages/wrangler/src/deployment-bundle/apply-middleware.ts: [@cloudflare/wrangler]
• packages/wrangler/src/deployment-bundle/bundle.ts: [@cloudflare/wrangler]
• packages/wrangler/templates/middleware/middleware-patch-console-prefix.ts: [@cloudflare/wrangler]

[ask-bonk]

I'm Bonk, and I've done a quick review of your PR.

Adds named-only module Worker support in local development.

1. P2: Named-only Workers lose multi-worker console prefixes. Posted one suggestion comment.

github run

[pkg-pr-new]

@cloudflare/autoconfig

npm i https://pkg.pr.new/@cloudflare/autoconfig@15611

@cloudflare/build-output-utils

npm i https://pkg.pr.new/@cloudflare/build-output-utils@15611

@cloudflare/codemods

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@cloudflare/config

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@cloudflare/containers-shared

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create-cloudflare

npm i https://pkg.pr.new/create-cloudflare@15611

@cloudflare/deploy-helpers

npm i https://pkg.pr.new/@cloudflare/deploy-helpers@15611

@cloudflare/kv-asset-handler

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miniflare

npm i https://pkg.pr.new/miniflare@15611

@cloudflare/pages-functions

npm i https://pkg.pr.new/@cloudflare/pages-functions@15611

@cloudflare/pages-shared

npm i https://pkg.pr.new/@cloudflare/pages-shared@15611

@cloudflare/unenv-preset

npm i https://pkg.pr.new/@cloudflare/unenv-preset@15611

@cloudflare/vite-plugin

npm i https://pkg.pr.new/@cloudflare/vite-plugin@15611

@cloudflare/vitest-plugin

npm i https://pkg.pr.new/@cloudflare/vitest-plugin@15611

@cloudflare/workers-auth

npm i https://pkg.pr.new/@cloudflare/workers-auth@15611

@cloudflare/workers-editor-shared

npm i https://pkg.pr.new/@cloudflare/workers-editor-shared@15611

@cloudflare/workers-utils

npm i https://pkg.pr.new/@cloudflare/workers-utils@15611

wrangler

npm i https://pkg.pr.new/wrangler@15611

commit: 226a196

[petebacondarwin]

packages/wrangler/src/deployment-bundle/apply-middleware.ts:R32-38

Export changes break watched rebuilds

After a running Worker adds or removes its default export, entry.exports remains the startup snapshot during watched rebuilds. The stale value regenerates the invalid facade or skips required development middleware, so the edited Worker cannot reload correctly.

Wrangler computes entry.exports while resolving the entrypoint, before starting the esbuild watch context. Each source edit rebuilds through #startBundle with that same Entry; esbuild does not rerun the facade-selection code with updated exports. Removing the default export therefore leaves "default" in the snapshot and recreates the facade that this change intends to avoid. Adding a default export to a named-only Worker leaves the snapshot named-only and keeps request-body draining, scheduled testing, and local error middleware disabled.

Example: Start wrangler dev with export default { fetch() {} }, then replace it with export class Api extends WorkerEntrypoint {}. The watch rebuild still treats the module as having a default export and fails on the generated default import instead of loading Api.

Recommended fix: Derive facade eligibility from each build's current export metadata, or restart/reconfigure the bundle when the entrypoint's export shape changes. Add watch-mode tests for both default-to-named-only and named-only-to-default edits.

[petebacondarwin]

Changeset exposes internal implementation
The second paragraph discusses the middleware facade and generated imports. REVIEW.md requires changesets to describe user-facing impact instead of internal implementation.