Fix "Cannot perform I/O on behalf of a different request" errors for deferred dynamic imports

[jamesopstad]

Fixes #12731.

Fix Cannot perform I/O on behalf of a different request errors for deferred dynamic imports

Concurrent requests that loaded the same dynamic import were previously sharing the same promise to resolve it in a Worker context. We now ensure that all imports execute within a Durable Object's IoContext before the result is returned to the Worker.

This PR also revises and improves the module runner implementation more generally. We now only use public Vite APIs.

---

• Tests
  • Tests included/updated
  • Automated tests not possible - manual testing has been completed as follows: tested with overlapping HMR updates and browser requests in Waku, TanStack Start and React Router.
  • Additional testing not necessary because:
• Public documentation
  • Cloudflare docs PR(s):
  • Documentation not necessary because: bug fix

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

---

[changeset-bot]

🦋 Changeset detected

Latest commit: 3a001b3

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

Not sure what this means? Click here to learn what changesets are.

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

[pkg-pr-new]

create-cloudflare

npm i https://pkg.pr.new/create-cloudflare@12953

@cloudflare/kv-asset-handler

npm i https://pkg.pr.new/@cloudflare/kv-asset-handler@12953

miniflare

npm i https://pkg.pr.new/miniflare@12953

@cloudflare/pages-shared

npm i https://pkg.pr.new/@cloudflare/pages-shared@12953

@cloudflare/unenv-preset

npm i https://pkg.pr.new/@cloudflare/unenv-preset@12953

@cloudflare/vite-plugin

npm i https://pkg.pr.new/@cloudflare/vite-plugin@12953

@cloudflare/vitest-pool-workers

npm i https://pkg.pr.new/@cloudflare/vitest-pool-workers@12953

@cloudflare/workers-editor-shared

npm i https://pkg.pr.new/@cloudflare/workers-editor-shared@12953

wrangler

npm i https://pkg.pr.new/wrangler@12953

commit: 3a001b3

[github-actions]

✅ All changesets look good

[workers-devprod]

Codeowners approval required for this PR:

• ✅ @cloudflare/wrangler

Show detailed file reviewers

[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no potential bugs to report.

View in Devin Review to see 5 additional findings.

[penalosa]

I'm not super familiar with the internals of Vite's module runner, so this should probably also get a review from someone else more familiar with Vite. However, this is the same fix as Vitest needs, and that bit seems accurate to what I'd expect, so approving from that perspective.