fix(miniflare): expose send_email in platform proxy

[edmundhung]

Fixes #13715

This was not originally supported because email bindings relied on the EmailMessage class from cloudflare:email module, which is not available in the Node environment. Now that send_email supports the plain-object MessageBuilder interface, I think we should be able to enable this through the getPlatformProxy().

The local email binding previously used Miniflare's loopback server to write preview files. That deadlocks when called through the Node proxy, so this switches those file writes to a workerd disk service instead.

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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: bugfix

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

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[changeset-bot]

🦋 Changeset detected

Latest commit: 65a1eb5

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

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[workers-devprod]

Codeowners approval required for this PR:

• @cloudflare/wrangler

Show detailed file reviewers

• packages/miniflare/src/plugins/email/index.ts: [@cloudflare/wrangler]
• packages/miniflare/src/workers/email/send_email.worker.ts: [@cloudflare/wrangler]
• packages/miniflare/test/plugins/email/index.spec.ts: [@cloudflare/wrangler]
• packages/wrangler/e2e/dev.test.ts: [@cloudflare/wrangler]
• packages/wrangler/e2e/get-platform-proxy.test.ts: [@cloudflare/wrangler]

[github-actions]

Changeset Review

File Reviewed

.changeset/email-platform-proxy.md

Review Results

✅ All changesets look good

Summary

• Version Type: patch for miniflare - acceptable choice as this is exposing existing binding functionality that was missing from the platform proxy
• Changelog Quality: Clear description explaining the change and user impact
• Markdown Headers: No h1/h2/h3 headers found - passes formatting rule
• Usage Example: Includes helpful example showing the API usage pattern

The changeset effectively communicates that send_email bindings are now accessible via getPlatformProxy() for local Node development, resolving failures when calling env.EMAIL.send().

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[devin-ai-integration]

✅ Devin Review: No Issues Found

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[pkg-pr-new]

create-cloudflare

npm i https://pkg.pr.new/create-cloudflare@13723

@cloudflare/kv-asset-handler

npm i https://pkg.pr.new/@cloudflare/kv-asset-handler@13723

miniflare

npm i https://pkg.pr.new/miniflare@13723

@cloudflare/pages-shared

npm i https://pkg.pr.new/@cloudflare/pages-shared@13723

@cloudflare/unenv-preset

npm i https://pkg.pr.new/@cloudflare/unenv-preset@13723

@cloudflare/vite-plugin

npm i https://pkg.pr.new/@cloudflare/vite-plugin@13723

@cloudflare/vitest-pool-workers

npm i https://pkg.pr.new/@cloudflare/vitest-pool-workers@13723

@cloudflare/workers-editor-shared

npm i https://pkg.pr.new/@cloudflare/workers-editor-shared@13723

@cloudflare/workers-utils

npm i https://pkg.pr.new/@cloudflare/workers-utils@13723

wrangler

npm i https://pkg.pr.new/wrangler@13723

commit: 65a1eb5