fix: use connect_pass_through flag instead of workaround for TCP regression

[penalosa]

Fixes #9238.

This PR reverts the workaround from #9246 and implements the proper fix for the TCP connection regression by adding the connect_pass_through compatibility flag to the globalOutbound worker.

Background

• In Miniflare v4.15.0, a global outbound service was introduced to strip CF-Connecting-IP headers
• This triggered a bug in workerd where the connect() API and globalOutbound setting caused TCP ingress failures (issue Regression with TCP connections in 4.15.0 #9238)
• @edmundhung added a workaround in fix: strips CF-Connecting-IP header within Wrangler #9246 that disabled the global outbound approach and used a JavaScript injection instead
• @kentonv fixed the underlying issue in Implement connect_pass_through experimental compat flag. workerd#4171 by adding the connect_pass_through compatibility flag

Changes

1. Reverted the workaround: Used git revert d033a7da1 to cleanly remove Edmund's temporary fix
2. Added the proper fix: Include compatibilityFlags: ["connect_pass_through"] in the outbound service worker configuration in packages/miniflare/src/plugins/core/index.ts:840

Impact

• Fixes the TCP connection regression that was affecting local development
• Removes the temporary JavaScript injection workaround
• Uses the cleaner global outbound service approach as originally intended
• Requires workerd version that includes Implement connect_pass_through experimental compat flag. workerd#4171

---

• Tests
  • TODO (before merge)
  • Tests included
  • Tests not necessary because:
• Wrangler / Vite E2E Tests CI Job required? (Use "e2e" label or ask maintainer to run separately)
  • I don't know
  • Required
  • Not required because: only affects Miniflare internal worker configuration
• Public documentation
  • TODO (before merge)
  • Cloudflare docs PR(s):
  • Documentation not necessary because: internal implementation change, no user-facing API changes
• Wrangler V3 Backport
  • TODO (before merge)
  • Wrangler PR: Backport changes from #9506 #9618
  • Not necessary because:

🤖 Generated with Claude Code

[changeset-bot]

🦋 Changeset detected

Latest commit: 21f899f

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

This PR includes changesets to release 5 packages

Name	Type
miniflare	Patch
wrangler	Patch
@cloudflare/pages-shared	Patch
@cloudflare/vite-plugin	Patch
@cloudflare/vitest-pool-workers	Patch

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[pkg-pr-new]

create-cloudflare

npm i https://pkg.pr.new/create-cloudflare@9506

@cloudflare/kv-asset-handler

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miniflare

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@cloudflare/pages-shared

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@cloudflare/unenv-preset

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@cloudflare/vite-plugin

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@cloudflare/vitest-pool-workers

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@cloudflare/workers-editor-shared

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wrangler

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commit: 21f899f

[petebacondarwin]

Claude forgot a changeset

[penalosa]

The deleted test (packages/wrangler/src/__tests__/api/startDevWorker/startWorker.test.ts) was specifically testing the JavaScript injection workaround that we're removing. Since we now use the proper workerd compatibility flag fix, this test is no longer relevant. The CF-Connecting-IP functionality is already covered by the existing Miniflare tests.

[github-actions]

Failed to automatically backport this PR's changes to Wrangler v3. Please manually create a PR targeting the v3-maintenance branch with your changes. Thank you for helping us keep Wrangler v3 supported!

Depending on your changes, running git rebase --onto v3-maintenance main penalosa/use-new-compat-flag might be a good starting point.

Notes:

• your PR branch should be named v3-backport-9506
• add the skip-v3-pr label to the current PR to stop this workflow from failing