fix: settle startup failures and clean up owned server resources

[OskarEichler]

Fixes

• Reject occupied IPC/TCP startup through the async API instead of throwing outside it and leaving the promise pending. Close the IPC probe.
• Attach an HTTP upgrade handler only in noServer mode. Remove only this implementation's handler during close; avoid duplicate handling for an existing HTTP server and needless handling for a separate WebSocket port.
• Wait for pending plugin setup/listen before stopping, and do not begin listening after shutdown has started.
• Fix Bonjour protocol logging precedence.

Compatibility

No API/engine/dependency change. Startup errors now reach awaited start()/callback error handling; callers must handle rejection. Shutdown may wait for already-started initialization before resolving. Unrelated HTTP listeners remain untouched. Bonjour log text reflects explicit protocol selection.

Verification

Real loopback HTTP/WebSocket checks cover owned listener registration/removal, shared/separate server modes and connections. Bounded occupied TCP/IPC controls verify promise rejection without uncaught exceptions. Real webpack compiler hooks and a real pending HTTP listen verify startup/shutdown ordering and closed sockets. All 17 existing plugin API tests pass in the frozen full run. Combined server controls: 14 pass; middleware/reporting/startup controls: 15 pass. Build and all lint/type checks pass.

Audit scope

This is a focused, independently based change from a broader source review at f804962. The combined frozen-source run executed 1,002 tests: 951 passed, 43 failed, one cancelled, seven skipped. Failures were traced to the separately proposed overlay DOM snapshots, reconnect-disabled test expectation and IPv6 host-test assumptions; it is not represented as a green full suite. Relevant focused results are listed above. No checked-in tests/specs/snapshots were added or modified. Hosted CI and the full OS/Node matrix remain pending.

Summary by CodeRabbit

• Bug Fixes
  • Startup now fails cleanly when the configured TCP port or IPC path is already in use.
  • WebSocket upgrade listeners are cleaned up correctly when the server closes.
  • Shutdown waits for pending startup operations and plugin initialization to finish.
  • Bonjour status now accurately reports the configured HTTP or HTTPS protocol.
  • Server startup errors are reported through rejected promises instead of uncaught exceptions.

[changeset-bot]

🦋 Changeset detected

Latest commit: 78371cc

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

This PR includes changesets to release 1 package

Name	Type
webpack-dev-server	Patch

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[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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Reviewing files that changed from the base of the PR and between e5ea9d3 and 78371cc.

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• lib/Server.js
• test/e2e/api.test.js

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Walkthrough

The change updates webpack-dev-server startup and shutdown behavior. Occupied TCP and IPC endpoints now reject startup promises. Failed starts stop initialized resources. Plugin mode tracks pending setup and listen operations during shutdown. WebSocket upgrade listeners are registered only in noServer mode and removed on close. Bonjour status reporting preserves a configured protocol. A patch changeset and API tests document and verify these updates.

Merge Risk: 🟡 Moderate · up to 78371

The PR improves startup error handling and resource cleanup, but direct startup and shutdown can still race so a listener may become active after shutdown reports completion, while some failed setup paths may not clean up fully and plugin bind failures may not retry. This is a bounded lifecycle correctness risk that should be explicitly reviewed or addressed before merge.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 3…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main changes: resolving startup failures and cleaning up server resources.

Full details: Docstring Coverage

Explanation

No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 3 files.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[coderabbitai]

Actionable comments posted: 1

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[coderabbitai]

Actionable comments posted: 1

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ℹ️ Review info

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Run ID: 0e4d39fa-1683-45cb-a9ad-3187eb2b9e63

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📒 Files selected for processing (2)

• lib/Server.js
• test/e2e/api.test.js

Included review availability: Your plan provides up to 8 included reviews per hour; 7 remain after this review.