fix: export and type the custom server extension class

[OskarEichler]

Fixes

• Export the documented webpack-dev-server/lib/servers/BaseServer.js extension point for ESM, CommonJS and TypeScript consumers.
• Unwrap the CommonJS class consistently with the main Server entrypoint, retaining .default interoperability.
• Type webSocketServer.type as a constructor extending BaseServer instead of a zero-argument callable returning a configuration object.

Compatibility

Restores the documented extension path blocked by the v6 export map. No runtime/engine/dependency removal. The declaration now accepts the class actually instantiated at runtime; invalid callable factories may require correction to constructible classes.

Verification

Unchanged v6 export map reproduces ERR_PACKAGE_PATH_NOT_EXPORTED. Real ESM and CommonJS subclasses construct successfully; CommonJS default interop is retained. Strict NodeNext TypeScript consumer accepts a custom subclass in webSocketServer configuration. Build and full lint/types/spelling/formatting 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

• New Features
  • Exported the BaseServer class as a public package entry point.
  • WebSocket server configuration now accepts custom server class constructors.
  • Added TypeScript declarations for the new public export.
  • Improved CommonJS imports so server classes are returned directly.

[changeset-bot]

🦋 Changeset detected

Latest commit: 3e67866

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

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

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[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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Plan: Pro Plus

Run ID: 16698ef9-66c1-4e92-b60c-1cc7fac4071a

📥 Commits

Reviewing files that changed from the base of the PR and between f804962 and 3e67866.

📒 Files selected for processing (5)

• .changeset/export-base-server.md
• lib/Server.js
• package.json
• scripts/finalize-cjs-build.mjs
• types/lib/Server.d.ts

Included review availability: Your plan provides up to 8 included reviews per hour; 2 remain after this review.

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Walkthrough

The change adds a package export for BaseServer with declaration, ESM, CommonJS, and default targets. The WebSocket server configuration type now accepts a BaseServer class constructor. The CommonJS finalization script unwraps both Server.js and servers/BaseServer.js so each entrypoint returns its class directly. A changeset documents these public API updates.

Merge Risk: ⚪ Minimal · up to 3e678

The PR restores the documented custom server extension path and aligns its TypeScript declaration with the existing runtime constructor behavior. No actionable merge-blocking risk remains beyond normal checks and review.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main changes: exporting and typing the custom server extension class.
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.

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. (2 skipped: 2 unsupported.)

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

Warning

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🔧 ESLint

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lib/Server.js

ESLint failed to execute (timeout).

package.json

ESLint skipped: the matched ESLint configuration already failed (timeout).

scripts/finalize-cjs-build.mjs

ESLint skipped: the matched ESLint configuration already failed (timeout).

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[bjohansebas]

That would be a minor, but honestly, I’m not sure it’s necessary. What’s your use case?

[OskarEichler]

The use case targeted here is a TypeScript/ESM consumer providing webSocketServer.type as a custom class that extends the documented BaseServer. Today that requires a deep import of an unexported CommonJS file, and the public type models the extension as a zero-argument factory instead of a constructor. The export and type change make the documented extension point usable without a private-path import.