From 3e6786671e3cadd308ae6e7e19f13915574eeb60 Mon Sep 17 00:00:00 2001
From: Oskar Eichler <62393985+OskarEichler@users.noreply.github.com>
Date: Fri, 28 Aug 2026 16:04:08 +0300
Subject: [PATCH] fix: export and type the custom server extension class

---
 .changeset/export-base-server.md |  5 +++++
 lib/Server.js                    |  2 +-
 package.json                     |  6 ++++++
 scripts/finalize-cjs-build.mjs   | 15 ++++++++-------
 types/lib/Server.d.ts            |  4 +++-
 5 files changed, 23 insertions(+), 9 deletions(-)
 create mode 100644 .changeset/export-base-server.md

diff --git a/.changeset/export-base-server.md b/.changeset/export-base-server.md
new file mode 100644
index 0000000000..3dbbf729df
--- /dev/null
+++ b/.changeset/export-base-server.md
@@ -0,0 +1,5 @@
+---
+"webpack-dev-server": patch
+---
+
+Export the documented `BaseServer` extension class and accept its constructors in the public `webSocketServer.type` declaration.
diff --git a/lib/Server.js b/lib/Server.js
index 38577856c9..2b54d1ce21 100644
--- a/lib/Server.js
+++ b/lib/Server.js
@@ -138,7 +138,7 @@ function loadWebpackPeer() {
 
 /**
  * @typedef {object} WebSocketServerConfiguration
- * @property {("ws" | string | (() => WebSocketServerConfiguration))=} type type
+ * @property {("ws" | string | typeof import("./servers/BaseServer.js").default)=} type type
  * @property {Record<string, EXPECTED_ANY>=} options options
  */
 
diff --git a/package.json b/package.json
index 38fbb1dd59..2c3b186d88 100644
--- a/package.json
+++ b/package.json
@@ -20,6 +20,12 @@
       "default": "./lib/Server.js"
     },
     "./client/*": "./client/*",
+    "./lib/servers/BaseServer.js": {
+      "types": "./types/lib/servers/BaseServer.d.ts",
+      "import": "./lib/servers/BaseServer.js",
+      "require": "./dist/servers/BaseServer.js",
+      "default": "./lib/servers/BaseServer.js"
+    },
     "./package.json": "./package.json"
   },
   "main": "./dist/Server.js",
diff --git a/scripts/finalize-cjs-build.mjs b/scripts/finalize-cjs-build.mjs
index ef4b61c818..6a7ea31be0 100644
--- a/scripts/finalize-cjs-build.mjs
+++ b/scripts/finalize-cjs-build.mjs
@@ -12,9 +12,8 @@ import { fileURLToPath } from "node:url";
 //    files in `dist/` as CommonJS regardless of the package's root
 //    `"type": "module"`.
 // 2. Babel emits the loader as `exports.default`. Append the `module.exports`
-//    unwrap so `require("webpack-dev-server")` returns the `Server` class
-//    directly (parity with the pre-ESM `module.exports = Server`), while
-//    `.default` keeps pointing at it for interop.
+//    unwrap so the public Server and BaseServer entrypoints return their
+//    classes directly, while `.default` keeps pointing at them for interop.
 
 const CJS_DIR = path.resolve(
   path.dirname(fileURLToPath(import.meta.url)),
@@ -27,7 +26,9 @@ await writeFile(
   `${JSON.stringify({ type: "commonjs" }, null, 2)}\n`,
 );
 
-await appendFile(
-  path.join(CJS_DIR, "Server.js"),
-  "module.exports = exports.default;\nmodule.exports.default = exports.default;\n",
-);
+for (const entry of ["Server.js", "servers/BaseServer.js"]) {
+  await appendFile(
+    path.join(CJS_DIR, entry),
+    "module.exports = exports.default;\nmodule.exports.default = exports.default;\n",
+  );
+}
diff --git a/types/lib/Server.d.ts b/types/lib/Server.d.ts
index 476d53ea36..bf1bf008ee 100644
--- a/types/lib/Server.d.ts
+++ b/types/lib/Server.d.ts
@@ -157,7 +157,9 @@ export type WebSocketServerConfiguration = {
   /**
    * type
    */
-  type?: ("ws" | string | (() => WebSocketServerConfiguration)) | undefined;
+  type?:
+    | ("ws" | string | typeof import("./servers/BaseServer.js").default)
+    | undefined;
   /**
    * options
    */