test: add test

Drain queue before emitting connect event
fix(sio-client): do not mangle the "_placeholder" attribute (bis)
2026-01-12 08:27:57 -05:00 · 2025-12-22 10:24:29 +01:00 · 2025-12-22 09:58:31 +01:00 · 2025-12-19 15:48:28 +01:00 · 2025-12-19 15:43:14 +01:00 · 2025-12-19 14:51:39 +01:00
65 changed files with 9207 additions and 2445 deletions
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -49,10 +49,10 @@ jobs:

    steps:
      - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6

      - name: Use Node.js ${{ matrix.node-version }}
-        uses: actions/setup-node@v4
+        uses: actions/setup-node@v6
        with:
          node-version: ${{ matrix.node-version }}

--- a/.github/workflows/publish.yml
+++ b/.github/workflows/publish.yml
@@ -1,4 +1,4 @@
-# reference: https://docs.npmjs.com/generating-provenance-statements
+# reference: https://docs.npmjs.com/trusted-publishers#for-github-actions

 name: Publish

@@ -32,6 +32,4 @@ jobs:
        run: npm run compile --workspaces --if-present

      - name: Publish package
-        run: npm publish --workspace=${GITHUB_REF_NAME%@*} --provenance --access public
-        env:
-          NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }}
+        run: npm publish --workspace=${GITHUB_REF_NAME%@*} --access public
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,14 +2,17 @@

 Here are the detailed changelogs for each package in this monorepo:

-| Package                        | Changelog                                               |
-|--------------------------------|---------------------------------------------------------|
-| `engine.io`                    | [link](packages/engine.io/CHANGELOG.md)                 |
-| `engine.io-client`             | [link](packages/engine.io-client/CHANGELOG.md)          |
-| `engine.io-parser`             | [link](packages/engine.io-parser/CHANGELOG.md)          |
-| `socket.io`                    | [link](packages/socket.io/CHANGELOG.md)                 |
-| `socket.io-adapter`            | [link](packages/socket.io-adapter/CHANGELOG.md)         |
-| `socket.io-client`             | [link](packages/socket.io-client/CHANGELOG.md)          |
-| `@socket.io/cluster-engine`    | [link](packages/socket.io-cluster-engine/CHANGELOG.md)  |
-| `@socket.io/component-emitter` | [link](packages/socket.io-component-emitter/History.md) |
-| `socket.io-parser`             | [link](packages/socket.io-parser/CHANGELOG.md)          |
+| Package                            | Changelog                                                      |
+|------------------------------------|----------------------------------------------------------------|
+| `engine.io`                        | [link](packages/engine.io/CHANGELOG.md)                        |
+| `engine.io-client`                 | [link](packages/engine.io-client/CHANGELOG.md)                 |
+| `engine.io-parser`                 | [link](packages/engine.io-parser/CHANGELOG.md)                 |
+| `socket.io`                        | [link](packages/socket.io/CHANGELOG.md)                        |
+| `socket.io-adapter`                | [link](packages/socket.io-adapter/CHANGELOG.md)                |
+| `socket.io-client`                 | [link](packages/socket.io-client/CHANGELOG.md)                 |
+| `@socket.io/cluster-adapter`       | [link](packages/socket.io-cluster-adapter/CHANGELOG.md)        |
+| `@socket.io/cluster-engine`        | [link](packages/socket.io-cluster-engine/CHANGELOG.md)         |
+| `@socket.io/component-emitter`     | [link](packages/socket.io-component-emitter/History.md)        |
+| `socket.io-parser`                 | [link](packages/socket.io-parser/CHANGELOG.md)                 |
+| `@socket.io/postgres-emitter`      | [link](packages/socket.io-postgres-emitter/CHANGELOG.md)       |
+| `@socket.io/redis-streams-emitter` | [link](/packages/socket.io-redis-streams-emitter/CHANGELOG.md) |
--- a/examples/basic-websocket-client/package.json
+++ b/examples/basic-websocket-client/package.json
@@ -7,7 +7,7 @@
    "prettier": "^2.8.4",
    "rollup": "^3.20.2",
    "socket.io": "^4.6.1",
-    "ws": "^8.13.0"
+    "ws": "^8.18.3"
  },
  "scripts": {
    "bundle": "rollup -c",
--- a/package-lock.json
+++ b/package-lock.json
--- a/package.json
+++ b/package.json
@@ -8,15 +8,17 @@
    "packages/socket.io-cluster-engine",
    "packages/engine.io-client",
    "packages/socket.io-adapter",
+    "packages/socket.io-cluster-adapter",
    "packages/socket.io-parser",
    "packages/socket.io-client",
    "packages/socket.io",
-    "packages/socket.io-postgres-emitter"
+    "packages/socket.io-postgres-emitter",
+    "packages/socket.io-redis-streams-emitter"
  ],
  "overrides": {
    "@types/estree": "0.0.52",
    "@types/lodash": "4.14.189",
-    "ws": "8.17.1"
+    "ws": "8.18.3"
  },
  "devDependencies": {
    "@babel/core": "^7.24.7",
@@ -31,6 +33,7 @@
    "@rollup/plugin-node-resolve": "^15.2.3",
    "@sinonjs/fake-timers": "^11.2.2",
    "@socket.io/postgres-adapter": "^0.1.0",
+    "@socket.io/redis-streams-adapter": "~0.2.2",
    "@types/debug": "^4.1.12",
    "@types/expect.js": "^0.3.32",
    "@types/mocha": "^10.0.7",
@@ -73,6 +76,7 @@
    "ts-loader": "^9.5.1",
    "ts-node": "^10.9.2",
    "tsd": "^0.31.1",
+    "tsx": "~4.20.6",
    "typescript": "^5.5.3",
    "uWebSockets.js": "github:uNetworking/uWebSockets.js#v20.48.0",
    "wdio-geckodriver-service": "^5.0.2"
--- a/packages/engine.io-client/lib/transport.ts
+++ b/packages/engine.io-client/lib/transport.ts
@@ -192,7 +192,7 @@ export abstract class Transport extends Emitter<
  private _port() {
    if (
      this.opts.port &&
-      ((this.opts.secure && Number(this.opts.port !== 443)) ||
+      ((this.opts.secure && Number(this.opts.port) !== 443) ||
        (!this.opts.secure && Number(this.opts.port) !== 80))
    ) {
      return ":" + this.opts.port;
--- a/packages/engine.io-client/package.json
+++ b/packages/engine.io-client/package.json
@@ -53,9 +53,9 @@
  ],
  "dependencies": {
    "@socket.io/component-emitter": "~3.1.0",
-    "debug": "~4.3.1",
+    "debug": "~4.4.1",
    "engine.io-parser": "~5.2.1",
-    "ws": "~8.17.1",
+    "ws": "~8.18.3",
    "xmlhttprequest-ssl": "~2.1.1"
  },
  "scripts": {
--- a/packages/engine.io-client/test/transport.js
+++ b/packages/engine.io-client/test/transport.js
@@ -116,6 +116,32 @@ describe("Transport", () => {
      expect(polling.uri()).to.contain("https://localhost/engine.io?sid=test");
    });

+    it("should generate an https uri w/o a port (string)", () => {
+      const polling = new eio.transports.polling({
+        path: "/engine.io",
+        hostname: "localhost",
+        secure: true,
+        query: { sid: "test" },
+        port: "443",
+        timestampRequests: false,
+      });
+      expect(polling.uri()).to.contain("https://localhost/engine.io?sid=test");
+    });
+
+    it("should generate an https uri with a port", () => {
+      const polling = new eio.transports.polling({
+        path: "/engine.io",
+        hostname: "localhost",
+        secure: true,
+        query: { sid: "test" },
+        port: 8443,
+        timestampRequests: false,
+      });
+      expect(polling.uri()).to.contain(
+        "https://localhost:8443/engine.io?sid=test",
+      );
+    });
+
    it("should generate a timestamped uri", () => {
      const polling = new eio.transports.polling({
        path: "/engine.io",
--- a/packages/engine.io/package.json
+++ b/packages/engine.io/package.json
@@ -37,9 +37,9 @@
    "base64id": "2.0.0",
    "cookie": "~0.7.2",
    "cors": "~2.8.5",
-    "debug": "~4.3.1",
+    "debug": "~4.4.1",
    "engine.io-parser": "~5.2.1",
-    "ws": "~8.17.1"
+    "ws": "~8.18.3"
  },
  "scripts": {
    "compile": "rimraf ./build && tsc",
--- a/packages/engine.io/test/fixtures/ca.crt
+++ b/packages/engine.io/test/fixtures/ca.crt
@@ -1,33 +1,19 @@
 -----BEGIN CERTIFICATE-----
-MIIFtTCCA52gAwIBAgIJAJKBPV3nMXjsMA0GCSqGSIb3DQEBBQUAMEUxCzAJBgNV
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 -----END CERTIFICATE-----
--- a/packages/engine.io/test/fixtures/ca.key
+++ b/packages/engine.io/test/fixtures/ca.key
@@ -1,51 +1,28 @@
-----BEGIN RSA PRIVATE KEY-----
-MIIJKQIBAAKCAgEAmNWKTumE1f+ptArhPTOcaUReoqBlri/ujIzm1N8Qr0hghS6B
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-----END RSA PRIVATE KEY-----
+-----BEGIN PRIVATE KEY-----
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+-----END PRIVATE KEY-----
--- a/packages/engine.io/test/fixtures/ca.key.org
+++ b/packages/engine.io/test/fixtures/ca.key.org
@@ -1,54 +0,0 @@
-----BEGIN RSA PRIVATE KEY-----
-Proc-Type: 4,ENCRYPTED
-DEK-Info: DES-EDE3-CBC,47A0291BAB679B36
-
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-----END RSA PRIVATE KEY-----
--- a/packages/engine.io/test/fixtures/client.crt
+++ b/packages/engine.io/test/fixtures/client.crt
@@ -1,22 +1,17 @@
 -----BEGIN CERTIFICATE-----
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 -----END CERTIFICATE-----
--- a/packages/engine.io/test/fixtures/client.csr
+++ b/packages/engine.io/test/fixtures/client.csr
@@ -1,12 +1,15 @@
 -----BEGIN CERTIFICATE REQUEST-----
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 -----END CERTIFICATE REQUEST-----
--- a/packages/engine.io/test/fixtures/client.key
+++ b/packages/engine.io/test/fixtures/client.key
@@ -1,15 +1,28 @@
-----BEGIN RSA PRIVATE KEY-----
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-----END RSA PRIVATE KEY-----
+-----BEGIN PRIVATE KEY-----
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+VNurVfn19LNgoLisW5c9tEs=
+-----END PRIVATE KEY-----
--- a/packages/engine.io/test/fixtures/client.key.orig
+++ b/packages/engine.io/test/fixtures/client.key.orig
@@ -1,18 +0,0 @@
-----BEGIN RSA PRIVATE KEY-----
-Proc-Type: 4,ENCRYPTED
-DEK-Info: DES-EDE3-CBC,081B123E7DBC9687
-
-c8gE0LQMMtV7GhUcP7GHBotlNNAsbyG/gERB//BFlvRPjs43ALvm5xMGUkcsZkw9
-H6ljvvgyRkud06x1mGxqlZ4fLlty0/mdXf6791R9gA/9bKLakHGlwnoVUrEPIeh3
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-NW36xgDNSQoia2splVNo51vtZomq1Hb3co6hD43D4xnrc6Aqucm3BsW6UCc/PVKv
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-QeYPihCi66F6Vuq/QT89dHtZE4IMPH7R95Yp18tCcyVGxaEiphw3HJYepMxoJesQ
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-VKsQByBwJlEo/YSEFjhhMgo0zSbqIRAY1XCDo+dgB2IB1KPAobhSCQ==
-----END RSA PRIVATE KEY-----
--- a/packages/engine.io/test/fixtures/client.pfx
+++ b/packages/engine.io/test/fixtures/client.pfx
--- a/packages/engine.io/test/fixtures/generate_certs.sh
+++ b/packages/engine.io/test/fixtures/generate_certs.sh
@@ -0,0 +1,22 @@
+#!/bin/bash
+
+# Generate CA private key and certificate
+openssl genrsa -out ca.key 2048
+openssl req -x509 -new -nodes -key ca.key -days 365 -out ca.crt -subj "/CN=Test CA"
+
+# Generate server key and certificate request
+openssl genrsa -out server.key 2048
+openssl req -new -key server.key -out server.csr -subj "/CN=localhost"
+
+# Generate client key and certificate request
+openssl genrsa -out client.key 2048
+openssl req -new -key client.key -out client.csr -subj "/CN=client"
+
+# Sign server certificate with CA
+openssl x509 -req -in server.csr -CA ca.crt -CAkey ca.key -CAcreateserial -out server.crt -days 365
+
+# Sign client certificate with CA
+openssl x509 -req -in client.csr -CA ca.crt -CAkey ca.key -CAcreateserial -out client.crt -days 365
+
+# Generate client PFX files
+openssl pkcs12 -export -passout pass: -out client.pfx -inkey client.key -in client.crt -certfile ca.crt
--- a/packages/engine.io/test/fixtures/server.crt
+++ b/packages/engine.io/test/fixtures/server.crt
@@ -1,22 +1,17 @@
 -----BEGIN CERTIFICATE-----
-MIIDtDCCAZwCFCt+tjtA9647yZp8eNZurQtNp4x/MA0GCSqGSIb3DQEBDQUAMEUx
-CzAJBgNVBAYTAkFVMRMwEQYDVQQIEwpTb21lLVN0YXRlMSEwHwYDVQQKExhJbnRl
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+9F+z6q7QL5+yOHzJgBepC7V5nQSQMQr9AgMBAAEwDQYJKoZIhvcNAQELBQADggEB
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+pd44wgDBbzbTtw3nRGy6RXm1vB2FyjvGWVXYL3XoE2r/xQPgaf93jeglbgo9C8Tj
+MQ2NdR4GPBtjqZNDmer6p2Jr31pkS4exT7oNysnZfoXll8F4PHos7Wc5VYo/2qQy
+uftfQqYIZLaZKzjR32Gsr6Z5yb8GlISWnRss5ebD6+wzh8sr4fat0SY/vy/3oq5V
+0lwYgNPo/OuwNMA7Eo/iNPY=
 -----END CERTIFICATE-----
--- a/packages/engine.io/test/fixtures/server.csr
+++ b/packages/engine.io/test/fixtures/server.csr
@@ -1,11 +1,15 @@
 -----BEGIN CERTIFICATE REQUEST-----
-MIIBrDCCARUCAQAwbDELMAkGA1UEBhMCRkkxEzARBgNVBAgTClNvbWUtU3RhdGUx
-ETAPBgNVBAcTCEhlbHNpbmtpMSEwHwYDVQQKExhJbnRlcm5ldCBXaWRnaXRzIFB0
-eSBMdGQxEjAQBgNVBAMTCWxvY2FsaG9zdDCBnzANBgkqhkiG9w0BAQEFAAOBjQAw
-gYkCgYEAwECzTwyC6jCLpbz4GuqIHIuvcWGkqedFO07/B8MN5uA/cNrm8hqke3Q1
-ttIhiSO7UzXL/1LS6oJJxIggV5KvzA6+YHVzSNFf4/qgDqnyUlcb8cR8S67e4r46
-WR2zuwdyu25FpgsQBc1gJROVPRV19W/FX3rSb/nAxGl7GMLmH6MCAwEAAaAAMA0G
-CSqGSIb3DQEBBQUAA4GBAClj/K2DAH5S64T6s7jervmk4N956Ho3aTLBgE+ReXLj
-btcTdk3vFbQApAlG6MrSKys4HjpKpP/RENx3Js0HHeb8ELmWtIQNxRhwIpl0K5AD
-xorKj+mwngLtVyARb/M7O3E8jYHzBPzpsolKWIY4AavYdmHu+Zhgm4hPKUcW+bAv
+MIICWTCCAUECAQAwFDESMBAGA1UEAwwJbG9jYWxob3N0MIIBIjANBgkqhkiG9w0B
+AQEFAAOCAQ8AMIIBCgKCAQEAycPe7U7Ek7WazlY3fPTSluePEsmgdeBobqqX3Nys
+RmuTjLml0FPWmJ56FAhFP2JUu+rfkoWbEAfV0eVBsu0+gAiaHZtrS7DJmjbdzl/C
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+ktXz5unhsb91xO2iGT8PSWDHcVReSZRdyhwjYrI=
 -----END CERTIFICATE REQUEST-----
--- a/packages/engine.io/test/fixtures/server.key
+++ b/packages/engine.io/test/fixtures/server.key
@@ -1,15 +1,28 @@
-----BEGIN RSA PRIVATE KEY-----
-MIICXgIBAAKBgQDAQLNPDILqMIulvPga6ogci69xYaSp50U7Tv8Hww3m4D9w2uby
-GqR7dDW20iGJI7tTNcv/UtLqgknEiCBXkq/MDr5gdXNI0V/j+qAOqfJSVxvxxHxL
-rt7ivjpZHbO7B3K7bkWmCxAFzWAlE5U9FXX1b8VfetJv+cDEaXsYwuYfowIDAQAB
-AoGBAL7tQmXl2fmz/mu5kHhCpKwcuT6TpxEo4aN132aY+qxn1flBHAwiE2mbTmDi
-rHViq/2GNrK5UUed3p60RdJSlgwIkyqtcGxWhUJGYCR/hU60qeeLp3MhhOoOFbiV
-YTDsoC7V/SuWbX+1qG5FxnHSnTZhAIRkZXS4uTZ5WDcQm/7BAkEA+TlZ1IT9CeU/
-FpHpqc8RgR8377Ehjy8o4Z4EGFnxQlAUWASnhs6dw4isr3+c7hA1OEmqmcRClPVZ
-t1JbHAPC4QJBAMV60WSJzPUccCF47T9Ao2CeWFl/9dmgQQe9idpTNuKMXNtPJN44
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-/ARN64nSx0u8y9evwVErucs0oL0we+BOGZAEhz9QN/M3pceESDWUwYtNbv4hAkBB
-Ku2MqvjK7k6GjTxlgjQn/zkSl+qOnZa4MjEarhlPm5hM+wokl0U1aK07BAwK4b6i
-d8YpmkXEAEEWFiEQMZX3AkEA1SkdiFj1u7HnzO7onLJsnFzowX3pm1UFl0azOMlM
-2GkjYxWeJ/4VL7Y6QkhHE0Nj3my2+MJQI9xpYgMbw/l11w==
-----END RSA PRIVATE KEY-----
+-----BEGIN PRIVATE KEY-----
+MIIEvQIBADANBgkqhkiG9w0BAQEFAASCBKcwggSjAgEAAoIBAQDJw97tTsSTtZrO
+Vjd89NKW548SyaB14Ghuqpfc3KxGa5OMuaXQU9aYnnoUCEU/YlS76t+ShZsQB9XR
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+da5jaFCjJhvH6qFhwsAkuGKsE1OPTs56iqZlSw9/8IJ6NW7/Igy6xR/Z5xRajAzl
+FsyRRSHduI5HNgDo7riv46M=
+-----END PRIVATE KEY-----
--- a/packages/engine.io/test/fixtures/server.key.orig
+++ b/packages/engine.io/test/fixtures/server.key.orig
@@ -1,18 +0,0 @@
-----BEGIN RSA PRIVATE KEY-----
-Proc-Type: 4,ENCRYPTED
-DEK-Info: DES-EDE3-CBC,8A14F3F31BF3CDF7
-
-84UpLjX5GbfCoP/+ZRLwHZHqmgKyc2cjQOQKhp2YTk+4E0JSO7KsKwJax55r5VqE
-ECGvbd8yvVZ3GRpU6bDCLelDN+Ob5ZSGhynI0f9is6Qle1/SbvaK+qL6MLf4H38l
-Y91eZxjE8hLvOMHBlbobLmy9UUzl2osBDAM1nm5d1X7pF7mN4xgY8s2G7UPq3ZZS
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-JCpvJQ7HS6Dfy6+GUaxcC6pyxqnoJHYccB5usJ2h4QD4Es3sT7Vw7M80JKw3vAWm
-TH7VkFX3yGfJ1p1jNzifN5687QqrjeI3/ecTs1rFhIC4TUPN9EDvw86Y6l6Mvo04
-Hl2cVzCnCrZYq0ICD0op3+7f9kuKl7bz54S/iRG2qQdICohPs7ra2yaUy+NFVDs1
-XdXyF5/xew+Rr2z7ygEd+OrvXxPV0zTFbicg9GXGeB/pIYAclmoSNXD5T3voN7y9
-5MjSGL375N3z+kqPzMNawYCnZLwQ5jYTDUkDTATYpjcIDVDQkzbl8mFp4i+Z9GhL
-H8FRAgmBbkgy3dxhFjxr/WzuaTkUCAbGhrtPd8WCPhBXJBzWdrBVR9SE8zT9n8lq
-ZwaPwkPLBrLe/XZFEQJ5cdvMVNy4QQwsyxHnCgO3VUc68UYXb39MvyM6t8+S1rSm
-SyvVAT+jB8T4VlE7tedQGuvyKMmeNIJe9znd3u4S+Aq2+vw6bOKeNYBMaupR5Gyl
-bJrscuTG1aLUe+XH9BuFBUoIwdXuBv4Ko/pDL0MYPghDAEGkp4Acmg==
-----END RSA PRIVATE KEY-----
--- a/packages/socket.io-adapter/lib/cluster-adapter.ts
+++ b/packages/socket.io-adapter/lib/cluster-adapter.ts
@@ -199,6 +199,14 @@ export abstract class ClusterAdapter extends Adapter {
      return debug("[%s] ignore message from self", this.uid);
    }

+    if (message.nsp !== this.nsp.name) {
+      return debug(
+        "[%s] ignore message from another namespace (%s)",
+        this.uid,
+        message.nsp,
+      );
+    }
+
    debug(
      "[%s] new event of type %d from %s",
      this.uid,
@@ -671,6 +679,8 @@ export abstract class ClusterAdapter extends Adapter {
  protected publish(
    message: DistributiveOmit<ClusterMessage, "nsp" | "uid">,
  ): void {
+    debug("[%s] sending message %s", this.uid, message.type);
+
    this.publishAndReturnOffset(message).catch((err) => {
      debug("[%s] error while publishing message: %s", this.uid, err);
    });
@@ -699,6 +709,14 @@ export abstract class ClusterAdapter extends Adapter {
  ) {
    (response as ClusterResponse).uid = this.uid;
    (response as ClusterResponse).nsp = this.nsp.name;
+
+    debug(
+      "[%s] sending response %s to %s",
+      this.uid,
+      response.type,
+      requesterUid,
+    );
+
    this.doPublishResponse(requesterUid, response as ClusterResponse).catch(
      (err) => {
        debug("[%s] error while publishing response: %s", this.uid, err);
@@ -790,17 +808,10 @@ export abstract class ClusterAdapterWithHeartbeat extends ClusterAdapter {
    }

    if (message.uid && message.uid !== EMITTER_UID) {
-      // we track the UID of each sender, in order to know how many servers there are in the cluster
+      // we track the UID of each sender to know how many servers there are in the cluster
      this.nodesMap.set(message.uid, Date.now());
    }

-    debug(
-      "[%s] new event of type %d from %s",
-      this.uid,
-      message.type,
-      message.uid,
-    );
-
    switch (message.type) {
      case MessageType.INITIAL_HEARTBEAT:
        this.publish({
--- a/packages/socket.io-adapter/package.json
+++ b/packages/socket.io-adapter/package.json
@@ -17,8 +17,8 @@
  "types": "./dist/index.d.ts",
  "description": "default socket.io in-memory adapter",
  "dependencies": {
-    "debug": "~4.3.4",
-    "ws": "~8.17.1"
+    "debug": "~4.4.1",
+    "ws": "~8.18.3"
  },
  "scripts": {
    "compile": "rimraf ./dist && tsc",
--- a/packages/socket.io-adapter/test/cluster-adapter.ts
+++ b/packages/socket.io-adapter/test/cluster-adapter.ts
@@ -67,11 +67,6 @@ describe("cluster adapter", () => {
          serverSockets.push(socket);
          servers.push(io);
          if (servers.length === NODES_COUNT) {
-            // ensure all nodes know each other
-            servers[0].emit("ping");
-            servers[1].emit("ping");
-            servers[2].emit("ping");
-
            done();
          }
        });
--- a/packages/socket.io-client/RELEASING.md
+++ b/packages/socket.io-client/RELEASING.md
@@ -0,0 +1,11 @@
+# Releasing
+
+1. Update the version in `package.json`
+2. Update the version in `support/package.esm.json`
+3. Update the changelog `CHANGELOG.md` with `conventional-changelog -p angular`
+4. Compile the TypeScript sources with `npm run compile`
+5. Generate the bundles with `npm run build`
+6. Commit the changes in `package.json`, `support/package.esm.json`, `CHANGELOG.md` and `dist/`
+7. Create the tag `socket.io-client@x.y.z` and push it to the GitHub repository. The workflow `.github/workflows/publish.yml` will safely publish the package to npm using trusted publishing.
+8. Create a new release at https://github.com/socketio/socket.io/releases
+9. Copy the bundles to the repository https://github.com/socketio/socket.io-cdn so that they are available at https://cdn.socket.io/
--- a/packages/socket.io-client/lib/index.ts
+++ b/packages/socket.io-client/lib/index.ts
@@ -1,6 +1,6 @@
 import { url } from "./url.js";
 import { Manager, ManagerOptions } from "./manager.js";
-import { Socket, SocketOptions } from "./socket.js";
+import { DisconnectDescription, Socket, SocketOptions } from "./socket.js";
 import debugModule from "debug"; // debug()

 const debug = debugModule("socket.io-client"); // debug()
@@ -91,6 +91,7 @@ export { protocol } from "socket.io-parser";
 */

 export {
+  DisconnectDescription,
  Manager,
  ManagerOptions,
  Socket,
--- a/packages/socket.io-client/lib/socket.ts
+++ b/packages/socket.io-client/lib/socket.ts
@@ -542,8 +542,7 @@ export class Socket<

    args.push((err, ...responseArgs) => {
      if (packet !== this._queue[0]) {
-        // the packet has already been acknowledged
-        return;
+        return debug("packet [%d] already acknowledged", packet.id);
      }
      const hasError = err !== null;
      if (hasError) {
@@ -834,8 +833,8 @@ export class Socket<
    this._pid = pid; // defined only if connection state recovery is enabled
    this.connected = true;
    this.emitBuffered();
-    this.emitReserved("connect");
    this._drainQueue(true);
+    this.emitReserved("connect");
  }

  /**
--- a/packages/socket.io-client/package.json
+++ b/packages/socket.io-client/package.json
@@ -46,7 +46,7 @@
  "types": "./build/esm/index.d.ts",
  "dependencies": {
    "@socket.io/component-emitter": "~3.1.0",
-    "debug": "~4.3.2",
+    "debug": "~4.4.1",
    "engine.io-client": "~6.6.1",
    "socket.io-parser": "~4.2.4"
  },
--- a/packages/socket.io-client/support/rollup.config.esm.js
+++ b/packages/socket.io-client/support/rollup.config.esm.js
@@ -20,6 +20,7 @@ module.exports = {
        mangle: {
          properties: {
            regex: /^_/,
+            reserved: ["_placeholder"],
          },
        },
      }),
--- a/packages/socket.io-client/test/retry.ts
+++ b/packages/socket.io-client/test/retry.ts
@@ -110,4 +110,40 @@ describe("retry", () => {
      }, 100);
    });
  });
+
+  it.only("should not emit a packet twice in the 'connect' handler", () => {
+    return wrap((done) => {
+      const socket = io(BASE_URL, {
+        forceNew: true,
+        retries: 3,
+      });
+
+      const received: string[] = [];
+      const sent: string[] = [];
+
+      socket.io.engine.on("packetCreate", ({ data }) => {
+        sent.push(data);
+      });
+
+      socket.io.engine.on("packet", ({ data }) => {
+        received.push(data);
+      });
+
+      socket.on("connect", () => {
+        socket.emit("echo", null);
+      });
+
+      setTimeout(() => {
+        expect(sent).to.eql(["0", '20["echo",null]']);
+
+        expect(received.length).to.eql(3);
+        // 1: engine.io OPEN packet
+        // 2: socket.io CONNECT packet
+        // 3: ack packet
+        expect(received[2]).to.eql("30[null]");
+
+        success(done, socket);
+      }, 100);
+    });
+  });
 });
--- a/packages/socket.io-client/wdio.conf.js
+++ b/packages/socket.io-client/wdio.conf.js
@@ -60,7 +60,7 @@ if (process.env.CI === "true") {
    {
      browserName: "internet explorer",
      browserVersion: "10",
-      platformName: "Windows 7",
+      platformName: "Windows 8",
      "sauce:options": BASE_SAUCE_OPTIONS,
    },
    {
--- a/packages/socket.io-cluster-adapter/CHANGELOG.md
+++ b/packages/socket.io-cluster-adapter/CHANGELOG.md
@@ -0,0 +1,60 @@
+# Changelog
+
+| Version                  | Release date |
+|--------------------------|--------------|
+| [0.3.0](#030-2025-10-16) | October 2025 |
+| [0.2.2](#022-2023-03-24) | March 2023   |
+| [0.2.1](#021-2022-10-13) | October 2022 |
+| [0.2.0](#020-2022-04-28) | April 2022   |
+| [0.1.0](#010-2021-06-22) | June 2021    |
+
+
+
+## [0.3.0](https://github.com/socketio/socket.io-cluster-adapter/compare/0.2.2...0.3.0) (2025-10-16)
+
+This release contains an important refactor of the adapter ([this commit](https://github.com/socketio/socket.io-cluster-adapter/commit/0c431243e28913fdd2a4a3de3e67a9f38d67a3aa)), as most of the logic has been moved in the `ClusterAdapter` class of the `socket.io-adapter` package.
+
+Besides, the `@socket.io/cluster-adapter` package is now part of the `socket.io` monorepo.
+
+
+
+## [0.2.2](https://github.com/socketio/socket.io-cluster-adapter/compare/0.2.1...0.2.2) (2023-03-24)
+
+The `socket.io-adapter` package was added to the list of `peerDependencies`, in order to fix sync issues with the version imported by the socket.io package (see [15fd56e](https://github.com/socketio/socket.io-cluster-adapter/commit/15fd56e78d52aa65c5fbf412dec57ab4bdaee7cc)).
+
+Support for connection state recovery (see [here](https://github.com/socketio/socket.io/releases/4.6.0)) will be added in the next release.
+
+
+
+## [0.2.1](https://github.com/socketio/socket.io-cluster-adapter/compare/0.2.0...0.2.1) (2022-10-13)
+
+
+### Bug Fixes
+
+* properly handle ERR_IPC_CHANNEL_CLOSED errors ([#6](https://github.com/socketio/socket.io-cluster-adapter/issues/6)) ([be0a0e3](https://github.com/socketio/socket.io-cluster-adapter/commit/be0a0e3217bd7100d569e5624194612bcc8b96ff))
+
+
+
+## [0.2.0](https://github.com/socketio/socket.io-cluster-adapter/compare/0.1.0...0.2.0) (2022-04-28)
+
+
+### Features
+
+* broadcast and expect multiple acks ([055b784](https://github.com/socketio/socket.io-cluster-adapter/commit/055b7840d8cf88173d8299041ef3fafa9791c97a))
+
+This feature was added in `socket.io@4.5.0`:
+
+```js
+io.timeout(1000).emit("some-event", (err, responses) => {
+  // ...
+});
+```
+
+Thanks to this change, it will now work within a Node.js cluster.
+
+
+
+## 0.1.0 (2021-06-22)
+
+Initial commit
+
--- a/packages/socket.io-cluster-adapter/LICENSE
+++ b/packages/socket.io-cluster-adapter/LICENSE
@@ -0,0 +1,7 @@
+Copyright (c) 2021 Damien Arrachequesne (@darrachequesne)
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
--- a/packages/socket.io-cluster-adapter/README.md
+++ b/packages/socket.io-cluster-adapter/README.md
@@ -0,0 +1,100 @@
+# Socket.IO cluster adapter
+
+The `@socket.io/cluster-adapter` package allows broadcasting packets between multiple Socket.IO servers.
+
+![Adapter diagram](./assets/adapter.png)
+
+It can be used in conjunction with [`@socket.io/sticky`](https://github.com/socketio/socket.io-sticky) to broadcast packets between the workers of the same Node.js [cluster](https://nodejs.org/api/cluster.html).
+
+Supported features:
+
+- [broadcasting](https://socket.io/docs/v4/broadcasting-events/)
+- [utility methods](https://socket.io/docs/v4/server-instance/#Utility-methods)
+  - [`socketsJoin`](https://socket.io/docs/v4/server-instance/#socketsJoin)
+  - [`socketsLeave`](https://socket.io/docs/v4/server-instance/#socketsLeave)
+  - [`disconnectSockets`](https://socket.io/docs/v4/server-instance/#disconnectSockets)
+  - [`fetchSockets`](https://socket.io/docs/v4/server-instance/#fetchSockets)
+  - [`serverSideEmit`](https://socket.io/docs/v4/server-instance/#serverSideEmit)
+
+Related packages:
+
+- Postgres adapter: https://github.com/socketio/socket.io-postgres-adapter/
+- Redis adapter: https://github.com/socketio/socket.io-redis-adapter/
+- MongoDB adapter: https://github.com/socketio/socket.io-mongo-adapter/
+
+**Table of contents**
+
+- [Installation](#installation)
+- [Usage](#usage)
+- [License](#license)
+
+## Installation
+
+```
+npm install @socket.io/cluster-adapter
+```
+
+## Usage
+
+```js
+const cluster = require("cluster");
+const http = require("http");
+const { Server } = require("socket.io");
+const numCPUs = require("os").cpus().length;
+const { setupMaster, setupWorker } = require("@socket.io/sticky");
+const { createAdapter, setupPrimary } = require("@socket.io/cluster-adapter");
+
+if (cluster.isMaster) {
+  console.log(`Master ${process.pid} is running`);
+
+  const httpServer = http.createServer();
+
+  // setup sticky sessions
+  setupMaster(httpServer, {
+    loadBalancingMethod: "least-connection",
+  });
+
+  // setup connections between the workers
+  setupPrimary();
+
+  // needed for packets containing buffers (you can ignore it if you only send plaintext objects)
+  // Node.js < 16.0.0
+  cluster.setupMaster({
+    serialization: "advanced",
+  });
+  // Node.js > 16.0.0
+  // cluster.setupPrimary({
+  //   serialization: "advanced",
+  // });
+
+  httpServer.listen(3000);
+
+  for (let i = 0; i < numCPUs; i++) {
+    cluster.fork();
+  }
+
+  cluster.on("exit", (worker) => {
+    console.log(`Worker ${worker.process.pid} died`);
+    cluster.fork();
+  });
+} else {
+  console.log(`Worker ${process.pid} started`);
+
+  const httpServer = http.createServer();
+  const io = new Server(httpServer);
+
+  // use the cluster adapter
+  io.adapter(createAdapter());
+
+  // setup connection with the primary process
+  setupWorker(io);
+
+  io.on("connection", (socket) => {
+    /* ... */
+  });
+}
+```
+
+## License
+
+[MIT](LICENSE)
--- a/packages/socket.io-cluster-adapter/assets/adapter.excalidraw
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--- a/packages/socket.io-cluster-adapter/assets/adapter.png
+++ b/packages/socket.io-cluster-adapter/assets/adapter.png
--- a/packages/socket.io-cluster-adapter/lib/index.ts
+++ b/packages/socket.io-cluster-adapter/lib/index.ts
@@ -0,0 +1,116 @@
+import cluster from "node:cluster";
+import {
+  ClusterAdapterWithHeartbeat,
+  ClusterAdapterOptions,
+  ClusterMessage,
+  ServerId,
+  ClusterResponse,
+  MessageType,
+} from "socket.io-adapter";
+import debugModule from "debug";
+
+const debug = debugModule("socket.io-cluster-adapter");
+const MESSAGE_SOURCE = "_sio_adapter";
+const hasOwnProperty = Object.prototype.hasOwnProperty;
+
+function ignoreError() {}
+
+/**
+ * Returns a function that will create a NodeClusterAdapter instance.
+ *
+ * @param opts - additional options
+ *
+ * @public
+ * @see https://nodejs.org/api/cluster.html
+ */
+export function createAdapter(opts: Partial<ClusterAdapterOptions> = {}) {
+  return function (nsp: any) {
+    return new NodeClusterAdapter(nsp, opts);
+  };
+}
+
+export class NodeClusterAdapter extends ClusterAdapterWithHeartbeat {
+  constructor(nsp: any, opts: ClusterAdapterOptions = {}) {
+    super(nsp, opts);
+    process.on("message", (message: any) => {
+      const isValidSource = message?.source === MESSAGE_SOURCE;
+      if (!isValidSource) {
+        debug("[%s] ignore unknown source", this.uid);
+        return;
+      }
+
+      // note: this check should be done in the onMessage() handler
+      if (message.nsp !== this.nsp.name) {
+        debug("[%s] ignore other namespace", this.uid);
+        return;
+      }
+
+      this.onMessage(message);
+    });
+
+    // until https://github.com/socketio/socket.io/commit/f3e1f5ebdf59158d0c8d1e20f8230275617fb355 is released
+    this.init();
+  }
+
+  protected override doPublish(message: ClusterMessage & { source: string }) {
+    message.source = MESSAGE_SOURCE;
+
+    process.send(message, null, {}, ignoreError);
+
+    return Promise.resolve(""); // connection state recovery is not supported
+  }
+
+  protected override doPublishResponse(
+    requesterUid: ServerId,
+    response: ClusterResponse & { source: string; requesterUid: string },
+  ) {
+    response.source = MESSAGE_SOURCE;
+    response.requesterUid = requesterUid;
+
+    process.send(response, null, {}, ignoreError);
+
+    return Promise.resolve();
+  }
+}
+
+const UIDS = Symbol("uids");
+
+export function setupPrimary() {
+  cluster.on("message", (worker, message) => {
+    const isValidSource = message?.source === MESSAGE_SOURCE;
+    if (!isValidSource) {
+      return;
+    }
+
+    // store the requester's uids (one per namespace) so that the response can be sent specifically to them
+    worker[UIDS] = worker[UIDS] || new Set();
+    worker[UIDS].add(message.uid);
+
+    switch (message.type) {
+      case MessageType.FETCH_SOCKETS_RESPONSE:
+      case MessageType.SERVER_SIDE_EMIT_RESPONSE:
+        const requesterUid = message.requesterUid;
+        for (const workerId in cluster.workers) {
+          if (
+            hasOwnProperty.call(cluster.workers, workerId) &&
+            cluster.workers[workerId][UIDS]?.has(requesterUid)
+          ) {
+            cluster.workers[workerId].send(message, null, ignoreError);
+            break;
+          }
+        }
+        break;
+      default:
+        const emitterIdAsString = String(worker.id);
+        // emit to all workers but the requester
+        for (const workerId in cluster.workers) {
+          if (
+            hasOwnProperty.call(cluster.workers, workerId) &&
+            workerId !== emitterIdAsString
+          ) {
+            cluster.workers[workerId].send(message, null, ignoreError);
+          }
+        }
+    }
+  });
+}
--- a/packages/socket.io-cluster-adapter/package-lock.json
+++ b/packages/socket.io-cluster-adapter/package-lock.json
--- a/packages/socket.io-cluster-adapter/package.json
+++ b/packages/socket.io-cluster-adapter/package.json
@@ -0,0 +1,40 @@
+{
+  "name": "@socket.io/cluster-adapter",
+  "version": "0.3.0",
+  "description": "The Socket.IO cluster adapter, allowing to broadcast events between several Socket.IO servers",
+  "license": "MIT",
+  "homepage": "https://github.com/socketio/socket.io/tree/main/packages/socket.io-cluster-adapter#readme",
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/socketio/socket.io.git"
+  },
+  "bugs": {
+    "url": "https://github.com/socketio/socket.io/issues"
+  },
+  "files": [
+    "dist/"
+  ],
+  "main": "./dist/index.js",
+  "types": "./dist/index.d.ts",
+  "scripts": {
+    "compile": "rimraf ./dist && tsc",
+    "test": "npm run format:check && npm run compile && nyc mocha --import=tsx test/index.ts",
+    "format:check": "prettier --check \"lib/**/*.ts\" \"test/**/*.ts\"",
+    "format:fix": "prettier --write \"lib/**/*.ts\" \"test/**/*.ts\"",
+    "prepack": "npm run compile"
+  },
+  "dependencies": {
+    "debug": "~4.4.1"
+  },
+  "peerDependencies": {
+    "socket.io-adapter": "~2.5.5"
+  },
+  "engines": {
+    "node": ">=10.0.0"
+  },
+  "keywords": [
+    "socket.io",
+    "cluster",
+    "adapter"
+  ]
+}
--- a/packages/socket.io-cluster-adapter/test/index.ts
+++ b/packages/socket.io-cluster-adapter/test/index.ts
@@ -0,0 +1,372 @@
+import { io as ioc, Socket as ClientSocket } from "socket.io-client";
+import expect = require("expect.js");
+import { setupPrimary } from "..";
+import { times, sleep } from "./util";
+import cluster, { Worker } from "node:cluster";
+
+const NODES_COUNT = 3;
+
+cluster.setupMaster({
+  exec: "./test/worker.js",
+  // @ts-ignore
+  serialization: "advanced", // needed for packets containing buffers
+});
+
+setupPrimary();
+
+const getRooms = (worker): Promise<Set<string>> => {
+  worker.send("get rooms");
+  return new Promise((resolve) => {
+    worker.once("message", (content) => {
+      resolve(content);
+    });
+  });
+};
+
+describe("@socket.io/cluster-adapter", () => {
+  let clientSockets: ClientSocket[], workers: Worker[];
+
+  beforeEach((done) => {
+    clientSockets = [];
+    workers = [];
+
+    for (let i = 1; i <= NODES_COUNT; i++) {
+      const PORT = 40000 + i;
+      const worker = cluster.fork({
+        PORT,
+      });
+
+      worker.on("listening", () => {
+        const clientSocket = ioc(`http://localhost:${PORT}`);
+
+        clientSocket.on("connect", async () => {
+          workers.push(worker);
+          clientSockets.push(clientSocket);
+          if (clientSockets.length === NODES_COUNT) {
+            done();
+          }
+        });
+      });
+    }
+  });
+
+  afterEach(() => {
+    for (const id in cluster.workers) {
+      cluster.workers[id].kill();
+    }
+    clientSockets.forEach((socket) => {
+      socket.disconnect();
+    });
+  });
+
+  describe("broadcast", function () {
+    it("broadcasts to all clients", (done) => {
+      const partialDone = times(3, done);
+
+      clientSockets.forEach((clientSocket) => {
+        clientSocket.on("test", (arg1, arg2, arg3) => {
+          expect(arg1).to.eql(1);
+          expect(arg2).to.eql("2");
+          expect(Buffer.isBuffer(arg3)).to.be(true);
+          partialDone();
+        });
+      });
+
+      workers[0].send("broadcasts to all clients");
+    });
+
+    it("broadcasts to all clients in a namespace", (done) => {
+      const partialDone = times(3, done);
+
+      const onConnect = times(3, async () => {
+        workers[0].send("broadcasts to all clients in a namespace");
+      });
+
+      clientSockets.forEach((clientSocket) => {
+        const socket = clientSocket.io.socket("/custom");
+        socket.on("connect", onConnect);
+        socket.on("test", () => {
+          socket.disconnect();
+          partialDone();
+        });
+      });
+    });
+
+    it("broadcasts to all clients in a room", (done) => {
+      workers[1].send("join room1");
+
+      clientSockets[0].on("test", () => {
+        done(new Error("should not happen"));
+      });
+
+      clientSockets[1].on("test", () => {
+        done();
+      });
+
+      clientSockets[2].on("test", () => {
+        done(new Error("should not happen"));
+      });
+
+      workers[0].send("broadcasts to all clients in a room");
+    });
+
+    it("broadcasts to all clients except in room", (done) => {
+      const partialDone = times(2, done);
+      workers[1].send("join room1");
+
+      clientSockets[0].on("test", () => {
+        partialDone();
+      });
+
+      clientSockets[1].on("test", () => {
+        done(new Error("should not happen"));
+      });
+
+      clientSockets[2].on("test", () => {
+        partialDone();
+      });
+
+      workers[0].send("broadcasts to all clients except in room");
+    });
+
+    it("broadcasts to local clients only", (done) => {
+      clientSockets[0].on("test", () => {
+        done();
+      });
+
+      clientSockets[1].on("test", () => {
+        done(new Error("should not happen"));
+      });
+
+      clientSockets[2].on("test", () => {
+        done(new Error("should not happen"));
+      });
+
+      workers[0].send("broadcasts to local clients only");
+    });
+
+    it("broadcasts with multiple acknowledgements", (done) => {
+      clientSockets[0].on("test", (cb) => {
+        cb(1);
+      });
+
+      clientSockets[1].on("test", (cb) => {
+        cb(2);
+      });
+
+      clientSockets[2].on("test", (cb) => {
+        cb(3);
+      });
+
+      workers[0].send("broadcasts with multiple acknowledgements");
+
+      workers[0].on("message", (result) => {
+        if (result === "ok") {
+          done();
+        }
+      });
+    });
+
+    it("broadcasts with multiple acknowledgements (binary content)", (done) => {
+      clientSockets[0].on("test", (cb) => {
+        cb(Buffer.from([1]));
+      });
+
+      clientSockets[1].on("test", (cb) => {
+        cb(Buffer.from([2]));
+      });
+
+      clientSockets[2].on("test", (cb) => {
+        cb(Buffer.from([3]));
+      });
+
+      workers[0].send(
+        "broadcasts with multiple acknowledgements (binary content)",
+      );
+
+      workers[0].on("message", (result) => {
+        if (result === "ok") {
+          done();
+        }
+      });
+    });
+
+    it("broadcasts with multiple acknowledgements (no client)", (done) => {
+      workers[0].send("broadcasts with multiple acknowledgements (no client)");
+
+      workers[0].on("message", (result) => {
+        if (result === "ok") {
+          done();
+        }
+      });
+    });
+
+    it("broadcasts with multiple acknowledgements (timeout)", (done) => {
+      clientSockets[0].on("test", (cb) => {
+        cb(1);
+      });
+
+      clientSockets[1].on("test", (cb) => {
+        cb(2);
+      });
+
+      clientSockets[2].on("test", (cb) => {
+        // do nothing
+      });
+
+      workers[0].send("broadcasts with multiple acknowledgements (timeout)");
+
+      workers[0].on("message", (result) => {
+        if (result === "ok") {
+          done();
+        }
+      });
+    });
+  });
+
+  describe("socketsJoin", () => {
+    it("makes all socket instances join the specified room", async () => {
+      workers[0].send("makes all socket instances join the specified room");
+
+      await sleep(100);
+
+      expect((await getRooms(workers[0])).has("room1")).to.be(true);
+      expect((await getRooms(workers[1])).has("room1")).to.be(true);
+      expect((await getRooms(workers[2])).has("room1")).to.be(true);
+    });
+
+    it("makes the matching socket instances join the specified room", async () => {
+      workers[0].send("join room1");
+      workers[2].send("join room1");
+
+      workers[0].send(
+        "makes the matching socket instances join the specified room",
+      );
+
+      await sleep(100);
+
+      expect((await getRooms(workers[0])).has("room2")).to.be(true);
+      expect((await getRooms(workers[1])).has("room2")).to.be(false);
+      expect((await getRooms(workers[2])).has("room2")).to.be(true);
+    });
+  });
+
+  describe("socketsLeave", () => {
+    it("makes all socket instances leave the specified room", async () => {
+      workers[0].send("join room1");
+      workers[2].send("join room1");
+
+      workers[0].send("makes all socket instances leave the specified room");
+
+      await sleep(100);
+
+      expect((await getRooms(workers[0])).has("room1")).to.be(false);
+      expect((await getRooms(workers[1])).has("room1")).to.be(false);
+      expect((await getRooms(workers[2])).has("room1")).to.be(false);
+    });
+
+    it("makes the matching socket instances leave the specified room", async () => {
+      workers[0].send("join room1 & room2");
+      workers[2].send("join room2");
+
+      workers[0].send(
+        "makes the matching socket instances leave the specified room",
+      );
+
+      await sleep(100);
+
+      expect((await getRooms(workers[0])).has("room2")).to.be(false);
+      expect((await getRooms(workers[1])).has("room2")).to.be(false);
+      expect((await getRooms(workers[2])).has("room2")).to.be(true);
+    });
+  });
+
+  describe("disconnectSockets", () => {
+    it("makes all socket instances disconnect", (done) => {
+      const partialDone = times(3, done);
+
+      clientSockets.forEach((clientSocket) => {
+        clientSocket.on("disconnect", (reason) => {
+          expect(reason).to.eql("io server disconnect");
+          partialDone();
+        });
+      });
+
+      workers[0].send("makes all socket instances disconnect");
+    });
+  });
+
+  describe("fetchSockets", () => {
+    it("returns all socket instances", (done) => {
+      workers[0].send("returns all socket instances");
+
+      workers[0].on("message", (result) => {
+        if (result === "ok") {
+          done();
+        }
+      });
+    });
+  });
+
+  describe("serverSideEmit", () => {
+    it("sends an event to other server instances", (done) => {
+      const partialDone = times(2, done);
+
+      workers[0].send("sends an event to other server instances");
+
+      workers[0].on("message", (result) => {
+        if (result === "ok") {
+          done(new Error("should not happen"));
+        }
+      });
+
+      workers[1].on("message", (result) => {
+        expect(result).to.eql("ok");
+        partialDone();
+      });
+
+      workers[2].on("message", (result) => {
+        expect(result).to.eql("ok");
+        partialDone();
+      });
+    });
+
+    it("sends an event and receives a response from the other server instances", (done) => {
+      workers[0].send(
+        "sends an event and receives a response from the other server instances (1)",
+      );
+      workers[1].send(
+        "sends an event and receives a response from the other server instances (2)",
+      );
+      workers[2].send(
+        "sends an event and receives a response from the other server instances (3)",
+      );
+
+      workers[0].on("message", (result) => {
+        if (result === "ok") {
+          done();
+        }
+      });
+    });
+
+    it("sends an event but timeout if one server does not respond", function (done) {
+      this.timeout(6000); // currently not possible to configure the timeout delay
+
+      workers[0].send(
+        "sends an event but timeout if one server does not respond (1)",
+      );
+      workers[1].send(
+        "sends an event but timeout if one server does not respond (2)",
+      );
+      workers[2].send(
+        "sends an event but timeout if one server does not respond (3)",
+      );
+
+      workers[0].on("message", (result) => {
+        if (result === "ok") {
+          done();
+        }
+      });
+    });
+  });
+});
--- a/packages/socket.io-cluster-adapter/test/util.ts
+++ b/packages/socket.io-cluster-adapter/test/util.ts
@@ -0,0 +1,13 @@
+export function times(count: number, fn: () => void) {
+  let i = 0;
+  return () => {
+    i++;
+    if (i === count) {
+      fn();
+    }
+  };
+}
+
+export function sleep(duration: number) {
+  return new Promise((resolve) => setTimeout(resolve, duration));
+}
--- a/packages/socket.io-cluster-adapter/test/worker.js
+++ b/packages/socket.io-cluster-adapter/test/worker.js
@@ -0,0 +1,182 @@
+const { createServer } = require("http");
+const { Server } = require("socket.io");
+const { createAdapter } = require("..");
+
+const httpServer = createServer();
+const io = new Server(httpServer);
+const expect = require("expect.js");
+
+io.adapter(createAdapter());
+
+let serverSocket;
+
+io.on("connection", (socket) => {
+  serverSocket = socket;
+});
+
+const customNamespace = io.of("/custom");
+
+process.on("message", async (msg) => {
+  switch (msg) {
+    case "broadcasts to all clients":
+      io.emit("test", 1, "2", Buffer.from([3, 4]));
+      break;
+    case "broadcasts to all clients in a namespace":
+      customNamespace.emit("test");
+      break;
+    case "join room1":
+      serverSocket.join("room1");
+      break;
+    case "join room1 & room2":
+      serverSocket.join(["room1", "room2"]);
+      break;
+    case "join room2":
+      serverSocket.join("room2");
+      break;
+    case "broadcasts to all clients in a room":
+      io.to("room1").emit("test");
+      break;
+    case "broadcasts to all clients except in room":
+      io.of("/").except("room1").emit("test");
+      break;
+    case "broadcasts to local clients only":
+      io.local.emit("test");
+      break;
+
+    case "broadcasts with multiple acknowledgements": {
+      io.timeout(500).emit("test", (err, responses) => {
+        expect(err).to.be(null);
+        expect(responses).to.contain(1);
+        expect(responses).to.contain(2);
+        expect(responses).to.contain(3);
+
+        setTimeout(() => {
+          expect(io.of("/").adapter.ackRequests.size).to.eql(0);
+
+          process.send("ok");
+        }, 500);
+      });
+      break;
+    }
+
+    case "broadcasts with multiple acknowledgements (binary content)": {
+      io.timeout(500).emit("test", (err, responses) => {
+        expect(err).to.be(null);
+        responses.forEach((response) => {
+          expect(Buffer.isBuffer(response)).to.be(true);
+        });
+
+        process.send("ok");
+      });
+      break;
+    }
+
+    case "broadcasts with multiple acknowledgements (no client)": {
+      io
+        .to("abc")
+        .timeout(500)
+        .emit("test", (err, responses) => {
+          expect(err).to.be(null);
+          expect(responses).to.eql([]);
+
+          process.send("ok");
+        });
+      break;
+    }
+
+    case "broadcasts with multiple acknowledgements (timeout)": {
+      io.timeout(500).emit("test", (err, responses) => {
+        expect(err).to.be.an(Error);
+        expect(responses).to.contain(1);
+        expect(responses).to.contain(2);
+
+        process.send("ok");
+      });
+      break;
+    }
+
+    case "get rooms":
+      process.send(serverSocket.rooms);
+      break;
+    case "makes all socket instances join the specified room":
+      io.socketsJoin("room1");
+      break;
+
+    case "makes the matching socket instances join the specified room":
+      io.in("room1").socketsJoin("room2");
+      break;
+
+    case "makes all socket instances leave the specified room":
+      io.socketsLeave("room1");
+      break;
+    case "makes the matching socket instances leave the specified room":
+      io.in("room1").socketsLeave("room2");
+      break;
+
+    case "makes all socket instances disconnect":
+      io.disconnectSockets();
+      break;
+
+    case "returns all socket instances":
+      const sockets = await io.fetchSockets();
+
+      expect(sockets).to.be.an(Array);
+      expect(sockets).to.have.length(3);
+      expect(io.of("/").adapter.requests.size).to.eql(0); // clean up
+
+      process.send("ok");
+      break;
+
+    case "sends an event to other server instances":
+      io.serverSideEmit("hello", "world", 1, "2");
+      break;
+    case "sends an event and receives a response from the other server instances (1)":
+      io.serverSideEmit("hello with ack", (err, response) => {
+        expect(err).to.be(null);
+        expect(response).to.be.an(Array);
+        expect(response).to.contain(2);
+        expect(response).to.contain("3");
+        process.send("ok");
+      });
+      break;
+    case "sends an event and receives a response from the other server instances (2)":
+      io.on("hello with ack", (cb) => {
+        cb(2);
+      });
+      break;
+    case "sends an event and receives a response from the other server instances (3)":
+      io.on("hello with ack", (cb) => {
+        cb("3");
+      });
+      break;
+    case "sends an event but timeout if one server does not respond (1)":
+      io.serverSideEmit("hello with ack", (err, response) => {
+        expect(err.message).to.be(
+          "timeout reached: missing 1 responses"
+        );
+        expect(response).to.be.an(Array);
+        expect(response).to.contain(2);
+        process.send("ok");
+      });
+      break;
+    case "sends an event but timeout if one server does not respond (2)":
+      io.on("hello with ack", (cb) => {
+        cb(2);
+      });
+      break;
+    case "sends an event but timeout if one server does not respond (3)":
+      io.on("hello with ack", (cb) => {
+        // do nothing
+      });
+      break;
+  }
+});
+
+io.on("hello", (arg1, arg2, arg3) => {
+  expect(arg1).to.eql("world");
+  expect(arg2).to.eql(1);
+  expect(arg3).to.eql("2");
+  process.send("ok");
+});
+
+httpServer.listen(parseInt(process.env.PORT, 10));
--- a/packages/socket.io-cluster-adapter/tsconfig.json
+++ b/packages/socket.io-cluster-adapter/tsconfig.json
@@ -0,0 +1,13 @@
+{
+  "compilerOptions": {
+    "outDir": "./dist",
+    "allowJs": false,
+    "target": "es2017",
+    "module": "commonjs",
+    "declaration": true,
+    "esModuleInterop": true
+  },
+  "include": [
+    "./lib/**/*"
+  ]
+}
--- a/packages/socket.io-cluster-engine/package.json
+++ b/packages/socket.io-cluster-engine/package.json
@@ -19,7 +19,7 @@
  ],
  "dependencies": {
    "@msgpack/msgpack": "~2.8.0",
-    "debug": "~4.3.3",
+    "debug": "~4.4.1",
    "engine.io": "~6.6.0",
    "engine.io-parser": "~5.2.3"
  },
--- a/packages/socket.io-parser/package.json
+++ b/packages/socket.io-parser/package.json
@@ -26,7 +26,7 @@
  },
  "dependencies": {
    "@socket.io/component-emitter": "~3.1.0",
-    "debug": "~4.3.1"
+    "debug": "~4.4.1"
  },
  "scripts": {
    "compile": "rimraf ./build && tsc && tsc -p tsconfig.esm.json && ./postcompile.sh",
--- a/packages/socket.io-parser/wdio.conf.js
+++ b/packages/socket.io-parser/wdio.conf.js
@@ -53,7 +53,7 @@ if (process.env.CI === "true") {
    {
      browserName: "internet explorer",
      browserVersion: "10",
-      platformName: "Windows 7",
+      platformName: "Windows 8",
      "sauce:options": BASE_SAUCE_OPTIONS,
    },
    {
--- a/packages/socket.io-postgres-emitter/package.json
+++ b/packages/socket.io-postgres-emitter/package.json
@@ -22,7 +22,7 @@
  },
  "dependencies": {
    "@msgpack/msgpack": "^2.7.0",
-    "debug": "~4.3.1"
+    "debug": "~4.4.1"
  },
  "keywords": [
    "socket.io",
--- a/packages/socket.io-redis-streams-emitter/CHANGELOG.md
+++ b/packages/socket.io-redis-streams-emitter/CHANGELOG.md
@@ -0,0 +1,19 @@
+# Changelog
+
+| Version                  | Release date  |
+|--------------------------|---------------|
+| [0.1.1](#011-2025-11-07) | November 2025 |
+| [0.1.0](#010-2025-11-06) | November 2025 |
+
+
+## [0.1.1](https://github.com/socketio/socket.io/compare/@socket.io/redis-streams-emitter@0.1.0...@socket.io/redis-streams-emitter@0.1.1) (2025-11-07)
+
+
+### Bug Fixes
+
+* remove dependency on socket.io-adapter ([7617707](https://github.com/socketio/socket.io/commit/7617707ed8f0defd0e19cb7c6963504ce7b87f6b))
+
+
+## 0.1.0 (2025-11-06)
+
+Initial release!
--- a/packages/socket.io-redis-streams-emitter/LICENSE
+++ b/packages/socket.io-redis-streams-emitter/LICENSE
@@ -0,0 +1,7 @@
+Copyright (c) 2025-present Guillermo Rauch and Socket.IO contributors
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
--- a/packages/socket.io-redis-streams-emitter/README.md
+++ b/packages/socket.io-redis-streams-emitter/README.md
@@ -0,0 +1,220 @@
+# Socket.IO Redis Streams emitter
+
+The `@socket.io/redis-streams-emitter` package allows you to easily communicate with a group of Socket.IO servers from another Node.js process (server-side).
+
+It must be used in conjunction with [`@socket.io/redis-streams-adapter`](https://github.com/socketio/socket.io-redis-streams-adapter).
+
+**Table of contents**
+
+<!-- TOC -->
+  * [Installation](#installation)
+  * [Usage](#usage)
+    * [With the `redis` package](#with-the-redis-package)
+    * [With the `redis` package and a Redis cluster](#with-the-redis-package-and-a-redis-cluster)
+    * [With the `ioredis` package](#with-the-ioredis-package)
+    * [With the `ioredis` package and a Redis cluster](#with-the-ioredis-package-and-a-redis-cluster)
+  * [Options](#options)
+  * [API](#api)
+    * [`Emitter(redisClient[, nsp][, opts])`](#emitterredisclient-nsp-opts)
+    * [`Emitter#to(room:string):BroadcastOperator`](#emittertoroomstringbroadcastoperator)
+    * [`Emitter#in(room:string):BroadcastOperator`](#emitterinroomstringbroadcastoperator)
+    * [`Emitter#except(room:string):BroadcastOperator`](#emitterexceptroomstringbroadcastoperator)
+    * [`Emitter#of(namespace:string):Emitter`](#emitterofnamespacestringemitter)
+    * [`Emitter#socketsJoin(rooms:string|string[])`](#emittersocketsjoinroomsstringstring)
+    * [`Emitter#socketsLeave(rooms:string|string[])`](#emittersocketsleaveroomsstringstring)
+    * [`Emitter#disconnectSockets(close:boolean)`](#emitterdisconnectsocketscloseboolean)
+    * [`Emitter#serverSideEmit(ev:string[,...args:any[]])`](#emitterserversideemitevstringargsany)
+  * [License](#license)
+<!-- TOC -->
+
+## Installation
+
+```
+npm install @socket.io/redis-streams-emitter redis
+```
+
+## Usage
+
+### With the `redis` package
+
+```js
+import { createClient } from "redis";
+import { Emitter } from "@socket.io/redis-streams-emitter";
+
+const redisClient = createClient({
+  url: "redis://localhost:6379"
+});
+
+await redisClient.connect();
+
+const io = new Emitter(redisClient);
+
+setInterval(() => {
+  io.emit("ping", new Date());
+}, 1000);
+```
+
+### With the `redis` package and a Redis cluster
+
+```js
+import { createCluster } from "redis";
+import { Emitter } from "@socket.io/redis-streams-emitter";
+
+const redisClient = createCluster({
+  rootNodes: [
+    {
+      url: "redis://localhost:7000",
+    },
+    {
+      url: "redis://localhost:7001",
+    },
+    {
+      url: "redis://localhost:7002",
+    },
+  ],
+});
+
+await redisClient.connect();
+
+const io = new Emitter(redisClient);
+
+setInterval(() => {
+  io.emit("ping", new Date());
+}, 1000);
+```
+
+### With the `ioredis` package
+
+```js
+import { Redis } from "ioredis";
+import { Emitter } from "@socket.io/redis-streams-emitter";
+
+const redisClient = new Redis();
+
+const io = new Emitter(redisClient);
+
+setInterval(() => {
+  io.emit("ping", new Date());
+}, 1000);
+```
+
+### With the `ioredis` package and a Redis cluster
+
+```js
+import { Cluster } from "ioredis";
+import { Emitter } from "@socket.io/redis-streams-emitter";
+
+const redisClient = new Cluster([
+  {
+    host: "localhost",
+    port: 7000,
+  },
+  {
+    host: "localhost",
+    port: 7001,
+  },
+  {
+    host: "localhost",
+    port: 7002,
+  },
+]);
+
+const io = new Emitter(redisClient);
+
+setInterval(() => {
+  io.emit("ping", new Date());
+}, 1000);
+```
+
+## Options
+
+| Name         | Description                                                        | Default value |
+|--------------|--------------------------------------------------------------------|---------------|
+| `streamName` | The name of the Redis stream.                                      | `socket.io`   |
+| `maxLen`     | The maximum size of the stream. Almost exact trimming (~) is used. | `10_000`      |
+
+## API
+
+### `Emitter(redisClient[, nsp][, opts])`
+
+```js
+const io = new Emitter(redisClient);
+```
+
+### `Emitter#to(room:string):BroadcastOperator`
+### `Emitter#in(room:string):BroadcastOperator`
+
+Specifies a specific `room` that you want to emit to.
+
+```js
+io.to("room1").emit("hello");
+```
+
+### `Emitter#except(room:string):BroadcastOperator`
+
+Specifies a specific `room` that you want to exclude from broadcasting.
+
+```js
+io.except("room2").emit("hello");
+```
+
+### `Emitter#of(namespace:string):Emitter`
+
+Specifies a specific namespace that you want to emit to.
+
+```js
+const customNamespace = io.of("/custom");
+
+customNamespace.emit("hello");
+```
+
+### `Emitter#socketsJoin(rooms:string|string[])`
+
+Makes the matching socket instances join the specified rooms:
+
+```js
+// make all Socket instances join the "room1" room
+io.socketsJoin("room1");
+
+// make all Socket instances of the "admin" namespace in the "room1" room join the "room2" room
+io.of("/admin").in("room1").socketsJoin("room2");
+```
+
+### `Emitter#socketsLeave(rooms:string|string[])`
+
+Makes the matching socket instances leave the specified rooms:
+
+```js
+// make all Socket instances leave the "room1" room
+io.socketsLeave("room1");
+
+// make all Socket instances of the "admin" namespace in the "room1" room leave the "room2" room
+io.of("/admin").in("room1").socketsLeave("room2");
+```
+
+### `Emitter#disconnectSockets(close:boolean)`
+
+Makes the matching socket instances disconnect:
+
+```js
+// make all Socket instances disconnect
+io.disconnectSockets();
+
+// make all Socket instances of the "admin" namespace in the "room1" room disconnect
+io.of("/admin").in("room1").disconnectSockets();
+
+// this also works with a single socket ID
+io.of("/admin").in(theSocketId).disconnectSockets();
+```
+
+### `Emitter#serverSideEmit(ev:string[,...args:any[]])`
+
+Emits an event that will be received by each Socket.IO server of the cluster.
+
+```js
+io.serverSideEmit("ping");
+```
+
+## License
+
+[MIT](./LICENSE)
--- a/packages/socket.io-redis-streams-emitter/compose.yaml
+++ b/packages/socket.io-redis-streams-emitter/compose.yaml
@@ -0,0 +1,15 @@
+services:
+  redis:
+    image: redis:5
+    ports:
+      - "6379:6379"
+
+  redis-cluster:
+    image: grokzen/redis-cluster:7.0.10
+    ports:
+      - "7000-7005:7000-7005"
+
+  valkey:
+    image: valkey/valkey:8
+    ports:
+      - "6389:6379"
--- a/packages/socket.io-redis-streams-emitter/lib/adapter-types.ts
+++ b/packages/socket.io-redis-streams-emitter/lib/adapter-types.ts
@@ -0,0 +1,75 @@
+// imported from the 'socket.io-adapter' package
+export enum MessageType {
+  INITIAL_HEARTBEAT = 1,
+  HEARTBEAT,
+  BROADCAST,
+  SOCKETS_JOIN,
+  SOCKETS_LEAVE,
+  DISCONNECT_SOCKETS,
+  FETCH_SOCKETS,
+  FETCH_SOCKETS_RESPONSE,
+  SERVER_SIDE_EMIT,
+  SERVER_SIDE_EMIT_RESPONSE,
+  BROADCAST_CLIENT_COUNT,
+  BROADCAST_ACK,
+  ADAPTER_CLOSE,
+}
+
+export type ServerId = string;
+
+export type ClusterMessage = {
+  uid: ServerId;
+  nsp: string;
+} & (
+  | {
+      type:
+        | MessageType.INITIAL_HEARTBEAT
+        | MessageType.HEARTBEAT
+        | MessageType.ADAPTER_CLOSE;
+    }
+  | {
+      type: MessageType.BROADCAST;
+      data: {
+        opts: { rooms: string[]; except: string[]; flags: BroadcastFlags };
+        packet: unknown;
+        requestId?: string;
+      };
+    }
+  | {
+      type: MessageType.SOCKETS_JOIN | MessageType.SOCKETS_LEAVE;
+      data: {
+        opts: { rooms: string[]; except: string[]; flags: BroadcastFlags };
+        rooms: string[];
+      };
+    }
+  | {
+      type: MessageType.DISCONNECT_SOCKETS;
+      data: {
+        opts: { rooms: string[]; except: string[]; flags: BroadcastFlags };
+        close?: boolean;
+      };
+    }
+  | {
+      type: MessageType.FETCH_SOCKETS;
+      data: {
+        opts: { rooms: string[]; except: string[]; flags: BroadcastFlags };
+        requestId: string;
+      };
+    }
+  | {
+      type: MessageType.SERVER_SIDE_EMIT;
+      data: {
+        requestId?: string;
+        packet: any[];
+      };
+    }
+);
+
+export interface BroadcastFlags {
+  volatile?: boolean;
+  compress?: boolean;
+  local?: boolean;
+  broadcast?: boolean;
+  binary?: boolean;
+  timeout?: number;
+}
--- a/packages/socket.io-redis-streams-emitter/lib/index.ts
+++ b/packages/socket.io-redis-streams-emitter/lib/index.ts
@@ -0,0 +1,496 @@
+import debugModule from "debug";
+import type {
+  DefaultEventsMap,
+  EventNames,
+  EventParams,
+  EventsMap,
+  TypedEventBroadcaster,
+} from "./typed-events";
+import { encode } from "@msgpack/msgpack";
+import { hasBinary, XADD } from "./util";
+import { ClusterMessage, MessageType, BroadcastFlags } from "./adapter-types";
+
+const debug = debugModule("socket.io-redis-streams-emitter");
+const EMITTER_UID = "emitter";
+
+type DistributiveOmit<T, K extends keyof any> = T extends any
+  ? Omit<T, K>
+  : never;
+
+// TODO move to the socket.io-adapter package
+abstract class BaseEmitter<
+  EmitEvents extends EventsMap = DefaultEventsMap,
+  ServerSideEvents extends EventsMap = DefaultEventsMap,
+> {
+  protected abstract publish(
+    message: DistributiveOmit<ClusterMessage, "uid" | "nsp">,
+  ): void;
+
+  /**
+   * Emits to all clients.
+   *
+   * @return Always true
+   * @public
+   */
+  public emit<Ev extends EventNames<EmitEvents>>(
+    ev: Ev,
+    ...args: EventParams<EmitEvents, Ev>
+  ): true {
+    return this.newBroadcastOperator().emit(ev, ...args);
+  }
+
+  /**
+   * Targets a room when emitting.
+   *
+   * @param room
+   * @return BroadcastOperator
+   * @public
+   */
+  public to(
+    room: string | string[],
+  ): BroadcastOperator<EmitEvents, ServerSideEvents> {
+    return this.newBroadcastOperator().to(room);
+  }
+
+  /**
+   * Targets a room when emitting.
+   *
+   * @param room
+   * @return BroadcastOperator
+   * @public
+   */
+  public in(
+    room: string | string[],
+  ): BroadcastOperator<EmitEvents, ServerSideEvents> {
+    return this.newBroadcastOperator().in(room);
+  }
+
+  /**
+   * Excludes a room when emitting.
+   *
+   * @param room
+   * @return BroadcastOperator
+   * @public
+   */
+  public except(
+    room: string | string[],
+  ): BroadcastOperator<EmitEvents, ServerSideEvents> {
+    return this.newBroadcastOperator().except(room);
+  }
+
+  /**
+   * Sets a modifier for a subsequent event emission that the event data may be lost if the client is not ready to
+   * receive messages (because of network slowness or other issues, or because they’re connected through long polling
+   * and is in the middle of a request-response cycle).
+   *
+   * @return BroadcastOperator
+   * @public
+   */
+  public get volatile(): BroadcastOperator<EmitEvents, ServerSideEvents> {
+    return this.newBroadcastOperator().volatile;
+  }
+
+  /**
+   * Sets the compress flag.
+   *
+   * @param compress - if `true`, compresses the sending data
+   * @return BroadcastOperator
+   * @public
+   */
+  public compress(
+    compress: boolean,
+  ): BroadcastOperator<EmitEvents, ServerSideEvents> {
+    return this.newBroadcastOperator().compress(compress);
+  }
+
+  /**
+   * Makes the matching socket instances join the specified rooms
+   *
+   * @param rooms
+   * @public
+   */
+  public socketsJoin(rooms: string | string[]): void {
+    return this.newBroadcastOperator().socketsJoin(rooms);
+  }
+
+  /**
+   * Makes the matching socket instances leave the specified rooms
+   *
+   * @param rooms
+   * @public
+   */
+  public socketsLeave(rooms: string | string[]): void {
+    return this.newBroadcastOperator().socketsLeave(rooms);
+  }
+
+  /**
+   * Makes the matching socket instances disconnect
+   *
+   * @param close - whether to close the underlying connection
+   * @public
+   */
+  public disconnectSockets(close: boolean = false): void {
+    return this.newBroadcastOperator().disconnectSockets(close);
+  }
+
+  /**
+   * Send a packet to the Socket.IO servers in the cluster
+   *
+   * @param ev - the event name
+   * @param args - any number of serializable arguments
+   */
+  public serverSideEmit<Ev extends EventNames<ServerSideEvents>>(
+    ev: Ev,
+    ...args: EventParams<ServerSideEvents, Ev>
+  ): void {
+    return this.newBroadcastOperator().serverSideEmit(ev, ...args);
+  }
+
+  private newBroadcastOperator() {
+    return new BroadcastOperator<EmitEvents, ServerSideEvents>((msg) =>
+      this.publish(msg),
+    );
+  }
+}
+
+export const RESERVED_EVENTS: ReadonlySet<string | Symbol> = new Set(<const>[
+  "connect",
+  "connect_error",
+  "disconnect",
+  "disconnecting",
+  "newListener",
+  "removeListener",
+]);
+
+export class BroadcastOperator<
+  EmitEvents extends EventsMap,
+  ServerSideEvents extends EventsMap,
+> implements TypedEventBroadcaster<EmitEvents>
+{
+  constructor(
+    private readonly publish: (
+      message: DistributiveOmit<ClusterMessage, "uid" | "nsp">,
+    ) => void,
+    private readonly rooms: Set<string> = new Set<string>(),
+    private readonly exceptRooms: Set<string> = new Set<string>(),
+    private readonly flags: BroadcastFlags = {},
+  ) {}
+
+  /**
+   * Targets a room when emitting.
+   *
+   * @param room
+   * @return a new BroadcastOperator instance
+   * @public
+   */
+  public to(
+    room: string | string[],
+  ): BroadcastOperator<EmitEvents, ServerSideEvents> {
+    const rooms = new Set(this.rooms);
+    if (Array.isArray(room)) {
+      room.forEach((r) => rooms.add(r));
+    } else {
+      rooms.add(room);
+    }
+    return new BroadcastOperator(
+      this.publish,
+      rooms,
+      this.exceptRooms,
+      this.flags,
+    );
+  }
+
+  /**
+   * Targets a room when emitting.
+   *
+   * @param room
+   * @return a new BroadcastOperator instance
+   * @public
+   */
+  public in(
+    room: string | string[],
+  ): BroadcastOperator<EmitEvents, ServerSideEvents> {
+    return this.to(room);
+  }
+
+  /**
+   * Excludes a room when emitting.
+   *
+   * @param room
+   * @return a new BroadcastOperator instance
+   * @public
+   */
+  public except(
+    room: string | string[],
+  ): BroadcastOperator<EmitEvents, ServerSideEvents> {
+    const exceptRooms = new Set(this.exceptRooms);
+    if (Array.isArray(room)) {
+      room.forEach((r) => exceptRooms.add(r));
+    } else {
+      exceptRooms.add(room);
+    }
+    return new BroadcastOperator(
+      this.publish,
+      this.rooms,
+      exceptRooms,
+      this.flags,
+    );
+  }
+
+  /**
+   * Sets the compress flag.
+   *
+   * @param compress - if `true`, compresses the sending data
+   * @return a new BroadcastOperator instance
+   * @public
+   */
+  public compress(
+    compress: boolean,
+  ): BroadcastOperator<EmitEvents, ServerSideEvents> {
+    const flags = Object.assign({}, this.flags, { compress });
+    return new BroadcastOperator(
+      this.publish,
+      this.rooms,
+      this.exceptRooms,
+      flags,
+    );
+  }
+
+  /**
+   * Sets a modifier for a subsequent event emission that the event data may be lost if the client is not ready to
+   * receive messages (because of network slowness or other issues, or because they’re connected through long polling
+   * and is in the middle of a request-response cycle).
+   *
+   * @return a new BroadcastOperator instance
+   * @public
+   */
+  public get volatile(): BroadcastOperator<EmitEvents, ServerSideEvents> {
+    const flags = Object.assign({}, this.flags, { volatile: true });
+    return new BroadcastOperator(
+      this.publish,
+      this.rooms,
+      this.exceptRooms,
+      flags,
+    );
+  }
+
+  /**
+   * Emits to all clients.
+   *
+   * @return Always true
+   * @public
+   */
+  public emit<Ev extends EventNames<EmitEvents>>(
+    ev: Ev,
+    ...args: EventParams<EmitEvents, Ev>
+  ): true {
+    if (RESERVED_EVENTS.has(ev)) {
+      throw new Error(`"${String(ev)}" is a reserved event name`);
+    }
+
+    // set up packet object
+    const data = [ev, ...args];
+    const packet = {
+      type: 2, // EVENT
+      data: data,
+    };
+
+    const opts = {
+      rooms: [...this.rooms],
+      flags: this.flags,
+      except: [...this.exceptRooms],
+    };
+
+    this.publish({
+      type: MessageType.BROADCAST,
+      data: {
+        packet,
+        opts,
+      },
+    });
+
+    return true;
+  }
+
+  /**
+   * Makes the matching socket instances join the specified rooms
+   *
+   * @param rooms
+   * @public
+   */
+  public socketsJoin(rooms: string | string[]): void {
+    this.publish({
+      type: MessageType.SOCKETS_JOIN,
+      data: {
+        opts: {
+          rooms: [...this.rooms],
+          except: [...this.exceptRooms],
+          flags: {},
+        },
+        rooms: Array.isArray(rooms) ? rooms : [rooms],
+      },
+    });
+  }
+
+  /**
+   * Makes the matching socket instances leave the specified rooms
+   *
+   * @param rooms
+   * @public
+   */
+  public socketsLeave(rooms: string | string[]): void {
+    this.publish({
+      type: MessageType.SOCKETS_LEAVE,
+      data: {
+        opts: {
+          rooms: [...this.rooms],
+          except: [...this.exceptRooms],
+          flags: {},
+        },
+        rooms: Array.isArray(rooms) ? rooms : [rooms],
+      },
+    });
+  }
+
+  /**
+   * Makes the matching socket instances disconnect
+   *
+   * @param close - whether to close the underlying connection
+   * @public
+   */
+  public disconnectSockets(close: boolean = false): void {
+    this.publish({
+      type: MessageType.DISCONNECT_SOCKETS,
+      data: {
+        opts: {
+          rooms: [...this.rooms],
+          except: [...this.exceptRooms],
+          flags: {},
+        },
+        close,
+      },
+    });
+  }
+
+  /**
+   * Send a packet to the Socket.IO servers in the cluster
+   *
+   * @param ev - the event name
+   * @param args - any number of serializable arguments
+   */
+  public serverSideEmit<Ev extends EventNames<ServerSideEvents>>(
+    ev: Ev,
+    ...args: EventParams<ServerSideEvents, Ev>
+  ): void {
+    const withAck = args.length && typeof args[args.length - 1] === "function";
+
+    if (withAck) {
+      throw new Error("Acknowledgements are not supported");
+    }
+
+    this.publish({
+      type: MessageType.SERVER_SIDE_EMIT,
+      data: {
+        packet: [ev, ...args],
+      },
+    });
+  }
+}
+
+function flattenPayload(message: ClusterMessage) {
+  const rawMessage = {
+    uid: message.uid,
+    nsp: message.nsp,
+    type: message.type.toString(),
+    data: undefined as string | undefined,
+  };
+
+  // @ts-expect-error
+  const data = message.data;
+
+  if (data) {
+    const mayContainBinary = [
+      MessageType.BROADCAST,
+      MessageType.FETCH_SOCKETS_RESPONSE,
+      MessageType.SERVER_SIDE_EMIT,
+      MessageType.SERVER_SIDE_EMIT_RESPONSE,
+      MessageType.BROADCAST_ACK,
+    ].includes(message.type);
+
+    if (mayContainBinary && hasBinary(data)) {
+      rawMessage.data = Buffer.from(encode(data)).toString("base64");
+    } else {
+      rawMessage.data = JSON.stringify(data);
+    }
+  }
+
+  return rawMessage;
+}
+
+export interface RedisStreamsEmitterOptions {
+  /**
+   * The name of the Redis stream.
+   * @default "socket.io"
+   */
+  streamName?: string;
+  /**
+   * The maximum size of the stream. Almost exact trimming (~) is used.
+   * @default 10_000
+   */
+  maxLen?: number;
+}
+
+export class Emitter<
+  EmitEvents extends EventsMap = DefaultEventsMap,
+  ServerSideEvents extends EventsMap = DefaultEventsMap,
+> extends BaseEmitter<EmitEvents, ServerSideEvents> {
+  readonly #redisClient: any;
+  readonly #opts: Required<RedisStreamsEmitterOptions>;
+  readonly #nsp: string;
+
+  constructor(
+    redisClient: any,
+    opts: RedisStreamsEmitterOptions = {},
+    nsp = "/",
+  ) {
+    super();
+    this.#redisClient = redisClient;
+    this.#opts = Object.assign(
+      {
+        streamName: "socket.io",
+        maxLen: 10_000,
+      },
+      opts,
+    );
+    this.#nsp = nsp;
+  }
+
+  public of(nsp: string) {
+    return new Emitter(this.#redisClient, this.#opts, nsp);
+  }
+
+  protected override publish(
+    message: DistributiveOmit<ClusterMessage, "uid" | "nsp">,
+  ) {
+    (message as ClusterMessage).uid = EMITTER_UID;
+    (message as ClusterMessage).nsp = this.#nsp;
+
+    debug(
+      "publishing message %s to stream %s",
+      message.type,
+      this.#opts.streamName,
+    );
+
+    if (message.type === MessageType.BROADCAST) {
+      // @ts-expect-error FIXME untyped packet object
+      message.data.packet.nsp = this.#nsp;
+    }
+
+    return XADD(
+      this.#redisClient,
+      this.#opts.streamName,
+      flattenPayload(message as ClusterMessage),
+      this.#opts.maxLen,
+    );
+  }
+}
--- a/packages/socket.io-redis-streams-emitter/lib/typed-events.ts
+++ b/packages/socket.io-redis-streams-emitter/lib/typed-events.ts
@@ -0,0 +1,37 @@
+/**
+ * An events map is an interface that maps event names to their value, which
+ * represents the type of the `on` listener.
+ */
+export interface EventsMap {
+  [event: string]: any;
+}
+
+/**
+ * The default events map, used if no EventsMap is given. Using this EventsMap
+ * is equivalent to accepting all event names, and any data.
+ */
+export interface DefaultEventsMap {
+  [event: string]: (...args: any[]) => void;
+}
+
+/**
+ * Returns a union type containing all the keys of an event map.
+ */
+export type EventNames<Map extends EventsMap> = keyof Map & (string | symbol);
+
+/** The tuple type representing the parameters of an event listener */
+export type EventParams<
+  Map extends EventsMap,
+  Ev extends EventNames<Map>,
+> = Parameters<Map[Ev]>;
+
+/**
+ * Interface for classes that aren't `EventEmitter`s, but still expose a
+ * strictly typed `emit` method.
+ */
+export interface TypedEventBroadcaster<EmitEvents extends EventsMap> {
+  emit<Ev extends EventNames<EmitEvents>>(
+    ev: Ev,
+    ...args: EventParams<EmitEvents, Ev>
+  ): boolean;
+}
--- a/packages/socket.io-redis-streams-emitter/lib/util.ts
+++ b/packages/socket.io-redis-streams-emitter/lib/util.ts
@@ -0,0 +1,68 @@
+export function hasBinary(obj: any, toJSON?: boolean): boolean {
+  if (!obj || typeof obj !== "object") {
+    return false;
+  }
+
+  if (obj instanceof ArrayBuffer || ArrayBuffer.isView(obj)) {
+    return true;
+  }
+
+  if (Array.isArray(obj)) {
+    for (let i = 0, l = obj.length; i < l; i++) {
+      if (hasBinary(obj[i])) {
+        return true;
+      }
+    }
+    return false;
+  }
+
+  for (const key in obj) {
+    if (Object.prototype.hasOwnProperty.call(obj, key) && hasBinary(obj[key])) {
+      return true;
+    }
+  }
+
+  if (obj.toJSON && typeof obj.toJSON === "function" && !toJSON) {
+    return hasBinary(obj.toJSON(), true);
+  }
+
+  return false;
+}
+
+/**
+ * Whether the client comes from the `redis` package
+ *
+ * @param redisClient
+ *
+ * @see https://github.com/redis/node-redis
+ */
+function isRedisV4Client(redisClient: any) {
+  return typeof redisClient.sSubscribe === "function";
+}
+
+/**
+ * @see https://redis.io/commands/xadd/
+ */
+export function XADD(
+  redisClient: any,
+  streamName: string,
+  payload: any,
+  maxLenThreshold: number,
+) {
+  if (isRedisV4Client(redisClient)) {
+    return redisClient.xAdd(streamName, "*", payload, {
+      TRIM: {
+        strategy: "MAXLEN",
+        strategyModifier: "~",
+        threshold: maxLenThreshold,
+      },
+    });
+  } else {
+    const args = [streamName, "MAXLEN", "~", maxLenThreshold, "*"];
+    Object.keys(payload).forEach((k) => {
+      args.push(k, payload[k]);
+    });
+
+    return redisClient.xadd.call(redisClient, args);
+  }
+}
--- a/packages/socket.io-redis-streams-emitter/package.json
+++ b/packages/socket.io-redis-streams-emitter/package.json
@@ -0,0 +1,38 @@
+{
+  "name": "@socket.io/redis-streams-emitter",
+  "version": "0.1.1",
+  "description": "The Socket.IO Redis streams emitter, allowing to communicate with a group of Socket.IO servers from another Node.js process",
+  "license": "MIT",
+  "homepage": "https://github.com/socketio/socket.io/tree/main/packages/socket.io-redis-streams-emitter#readme",
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/socketio/socket.io.git"
+  },
+  "files": [
+    "dist/"
+  ],
+  "main": "./dist/index.js",
+  "types": "./dist/index.d.ts",
+  "scripts": {
+    "compile": "rimraf ./dist && tsc",
+    "format:check": "prettier --parser typescript --check 'lib/**/*.ts' 'test/**/*.ts'",
+    "format:fix": "prettier --parser typescript --write 'lib/**/*.ts' 'test/**/*.ts'",
+    "prepack": "npm run compile",
+    "test": "npm run format:check && npm run compile && npm run test:redis-standalone && npm run test:ioredis-standalone",
+    "test:redis-standalone": "nyc mocha --import=tsx test/**/*.ts",
+    "test:redis-cluster": "REDIS_CLUSTER=1 mocha --import=tsx test/**/*.ts",
+    "test:ioredis-standalone": "REDIS_LIB=ioredis mocha --import=tsx test/**/*.ts",
+    "test:ioredis-cluster": "REDIS_LIB=ioredis REDIS_CLUSTER=1 mocha --import=tsx test/**/*.ts",
+    "test:valkey-standalone": "VALKEY=1 mocha --import=tsx test/**/*.ts"
+  },
+  "dependencies": {
+    "@msgpack/msgpack": "~2.8.0",
+    "debug": "~4.4.1"
+  },
+  "keywords": [
+    "socket.io",
+    "redis",
+    "redis-streams",
+    "emitter"
+  ]
+}
--- a/packages/socket.io-redis-streams-emitter/test/index.ts
+++ b/packages/socket.io-redis-streams-emitter/test/index.ts
@@ -0,0 +1,225 @@
+import { type Server, type Socket as ServerSocket } from "socket.io";
+import { type Socket as ClientSocket } from "socket.io-client";
+import expect = require("expect.js");
+import { times, sleep, setup, initRedisClient } from "./util";
+import { Emitter } from "../lib";
+
+const PROPAGATION_DELAY_IN_MS = 100;
+
+describe("@socket.io/redis-streams-emitter", () => {
+  let servers: Server[],
+    serverSockets: ServerSocket[],
+    clientSockets: ClientSocket[],
+    cleanup: () => void,
+    emitter: Emitter;
+
+  beforeEach(async () => {
+    const testContext = await setup();
+    servers = testContext.servers;
+    serverSockets = testContext.serverSockets;
+    clientSockets = testContext.clientSockets;
+    const redisClient = await initRedisClient();
+    emitter = new Emitter(redisClient);
+
+    cleanup = () => {
+      testContext.cleanup();
+      redisClient.quit();
+    };
+  });
+
+  afterEach(() => cleanup());
+
+  describe("broadcast", function () {
+    it("broadcasts to all clients", (done) => {
+      const partialDone = times(3, done);
+
+      clientSockets.forEach((clientSocket) => {
+        clientSocket.on("test", (arg1, arg2, arg3) => {
+          expect(arg1).to.eql(1);
+          expect(arg2).to.eql("2");
+          expect(Buffer.isBuffer(arg3)).to.be(true);
+          partialDone();
+        });
+      });
+
+      emitter.emit("test", 1, "2", Buffer.from([3, 4]));
+    });
+
+    it("broadcasts to all clients in a namespace", (done) => {
+      const partialDone = times(3, () => {
+        servers.forEach((server) => server.of("/custom").adapter.close());
+        done();
+      });
+
+      servers.forEach((server) => server.of("/custom"));
+
+      const onConnect = times(3, async () => {
+        await sleep(PROPAGATION_DELAY_IN_MS);
+
+        emitter.of("/custom").emit("test");
+      });
+
+      clientSockets.forEach((clientSocket) => {
+        const socket = clientSocket.io.socket("/custom");
+        socket.on("connect", onConnect);
+        socket.on("test", () => {
+          socket.disconnect();
+          partialDone();
+        });
+      });
+    });
+
+    it("broadcasts to all clients in a room", (done) => {
+      serverSockets[1].join("room1");
+
+      clientSockets[0].on("test", () => {
+        done(new Error("should not happen"));
+      });
+
+      clientSockets[1].on("test", () => {
+        done();
+      });
+
+      clientSockets[2].on("test", () => {
+        done(new Error("should not happen"));
+      });
+
+      emitter.to("room1").emit("test");
+    });
+
+    it("broadcasts to all clients except in room", (done) => {
+      const partialDone = times(2, done);
+      serverSockets[1].join("room1");
+
+      clientSockets[0].on("test", () => {
+        partialDone();
+      });
+
+      clientSockets[1].on("test", () => {
+        done(new Error("should not happen"));
+      });
+
+      clientSockets[2].on("test", () => {
+        partialDone();
+      });
+
+      emitter.of("/").except("room1").emit("test");
+    });
+  });
+
+  describe("socketsJoin", () => {
+    it("makes all socket instances join the specified room", async () => {
+      emitter.socketsJoin("room1");
+
+      await sleep(PROPAGATION_DELAY_IN_MS);
+
+      expect(serverSockets[0].rooms.has("room1")).to.be(true);
+      expect(serverSockets[1].rooms.has("room1")).to.be(true);
+      expect(serverSockets[2].rooms.has("room1")).to.be(true);
+    });
+
+    it("makes the matching socket instances join the specified room", async () => {
+      serverSockets[0].join("room1");
+      serverSockets[2].join("room1");
+
+      emitter.in("room1").socketsJoin("room2");
+
+      await sleep(PROPAGATION_DELAY_IN_MS);
+
+      expect(serverSockets[0].rooms.has("room2")).to.be(true);
+      expect(serverSockets[1].rooms.has("room2")).to.be(false);
+      expect(serverSockets[2].rooms.has("room2")).to.be(true);
+    });
+
+    it("makes the given socket instance join the specified room", async () => {
+      emitter.in(serverSockets[1].id).socketsJoin("room3");
+
+      await sleep(PROPAGATION_DELAY_IN_MS);
+
+      expect(serverSockets[0].rooms.has("room3")).to.be(false);
+      expect(serverSockets[1].rooms.has("room3")).to.be(true);
+      expect(serverSockets[2].rooms.has("room3")).to.be(false);
+    });
+  });
+
+  describe("socketsLeave", () => {
+    it("makes all socket instances leave the specified room", async () => {
+      serverSockets[0].join("room1");
+      serverSockets[2].join("room1");
+
+      emitter.socketsLeave("room1");
+
+      await sleep(PROPAGATION_DELAY_IN_MS);
+
+      expect(serverSockets[0].rooms.has("room1")).to.be(false);
+      expect(serverSockets[1].rooms.has("room1")).to.be(false);
+      expect(serverSockets[2].rooms.has("room1")).to.be(false);
+    });
+
+    it("makes the matching socket instances leave the specified room", async () => {
+      serverSockets[0].join(["room1", "room2"]);
+      serverSockets[1].join(["room1", "room2"]);
+      serverSockets[2].join(["room2"]);
+
+      emitter.in("room1").socketsLeave("room2");
+
+      await sleep(PROPAGATION_DELAY_IN_MS);
+
+      expect(serverSockets[0].rooms.has("room2")).to.be(false);
+      expect(serverSockets[1].rooms.has("room2")).to.be(false);
+      expect(serverSockets[2].rooms.has("room2")).to.be(true);
+    });
+
+    it("makes the given socket instance leave the specified room", async () => {
+      serverSockets[0].join("room3");
+      serverSockets[1].join("room3");
+      serverSockets[2].join("room3");
+
+      emitter.in(serverSockets[1].id).socketsLeave("room3");
+
+      await sleep(PROPAGATION_DELAY_IN_MS);
+
+      expect(serverSockets[0].rooms.has("room3")).to.be(true);
+      expect(serverSockets[1].rooms.has("room3")).to.be(false);
+      expect(serverSockets[2].rooms.has("room3")).to.be(true);
+    });
+  });
+
+  describe("disconnectSockets", () => {
+    it("makes all socket instances disconnect", (done) => {
+      const partialDone = times(3, done);
+
+      clientSockets.forEach((clientSocket) => {
+        clientSocket.on("disconnect", (reason) => {
+          expect(reason).to.eql("io server disconnect");
+          partialDone();
+        });
+      });
+
+      emitter.disconnectSockets();
+    });
+  });
+
+  describe("serverSideEmit", () => {
+    it("sends an event to other server instances", (done) => {
+      const partialDone = times(3, done);
+
+      emitter.serverSideEmit("hello", "world", 1, "2");
+
+      servers[0].on("hello", (arg1, arg2, arg3) => {
+        expect(arg1).to.eql("world");
+        expect(arg2).to.eql(1);
+        expect(arg3).to.eql("2");
+        partialDone();
+      });
+
+      servers[1].on("hello", (arg1, arg2, arg3) => {
+        partialDone();
+      });
+
+      servers[2].of("/").on("hello", () => {
+        partialDone();
+      });
+    });
+  });
+});
--- a/packages/socket.io-redis-streams-emitter/test/util.ts
+++ b/packages/socket.io-redis-streams-emitter/test/util.ts
@@ -0,0 +1,156 @@
+import { createServer } from "node:http";
+import { type AddressInfo } from "node:net";
+import { createClient, createCluster } from "redis";
+import { Redis, Cluster } from "ioredis";
+import { Server, type Socket as ServerSocket } from "socket.io";
+import { io as ioc, type Socket as ClientSocket } from "socket.io-client";
+import { createAdapter } from "@socket.io/redis-streams-adapter";
+
+export function times(count: number, fn: () => void) {
+  let i = 0;
+  return () => {
+    i++;
+    if (i === count) {
+      fn();
+    } else if (i > count) {
+      throw new Error(`too many calls: ${i} instead of ${count}`);
+    }
+  };
+}
+
+export function sleep(duration: number) {
+  return new Promise((resolve) => setTimeout(resolve, duration));
+}
+
+const mode = process.env.REDIS_CLUSTER === "1" ? "cluster" : "standalone";
+const lib = process.env.REDIS_LIB || "redis";
+
+console.log(`[INFO] testing in ${mode} mode with ${lib}`);
+
+export async function initRedisClient() {
+  if (mode === "cluster") {
+    if (lib === "ioredis") {
+      return new Cluster([
+        {
+          host: "localhost",
+          port: 7000,
+        },
+        {
+          host: "localhost",
+          port: 7001,
+        },
+        {
+          host: "localhost",
+          port: 7002,
+        },
+        {
+          host: "localhost",
+          port: 7003,
+        },
+        {
+          host: "localhost",
+          port: 7004,
+        },
+        {
+          host: "localhost",
+          port: 7005,
+        },
+      ]);
+    } else {
+      const redisClient = createCluster({
+        rootNodes: [
+          {
+            url: "redis://localhost:7000",
+          },
+          {
+            url: "redis://localhost:7001",
+          },
+          {
+            url: "redis://localhost:7002",
+          },
+          {
+            url: "redis://localhost:7003",
+          },
+          {
+            url: "redis://localhost:7004",
+          },
+          {
+            url: "redis://localhost:7005",
+          },
+        ],
+      });
+
+      await redisClient.connect();
+
+      return redisClient;
+    }
+  } else {
+    if (lib === "ioredis") {
+      return new Redis();
+    } else {
+      const port = process.env.VALKEY === "1" ? 6389 : 6379;
+      const redisClient = createClient({
+        url: `redis://localhost:${port}`,
+      });
+      await redisClient.connect();
+
+      return redisClient;
+    }
+  }
+}
+
+async function init() {
+  const redisClient = await initRedisClient();
+
+  const httpServer = createServer();
+  const io = new Server(httpServer, {
+    adapter: createAdapter(redisClient, {
+      readCount: 1, // return as soon as possible
+    }),
+  });
+
+  return new Promise<{
+    io: Server;
+    socket: ServerSocket;
+    clientSocket: ClientSocket;
+    cleanup: () => void;
+  }>((resolve) => {
+    httpServer.listen(() => {
+      const port = (httpServer.address() as AddressInfo).port;
+      const clientSocket = ioc(`http://localhost:${port}`);
+
+      io.on("connection", async (socket) => {
+        resolve({
+          io,
+          socket,
+          clientSocket,
+          cleanup: () => {
+            io.close();
+            clientSocket.disconnect();
+            redisClient.quit();
+          },
+        });
+      });
+    });
+  });
+}
+
+export async function setup() {
+  const results = await Promise.all([init(), init(), init()]);
+
+  const servers = results.map(({ io }) => io);
+  const serverSockets = results.map(({ socket }) => socket);
+  const clientSockets = results.map(({ clientSocket }) => clientSocket);
+  const cleanupMethods = results.map(({ cleanup }) => cleanup);
+
+  return {
+    servers,
+    serverSockets,
+    clientSockets,
+    cleanup: () => {
+      for (const cleanup of cleanupMethods) {
+        cleanup();
+      }
+    },
+  };
+}
--- a/packages/socket.io-redis-streams-emitter/tsconfig.json
+++ b/packages/socket.io-redis-streams-emitter/tsconfig.json
@@ -0,0 +1,13 @@
+{
+  "compilerOptions": {
+    "outDir": "./dist",
+    "allowJs": false,
+    "target": "es2022",
+    "module": "commonjs",
+    "declaration": true,
+    "strict": true
+  },
+  "include": [
+    "./lib/**/*"
+  ]
+}
--- a/packages/socket.io/RELEASING.md
+++ b/packages/socket.io/RELEASING.md
@@ -0,0 +1,8 @@
+# Releasing
+
+1. Update the version in `package.json`
+2. Update the changelog `CHANGELOG.md` with `conventional-changelog -p angular`
+3. Copy the bundles from the client project to `client-dist/`
+4. Commit the changes in `package.json`, `CHANGELOG.md` and `client-dist/`
+5. Create the tag `socket.io@x.y.z` and push it to the GitHub repository. The workflow `.github/workflows/publish.yml` will safely publish the package to npm using trusted publishing.
+6. Create a new release at https://github.com/socketio/socket.io/releases
--- a/packages/socket.io/lib/client.ts
+++ b/packages/socket.io/lib/client.ts
@@ -267,16 +267,7 @@ export class Client<
   * @private
   */
  private ondecoded(packet: Packet): void {
-    let namespace: string;
-    let authPayload: Record<string, unknown>;
-    if (this.conn.protocol === 3) {
-      const parsed = url.parse(packet.nsp, true);
-      namespace = parsed.pathname!;
-      authPayload = parsed.query;
-    } else {
-      namespace = packet.nsp;
-      authPayload = packet.data;
-    }
+    const { namespace, authPayload } = this._parseNamespace(packet);
    const socket = this.nsps.get(namespace);

    if (!socket && packet.type === PacketType.CONNECT) {
@@ -295,6 +286,20 @@ export class Client<
    }
  }

+  private _parseNamespace(packet: Packet) {
+    if (this.conn.protocol !== 3) {
+      return {
+        namespace: packet.nsp,
+        authPayload: packet.data,
+      };
+    }
+    const url = new URL(packet.nsp, "https://socket.io");
+    return {
+      namespace: url.pathname,
+      authPayload: Object.fromEntries(url.searchParams.entries()),
+    };
+  }
+
  /**
   * Handles an error.
   *
--- a/packages/socket.io/lib/namespace.ts
+++ b/packages/socket.io/lib/namespace.ts
@@ -197,6 +197,10 @@ export class Namespace<
  _initAdapter(): void {
    // @ts-ignore
    this.adapter = new (this.server.adapter()!)(this);
+
+    Promise.resolve(this.adapter.init()).catch((err) => {
+      debug("error while initializing adapter: %s", err);
+    });
  }

  /**
--- a/packages/socket.io/package.json
+++ b/packages/socket.io/package.json
@@ -53,7 +53,7 @@
    "accepts": "~1.3.4",
    "base64id": "~2.0.0",
    "cors": "~2.8.5",
-    "debug": "~4.3.2",
+    "debug": "~4.4.1",
    "engine.io": "~6.6.0",
    "socket.io-adapter": "~2.5.2",
    "socket.io-parser": "~4.2.4"
Author	SHA1	Message	Date
Damien Arrachequesne	2a2b44f20d	test: add test	2025-12-22 10:24:29 +01:00
Suraj Rana	e1ad89a708	Drain queue before emitting connect event	2025-12-22 09:58:31 +01:00
Damien Arrachequesne	cdae01983a	fix(sio-client): do not mangle the "_placeholder" attribute (bis) The "_placeholder" attribute is used when sending binary data, and was incorrectly mangled (converted to a random short property, like "it", to reduce the bundle size). Related: - `ca9e994815` - https://github.com/socketio/socket.io/issues/5215 [skip ci]	2025-12-19 15:48:28 +01:00
Damien Arrachequesne	39bb72039d	docs: add release steps [skip ci]	2025-12-19 15:43:14 +01:00
Valentin Rault	98741e15e9	refactor(sio-client): export DisconnectDescription type (#5392 ) Related: https://github.com/socketio/socket.io/issues/4556	2025-12-19 14:51:39 +01:00
Damien Arrachequesne	8af70195bb	refactor(sio): use URL constructor instead of url.parse() Related: https://github.com/socketio/socket.io/issues/5377	2025-12-19 14:44:30 +01:00
Damien Arrachequesne	d88f3f4578	ci: use actions/checkout@v6 and actions/setup-node@v6 Release notes: - https://github.com/actions/checkout/blob/main/CHANGELOG.md - https://github.com/actions/setup-node/releases/tag/v6.0.0	2025-12-15 09:38:45 +01:00
Damien Arrachequesne	f5ee981ee8	ci(publish): use trusted publishing Reference: https://docs.npmjs.com/trusted-publishers [skip ci]	2025-12-15 08:57:17 +01:00
Damien Arrachequesne	76e3a72bba	docs: add missing changelog links [skip ci]	2025-12-15 08:55:26 +01:00
Damien Arrachequesne	a7b1938d06	test: regenerate SSL certs	2025-12-15 08:45:47 +01:00
Damien Arrachequesne	54743633ff	chore(release): @socket.io/redis-streams-emitter@0.1.1 Diff: https://github.com/socketio/socket.io/compare/@socket.io/redis-streams-emitter@0.1.0...@socket.io/redis-streams-emitter@0.1.1	2025-11-07 10:33:07 +01:00
Damien Arrachequesne	7617707ed8	fix(redis-streams-emitter): remove dependency on socket.io-adapter Related: https://github.com/socketio/socket.io/issues/5414	2025-11-07 10:28:27 +01:00
Damien Arrachequesne	599001d213	chore(release): @socket.io/redis-streams-emitter@0.1.0	2025-11-06 18:23:00 +01:00
Damien Arrachequesne	1c3e4711c1	feat: add emitter based on Redis streams Related: https://github.com/socketio/socket.io-redis-streams-adapter/issues/8	2025-11-06 18:03:37 +01:00
Damien Arrachequesne	693080cac7	refactor(sio-adapter): add more debug logs	2025-10-20 15:11:21 +02:00
Damien Arrachequesne	5080c73e1e	refactor: fix npm command	2025-10-17 09:41:39 +02:00
Damien Arrachequesne	47ff1cd04c	chore(release): @socket.io/cluster-adapter@0.3.0 Diff: https://github.com/socketio/socket.io-cluster-adapter/compare/0.2.2...0.3.0	2025-10-16 19:55:56 +02:00
Damien Arrachequesne	0ae76360f9	Merge remote-tracking branch 'socket.io-cluster-adapter/monorepo'	2025-10-16 19:35:51 +02:00
Damien Arrachequesne	27fd420e75	refactor: prepare migration to monorepo	2025-10-16 19:31:30 +02:00
Damien Arrachequesne	0c431243e2	refactor: use the ClusterAdapter class from socket.io-adapter package The ClusterAdapter class has been moved to [1], so that this adapter only needs to implement to pub/sub mechanism. Also, [2] should reduce the number of "timeout reached: only x responses received out of y" errors, since the fetchSockets() requests will now succeed even if a server leaves the cluster. [1]: https://github.com/socketio/socket.io/tree/main/packages/socket.io-adapter [2]: `0e23ff0cc6`	2025-10-16 19:16:20 +02:00
Damien Arrachequesne	4fc25d80ec	ci: add Node.js 24 Reference: https://github.com/nodejs/Release	2025-10-16 12:03:32 +02:00
Damien Arrachequesne	1dd729b1a1	refactor: upgrade to prettier 3	2025-10-16 11:51:11 +02:00
Damien Arrachequesne	6877512f57	refactor: upgrade to TypeScript 5	2025-10-16 11:49:12 +02:00
Damien Arrachequesne	cf6816afcf	chore: npm audit fix	2025-10-10 09:29:29 +02:00
Damien Arrachequesne	625fd66d73	chore: dedupe debug dependency	2025-10-10 09:11:54 +02:00
Damien Arrachequesne	f3e1f5ebdf	fix(sio): call adapter.init() when creating each namespace The init() method of the adapter will now be called when creating a namespace with `io.of(<the-namespace>)`. Note: any promise rejection is silently caught, as I don't see how we could properly expose the promise. ```js const io = new Server({ adapter: myAdapter }); // under the hood, this: // - implicitly creates the main namespace (/) // - creates an instance of `myAdapter` for the main namespace // - calls `myAdapter.init()` (with this change) ``` Related: - https://github.com/socketio/socket.io/issues/3662 - https://github.com/socketio/socket.io-postgres-adapter/issues/16	2025-10-09 09:48:07 +02:00
Damien Arrachequesne	e97549259e	ci(browser): use Windows 8 for IE tests	2025-09-30 11:44:50 +02:00
MiaoWoo	1da9cddeab	fix(eio-client): properly handle port option (#5241 ) Passing { port: "443" } would include the port in the URL (":443").	2025-09-30 10:57:43 +02:00
Avi Vahl	6f9b198bc8	chore(deps): ws@8.18.3, debug@4.4.1 (#5335 ) Release notes: - https://github.com/websockets/ws/releases/tag/8.18.3 - https://github.com/debug-js/debug/releases/tag/4.4.1	2025-09-11 07:51:07 +02:00
Damien Arrachequesne	56a53bceb9	ci: add Node.js 20 in the test matrix	2023-07-09 10:03:47 +02:00
Damien Arrachequesne	683720a67d	test: fix flaky test	2023-07-09 10:03:46 +02:00
Damien Arrachequesne	a529eb08d6	chore: bump dev dependencies	2023-07-09 10:03:32 +02:00
Damien Arrachequesne	cddb78e5fa	chore(release): 0.2.2 Diff: https://github.com/socketio/socket.io-cluster-adapter/compare/0.2.1...0.2.2	2023-03-24 17:32:35 +01:00
Damien Arrachequesne	15fd56e78d	chore: add socket.io-parser to peerDependencies This should (at least in theory) fix sync issues for the `socket.io-adapter` package, which is imported by both the `socket.io` and `@socket.io/cluster-adapter` packages: - `socket.io@4.5.0` should resolve `socket.io-adapter@~2.4.0` - `socket.io@4.6.0` should resolve `socket.io-adapter@~2.5.0`	2023-03-24 17:28:57 +01:00
Damien Arrachequesne	e86ef45f87	ci: upgrade to actions/checkout@3 and actions/setup-node@3 Reference: https://github.blog/changelog/2022-09-22-github-actions-all-actions-will-begin-running-on-node16-instead-of-node12/	2023-03-24 17:16:25 +01:00
Damien Arrachequesne	fe840e2eb3	chore(release): 0.2.1 Diff: https://github.com/socketio/socket.io-cluster-adapter/compare/0.2.0...0.2.1	2022-10-13 09:23:36 +02:00
Damien Arrachequesne	a5a1c29082	chore: update dev dependencies	2022-10-13 09:17:46 +02:00
Damien Arrachequesne	66b4079953	ci: add Node.js 18 in the test matrix Reference: https://github.com/nodejs/Release	2022-10-13 09:15:34 +02:00
Rolando Andrade	be0a0e3217	fix: properly handle ERR_IPC_CHANNEL_CLOSED errors (#6 ) Related: https://github.com/socketio/socket.io-cluster-adapter/issues/5	2022-10-13 09:11:37 +02:00
Damien Arrachequesne	43f9ee8d23	chore(release): 0.2.0 Diff: https://github.com/socketio/socket.io-cluster-adapter/compare/0.1.0...0.2.0	2022-04-28 16:16:13 +02:00
Damien Arrachequesne	055b7840d8	feat: broadcast and expect multiple acks This feature was added in `socket.io@4.5.0`: ```js io.timeout(1000).emit("some-event", (err, responses) => { // ... }); ``` Thanks to this change, it will now work with multiple Socket.IO servers. Related: https://github.com/socketio/socket.io/issues/4163	2022-04-28 16:11:12 +02:00
Damien Arrachequesne	6397c1bdfd	chore(release): 0.1.0	2021-06-22 07:06:15 +02:00
Damien Arrachequesne	ff370cfc46	Initial commit	2021-06-22 07:02:16 +02:00