Simplifies the format for client IDs.

pkgs/sse/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 4.1.8
+
+- Simplify the format of client ID strings.
+
 ## 4.1.7
 
 - Move to `dart-lang/tools` monorepo.

pkgs/sse/lib/client/sse_client.dart

@@ -11,7 +11,7 @@ import 'package:pool/pool.dart';
 import 'package:stream_channel/stream_channel.dart';
 import 'package:web/web.dart';
 
-import '../src/util/uuid.dart';
+import '../src/util/id.dart';
 
 /// Limit for the number of concurrent outgoing requests.
 ///
@@ -21,7 +21,7 @@ import '../src/util/uuid.dart';
 /// Note Chrome's limit is 6000. So this gives us plenty of headroom.
 final _requestPool = Pool(1000);
 
-/// A client for bi-directional sse communication.
+/// A client for bi-directional SSE communication.
 ///
 /// The client can send any JSON-encodable messages to the server by adding
 /// them to the [sink] and listen to messages from the server on the [stream].
@@ -48,9 +48,8 @@ class SseClient extends StreamChannelMixin<String?> {
   /// incoming bi-directional SSE connections. [debugKey] is an optional key
   /// that can be used to identify the SSE connection.
   SseClient(String serverUrl, {String? debugKey})
-      : _clientId = debugKey == null
-            ? generateUuidV4()
-            : '$debugKey-${generateUuidV4()}' {
+      : _clientId =
+            debugKey == null ? generateId() : '$debugKey-${generateId()}' {
     _serverUrl = '$serverUrl?sseClientId=$_clientId';
     _eventSource =
         EventSource(_serverUrl, EventSourceInit(withCredentials: true));

pkgs/sse/lib/src/util/id.dart

@@ -0,0 +1,22 @@
+// Copyright (c) 2025, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:math' show Random;
+
+/// Generates a pseudo-random ID string with 32 bits of entropy.
+String generateId() {
+  final chars = List<int>.filled(6, 0);
+  final random = Random();
+  var bits = random.nextInt(0x100000000);
+  for (var i = 0; i < 6; i++) {
+    chars[i] = _base64Chars.codeUnitAt(bits & 0x3F);
+    bits >>>= 6;
+  }
+  return String.fromCharCodes(chars);
+}
+
+// A standard encoding of 6 bits per character, without any non-ASCII,
+// non-printable or disallowed characters.
+const _base64Chars =
+    'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';

pkgs/sse/pubspec.yaml

@@ -1,5 +1,5 @@
 name: sse
-version: 4.1.7
+version: 4.1.8
 description: >-
   Provides client and server functionality for setting up bi-directional
   communication through Server Sent Events (SSE) and corresponding POST