Fix IPv6 hosts missing brackets in constructed URIs

src/common/lib/client/baseclient.ts

@@ -1,5 +1,5 @@
 import Logger, { LoggerOptions } from '../util/logger';
-import Defaults from '../util/defaults';
+import Defaults, { formatHostForUri } from '../util/defaults';
 import Auth from './auth';
 import { HttpPaginatedResponse, PaginatedResult } from './paginatedresource';
 import ErrorInfo from '../types/errorinfo';
@@ -205,7 +205,7 @@ class BaseClient {
   }
 
   baseUri(host: string) {
-    return Defaults.getHttpScheme(this.options) + host + ':' + Defaults.getPort(this.options, false);
+    return Defaults.getHttpScheme(this.options) + formatHostForUri(host) + ':' + Defaults.getPort(this.options, false);
   }
 
   async stats(params?: RequestParams): Promise<PaginatedResult<Stats>> {

src/common/lib/transport/comettransport.ts

@@ -6,7 +6,7 @@ import ProtocolMessage, {
 } from '../types/protocolmessage';
 import Transport from './transport';
 import Logger from '../util/logger';
-import Defaults from '../util/defaults';
+import Defaults, { formatHostForUri } from '../util/defaults';
 import ConnectionErrors from './connectionerrors';
 import Auth from '../client/auth';
 import ErrorInfo from '../types/errorinfo';
@@ -81,7 +81,7 @@ abstract class CometTransport extends Transport {
     const port = Defaults.getPort(options);
     const cometScheme = options.tls ? 'https://' : 'http://';
 
-    this.baseUri = cometScheme + host + ':' + port + '/comet/';
+    this.baseUri = cometScheme + formatHostForUri(host) + ':' + port + '/comet/';
     const connectUri = this.baseUri + 'connect';
     Logger.logAction(this.logger, Logger.LOG_MINOR, 'CometTransport.connect()', 'uri: ' + connectUri);
     Utils.whenPromiseSettles(this.auth.getAuthParams(), (err: Error | null, authParams?: Record<string, any>) => {

src/common/lib/transport/websockettransport.ts

@@ -1,7 +1,7 @@
 import Platform from 'common/platform';
 import * as Utils from '../util/utils';
 import Transport from './transport';
-import Defaults from '../util/defaults';
+import Defaults, { formatHostForUri } from '../util/defaults';
 import Logger from '../util/logger';
 import ProtocolMessage, {
   serialize as serializeProtocolMessage,
@@ -52,7 +52,7 @@ class WebSocketTransport extends Transport {
       params = this.params,
       options = params.options;
     const wsScheme = options.tls ? 'wss://' : 'ws://';
-    const wsUri = wsScheme + this.wsHost + ':' + Defaults.getPort(options) + '/';
+    const wsUri = wsScheme + formatHostForUri(this.wsHost) + ':' + Defaults.getPort(options) + '/';
     Logger.logAction(this.logger, Logger.LOG_MINOR, 'WebSocketTransport.connect()', 'uri: ' + wsUri);
     Utils.whenPromiseSettles(
       this.auth.getAuthParams(),

src/common/lib/util/defaults.ts

@@ -114,6 +114,17 @@ export function getHttpScheme(options: ClientOptions): string {
   return options.tls ? 'https://' : 'http://';
 }
 
+/**
+ * REC1b2 / RFC 3986 §3.2.2: an IPv6 literal used as a URI host must be enclosed in '[' and ']'.
+ * Host identity is stored unbracketed; this is applied only when concatenating a URI.
+ */
+export function formatHostForUri(host: string): string {
+  if (host.includes(':') && !host.startsWith('[')) {
+    return '[' + host + ']';
+  }
+  return host;
+}
+
 /**
  * REC1b2
  */

test/uts/deviations.md

@@ -122,18 +122,6 @@ These tests assert spec behavior but are skipped by default because they are kno
 
 ---
 
-### fallback: REC1b2 - IPv6 endpoint address not bracketed
-
-**Spec (REC1b2)**: IPv6 addresses should be supported as endpoint values.
-
-**ably-js behavior**: URL construction produces `https://::1:443/time` instead of `https://[::1]:443/time`.
-
-**Test**: `REC1b2 - endpoint as IPv6 address`.
-
-**Issue**: [#2198](https://github.com/ably/ably-js/issues/2198)
-
----
-
 ### options_types: AO2 - authMethod default not stored
 
 **Spec (AO2)**: `authMethod` should default to `'GET'` and be stored in auth options.

test/uts/rest/unit/fallback.test.ts

@@ -816,8 +816,6 @@ describe('uts/rest/unit/fallback', function () {
 
   // UTS: rest/unit/REC1b2/endpoint-ipv6-address-2
   it('REC1b2 - endpoint as IPv6 address', async function () {
-    // DEVIATION: see deviations.md
-    if (!process.env.RUN_DEVIATIONS) this.skip();
     const captured: any[] = [];
     const mock = new MockHttpClient({
       onConnectionAttempt: (conn) => conn.respond_with_success(),
@@ -828,17 +826,12 @@ describe('uts/rest/unit/fallback', function () {
     });
     installMockHttp(mock);
 
-    // Spec: endpoint '::1' should be treated as an explicit IPv6 hostname.
-    // DEVIATION: ably-js constructs an invalid URI (no brackets around IPv6). See deviations.md.
-    try {
-      const client = new Ably.Rest({ key: 'app.key:secret', useBinaryProtocol: false, endpoint: '::1' });
-      await client.time();
+    const client = new Ably.Rest({ key: 'app.key:secret', useBinaryProtocol: false, endpoint: '::1' });
+    await client.time();
 
-      expect(captured).to.have.length(1);
-      expect(captured[0].url.hostname).to.satisfy((h: string) => h === '::1' || h === '[::1]');
-    } catch (e) {
-      expect.fail('IPv6 endpoint should work, but ably-js threw: ' + (e as Error).message);
-    }
+    expect(captured).to.have.length(1);
+    expect(captured[0].url.hostname).to.satisfy((h: string) => h === '::1' || h === '[::1]');
+    expect(captured[0].url.href).to.include('[::1]');
   });
 
   // UTS: rest/unit/REC1b3/nonprod-routing-policy-0