fix(desktop): make tab audio indicator clickable to mute/unmute

The tab-strip speaker icon rendered but couldn't mute/unmute: the clickable
control is gated by media::kEnableTabMuting, which is DISABLED_BY_DEFAULT in
Chromium 131. Stock Chrome only enables it via Finch, which an ungoogled build
never receives — so a muted tab was invisible and unrecoverable from the tab.

Force it on with --enable-features=EnableTabMuting in all launch paths
(tronbrowser POSIX shell, tronbrowser.cmd, chromium-flags.ts UX_FEATURE_FLAGS).
Runtime flag — no Chromium rebuild; applies on Linux/KDE, macOS, Windows.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: ralyodio

apps/desktop/launcher/tronbrowser

@@ -282,6 +282,13 @@ fi
 MV2_KEEP="ExtensionManifestV2Disabled,ExtensionManifestV2Unsupported,ExtensionManifestV2DeprecationWarning,ExtensionManifestV2DeprecationUnsupported"
 FLAGS="--user-data-dir=$DATA --class=TronBrowser --no-first-run --no-default-browser-check --no-pings --disable-background-networking --disable-breakpad --disable-domain-reliability --disable-sync --disable-features=Translate,OptimizationHints,InterestFeedContentSuggestions,$MV2_KEEP --load-extension=$EXT"
 
+# Make the tab-strip audio indicator a clickable mute/unmute control. Upstream
+# media::kEnableTabMuting is DISABLED_BY_DEFAULT and stock Chrome only turns it
+# on via Finch, so an ungoogled build ships it OFF — the speaker icon renders
+# but you cannot tell which tab is making sound or mute it from the tab. Force
+# it on to match stock Chrome (Linux/KDE, macOS, Windows).
+FLAGS="$FLAGS --enable-features=EnableTabMuting"
+
 # Chromium spews benign ERROR/WARNING noise to stderr (EV cert OID, mojo
 # WidgetHost, GPU, etc.). Route it to a log so `tron <url>` returns clean;
 # set TRONBROWSER_VERBOSE=1 to see it inline. --log-level=2 trims the rest.

apps/desktop/launcher/tronbrowser.cmd

@@ -39,7 +39,11 @@ if not defined BROWSER (
   exit /b 1
 )
 
+rem --enable-features=EnableTabMuting makes the tab audio indicator a clickable
+rem mute/unmute control (media::kEnableTabMuting is DISABLED_BY_DEFAULT upstream;
+rem stock Chrome only enables it via Finch, which an ungoogled build never gets).
 "%BROWSER%" --user-data-dir="%DATA%" --no-first-run --no-default-browser-check --no-pings ^
   --disable-background-networking --disable-breakpad --disable-domain-reliability ^
   --disable-sync --disable-features=Translate,OptimizationHints,InterestFeedContentSuggestions ^
+  --enable-features=EnableTabMuting ^
   --log-level=2 --load-extension="%EXT%" %*

apps/desktop/src/chromium-flags.test.ts

@@ -6,6 +6,7 @@ import {
   torEnabled,
   incognitoEnabled,
   PRIVACY_FLAGS,
+  UX_FEATURE_FLAGS,
   DEFAULT_TOR_SOCKS_PORT,
 } from './chromium-flags.js';
 
@@ -25,6 +26,20 @@ describe('chromium launch flags', () => {
     expect(flags).not.toContain('--disable-background-networking');
   });
 
+  it('enables clickable tab audio muting on every platform', () => {
+    // media::kEnableTabMuting is DISABLED_BY_DEFAULT upstream; without this the
+    // tab speaker icon is inert in an ungoogled build (no Finch to turn it on).
+    expect(UX_FEATURE_FLAGS).toContain('--enable-features=EnableTabMuting');
+    expect(buildLaunchFlags()).toContain('--enable-features=EnableTabMuting');
+  });
+
+  it('keeps tab audio muting even when telemetry is opted in or under tor', () => {
+    expect(buildLaunchFlags({ telemetry: true })).toContain(
+      '--enable-features=EnableTabMuting',
+    );
+    expect(buildLaunchFlags({ tor: true })).toContain('--enable-features=EnableTabMuting');
+  });
+
   it('passes through the user data dir', () => {
     const flags = buildLaunchFlags({ userDataDir: '/home/u/.tronbrowser' });
     expect(flags).toContain('--user-data-dir=/home/u/.tronbrowser');

apps/desktop/src/chromium-flags.ts

@@ -52,6 +52,21 @@ export const PRIVACY_FLAGS = [
   '--disable-sync',
 ] as const;
 
+/**
+ * Feature flags that restore standard Chromium UX which our fork does not get
+ * because it never talks to Google's server-side field-trial (Finch) service.
+ *
+ * `EnableTabMuting` (`media::kEnableTabMuting`) makes the tab-strip audio
+ * indicator a clickable mute/unmute control. Upstream the feature is
+ * `FEATURE_DISABLED_BY_DEFAULT` and stock Chrome only turns it on via Finch, so
+ * an ungoogled build ships it OFF: the speaker icon renders but the button is
+ * disabled — you can neither tell which tab is making sound nor mute it from the
+ * tab. Forcing it on here matches stock-Chrome behavior on every platform
+ * (Linux/KDE, macOS, Windows). Applied even when telemetry is opted in — it is a
+ * UI fix, not a phone-home surface.
+ */
+export const UX_FEATURE_FLAGS = ['--enable-features=EnableTabMuting'] as const;
+
 /**
  * Builds the flags that route the browser through the local Tor SOCKS5 proxy.
  *
@@ -84,6 +99,10 @@ export const FORBIDDEN_FLAG_SUBSTRINGS = [
 export function buildLaunchFlags(opts: LaunchOptions = {}): string[] {
   const flags: string[] = [];
 
+  // Standard-UX feature flags first (e.g. clickable tab audio muting). Always
+  // present — these are usability parity with stock Chrome, not telemetry.
+  flags.push(...UX_FEATURE_FLAGS);
+
   if (!opts.telemetry) {
     flags.push(...PRIVACY_FLAGS);
   }