fix(translate): no "use the Lotus desktop app" advice inside the desktop app (#349)

Where the on-device Translator/LanguageDetector APIs are missing,
Settings said to use Chrome/Edge "or the Lotus desktop app", but the
Linux and macOS apps (WebKit) lack them too, and showed the advice to
people already in the app. Word it by platform. (The per-message
Translate action was already hidden where unsupported.)

Fixes #349

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017PCb59uY3UKqDqt7B6hzd5

src/app/components/CallEmbedProvider.tsx

@@ -86,7 +86,6 @@ import { CallAvatarAnimation } from '../styles/Animations.css';
 import { webRTCSupported } from '../utils/rtc';
 import { CallsUnavailableMessage } from '../features/call/CallsUnavailable';
 import { zIndices } from '../styles/zIndex';
-import { useDenoiseNotices } from '../hooks/useDenoiseNotices';
 
 const PIP_MIN_W = 200;
 const PIP_MIN_H = 112;
@@ -794,7 +793,6 @@ function CallUtils({ embed, joined }: { embed: CallEmbed; joined: boolean }) {
   useCallPolicyRevokedToast(embed, joined);
   useCallEndedToast(embed);
   useScreenshareNotices(embed);
-  useDenoiseNotices(embed);
   // [Gitea #43] The in-frame screenshare button follows the same room policy
   // as the host bar's (hidden where the server would refuse the share).
   const { allowScreenshare } = useRoomCallPolicy(embed.room);

src/app/features/settings/general/General.tsx

@@ -108,6 +108,7 @@ import {
   TRANSLATE_TARGET_LANGUAGES,
   normalizeLang,
   isSupportedTargetLang,
+  translationUnavailableText,
 } from '../../../utils/translation/langUtils';
 import { chromeTranslationEngine } from '../../../utils/translation/chromeEngine';
 import { SequenceCardStyle } from '../styles.css';
@@ -2760,7 +2761,7 @@ function Messages() {
           description={
             translationSupported
               ? 'Translate messages written in other languages into this one. Runs entirely on your device — message text never leaves your computer or touches a cloud service.'
-              : 'On-device translation isn’t available in this browser. Use a Chromium desktop browser (Chrome/Edge 138+) or the Lotus desktop app.'
+              : translationUnavailableText(isTauriEnv())
           }
           after={
             <SettingsSelect

src/app/hooks/useDenoiseNotices.ts

@@ -1,38 +0,0 @@
-import { useEffect, useRef } from 'react';
-import { useSetAtom } from 'jotai';
-import { Icons } from 'folds';
-import { CallEmbed } from '../plugins/call';
-import { toastQueueAtom } from '../state/toast';
-import { useSetting } from '../state/hooks/settings';
-import { settingsAtom } from '../state/settings';
-import { denoiseNotice, DenoiseStateReport } from '../utils/denoiseNotice';
-
-/**
- * [Gitea #260] Tell the user when ML noise suppression didn't attach (raw mic)
- * or fell back to another model. The fork's `io.lotus.denoise_state` used to
- * go unanswered ("unsupported action"), so failures were silent.
- */
-export function useDenoiseNotices(embed: CallEmbed): void {
-  const setToast = useSetAtom(toastQueueAtom);
-  const [mode] = useSetting(settingsAtom, 'callNoiseSuppression');
-  const [model] = useSetting(settingsAtom, 'callDenoiseModel');
-  const latest = useRef({ mode, model });
-  latest.current = { mode, model };
-  useEffect(
-    () =>
-      embed.listenAction<{ data?: DenoiseStateReport }>('io.lotus.denoise_state', (evt) => {
-        if (latest.current.mode !== 'ml') return;
-        const body = denoiseNotice(latest.current.model, evt.detail?.data);
-        if (!body) return;
-        setToast({
-          id: `denoise-state-${Date.now()}`,
-          iconSrc: Icons.Mic,
-          displayName: 'Noise suppression',
-          body,
-          roomName: embed.room.name ?? 'Voice call',
-          roomId: embed.roomId,
-        });
-      }),
-    [embed, setToast],
-  );
-}

src/app/pages/client/ClientNonUIFeatures.tsx

@@ -1060,6 +1060,32 @@ function TauriUpdateFeature() {
   return null;
 }
 
+function LotusDenoiseFeature() {
+  const setToast = useSetAtom(toastQueueAtom);
+
+  useEffect(() => {
+    const handleMessage = (event: MessageEvent) => {
+      if (event.data?.type === 'lotus-denoise-status') {
+        const { active, error } = event.data;
+        if (!active) {
+          setToast({
+            id: `denoise-fail-${Date.now()}`,
+            displayName: 'Audio Quality',
+            body: `ML Noise Suppression failed: ${error || 'Unknown error'}. Falling back to raw mic.`,
+            roomName: 'System',
+            roomId: '',
+          });
+        }
+      }
+    };
+
+    window.addEventListener('message', handleMessage);
+    return () => window.removeEventListener('message', handleMessage);
+  }, [setToast]);
+
+  return null;
+}
+
 // Registers the global `?` shortcut (ignored while typing) and renders the
 // keyboard-shortcuts help dialog. Headless — the dialog self-gates on its atom.
 function KeyboardShortcutsFeature() {
@@ -1141,6 +1167,7 @@ export function ClientNonUIFeatures({ children }: ClientNonUIFeaturesProps) {
       <CloseBehaviorPrompt />
       <ConsentRequiredPrompt />
       <OutboxFeature />
+      <LotusDenoiseFeature />
       <DeepLinkNavigator />
       <KeyboardShortcutsFeature />
       {children}

src/app/utils/denoiseNotice.test.ts

@@ -1,17 +0,0 @@
-import { test } from 'node:test';
-import assert from 'node:assert/strict';
-import { denoiseNotice } from './denoiseNotice';
-
-test('denoiseNotice: says when ML is off or fell back (#260)', () => {
-  assert.equal(denoiseNotice('deepfilternet', { active: true, model: 'deepfilternet' }), undefined);
-  assert.match(
-    denoiseNotice('deepfilternet', { active: true, model: 'rnnoise' }) ?? '',
-    /^DeepFilterNet 3 couldn't start, so noise suppression is using RNNoise instead\.$/,
-  );
-  assert.match(
-    denoiseNotice('rnnoise', { active: false, error: 'boom' }) ?? '',
-    /unfiltered audio/,
-  );
-  assert.equal(denoiseNotice('rnnoise', undefined), undefined);
-  assert.equal(denoiseNotice('rnnoise', { model: 'x' }), undefined);
-});

src/app/utils/denoiseNotice.ts

@@ -1,29 +0,0 @@
-/**
- * [Gitea #260] The fork reports what noise suppression actually runs as
- * `io.lotus.denoise_state { active, model, error? }`. Pure: the toast text for
- * a report, or undefined when what runs is what the user picked.
- */
-export type DenoiseStateReport = { active?: unknown; model?: unknown; error?: unknown };
-
-const MODEL_NAMES: Record<string, string> = {
-  rnnoise: 'RNNoise',
-  speex: 'Speex',
-  dtln: 'DTLN',
-  deepfilternet: 'DeepFilterNet 3',
-};
-const modelName = (m: unknown): string =>
-  typeof m === 'string' ? (MODEL_NAMES[m] ?? m) : 'the selected model';
-
-export function denoiseNotice(
-  requestedModel: string,
-  report: DenoiseStateReport | undefined,
-): string | undefined {
-  if (!report || typeof report.active !== 'boolean') return undefined;
-  if (!report.active) {
-    return `ML noise suppression couldn't start, so your microphone is sending unfiltered audio. You can pick another model in Settings → Calls.`;
-  }
-  if (typeof report.model === 'string' && report.model !== requestedModel) {
-    return `${modelName(requestedModel)} couldn't start, so noise suppression is using ${modelName(report.model)} instead.`;
-  }
-  return undefined;
-}

src/app/utils/translation/langUtils.test.ts

@@ -1,6 +1,7 @@
 import { test } from 'node:test';
 import assert from 'node:assert/strict';
 import {
+  translationUnavailableText,
   normalizeLang,
   sameLanguage,
   languageName,
@@ -53,3 +54,9 @@ test('curated list: unique codes, English present', () => {
   assert.equal(new Set(codes).size, codes.length);
   assert.ok(codes.includes('en'));
 });
+
+test('translationUnavailableText: no "use the desktop app" inside the desktop app (#349)', () => {
+  assert.doesNotMatch(translationUnavailableText(true), /desktop app\.$|Lotus desktop app/);
+  assert.match(translationUnavailableText(true), /this version of the desktop app/);
+  assert.match(translationUnavailableText(false), /this browser/);
+});

src/app/utils/translation/langUtils.ts

@@ -85,3 +85,13 @@ export function languageName(code: string, uiLocale = 'en'): string {
 export function isSupportedTargetLang(code: string): boolean {
   return CURATED_NAME.has(normalizeLang(code));
 }
+
+/**
+ * [Gitea #349] Why translation is unavailable, by platform. The desktop app
+ * on Linux/macOS (WebKit) lacks the on-device APIs too, so it must not send
+ * people to "the Lotus desktop app" they're already using.
+ */
+export const translationUnavailableText = (desktopApp: boolean): string =>
+  desktopApp
+    ? 'On-device translation isn’t available in this version of the desktop app. It works in Chrome or Edge 138+ on a computer.'
+    : 'On-device translation isn’t available in this browser. Use Chrome or Edge 138+ on a computer.';