feat(desktop): mirror voice.auto_tts into an $autoSpeakReplies store

apps/desktop/src/app/session/hooks/use-hermes-config.ts

@@ -12,6 +12,7 @@ import {
   setCurrentServiceTier,
   setIntroPersonality
 } from '@/store/session'
+import { applyAutoSpeakFromConfig } from '@/store/voice-prefs'
 
 const DEFAULT_VOICE_SECONDS = 120
 const FAST_TIERS = new Set(['fast', 'priority', 'on'])
@@ -65,6 +66,7 @@ export function useHermesConfig({ activeSessionIdRef, refreshProjectBranch }: He
 
       setVoiceMaxRecordingSeconds(recordingLimit(config.voice?.max_recording_seconds))
       setSttEnabled(config.stt?.enabled !== false)
+      applyAutoSpeakFromConfig(config)
     } catch {
       // Config is nice-to-have; chat still works without it.
     }

apps/desktop/src/store/voice-prefs.ts

@@ -0,0 +1,38 @@
+import { atom } from 'nanostores'
+
+import { getHermesConfigRecord, saveHermesConfig } from '@/hermes'
+
+// "Read replies aloud" — mirrors the canonical `voice.auto_tts` config key (also
+// in Settings → Voice, honored by the messaging gateway) so the composer toggle
+// and the Settings switch are one source of truth, not two that can disagree.
+export const $autoSpeakReplies = atom<boolean>(false)
+
+/** Seed the atom from a loaded config payload (mount / refresh). */
+export function applyAutoSpeakFromConfig(config: { voice?: { auto_tts?: unknown } | null } | null | undefined) {
+  $autoSpeakReplies.set(Boolean(config?.voice?.auto_tts))
+}
+
+/**
+ * Flip the preference and persist it. Optimistic — the atom updates instantly and
+ * reverts if the config write fails. Read-modify-writes the whole record (the
+ * same path the Settings page uses; there's no partial-update endpoint).
+ */
+export async function setAutoSpeakReplies(enabled: boolean): Promise<void> {
+  const previous = $autoSpeakReplies.get()
+
+  if (previous === enabled) {
+    return
+  }
+
+  $autoSpeakReplies.set(enabled)
+
+  try {
+    const record = await getHermesConfigRecord()
+    const voice = record.voice && typeof record.voice === 'object' ? (record.voice as Record<string, unknown>) : {}
+
+    await saveHermesConfig({ ...record, voice: { ...voice, auto_tts: enabled } })
+  } catch (error) {
+    $autoSpeakReplies.set(previous)
+    throw error
+  }
+}