diff --git a/apps/desktop/src/app/chat/composer/hooks/use-mic-recorder.ts b/apps/desktop/src/app/chat/composer/hooks/use-mic-recorder.ts
index 5389d9f4d5..c560ef9ad2 100644
--- a/apps/desktop/src/app/chat/composer/hooks/use-mic-recorder.ts
+++ b/apps/desktop/src/app/chat/composer/hooks/use-mic-recorder.ts
@@ -33,7 +33,11 @@ interface MicRecorderHandle {
   cancel: () => void
 }
 
-function micError(error: unknown, copy: MicRecorderErrorCopy): Error {
+/** Recorder + live-start mic failures → the same friendly copy: a DOMException
+ *  name is mapped, an unrecognized DOMException falls back to the generic start
+ *  copy, and anything else keeps its own message (non-mic failures must not be
+ *  mislabeled as microphone problems). */
+export function micError(error: unknown, copy: MicRecorderErrorCopy): Error {
   const name = error instanceof DOMException ? error.name : ''
 
   if (name === 'NotAllowedError' || name === 'SecurityError') {
@@ -52,6 +56,10 @@ function micError(error: unknown, copy: MicRecorderErrorCopy): Error {
     return new Error(copy.microphoneConstraintsUnsupported)
   }
 
+  if (error instanceof DOMException) {
+    return new Error(copy.microphoneStartFailed)
+  }
+
   if (error instanceof Error) {
     return error
   }
diff --git a/apps/desktop/src/app/chat/composer/hooks/use-voice-live-conversation.test.ts b/apps/desktop/src/app/chat/composer/hooks/use-voice-live-conversation.test.ts
index 5046a8f59e..089c661f2e 100644
--- a/apps/desktop/src/app/chat/composer/hooks/use-voice-live-conversation.test.ts
+++ b/apps/desktop/src/app/chat/composer/hooks/use-voice-live-conversation.test.ts
@@ -1,9 +1,190 @@
 // @vitest-environment jsdom
-import { describe, expect, it } from 'vitest'
+import { act, cleanup, renderHook } from '@testing-library/react'
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
 
-import { chunkForCommentary, toLiveHistory } from '@/lib/voice-live'
+import { en } from '@/i18n/en'
+import { chunkForCommentary, toLiveHistory, type VoiceLiveHandlers } from '@/lib/voice-live'
+import { $notifications, clearNotifications } from '@/store/notifications'
 
-import { delegationPrompt } from './use-voice-live-conversation'
+import { delegationPrompt, useVoiceLiveConversation } from './use-voice-live-conversation'
+
+// Issue #111987: the live-voice toasts must not show machine strings — neither
+// the wire close reasons (`connection_lost`, `closed`) nor the raw
+// `DOMException` text a denied `getUserMedia` throws.
+//
+// The transport is the only seam in the live hook, so the fake session records
+// the handlers it registers (tests drive the close/error paths directly) and
+// lets `start` reject with exactly what the real `getUserMedia` would throw.
+const transport = vi.hoisted(() => ({ failure: null as unknown, handlers: [] as VoiceLiveHandlers[] }))
+
+vi.mock('@/lib/voice-live', async importOriginal => {
+  const actual = (await importOriginal()) as Record<string, unknown>
+
+  return {
+    ...actual,
+    VoiceLiveSession: class {
+      close = vi.fn()
+      instruct = vi.fn()
+      setMuted = vi.fn()
+      speak = vi.fn()
+      think = vi.fn()
+
+      constructor(handlers: VoiceLiveHandlers) {
+        transport.handlers.push(handlers)
+      }
+
+      async start(): Promise<void> {
+        if (transport.failure) {
+          throw transport.failure
+        }
+      }
+    }
+  }
+})
+
+const voice = en.notifications.voice
+
+function mountLive() {
+  return renderHook(() =>
+    useVoiceLiveConversation({
+      busy: false,
+      consumePendingResponse: vi.fn(),
+      enabled: true,
+      onSubmit: vi.fn(),
+      pendingResponse: () => null,
+      seedHistory: () => []
+    })
+  )
+}
+
+/** Mount, start, and hand back the handlers the started session registered. */
+async function openSession(): Promise<VoiceLiveHandlers> {
+  const hook = mountLive()
+
+  await act(async () => {
+    await hook.result.current.start()
+  })
+
+  return transport.handlers.at(-1) as VoiceLiveHandlers
+}
+
+/** Start a session whose transport fails the way the real one can. */
+async function failedStart(failure: unknown): Promise<void> {
+  transport.failure = failure
+  const hook = mountLive()
+
+  await act(async () => {
+    await hook.result.current.start()
+  })
+}
+
+function resetToasts() {
+  clearNotifications()
+  transport.failure = null
+  transport.handlers.length = 0
+}
+
+describe('Voice-live session-end toast copy (#111987)', () => {
+  beforeEach(resetToasts)
+  afterEach(cleanup)
+
+  it('names the lost connection in copy instead of the internal reason code', async () => {
+    const handlers = await openSession()
+
+    act(() => {
+      handlers.onClosed('connection_lost', 127)
+    })
+
+    const toast = $notifications.get()[0]
+
+    expect(toast.title).toBe(voice.liveEnded)
+    expect(toast.message).toBe(`${voice.liveEndedConnectionLost} (127s)`)
+    expect(toast.message).not.toContain('connection_lost')
+  })
+
+  it('names the vendor-side close in copy instead of the "closed" fallback code', async () => {
+    const handlers = await openSession()
+
+    act(() => {
+      handlers.onClosed('closed', null)
+    })
+
+    const toast = $notifications.get()[0]
+
+    expect(toast.kind).toBe('warning')
+    expect(toast.message).toBe(voice.liveEndedClosed)
+  })
+
+  it('falls back to the ended copy when the wire reason is blank', async () => {
+    const handlers = await openSession()
+
+    act(() => {
+      handlers.onClosed('', null)
+    })
+
+    expect($notifications.get()[0].message).toBe(voice.liveEndedClosed)
+  })
+
+  it('passes an unrecognized server-sent reason through verbatim (unbounded by contract)', async () => {
+    const handlers = await openSession()
+
+    act(() => {
+      handlers.onClosed('quota_exhausted', 12)
+    })
+
+    expect($notifications.get()[0].message).toBe('quota_exhausted (12s)')
+  })
+
+  it('still drops close_requested (our own close) without a toast', async () => {
+    const handlers = await openSession()
+
+    act(() => {
+      handlers.onClosed('close_requested', 30)
+    })
+
+    expect($notifications.get()).toHaveLength(0)
+  })
+})
+
+describe('Voice-live mic failure toast copy (#111987)', () => {
+  beforeEach(resetToasts)
+  afterEach(cleanup)
+
+  it('reuses the recorder mic copy for a getUserMedia DOMException', async () => {
+    const cases: Array<[string, string]> = [
+      ['NotAllowedError', voice.microphonePermissionDenied],
+      ['NotFoundError', voice.noMicrophone],
+      ['NotReadableError', voice.microphoneInUse],
+      ['OverconstrainedError', voice.microphoneConstraintsUnsupported]
+    ]
+
+    for (const [name, copy] of cases) {
+      await failedStart(
+        new DOMException('The request is not allowed by the user agent or the platform in the current context.', name)
+      )
+
+      const toast = $notifications.get()[0]
+
+      expect(toast.title).toBe(voice.couldNotStartSession)
+      expect(toast.message).toBe(copy)
+      expect(toast.message).not.toContain('user agent')
+
+      cleanup()
+      resetToasts()
+    }
+  })
+
+  it('keeps a non-mic start failure message untouched', async () => {
+    for (const message of ['GPT-Live session already started', 'Missing local SDP offer']) {
+      await failedStart(new Error(message))
+
+      expect($notifications.get()[0].message).toBe(message)
+
+      cleanup()
+      resetToasts()
+    }
+  })
+})
 
 describe('GPT-Live delegation → Hermes turn', () => {
   it('sends the latest user words as the turn and the exchange as model-only context', () => {
diff --git a/apps/desktop/src/app/chat/composer/hooks/use-voice-live-conversation.ts b/apps/desktop/src/app/chat/composer/hooks/use-voice-live-conversation.ts
index f9677709a6..3e45ead577 100644
--- a/apps/desktop/src/app/chat/composer/hooks/use-voice-live-conversation.ts
+++ b/apps/desktop/src/app/chat/composer/hooks/use-voice-live-conversation.ts
@@ -6,6 +6,7 @@ import { type LiveHistoryMessage, type LiveTranscriptFragment, VoiceLiveSession
 import { isVoiceStopCommand } from '@/lib/voice-stop-word'
 import { notify, notifyError } from '@/store/notifications'
 
+import { micError } from './use-mic-recorder'
 import type { ConversationStatus } from './use-voice-conversation'
 
 /** How long an accepted delegation may sit before the gateway shows the turn running. */
@@ -67,6 +68,29 @@ export function delegationPrompt(context: LiveTranscriptFragment[]): { context:
   return { context: transcript, prompt: prompt || transcript.slice(-400) }
 }
 
+/**
+ * Body of the session-end toast. `connection_lost` and `closed` are our own
+ * machine reasons (`lib/voice-live.ts`) and get i18n copy; so does a blank
+ * reason, which has no wording of its own. Any other reason is server-sent and
+ * unbounded, so it passes through verbatim (issue #111987 — no redaction claim
+ * for vendor strings).
+ */
+export function liveEndedMessage(
+  reason: string,
+  usageSeconds: null | number,
+  copy: { liveEndedClosed: string; liveEndedConnectionLost: string }
+): string {
+  let text = reason?.trim() ?? ''
+
+  if (text === 'connection_lost') {
+    text = copy.liveEndedConnectionLost
+  } else if (text === 'closed' || !text) {
+    text = copy.liveEndedClosed
+  }
+
+  return usageSeconds != null ? `${text} (${Math.round(usageSeconds)}s)` : text
+}
+
 /**
  * GPT-Live conversation engine — same public shape as `useVoiceConversation`
  * so the composer can mount either from `voice.voice_chat_mode`.
@@ -252,7 +276,7 @@ export function useVoiceLiveConversation({
         if (reason !== 'close_requested') {
           notify({
             kind: 'warning',
-            message: usageSeconds != null ? `${reason} (${Math.round(usageSeconds)}s)` : reason,
+            message: liveEndedMessage(reason, usageSeconds, voiceCopy),
             title: voiceCopy.liveEnded
           })
           latest.current.onFatalError?.()
@@ -330,19 +354,14 @@ export function useVoiceLiveConversation({
         return
       }
 
-      notifyError(error, voiceCopy.couldNotStartSession)
+      // Only a mic DOMException gets the recorder's copy: this catch also
+      // takes non-mic start failures ('GPT-Live session already started',
+      // 'Missing local SDP offer', API errors) — those keep their own message.
+      notifyError(error instanceof DOMException ? micError(error, voiceCopy) : error, voiceCopy.couldNotStartSession)
       setStatus('idle')
       latest.current.onFatalError?.()
     }
-  }, [
-    end,
-    refreshStatus,
-    setDelegation,
-    voiceCopy.couldNotStartSession,
-    voiceCopy.liveDelegationFailed,
-    voiceCopy.liveEnded,
-    voiceCopy.liveError
-  ])
+  }, [end, refreshStatus, setDelegation, voiceCopy])
 
   // Drive the reply back into the voice: stream commentary as Hermes writes
   // it (sentence-chunked), quiet tool progress as thinking appends, and clear
diff --git a/apps/desktop/src/i18n/en.ts b/apps/desktop/src/i18n/en.ts
index 61ba7795c0..0ce996a314 100644
--- a/apps/desktop/src/i18n/en.ts
+++ b/apps/desktop/src/i18n/en.ts
@@ -278,6 +278,8 @@ export const en: Translations = {
       tryRecordingAgain: 'Try recording again.',
       unavailable: 'Voice unavailable',
       liveEnded: 'Live voice session ended',
+      liveEndedConnectionLost: 'The live voice session lost its connection.',
+      liveEndedClosed: 'The live voice session was closed by the service.',
       liveError: 'Live voice',
       liveDelegationFailed: 'Could not hand the request to Hermes',
       liveUnavailable: reason => `GPT-Live voice chat is not available: ${reason}. Using speech-to-text instead.`
diff --git a/apps/desktop/src/i18n/types.ts b/apps/desktop/src/i18n/types.ts
index b36257e660..62fdf475e0 100644
--- a/apps/desktop/src/i18n/types.ts
+++ b/apps/desktop/src/i18n/types.ts
@@ -322,6 +322,8 @@ export interface Translations {
       tryRecordingAgain: string
       unavailable: string
       liveEnded: string
+      liveEndedConnectionLost: string
+      liveEndedClosed: string
       liveError: string
       liveDelegationFailed: string
       liveUnavailable: (reason: string) => string
diff --git a/apps/desktop/src/i18n/zh.ts b/apps/desktop/src/i18n/zh.ts
index 1a0277d410..b31f823cc2 100644
--- a/apps/desktop/src/i18n/zh.ts
+++ b/apps/desktop/src/i18n/zh.ts
@@ -242,6 +242,8 @@ export const zh = defineLocale({
       tryRecordingAgain: '请再录一次。',
       unavailable: '语音不可用',
       liveEnded: '实时语音会话已结束',
+      liveEndedConnectionLost: '实时语音会话连接已断开。',
+      liveEndedClosed: '实时语音会话已被服务端关闭。',
       liveError: '实时语音',
       liveDelegationFailed: '无法将请求交给 Hermes',
       liveUnavailable: reason => `GPT-Live 语音聊天不可用：${reason}。已改用语音转文字。`