diff --git a/packages/ui/src/components/prompt-input.tsx b/packages/ui/src/components/prompt-input.tsx
index 214ed534..4e5d5a20 100644
--- a/packages/ui/src/components/prompt-input.tsx
+++ b/packages/ui/src/components/prompt-input.tsx
@@ -1,5 +1,5 @@
 import { Suspense, createEffect, createSignal, lazy, on, onCleanup, Show } from "solid-js"
-import { ArrowBigUp, ArrowBigDown, Loader2, Mic, X } from "lucide-solid"
+import { ArrowBigUp, ArrowBigDown, Loader2, Mic, Volume2, X } from "lucide-solid"
 import ExpandButton from "./expand-button"
 import { clearAttachments, removeAttachment } from "../stores/attachments"
 import { resolvePastedPlaceholders } from "../lib/prompt-placeholders"
@@ -19,6 +19,7 @@ import { usePromptAttachments } from "./prompt-input/usePromptAttachments"
 import { usePromptPicker } from "./prompt-input/usePromptPicker"
 import { usePromptKeyDown } from "./prompt-input/usePromptKeyDown"
 import { usePromptVoiceInput } from "./prompt-input/usePromptVoiceInput"
+import { canUseConversationMode, isConversationModeEnabled, toggleConversationMode } from "../stores/conversation-speech"
 const log = getLogger("actions")
 const LazyUnifiedPicker = lazy(() => import("./unified-picker"))
 
@@ -476,6 +477,13 @@ export default function PromptInput(props: PromptInputProps) {
   const showVoiceInput = () =>
     preferences().showPromptVoiceInput &&
     (voiceInput.canUseVoiceInput() || voiceInput.isRecording() || voiceInput.isTranscribing())
+  const conversationModeEnabled = () => isConversationModeEnabled(props.instanceId)
+  const showConversationToggle = () => showVoiceInput() || conversationModeEnabled()
+  const canToggleConversationMode = () => canUseConversationMode()
+  const conversationModeButtonTitle = () =>
+    conversationModeEnabled()
+      ? t("promptInput.conversationMode.disable.title")
+      : t("promptInput.conversationMode.enable.title")
 
   const instance = () => getActiveInstance()
 
@@ -601,6 +609,19 @@ export default function PromptInput(props: PromptInputProps) {
                       </Show>
                     </button>
                   </Show>
+                  <Show when={showConversationToggle()}>
+                    <button
+                      type="button"
+                      class={`prompt-voice-button prompt-nav-voice-button prompt-conversation-button ${conversationModeEnabled() ? "is-active" : ""}`}
+                      onClick={() => toggleConversationMode(props.instanceId)}
+                      disabled={!conversationModeEnabled() && !canToggleConversationMode()}
+                      aria-pressed={conversationModeEnabled()}
+                      aria-label={conversationModeButtonTitle()}
+                      title={conversationModeButtonTitle()}
+                    >
+                      <Volume2 class="h-4 w-4" aria-hidden="true" />
+                    </button>
+                  </Show>
                   <button
                     type="button"
                     class="prompt-clear-button"
diff --git a/packages/ui/src/components/session/session-view.tsx b/packages/ui/src/components/session/session-view.tsx
index ba78382c..04a32613 100644
--- a/packages/ui/src/components/session/session-view.tsx
+++ b/packages/ui/src/components/session/session-view.tsx
@@ -16,6 +16,7 @@ import { getLogger } from "../../lib/logger"
 import { requestData } from "../../lib/opencode-api"
 import { useI18n } from "../../lib/i18n"
 import type { PromptInputApi, PromptInsertMode } from "../prompt-input/types"
+import { clearConversationPlaybackForSession } from "../../stores/conversation-speech"
 
 const log = getLogger("session")
 
@@ -88,6 +89,10 @@ export const SessionView: Component<SessionViewProps> = (props) => {
     on(
       () => props.isActive,
       (isActive) => {
+        if (!isActive) {
+          clearConversationPlaybackForSession(props.instanceId, props.sessionId)
+          return
+        }
         if (!isActive) return
 
         // On phones, focusing the prompt on session switch is disruptive (it raises the OSK).
diff --git a/packages/ui/src/lib/i18n/messages/en/messaging.ts b/packages/ui/src/lib/i18n/messages/en/messaging.ts
index ae32e79c..49e82226 100644
--- a/packages/ui/src/lib/i18n/messages/en/messaging.ts
+++ b/packages/ui/src/lib/i18n/messages/en/messaging.ts
@@ -147,6 +147,10 @@ export const messagingMessages = {
   "promptInput.send.ariaLabel": "Send message",
   "promptInput.send.errorFallback": "Failed to send message",
   "promptInput.send.errorTitle": "Send failed",
+  "promptInput.conversationMode.enable.title": "Enable conversation mode",
+  "promptInput.conversationMode.disable.title": "Disable conversation mode",
+  "promptInput.conversationMode.error.title": "Conversation playback failed",
+  "promptInput.conversationMode.error.message": "Unable to continue speaking assistant replies.",
   "promptInput.voiceInput.start.title": "Start voice input",
   "promptInput.voiceInput.stop.title": "Stop recording and transcribe",
   "promptInput.voiceInput.transcribing.title": "Transcribing audio",
diff --git a/packages/ui/src/lib/i18n/messages/es/messaging.ts b/packages/ui/src/lib/i18n/messages/es/messaging.ts
index f363b61e..9a8297d6 100644
--- a/packages/ui/src/lib/i18n/messages/es/messaging.ts
+++ b/packages/ui/src/lib/i18n/messages/es/messaging.ts
@@ -149,6 +149,10 @@ export const messagingMessages = {
   "promptInput.send.ariaLabel": "Enviar mensaje",
   "promptInput.send.errorFallback": "No se pudo enviar el mensaje",
   "promptInput.send.errorTitle": "Error al enviar",
+  "promptInput.conversationMode.enable.title": "Activar modo conversacion",
+  "promptInput.conversationMode.disable.title": "Desactivar modo conversacion",
+  "promptInput.conversationMode.error.title": "Fallo la reproduccion de la conversacion",
+  "promptInput.conversationMode.error.message": "No se pudieron seguir reproduciendo las respuestas del asistente.",
   "promptInput.voiceInput.start.title": "Iniciar entrada de voz",
   "promptInput.voiceInput.stop.title": "Detener grabación y transcribir",
   "promptInput.voiceInput.transcribing.title": "Transcribiendo audio",
diff --git a/packages/ui/src/lib/i18n/messages/fr/messaging.ts b/packages/ui/src/lib/i18n/messages/fr/messaging.ts
index b3ba59a9..02f2d1e4 100644
--- a/packages/ui/src/lib/i18n/messages/fr/messaging.ts
+++ b/packages/ui/src/lib/i18n/messages/fr/messaging.ts
@@ -149,6 +149,10 @@ export const messagingMessages = {
   "promptInput.send.ariaLabel": "Envoyer le message",
   "promptInput.send.errorFallback": "Impossible d'envoyer le message",
   "promptInput.send.errorTitle": "Échec de l'envoi",
+  "promptInput.conversationMode.enable.title": "Activer le mode conversation",
+  "promptInput.conversationMode.disable.title": "Desactiver le mode conversation",
+  "promptInput.conversationMode.error.title": "La lecture de la conversation a echoue",
+  "promptInput.conversationMode.error.message": "Impossible de continuer a lire les reponses de l'assistant.",
   "promptInput.voiceInput.start.title": "Démarrer la saisie vocale",
   "promptInput.voiceInput.stop.title": "Arrêter l'enregistrement et transcrire",
   "promptInput.voiceInput.transcribing.title": "Transcription de l'audio",
diff --git a/packages/ui/src/lib/i18n/messages/he/messaging.ts b/packages/ui/src/lib/i18n/messages/he/messaging.ts
index f45cc8e2..fa0c98ff 100644
--- a/packages/ui/src/lib/i18n/messages/he/messaging.ts
+++ b/packages/ui/src/lib/i18n/messages/he/messaging.ts
@@ -147,6 +147,10 @@ export const messagingMessages = {
   "promptInput.send.ariaLabel": "שלח הודעה",
   "promptInput.send.errorFallback": "שליחת ההודעה נכשלה",
   "promptInput.send.errorTitle": "השליחה נכשלה",
+  "promptInput.conversationMode.enable.title": "הפעל מצב שיחה",
+  "promptInput.conversationMode.disable.title": "כבה מצב שיחה",
+  "promptInput.conversationMode.error.title": "ניגון השיחה נכשל",
+  "promptInput.conversationMode.error.message": "לא ניתן היה להמשיך להקריא את תגובות העוזר.",
   "promptInput.voiceInput.start.title": "התחל קלט קולי",
   "promptInput.voiceInput.stop.title": "עצור הקלטה ותמלל",
   "promptInput.voiceInput.transcribing.title": "מתמלל אודיו",
diff --git a/packages/ui/src/lib/i18n/messages/ja/messaging.ts b/packages/ui/src/lib/i18n/messages/ja/messaging.ts
index f8e3cf46..566e5f4a 100644
--- a/packages/ui/src/lib/i18n/messages/ja/messaging.ts
+++ b/packages/ui/src/lib/i18n/messages/ja/messaging.ts
@@ -149,6 +149,10 @@ export const messagingMessages = {
   "promptInput.send.ariaLabel": "メッセージを送信",
   "promptInput.send.errorFallback": "メッセージの送信に失敗しました",
   "promptInput.send.errorTitle": "送信に失敗",
+  "promptInput.conversationMode.enable.title": "会話モードを有効化",
+  "promptInput.conversationMode.disable.title": "会話モードを無効化",
+  "promptInput.conversationMode.error.title": "会話の読み上げに失敗しました",
+  "promptInput.conversationMode.error.message": "アシスタントの返信の読み上げを続行できませんでした。",
   "promptInput.voiceInput.start.title": "音声入力を開始",
   "promptInput.voiceInput.stop.title": "録音を停止して文字起こし",
   "promptInput.voiceInput.transcribing.title": "音声を文字起こし中",
diff --git a/packages/ui/src/lib/i18n/messages/ru/messaging.ts b/packages/ui/src/lib/i18n/messages/ru/messaging.ts
index c696a114..0b2019aa 100644
--- a/packages/ui/src/lib/i18n/messages/ru/messaging.ts
+++ b/packages/ui/src/lib/i18n/messages/ru/messaging.ts
@@ -149,6 +149,10 @@ export const messagingMessages = {
   "promptInput.send.ariaLabel": "Отправить сообщение",
   "promptInput.send.errorFallback": "Не удалось отправить сообщение",
   "promptInput.send.errorTitle": "Не удалось отправить",
+  "promptInput.conversationMode.enable.title": "Включить режим разговора",
+  "promptInput.conversationMode.disable.title": "Выключить режим разговора",
+  "promptInput.conversationMode.error.title": "Сбой озвучивания разговора",
+  "promptInput.conversationMode.error.message": "Не удалось продолжить озвучивание ответов ассистента.",
   "promptInput.voiceInput.start.title": "Начать голосовой ввод",
   "promptInput.voiceInput.stop.title": "Остановить запись и расшифровать",
   "promptInput.voiceInput.transcribing.title": "Идёт расшифровка аудио",
diff --git a/packages/ui/src/lib/i18n/messages/zh-Hans/messaging.ts b/packages/ui/src/lib/i18n/messages/zh-Hans/messaging.ts
index 6d618bbd..b047e36e 100644
--- a/packages/ui/src/lib/i18n/messages/zh-Hans/messaging.ts
+++ b/packages/ui/src/lib/i18n/messages/zh-Hans/messaging.ts
@@ -149,6 +149,10 @@ export const messagingMessages = {
   "promptInput.send.ariaLabel": "发送消息",
   "promptInput.send.errorFallback": "发送消息失败",
   "promptInput.send.errorTitle": "发送失败",
+  "promptInput.conversationMode.enable.title": "开启对话模式",
+  "promptInput.conversationMode.disable.title": "关闭对话模式",
+  "promptInput.conversationMode.error.title": "对话播报失败",
+  "promptInput.conversationMode.error.message": "无法继续播报助手回复。",
   "promptInput.voiceInput.start.title": "开始语音输入",
   "promptInput.voiceInput.stop.title": "停止录音并转写",
   "promptInput.voiceInput.transcribing.title": "正在转写音频",
diff --git a/packages/ui/src/stores/conversation-speech.ts b/packages/ui/src/stores/conversation-speech.ts
new file mode 100644
index 00000000..802725ef
--- /dev/null
+++ b/packages/ui/src/stores/conversation-speech.ts
@@ -0,0 +1,507 @@
+import { createSignal } from "solid-js"
+import { tGlobal } from "../lib/i18n"
+import { showToastNotification } from "../lib/notifications"
+import { serverApi } from "../lib/api-client"
+import { getLogger } from "../lib/logger"
+import { formatToMimeType, getSpeechPlaybackSupport } from "../lib/speech-playback-support"
+import { serverSettings } from "./preferences"
+import { loadSpeechCapabilities, speechCapabilities } from "./speech"
+import { getActiveSession, sessions } from "./session-state"
+import type { ClientPart, MessageInfo } from "../types/message"
+import { messageStoreBus } from "./message-v2/bus"
+import { activeInstanceId } from "./instances"
+
+type SpeechPlaybackMode = "streaming" | "buffered"
+type SpeechTtsFormat = "mp3" | "wav" | "opus" | "aac"
+
+interface ConversationQueueEntry {
+  key: string
+  instanceId: string
+  sessionId: string
+  messageId: string
+  partId: string
+  text: string
+}
+
+interface PlaybackHandle {
+  stop: () => void
+  done: Promise<void>
+}
+
+const log = getLogger("actions")
+const [conversationModeInstances, setConversationModeInstances] = createSignal<Map<string, boolean>>(new Map())
+
+const queuedKeys = new Set<string>()
+const spokenKeysBySession = new Map<string, Set<string>>()
+let queue: ConversationQueueEntry[] = []
+let currentPlayback:
+  | {
+      entry: ConversationQueueEntry
+      handle: PlaybackHandle
+    }
+  | null = null
+let queueRunner: Promise<void> | null = null
+let playbackErrorShown = false
+
+function getEntryKey(instanceId: string, sessionId: string, messageId: string, partId: string): string {
+  return `${instanceId}:${sessionId}:${messageId}:${partId}`
+}
+
+function getSpokenKeySet(instanceId: string, sessionId: string): Set<string> {
+  const sessionKey = `${instanceId}:${sessionId}`
+  const existing = spokenKeysBySession.get(sessionKey)
+  if (existing) return existing
+  const next = new Set<string>()
+  spokenKeysBySession.set(sessionKey, next)
+  return next
+}
+
+function resolveTextPartContent(part: ClientPart): string {
+  if (part.type !== "text") return ""
+  if (typeof part.text === "string") {
+    return part.text
+  }
+
+  if (part.text && typeof part.text === "object") {
+    const value = part.text as { text?: unknown; value?: unknown; content?: unknown[] }
+    const segments: string[] = []
+    if (typeof value.text === "string") {
+      segments.push(value.text)
+    }
+    if (typeof value.value === "string") {
+      segments.push(value.value)
+    }
+    if (Array.isArray(value.content)) {
+      for (const segment of value.content) {
+        if (typeof segment === "string") {
+          segments.push(segment)
+        } else if (segment && typeof segment === "object") {
+          const typedSegment = segment as { text?: unknown; value?: unknown }
+          if (typeof typedSegment.text === "string") segments.push(typedSegment.text)
+          if (typeof typedSegment.value === "string") segments.push(typedSegment.value)
+        }
+      }
+    }
+    return segments.join("\n")
+  }
+
+  return ""
+}
+
+export function isConversationModeEnabled(instanceId: string): boolean {
+  return conversationModeInstances().get(instanceId) === true
+}
+
+export function canUseConversationMode(): boolean {
+  const capabilities = speechCapabilities()
+  if (!capabilities?.available || !capabilities.configured || !capabilities.supportsTts) {
+    return false
+  }
+
+  const settings = serverSettings().speech
+  return getSpeechPlaybackSupport({
+    playbackMode: settings.playbackMode,
+    ttsFormat: settings.ttsFormat,
+    capabilities,
+  }).available
+}
+
+export function setConversationModeEnabled(instanceId: string, enabled: boolean): void {
+  setConversationModeInstances((prev) => {
+    const next = new Map(prev)
+    if (enabled) {
+      next.set(instanceId, true)
+    } else {
+      next.delete(instanceId)
+    }
+    return next
+  })
+
+  if (!enabled) {
+    clearConversationPlaybackForInstance(instanceId)
+  }
+}
+
+export function toggleConversationMode(instanceId: string): void {
+  setConversationModeEnabled(instanceId, !isConversationModeEnabled(instanceId))
+}
+
+export function clearConversationPlaybackForSession(instanceId: string, sessionId: string): void {
+  const sessionKey = `${instanceId}:${sessionId}`
+  queue = queue.filter((entry) => {
+    if (`${entry.instanceId}:${entry.sessionId}` === sessionKey) {
+      queuedKeys.delete(entry.key)
+      return false
+    }
+    return true
+  })
+
+  if (currentPlayback && `${currentPlayback.entry.instanceId}:${currentPlayback.entry.sessionId}` === sessionKey) {
+    currentPlayback.handle.stop()
+    currentPlayback = null
+  }
+}
+
+export function clearConversationPlaybackForInstance(instanceId: string): void {
+  queue = queue.filter((entry) => {
+    if (entry.instanceId === instanceId) {
+      queuedKeys.delete(entry.key)
+      return false
+    }
+    return true
+  })
+
+  if (currentPlayback?.entry.instanceId === instanceId) {
+    currentPlayback.handle.stop()
+    currentPlayback = null
+  }
+}
+
+function isSpeakableSession(instanceId: string, sessionId: string): boolean {
+  if (activeInstanceId() !== instanceId) {
+    return false
+  }
+
+  const activeSession = getActiveSession(instanceId)
+  if (!activeSession || activeSession.id !== sessionId) {
+    return false
+  }
+
+  const session = sessions().get(instanceId)?.get(sessionId) ?? activeSession
+  return !session?.parentId
+}
+
+export function handleConversationAssistantPartUpdated(instanceId: string, part: ClientPart, messageInfo?: MessageInfo): void {
+  if (part.type !== "text") return
+
+  const sessionId = typeof part.sessionID === "string" ? part.sessionID : messageInfo?.sessionID
+  const messageId = typeof part.messageID === "string" ? part.messageID : messageInfo?.id
+  const partId = typeof part.id === "string" ? part.id : undefined
+  if (!sessionId || !messageId || !partId) return
+
+  const messageRole =
+    messageInfo?.role ??
+    messageStoreBus.getOrCreate(instanceId).getMessage(messageId)?.role ??
+    null
+  if (messageRole !== "assistant") return
+
+  if (!isConversationModeEnabled(instanceId)) return
+  if (!isSpeakableSession(instanceId, sessionId)) return
+
+  const text = resolveTextPartContent(part).trim()
+  if (!text) return
+
+  const key = getEntryKey(instanceId, sessionId, messageId, partId)
+  const spokenKeys = getSpokenKeySet(instanceId, sessionId)
+  if (spokenKeys.has(key) || queuedKeys.has(key) || currentPlayback?.entry.key === key) {
+    return
+  }
+
+  queuedKeys.add(key)
+  queue.push({ key, instanceId, sessionId, messageId, partId, text })
+  void runConversationQueue()
+}
+
+async function runConversationQueue(): Promise<void> {
+  if (queueRunner) {
+    await queueRunner
+    return
+  }
+
+  queueRunner = (async () => {
+    while (queue.length > 0) {
+      const entry = queue.shift()!
+      queuedKeys.delete(entry.key)
+
+      if (!isConversationModeEnabled(entry.instanceId)) {
+        continue
+      }
+      if (!isSpeakableSession(entry.instanceId, entry.sessionId)) {
+        continue
+      }
+
+      const spokenKeys = getSpokenKeySet(entry.instanceId, entry.sessionId)
+      spokenKeys.add(entry.key)
+
+      try {
+        const handle = await createPlaybackHandle(entry.text)
+        currentPlayback = { entry, handle }
+        await handle.done
+      } catch (error) {
+        spokenKeys.delete(entry.key)
+        clearConversationPlaybackForInstance(entry.instanceId)
+        if (!playbackErrorShown) {
+          playbackErrorShown = true
+          showToastNotification({
+            title: tGlobal("promptInput.conversationMode.error.title"),
+            message:
+              error instanceof Error && error.message
+                ? error.message
+                : tGlobal("promptInput.conversationMode.error.message"),
+            variant: "error",
+          })
+        }
+        log.error("Conversation playback failed", error)
+        break
+      } finally {
+        if (currentPlayback?.entry.key === entry.key) {
+          currentPlayback = null
+        }
+      }
+    }
+  })()
+
+  try {
+    await queueRunner
+  } finally {
+    queueRunner = null
+    if (queue.length === 0) {
+      playbackErrorShown = false
+    }
+  }
+}
+
+async function createPlaybackHandle(text: string): Promise<PlaybackHandle> {
+  const capabilities = (await loadSpeechCapabilities()) ?? speechCapabilities()
+  const settings = serverSettings().speech
+
+  if (!capabilities?.available || !capabilities.configured || !capabilities.supportsTts) {
+    throw new Error(tGlobal("messageItem.actions.speak.error.unavailable"))
+  }
+
+  const support = getSpeechPlaybackSupport({
+    playbackMode: settings.playbackMode,
+    ttsFormat: settings.ttsFormat,
+    capabilities,
+  })
+  if (!support.available) {
+    if (support.reason === "provider-streaming-unavailable") {
+      throw new Error(tGlobal("settings.speech.compatibility.streamingUnavailable"))
+    }
+    if (support.reason === "browser-streaming-unavailable") {
+      throw new Error(tGlobal("settings.speech.compatibility.browserStreamingUnavailable"))
+    }
+    throw new Error(tGlobal("messageItem.actions.speak.error.unsupported"))
+  }
+
+  return settings.playbackMode === "streaming"
+    ? createStreamingPlaybackHandle(text, settings.ttsFormat)
+    : createBufferedPlaybackHandle(text, settings.ttsFormat)
+}
+
+async function createBufferedPlaybackHandle(text: string, format: SpeechTtsFormat): Promise<PlaybackHandle> {
+  const response = await serverApi.synthesizeSpeech({ text, format })
+  const objectUrl = createObjectUrlFromBase64(response.audioBase64, response.mimeType)
+  const audio = new Audio(objectUrl)
+
+  let settled = false
+  let resolveDone!: () => void
+  let rejectDone!: (error: unknown) => void
+
+  const cleanup = () => {
+    audio.pause()
+    audio.src = ""
+    audio.load()
+    URL.revokeObjectURL(objectUrl)
+  }
+
+  const done = new Promise<void>((resolve, reject) => {
+    resolveDone = () => {
+      if (settled) return
+      settled = true
+      cleanup()
+      resolve()
+    }
+    rejectDone = (error) => {
+      if (settled) return
+      settled = true
+      cleanup()
+      reject(error)
+    }
+  })
+
+  audio.addEventListener("ended", () => resolveDone(), { once: true })
+  audio.addEventListener("error", () => rejectDone(new Error(tGlobal("messageItem.actions.speak.error.generate"))), {
+    once: true,
+  })
+
+  await audio.play()
+
+  return {
+    stop: () => resolveDone(),
+    done,
+  }
+}
+
+async function createStreamingPlaybackHandle(text: string, format: SpeechTtsFormat): Promise<PlaybackHandle> {
+  if (typeof MediaSource === "undefined") {
+    throw new Error(tGlobal("messageItem.actions.speak.error.unsupported"))
+  }
+
+  const abortController = new AbortController()
+  const response = await serverApi.synthesizeSpeechStream({ text, format }, abortController.signal)
+  const mimeType = response.headers.get("content-type") || formatToMimeType(format)
+  const stream = response.body
+  if (!stream) {
+    throw new Error(tGlobal("messageItem.actions.speak.error.generate"))
+  }
+
+  if (!MediaSource.isTypeSupported(mimeType)) {
+    throw new Error(tGlobal("settings.speech.compatibility.browserStreamingUnavailable"))
+  }
+
+  const mediaSource = new MediaSource()
+  const objectUrl = URL.createObjectURL(mediaSource)
+  const audio = new Audio(objectUrl)
+
+  let settled = false
+  let startedPlayback = false
+  let resolveDone!: () => void
+  let rejectDone!: (error: unknown) => void
+
+  const cleanup = () => {
+    abortController.abort()
+    audio.pause()
+    audio.src = ""
+    audio.load()
+    URL.revokeObjectURL(objectUrl)
+  }
+
+  const done = new Promise<void>((resolve, reject) => {
+    resolveDone = () => {
+      if (settled) return
+      settled = true
+      cleanup()
+      resolve()
+    }
+    rejectDone = (error) => {
+      if (settled) return
+      settled = true
+      cleanup()
+      reject(error)
+    }
+  })
+
+  audio.addEventListener("ended", () => resolveDone(), { once: true })
+  audio.addEventListener("error", () => rejectDone(new Error(tGlobal("messageItem.actions.speak.error.generate"))), {
+    once: true,
+  })
+
+  await new Promise<void>((resolve, reject) => {
+    mediaSource.addEventListener(
+      "sourceopen",
+      () => {
+        void streamToMediaSource({
+          mediaSource,
+          stream,
+          mimeType,
+          onPlayable: async () => {
+            if (startedPlayback) return
+            startedPlayback = true
+            try {
+              await audio.play()
+              resolve()
+            } catch (error) {
+              reject(error)
+            }
+          },
+          onError: reject,
+        })
+      },
+      { once: true },
+    )
+  })
+
+  return {
+    stop: () => resolveDone(),
+    done,
+  }
+}
+
+async function streamToMediaSource(options: {
+  mediaSource: MediaSource
+  stream: ReadableStream<Uint8Array>
+  mimeType: string
+  onPlayable: () => Promise<void>
+  onError: (error: unknown) => void
+}) {
+  try {
+    const sourceBuffer = options.mediaSource.addSourceBuffer(options.mimeType)
+    const reader = options.stream.getReader()
+    const queue: Uint8Array[] = []
+    let processing = false
+    let playbackStarted = false
+
+    const flushQueue = async () => {
+      if (processing || sourceBuffer.updating || queue.length === 0) return
+      processing = true
+      const chunk = queue.shift()!
+      await appendChunk(sourceBuffer, chunk)
+      if (!playbackStarted) {
+        playbackStarted = true
+        await options.onPlayable()
+      }
+      processing = false
+      await flushQueue()
+    }
+
+    while (true) {
+      const { done, value } = await reader.read()
+      if (done) break
+      if (value && value.byteLength > 0) {
+        queue.push(value)
+        await flushQueue()
+      }
+    }
+
+    while (queue.length > 0 || sourceBuffer.updating) {
+      if (queue.length > 0) {
+        await flushQueue()
+      } else {
+        await waitForUpdateEnd(sourceBuffer)
+      }
+    }
+
+    if (options.mediaSource.readyState === "open") {
+      options.mediaSource.endOfStream()
+    }
+  } catch (error) {
+    options.onError(error)
+  }
+}
+
+function appendChunk(sourceBuffer: SourceBuffer, chunk: Uint8Array): Promise<void> {
+  return new Promise((resolve, reject) => {
+    const handleUpdateEnd = () => {
+      cleanup()
+      resolve()
+    }
+    const handleError = () => {
+      cleanup()
+      reject(new Error(tGlobal("messageItem.actions.speak.error.generate")))
+    }
+    const cleanup = () => {
+      sourceBuffer.removeEventListener("updateend", handleUpdateEnd)
+      sourceBuffer.removeEventListener("error", handleError)
+    }
+
+    sourceBuffer.addEventListener("updateend", handleUpdateEnd, { once: true })
+    sourceBuffer.addEventListener("error", handleError, { once: true })
+    sourceBuffer.appendBuffer(new Uint8Array(chunk).buffer)
+  })
+}
+
+function waitForUpdateEnd(sourceBuffer: SourceBuffer): Promise<void> {
+  return new Promise((resolve) => {
+    sourceBuffer.addEventListener("updateend", () => resolve(), { once: true })
+  })
+}
+
+function createObjectUrlFromBase64(audioBase64: string, mimeType: string): string {
+  const binary = atob(audioBase64)
+  const bytes = new Uint8Array(binary.length)
+  for (let index = 0; index < binary.length; index += 1) {
+    bytes[index] = binary.charCodeAt(index)
+  }
+  return URL.createObjectURL(new Blob([bytes], { type: mimeType || "audio/mpeg" }))
+}
diff --git a/packages/ui/src/stores/session-actions.ts b/packages/ui/src/stores/session-actions.ts
index 8e193c6d..3cdf0321 100644
--- a/packages/ui/src/stores/session-actions.ts
+++ b/packages/ui/src/stores/session-actions.ts
@@ -10,6 +10,7 @@ import { messageStoreBus } from "./message-v2/bus"
 import { removeMessagePartV2, removeMessageV2 } from "./message-v2/bridge"
 import { getLogger } from "../lib/logger"
 import { requestData } from "../lib/opencode-api"
+import { clearConversationPlaybackForSession } from "./conversation-speech"
 
 const log = getLogger("actions")
 
@@ -165,6 +166,8 @@ async function sendMessage(
   const store = messageStoreBus.getOrCreate(instanceId)
   const createdAt = Date.now()
 
+  clearConversationPlaybackForSession(instanceId, sessionId)
+
   store.upsertMessage({
     id: messageId,
     sessionId,
diff --git a/packages/ui/src/stores/session-events.ts b/packages/ui/src/stores/session-events.ts
index bb780d59..91c4aabc 100644
--- a/packages/ui/src/stores/session-events.ts
+++ b/packages/ui/src/stores/session-events.ts
@@ -63,6 +63,7 @@ import {
 } from "./message-v2/bridge"
 import { messageStoreBus } from "./message-v2/bus"
 import type { InstanceMessageStore } from "./message-v2/instance-store"
+import { handleConversationAssistantPartUpdated } from "./conversation-speech"
 
 const log = getLogger("sse")
 const pendingSessionFetches = new Map<string, Promise<void>>()
@@ -330,8 +331,9 @@ function handleMessageUpdate(instanceId: string, event: MessageUpdateEvent | Mes
     if (messageInfo) {
       upsertMessageInfoV2(instanceId, messageInfo, { status: "streaming" })
     }
- 
+  
     applyPartUpdateV2(instanceId, { ...part, sessionID: sessionId, messageID: messageId })
+    handleConversationAssistantPartUpdated(instanceId, { ...part, sessionID: sessionId, messageID: messageId }, messageInfo)
 
     if (part.type === "tool" && part.tool === "question") {
       // Questions can arrive before their tool part exists; re-link now.
diff --git a/packages/ui/src/styles/messaging/prompt-input.css b/packages/ui/src/styles/messaging/prompt-input.css
index d0a9d87e..314660d1 100644
--- a/packages/ui/src/styles/messaging/prompt-input.css
+++ b/packages/ui/src/styles/messaging/prompt-input.css
@@ -236,6 +236,16 @@
   @apply opacity-50 cursor-not-allowed;
 }
 
+.prompt-conversation-button.is-active {
+  background-color: color-mix(in oklab, var(--accent-primary) 76%, var(--surface-secondary));
+  color: var(--text-inverted);
+}
+
+.prompt-conversation-button.is-active:hover:not(:disabled) {
+  background-color: color-mix(in oklab, var(--accent-primary) 88%, var(--surface-secondary));
+  color: var(--text-inverted);
+}
+
 .prompt-voice-timer {
   font-size: 0.68rem;
   font-variant-numeric: tabular-nums;