diff --git a/src/talk/session-runtime.test.ts b/src/talk/session-runtime.test.ts
index 8d944bd92ba8..bf5f58f878cd 100644
--- a/src/talk/session-runtime.test.ts
+++ b/src/talk/session-runtime.test.ts
@@ -343,6 +343,167 @@ describe("realtime voice bridge session runtime", () => {
     expect(onError).not.toHaveBeenCalled();
   });
 
+  it("permanently closes once while preserving synchronous transcript flush", async () => {
+    let callbacks: Parameters<RealtimeVoiceProviderPlugin["createBridge"]>[0] | undefined;
+    const close = vi.fn(() => {
+      callbacks?.onTranscript?.("assistant", "final transcript", true);
+    });
+    const connect = vi.fn(async () => {});
+    const sendProviderAudio = vi.fn();
+    const sendSinkAudio = vi.fn();
+    const onTranscript = vi.fn();
+    const provider: RealtimeVoiceProviderPlugin = {
+      id: "test",
+      label: "Test",
+      isConfigured: () => true,
+      createBridge: (request) => {
+        callbacks = request;
+        return makeBridge({ close, connect, sendAudio: sendProviderAudio });
+      },
+    };
+    const session = createRealtimeVoiceBridgeSession({
+      provider,
+      providerConfig: {},
+      audioSink: { sendAudio: sendSinkAudio },
+      onTranscript,
+    });
+
+    session.close();
+    session.close();
+    session.sendAudio(Buffer.from("late-input"));
+    callbacks?.onAudio(Buffer.from("late-output"));
+    await expect(session.connect()).rejects.toThrow("Realtime voice session is closed");
+
+    expect(close).toHaveBeenCalledTimes(1);
+    expect(connect).not.toHaveBeenCalled();
+    expect(sendProviderAudio).not.toHaveBeenCalled();
+    expect(sendSinkAudio).not.toHaveBeenCalled();
+    expect(onTranscript).toHaveBeenCalledExactlyOnceWith("assistant", "final transcript", true);
+  });
+
+  it("stops audio admission after provider close and still closes the provider once", () => {
+    let callbacks: Parameters<RealtimeVoiceProviderPlugin["createBridge"]>[0] | undefined;
+    const close = vi.fn();
+    const sendProviderAudio = vi.fn();
+    const sendSinkAudio = vi.fn();
+    const onClose = vi.fn();
+    const provider: RealtimeVoiceProviderPlugin = {
+      id: "test",
+      label: "Test",
+      isConfigured: () => true,
+      createBridge: (request) => {
+        callbacks = request;
+        return makeBridge({ close, sendAudio: sendProviderAudio });
+      },
+    };
+    const session = createRealtimeVoiceBridgeSession({
+      provider,
+      providerConfig: {},
+      audioSink: { sendAudio: sendSinkAudio },
+      onClose,
+    });
+
+    callbacks?.onClose?.("completed");
+    callbacks?.onClose?.("completed");
+    session.sendAudio(Buffer.from("late-input"));
+    callbacks?.onAudio(Buffer.from("late-output"));
+    session.close();
+    session.close();
+
+    expect(onClose).toHaveBeenCalledTimes(1);
+    expect(close).toHaveBeenCalledTimes(1);
+    expect(sendProviderAudio).not.toHaveBeenCalled();
+    expect(sendSinkAudio).not.toHaveBeenCalled();
+  });
+
+  it("reopens audio and close reporting for an explicit connection generation", async () => {
+    let callbacks: Parameters<RealtimeVoiceProviderPlugin["createBridge"]>[0] | undefined;
+    const connect = vi.fn(async () => {});
+    const sendProviderAudio = vi.fn();
+    const sendSinkAudio = vi.fn();
+    const onClose = vi.fn();
+    const onReady = vi.fn();
+    const provider: RealtimeVoiceProviderPlugin = {
+      id: "test",
+      label: "Test",
+      isConfigured: () => true,
+      createBridge: (request) => {
+        callbacks = request;
+        request.onClose?.("error");
+        return makeBridge({ connect, sendAudio: sendProviderAudio });
+      },
+    };
+    const session = createRealtimeVoiceBridgeSession({
+      provider,
+      providerConfig: {},
+      audioSink: { sendAudio: sendSinkAudio },
+      onClose,
+      onReady,
+    });
+
+    session.sendAudio(Buffer.from("closed-input"));
+    callbacks?.onAudio(Buffer.from("closed-output"));
+    callbacks?.onClose?.("error");
+    callbacks?.onReady?.();
+    expect(onReady).not.toHaveBeenCalled();
+
+    await session.connect();
+    callbacks?.onReady?.();
+    session.sendAudio(Buffer.from("next-input"));
+    callbacks?.onAudio(Buffer.from("next-output"));
+    callbacks?.onClose?.("completed");
+    callbacks?.onClose?.("completed");
+    await expect(session.connect()).rejects.toThrow("Realtime voice connection is closed");
+
+    expect(connect).toHaveBeenCalledTimes(1);
+    expect(onReady).toHaveBeenCalledWith(session);
+    expect(onClose).toHaveBeenNthCalledWith(1, "error");
+    expect(onClose).toHaveBeenNthCalledWith(2, "completed");
+    expect(onClose).toHaveBeenCalledTimes(2);
+    expect(sendProviderAudio).toHaveBeenCalledExactlyOnceWith(Buffer.from("next-input"));
+    expect(sendSinkAudio).toHaveBeenCalledExactlyOnceWith(Buffer.from("next-output"));
+  });
+
+  it("rejects reconnect and ignores tool failures after an established provider close", async () => {
+    let callbacks: Parameters<RealtimeVoiceProviderPlugin["createBridge"]>[0] | undefined;
+    let rejectToolCall: ((error: Error) => void) | undefined;
+    const connect = vi.fn(async () => {});
+    const onError = vi.fn();
+    const provider: RealtimeVoiceProviderPlugin = {
+      id: "test",
+      label: "Test",
+      isConfigured: () => true,
+      createBridge: (request) => {
+        callbacks = request;
+        return makeBridge({ connect });
+      },
+    };
+    const session = createRealtimeVoiceBridgeSession({
+      provider,
+      providerConfig: {},
+      audioSink: { sendAudio: vi.fn() },
+      onToolCall: () =>
+        new Promise<void>((_resolve, reject) => {
+          rejectToolCall = reject;
+        }),
+      onError,
+    });
+
+    callbacks?.onToolCall?.({
+      itemId: "item-1",
+      callId: "call-1",
+      name: "lookup",
+      args: {},
+    });
+    callbacks?.onClose?.("error");
+    await expect(session.connect()).rejects.toThrow("Realtime voice connection is closed");
+    rejectToolCall?.(new Error("late tool callback failure"));
+    await Promise.resolve();
+
+    expect(connect).not.toHaveBeenCalled();
+    expect(onError).not.toHaveBeenCalled();
+  });
+
   it("forwards tool result continuation options and async acceptance to the provider bridge", () => {
     const acceptance = Promise.resolve();
     const submitToolResult = vi.fn(() => acceptance);
diff --git a/src/talk/session-runtime.ts b/src/talk/session-runtime.ts
index b46c2aace94a..68b9a5c28593 100644
--- a/src/talk/session-runtime.ts
+++ b/src/talk/session-runtime.ts
@@ -78,6 +78,8 @@ export type RealtimeVoiceBridgeSessionParams = {
   onClose?: (reason: RealtimeVoiceCloseReason) => void;
 };
 
+type RealtimeVoiceSessionPhase = "admitting" | "provider-terminal" | "disposed";
+
 /**
  * Creates a realtime voice bridge session and wires provider events to the configured audio sink.
  */
@@ -85,7 +87,12 @@ export function createRealtimeVoiceBridgeSession(
   params: RealtimeVoiceBridgeSessionParams,
 ): RealtimeVoiceBridgeSession {
   const bridgeRef: { current?: RealtimeVoiceBridge } = {};
-  let isActive = true;
+  // Local disposal owns provider cleanup. Only a terminal callback fired before bridge
+  // adoption may reopen; adopted bridges own reconnects and stale-event fencing internally.
+  let phase: RealtimeVoiceSessionPhase = "admitting";
+  let terminalBeforeBridgeAdoption = false;
+  let closeReported = false;
+  const isAdmitting = () => phase === "admitting";
   const requireBridge = () => {
     if (!bridgeRef.current) {
       throw new Error("Realtime voice bridge is not ready");
@@ -100,12 +107,32 @@ export function createRealtimeVoiceBridgeSession(
     },
     acknowledgeMark: (markName) => requireBridge().acknowledgeMark(markName),
     close: () => {
+      if (phase === "disposed") {
+        return;
+      }
       const bridge = requireBridge();
-      isActive = false;
+      phase = "disposed";
       bridge.close();
     },
-    connect: () => requireBridge().connect(),
-    sendAudio: (audio) => requireBridge().sendAudio(audio),
+    connect: () => {
+      if (phase === "disposed") {
+        return Promise.reject(new Error("Realtime voice session is closed"));
+      }
+      if (phase === "provider-terminal") {
+        if (!terminalBeforeBridgeAdoption) {
+          return Promise.reject(new Error("Realtime voice connection is closed"));
+        }
+        terminalBeforeBridgeAdoption = false;
+        phase = "admitting";
+        closeReported = false;
+      }
+      return requireBridge().connect();
+    },
+    sendAudio: (audio) => {
+      if (isAdmitting()) {
+        requireBridge().sendAudio(audio);
+      }
+    },
     sendUserMessage: (text) => requireBridge().sendUserMessage?.(text),
     handleBargeIn: (options) => requireBridge().handleBargeIn?.(options),
     setMediaTimestamp: (ts) => requireBridge().setMediaTimestamp(ts),
@@ -118,11 +145,13 @@ export function createRealtimeVoiceBridgeSession(
     },
     triggerGreeting: (instructions) => requireBridge().triggerGreeting?.(instructions),
   };
-  const canSendAudio = () => params.audioSink.isOpen?.() ?? true;
+  // Session inactivity is the shared admission boundary for both audio directions.
+  // Provider and transport callbacks may still race after close, but cannot retain new audio.
+  const canSendAudio = () => isAdmitting() && (params.audioSink.isOpen?.() ?? true);
   const reportCallbackError = (error: unknown) => {
     // Async tool handlers can settle after the provider closes. Once inactive, no
     // callback may report stale failures into the next session lifecycle.
-    if (!isActive) {
+    if (!isAdmitting()) {
       return;
     }
     try {
@@ -167,7 +196,7 @@ export function createRealtimeVoiceBridgeSession(
     onTranscript: params.onTranscript,
     onEvent: params.onEvent,
     onToolCall: (event) => {
-      if (!bridgeRef.current || !isActive) {
+      if (!bridgeRef.current || !isAdmitting()) {
         return;
       }
       try {
@@ -180,7 +209,7 @@ export function createRealtimeVoiceBridgeSession(
       }
     },
     onReady: () => {
-      if (!bridgeRef.current) {
+      if (!bridgeRef.current || !isAdmitting()) {
         return;
       }
       if (params.triggerGreetingOnReady) {
@@ -190,7 +219,16 @@ export function createRealtimeVoiceBridgeSession(
     },
     onError: params.onError,
     onClose: (reason) => {
-      isActive = false;
+      if (!bridgeRef.current) {
+        terminalBeforeBridgeAdoption = true;
+      }
+      if (phase !== "disposed") {
+        phase = "provider-terminal";
+      }
+      if (closeReported) {
+        return;
+      }
+      closeReported = true;
       params.onClose?.(reason);
     },
   });