diff --git a/src/tests/websocket/listen-client-protocol.test.ts b/src/tests/websocket/listen-client-protocol.test.ts
index 9006b05..0f76a2a 100644
--- a/src/tests/websocket/listen-client-protocol.test.ts
+++ b/src/tests/websocket/listen-client-protocol.test.ts
@@ -194,6 +194,39 @@ describe("listen-client parseServerMessage", () => {
   });
 });
 
+describe("listen-client permission mode scope keys", () => {
+  test("falls back from legacy default key and migrates to agent-scoped key", () => {
+    const listener = __listenClientTestUtils.createListenerRuntime();
+
+    // Simulate a pre-existing/legacy persisted entry without agent binding.
+    listener.permissionModeByConversation.set(
+      "agent:__unknown__::conversation:default",
+      {
+        mode: "acceptEdits",
+        planFilePath: null,
+        modeBeforePlan: null,
+      },
+    );
+
+    const status = __listenClientTestUtils.buildDeviceStatus(listener, {
+      agent_id: "agent-123",
+      conversation_id: "default",
+    });
+
+    expect(status.current_permission_mode).toBe("acceptEdits");
+    expect(
+      listener.permissionModeByConversation.has(
+        "agent:agent-123::conversation:default",
+      ),
+    ).toBe(true);
+    expect(
+      listener.permissionModeByConversation.has(
+        "agent:__unknown__::conversation:default",
+      ),
+    ).toBe(false);
+  });
+});
+
 describe("listen-client approval resolver wiring", () => {
   test("resolves matching pending resolver", async () => {
     const runtime = __listenClientTestUtils.createRuntime();
diff --git a/src/websocket/listener/permissionMode.ts b/src/websocket/listener/permissionMode.ts
index 7fddda3..03462e8 100644
--- a/src/websocket/listener/permissionMode.ts
+++ b/src/websocket/listener/permissionMode.ts
@@ -37,13 +37,36 @@ export function getConversationPermissionModeState(
   conversationId?: string | null,
 ): ConversationPermissionModeState {
   const scopeKey = getPermissionModeScopeKey(agentId, conversationId);
-  return (
-    runtime.permissionModeByConversation.get(scopeKey) ?? {
-      mode: globalPermissionMode.getMode(),
-      planFilePath: null,
-      modeBeforePlan: null,
+  const normalizedConversationId = normalizeConversationId(conversationId);
+
+  const direct = runtime.permissionModeByConversation.get(scopeKey);
+  if (direct) {
+    return direct;
+  }
+
+  // Backward/interop fallback for default-conversation entries that were
+  // keyed without an agent id (agent:__unknown__). If we find one while a
+  // concrete agent id is available, migrate it to the canonical key.
+  if (normalizedConversationId === "default") {
+    const legacyDefaultKey = getPermissionModeScopeKey(null, "default");
+    const legacyDefault =
+      runtime.permissionModeByConversation.get(legacyDefaultKey);
+    if (legacyDefault) {
+      if (normalizeCwdAgentId(agentId)) {
+        runtime.permissionModeByConversation.set(scopeKey, {
+          ...legacyDefault,
+        });
+        runtime.permissionModeByConversation.delete(legacyDefaultKey);
+      }
+      return legacyDefault;
     }
-  );
+  }
+
+  return {
+    mode: globalPermissionMode.getMode(),
+    planFilePath: null,
+    modeBeforePlan: null,
+  };
 }
 
 export function setConversationPermissionModeState(