fix: prevent config overwrite, session history race, and streaming message loss (#663)

Co-authored-by: zuolingxuan <zuolingxuan@bytedance.com>
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

src/lib/host-events.ts

@@ -45,7 +45,16 @@ export function subscribeHostEvent<T = unknown>(
     const listener = (payload: unknown) => {
       handler(payload as T);
     };
-    ipc.on(ipcChannel, listener);
+    // preload's `on()` wraps the callback in an internal subscription function
+    // and returns a cleanup function that removes that exact wrapper.  We MUST
+    // use the returned cleanup rather than calling `off(channel, listener)`,
+    // because `listener` !== the internal wrapper and removeListener would be
+    // a no-op, leaking the subscription.
+    const unsubscribe = ipc.on(ipcChannel, listener);
+    if (typeof unsubscribe === 'function') {
+      return unsubscribe;
+    }
+    // Fallback for environments where on() doesn't return cleanup
     return () => {
       ipc.off(ipcChannel, listener);
     };