fix(cua): make session.stop() idempotent on repeated call

pkg/templates/python/cua/session.py

@@ -111,28 +111,46 @@ async def start(self) -> SessionInfo:
         return self.info
 
     async def stop(self) -> SessionInfo:
-        info = self.info
+        session_id = self._session_id
+        if not session_id:
+            # Already stopped — return a snapshot of the (cleared) state without
+            # touching `self.info`, whose `session_id` property raises on None.
+            return SessionInfo(
+                session_id="",
+                live_view_url=self._live_view_url or "",
+                replay_id=self._replay_id,
+                replay_view_url=self._replay_view_url,
+                viewport_width=self.opts.viewport_width,
+                viewport_height=self.opts.viewport_height,
+            )
+
+        info = SessionInfo(
+            session_id=session_id,
+            live_view_url=self._live_view_url or "",
+            replay_id=self._replay_id,
+            replay_view_url=self._replay_view_url,
+            viewport_width=self.opts.viewport_width,
+            viewport_height=self.opts.viewport_height,
+        )
 
-        if self._session_id:
-            session_id = self._session_id
-            try:
-                if self.opts.record_replay and self._replay_id:
-                    if self.opts.replay_grace_period > 0:
-                        await asyncio.sleep(self.opts.replay_grace_period)
-                    await self._stop_replay()
-                    info.replay_view_url = self._replay_view_url
-            finally:
-                # Reset state up front so that if browser deletion or a thrown replay
-                # error propagates, a follow-up stop() call from the caller's error path
-                # is a no-op instead of attempting to delete the same session twice.
-                self._session_id = None
-                self._live_view_url = None
-                self._replay_id = None
-                self._replay_view_url = None
-                print(f"Destroying browser session: {session_id}")
-                await asyncio.to_thread(
-                    self.kernel.browsers.delete_by_id, session_id,
-                )
+        try:
+            if self.opts.record_replay and self._replay_id:
+                if self.opts.replay_grace_period > 0:
+                    await asyncio.sleep(self.opts.replay_grace_period)
+                await self._stop_replay()
+                info.replay_view_url = self._replay_view_url
+        finally:
+            # Reset state up front so that if browser deletion or a thrown replay
+            # error propagates, a follow-up stop() call from the caller's error path
+            # is a no-op instead of attempting to delete the same session twice.
+            self._session_id = None
+            self._live_view_url = None
+            self._replay_id = None
+            self._replay_view_url = None
+            print(f"Destroying browser session: {session_id}")
+            await asyncio.to_thread(
+                self.kernel.browsers.delete_by_id, session_id,
+            )
 
         return info
 

pkg/templates/typescript/cua/session.ts

@@ -103,29 +103,47 @@ export class KernelBrowserSession {
   }
 
   async stop(): Promise<SessionInfo> {
-    const info = this.info;
+    const sessionId = this._sessionId;
+    if (!sessionId) {
+      // Already stopped — return a snapshot of the (cleared) state without
+      // touching `this.info`, whose `sessionId` getter throws on null.
+      return {
+        sessionId: '',
+        liveViewUrl: this._liveViewUrl ?? '',
+        replayId: this._replayId ?? undefined,
+        replayViewUrl: this._replayViewUrl ?? undefined,
+        viewportWidth: this.opts.viewportWidth,
+        viewportHeight: this.opts.viewportHeight,
+      };
+    }
 
-    if (this._sessionId) {
-      const sessionId = this._sessionId;
-      try {
-        if (this.opts.recordReplay && this._replayId) {
-          if (this.opts.replayGracePeriod > 0) {
-            await sleep(this.opts.replayGracePeriod * 1000);
-          }
-          await this.stopReplay();
-          info.replayViewUrl = this._replayViewUrl || undefined;
+    const info: SessionInfo = {
+      sessionId,
+      liveViewUrl: this._liveViewUrl ?? '',
+      replayId: this._replayId ?? undefined,
+      replayViewUrl: this._replayViewUrl ?? undefined,
+      viewportWidth: this.opts.viewportWidth,
+      viewportHeight: this.opts.viewportHeight,
+    };
+
+    try {
+      if (this.opts.recordReplay && this._replayId) {
+        if (this.opts.replayGracePeriod > 0) {
+          await sleep(this.opts.replayGracePeriod * 1000);
         }
-      } finally {
-        // Reset state up front so that if browser deletion or a thrown replay error
-        // propagates, a follow-up stop() call from the caller's error path is a no-op
-        // instead of attempting to delete the same session twice.
-        this._sessionId = null;
-        this._liveViewUrl = null;
-        this._replayId = null;
-        this._replayViewUrl = null;
-        console.log(`Destroying browser session: ${sessionId}`);
-        await this.kernel.browsers.deleteByID(sessionId);
+        await this.stopReplay();
+        info.replayViewUrl = this._replayViewUrl || undefined;
       }
+    } finally {
+      // Reset state up front so that if browser deletion or a thrown replay error
+      // propagates, a follow-up stop() call from the caller's error path is a no-op
+      // instead of attempting to delete the same session twice.
+      this._sessionId = null;
+      this._liveViewUrl = null;
+      this._replayId = null;
+      this._replayViewUrl = null;
+      console.log(`Destroying browser session: ${sessionId}`);
+      await this.kernel.browsers.deleteByID(sessionId);
     }
 
     return info;