fix(seer-explorer): Ensure 30s safety timeout always fires for optimistic UI

The early return when the server data signature matches the baseline
prevented the setTimeout from ever being scheduled. If the backend
never persisted the new block, the optimistic "Thinking" block would
persist indefinitely.

Author: Mihir-Mavalankar

static/app/views/seerExplorer/hooks/useSeerExplorer.tsx

@@ -466,6 +466,14 @@ export const useSeerExplorer = () => {
       return undefined;
     }
 
+    const isTimedOut = Date.now() - optimistic.createdAt > 30_000;
+
+    if (isTimedOut) {
+      setOptimistic(null);
+      setDeletedFromIndex(null);
+      return undefined;
+    }
+
     const currentSignature = JSON.stringify(
       (apiData?.session?.blocks || []).map(b => [
         b.id,
@@ -475,33 +483,27 @@ export const useSeerExplorer = () => {
       ])
     );
 
-    if (currentSignature === optimistic.baselineSignature) {
-      return undefined;
-    }
-
-    const serverBlocks = apiData?.session?.blocks || [];
-    const hasAssistantResponse = serverBlocks.some(
-      (b, i) => i >= optimistic.insertIndex && b.message.role === 'assistant'
-    );
-    const isTimedOut = Date.now() - optimistic.createdAt > 30_000;
-
-    if (hasAssistantResponse || isTimedOut) {
-      setOptimistic(null);
-      setDeletedFromIndex(null);
-      return undefined;
-    }
+    if (currentSignature !== optimistic.baselineSignature) {
+      const serverBlocks = apiData?.session?.blocks || [];
+      const hasAssistantResponse = serverBlocks.some(
+        (b, i) => i >= optimistic.insertIndex && b.message.role === 'assistant'
+      );
 
-    // Schedule a forced clear at the 30s mark in case no new poll data arrives
-    const remaining = 30_000 - (Date.now() - optimistic.createdAt);
-    if (remaining > 0) {
-      const timer = setTimeout(() => {
+      if (hasAssistantResponse) {
         setOptimistic(null);
         setDeletedFromIndex(null);
-      }, remaining);
-      return () => clearTimeout(timer);
+        return undefined;
+      }
     }
 
-    return undefined;
+    // Always schedule the safety timeout so the optimistic UI cannot persist
+    // indefinitely when the server data signature never diverges from baseline.
+    const remaining = 30_000 - (Date.now() - optimistic.createdAt);
+    const timer = setTimeout(() => {
+      setOptimistic(null);
+      setDeletedFromIndex(null);
+    }, remaining);
+    return () => clearTimeout(timer);
   }, [apiData?.session?.blocks, optimistic]);
 
   // Detect PR creation errors and show error messages