fix(preview): resolve ReferenceError by hoisting isForceStarting state declaration

vibn-frontend/app/[workspace]/project/[projectId]/(home)/preview/page.tsx

@@ -155,6 +155,8 @@ export default function PreviewTab() {
   const refreshKey = usePreviewToolbarStore((s) => s.refreshKey);
   const currentPath = usePreviewToolbarStore((s) => s.currentPath);
 
+  const [isForceStarting, setIsForceStarting] = useState(false);
+
   // When the user clicks the manual refresh button in the toolbar, we don't
   // just want to reload the iframe — we also want to trigger the same ghost/zombie
   // check as the initial mount, in case the server died while they were looking at it.
@@ -163,9 +165,13 @@ export default function PreviewTab() {
     if (refreshKey === prevRefreshKeyRef.current) return;
     prevRefreshKeyRef.current = refreshKey;
 
-    // Reset the ensure called flag so the ensure effect (below) fires again.
+    // We only reset the ensure flag if we aren't currently waiting for a forced start.
+    // If they hit refresh while it's already booting, don't break the state machine.
+    if (!isForceStarting) {
       ensureCalledRef.current = false;
-  }, [refreshKey]);
+      setEnsureStatus("idle");
+    }
+  }, [refreshKey, isForceStarting]);
 
   useLayoutEffect(() => {
     if (!primaryRunning?.url) {
@@ -184,29 +190,26 @@ export default function PreviewTab() {
     bridge.registerPreviewIframe(iframeDomRef.current, iframeSrc);
   }, [bridge, iframeSrc]);
 
-  const [isForceStarting, setIsForceStarting] = useState(false);
-
   // Determine which empty state to show.
   const emptyContent = (() => {
     if (loading && !anatomy) return <InitialLoader />;
     if (inFlightApp) return <BuildingState app={inFlightApp} />;
     if (failedApp) return <FailedState app={failedApp} />;
+
     // Dev server is in the process of booting (either picked up from anatomy
     // or we just fired the ensure endpoint and are waiting for the DB row).
-    if (primaryStarting) {
+    // If isForceStarting is true, we know we clicked the manual start button
+    // and are waiting for the DB to reflect 'starting'.
+    if (primaryStarting || ensureStatus === "starting" || isForceStarting) {
       return (
         <WarmingUpState
-          startedAt={primaryStarting.startedAt}
+          startedAt={primaryStarting?.startedAt}
           fallbackUrl={fallbackUrl}
           port={selectedPort}
         />
       );
     }
-    if (
-      ensureStatus === "calling" ||
-      ensureStatus === "starting" ||
-      isForceStarting
-    ) {
+    if (ensureStatus === "calling") {
       return (
         <WarmingUpState
           startedAt={undefined}
@@ -225,7 +228,11 @@ export default function PreviewTab() {
             {
               method: "POST",
             },
-          ).catch(() => setIsForceStarting(false));
+          )
+            .then((res) => {
+              if (!res.ok) throw new Error("Failed to start");
+            })
+            .catch(() => setIsForceStarting(false));
         }}
       />
     );