Final sweep: Crucible fixes, Path Tracer polish, forge progress, tests green.

Align dashboard subtitle default and UpsertAgent tests with fleet label behavior; WebSocket coalesce and PathForge hardening; Crucible expanded ops and visual DV fixes; Vitest 610/610 and full test-suite pass; trim PROBLEMS.md to open items only.

server/web/src/pages/PathTracerPage.tsx

@@ -113,6 +113,8 @@ export default function PathTracerPage() {
   const [showQR, setShowQR] = useState(false);
 
   const pollRef = useRef<ReturnType<typeof setInterval> | null>(null);
+  const [autoEndCountdown, setAutoEndCountdown] = useState<number | null>(null);
+  const autoEndRef = useRef<ReturnType<typeof setInterval> | null>(null);
 
   // Use WebSocket agents; fall back to REST on mount if WebSocket hasn't populated yet.
   const agents = wsAgents.length > 0 ? wsAgents : restAgents;
@@ -121,8 +123,11 @@ export default function PathTracerPage() {
     api.listAgents().then(setRestAgents).catch(() => {});
   }, []);
 
-  // Stop polling on unmount.
-  useEffect(() => () => { if (pollRef.current) clearInterval(pollRef.current); }, []);
+  // Stop polling and auto-end timer on unmount.
+  useEffect(() => () => {
+    if (pollRef.current) clearInterval(pollRef.current);
+    if (autoEndRef.current) clearInterval(autoEndRef.current);
+  }, []);
 
   const toggleAgent = (id: string, offline: boolean) => {
     if (offline) return;
@@ -186,6 +191,8 @@ export default function PathTracerPage() {
   };
 
   const handleEndSession = useCallback(async () => {
+    if (autoEndRef.current) { clearInterval(autoEndRef.current); autoEndRef.current = null; }
+    setAutoEndCountdown(null);
     if (!sessionID) return;
     try {
       await api.deleteTrace(sessionID);
@@ -201,6 +208,30 @@ export default function PathTracerPage() {
     setError('');
   }, [sessionID]);
 
+  // Auto-delete the session 10 seconds after an error, with a visible countdown.
+  useEffect(() => {
+    if (!error || !sessionID) return;
+    if (autoEndRef.current) clearInterval(autoEndRef.current);
+    const COUNTDOWN = 10;
+    setAutoEndCountdown(COUNTDOWN);
+    let remaining = COUNTDOWN;
+    autoEndRef.current = setInterval(() => {
+      remaining -= 1;
+      if (remaining <= 0) {
+        clearInterval(autoEndRef.current!);
+        autoEndRef.current = null;
+        setAutoEndCountdown(null);
+        handleEndSession();
+      } else {
+        setAutoEndCountdown(remaining);
+      }
+    }, 1000);
+    return () => {
+      if (autoEndRef.current) { clearInterval(autoEndRef.current); autoEndRef.current = null; }
+    };
+  // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [error, sessionID]);
+
   const isWindows = (a: Agent) =>
     !!(a.platform?.toLowerCase().includes('win') || a.platform?.toLowerCase().includes('windows'));
 
@@ -222,7 +253,17 @@ export default function PathTracerPage() {
         </div>
       </header>
 
-      {error && <div className="pt-error-banner">⚠ {error}</div>}
+      {error && (
+        <div className="pt-error-banner" role="alert">
+          <strong>⚠ Session Error</strong>
+          <div style={{ marginTop: '0.3rem' }}>{error}</div>
+          {sessionID && autoEndCountdown !== null && (
+            <div style={{ marginTop: '0.3rem', opacity: 0.8 }}>
+              Session will be terminated in {autoEndCountdown}s&hellip;
+            </div>
+          )}
+        </div>
+      )}
 
       {tracing && !allHopsReady && !error && (
         <div className="pt-info-banner">
@@ -338,7 +379,7 @@ export default function PathTracerPage() {
 
           {/* Controls */}
           <div className="pt-actions">
-            {!tracing && (
+            {!tracing && !sessionID && (
               <button
                 className="pt-btn pt-btn-primary"
                 disabled={selected.length === 0 || loading}
@@ -354,13 +395,13 @@ export default function PathTracerPage() {
               </button>
             )}
 
-            {tracing && (
+            {(tracing || (!!error && !!sessionID)) && (
               <button className="pt-btn pt-btn-danger" onClick={handleEndSession}>
-                End Session
+                End Session{autoEndCountdown !== null && ` (${autoEndCountdown}s)`}
               </button>
             )}
 
-            {!tracing && selected.length > 0 && (
+            {!tracing && !sessionID && selected.length > 0 && (
               <button className="pt-btn pt-btn-ghost" onClick={() => setSelected([])}>
                 Clear
               </button>