diff --git a/src/components/layout/NotificationCenter.tsx b/src/components/layout/NotificationCenter.tsx
index ed580de..3ef2c00 100644
--- a/src/components/layout/NotificationCenter.tsx
+++ b/src/components/layout/NotificationCenter.tsx
@@ -142,19 +142,19 @@ export default function NotificationCenter() {
   }, [filter, notifications]);
 
   async function handleOpenNotification(notification: OrchaiNotification) {
-    if (!notification.read) {
-      try {
-        await markNotificationRead(notification.id);
-        setNotifications((prev) =>
-          prev.map((n) => (n.id === notification.id ? { ...n, read: true } : n))
-        );
-      } catch {
-        // ignore
-      }
-    }
-
     setOpen(false);
 
+    if (!notification.read) {
+      setNotifications((prev) =>
+        prev.map((n) => (n.id === notification.id ? { ...n, read: true } : n))
+      );
+
+      // Do not block navigation on read acknowledgement.
+      void markNotificationRead(notification.id).catch(() => {
+        // ignore
+      });
+    }
+
     if (notification.ticket_id) {
       navigate(`/tickets/${notification.ticket_id}`);
       return;
diff --git a/src/components/tickets/TicketDetail.tsx b/src/components/tickets/TicketDetail.tsx
index bd5bef2..5a507db 100644
--- a/src/components/tickets/TicketDetail.tsx
+++ b/src/components/tickets/TicketDetail.tsx
@@ -58,8 +58,11 @@ export default function TicketDetail() {
   const [targetBranch, setTargetBranch] = useState("");
   const [availableBranches, setAvailableBranches] = useState<string[]>([]);
   const [branchInputMode, setBranchInputMode] = useState<"select" | "manual">("select");
+  const [branchesLoadedForWorktreeId, setBranchesLoadedForWorktreeId] = useState<string | null>(null);
   const [branchesLoading, setBranchesLoading] = useState(false);
   const [branchesError, setBranchesError] = useState("");
+  const [diffLoading, setDiffLoading] = useState(false);
+  const [diffError, setDiffError] = useState("");
   const [tab, setTab] = useState<"info" | "analyst" | "developer" | "diff">("info");
   const [loading, setLoading] = useState(false);
   const [error, setError] = useState("");
@@ -93,29 +96,24 @@ export default function TicketDetail() {
 
   async function loadData() {
     if (!ticketId) return;
+    setError("");
     try {
       const result = await getTicketResult(ticketId);
       setTicket(result.ticket);
       setWorktree(result.worktree);
-
-      if (result.ticket.developer_report) setTab("developer");
-      else if (result.ticket.analyst_report) setTab("analyst");
+      setTab("info");
+      setDiff(null);
+      setDiffError("");
+      setDiffLoading(false);
+      setAvailableBranches([]);
+      setBranchInputMode("select");
+      setTargetBranch("");
+      setBranchesError("");
+      setBranchesLoading(false);
+      setBranchesLoadedForWorktreeId(null);
 
       if (result.worktree && result.worktree.status === "Active") {
-        await loadBranchOptions(result.worktree.id);
-        try {
-          const d = await getWorktreeDiff(result.worktree.id);
-          setDiff(d);
-        } catch {
-          setDiff(null);
-        }
-      } else {
-        setDiff(null);
-        setAvailableBranches([]);
-        setBranchInputMode("select");
-        setTargetBranch("");
-        setBranchesError("");
-        setBranchesLoading(false);
+        return;
       }
     } catch (err) {
       setError(getErrorMessage(err));
@@ -123,9 +121,61 @@ export default function TicketDetail() {
   }
 
   useEffect(() => {
-    loadData();
+    void loadData();
   }, [ticketId]);
 
+  useEffect(() => {
+    if (tab !== "info") return;
+    if (!worktree || worktree.status !== "Active") return;
+    if (branchesLoading) return;
+    if (branchesLoadedForWorktreeId === worktree.id) return;
+
+    let cancelled = false;
+
+    void (async () => {
+      await loadBranchOptions(worktree.id);
+      if (!cancelled) {
+        setBranchesLoadedForWorktreeId(worktree.id);
+      }
+    })();
+
+    return () => {
+      cancelled = true;
+    };
+  }, [tab, worktree?.id, worktree?.status, branchesLoading, branchesLoadedForWorktreeId]);
+
+  useEffect(() => {
+    if (tab !== "diff") return;
+    if (!worktree || worktree.status !== "Active") return;
+    if (diff !== null || diffLoading) return;
+
+    let cancelled = false;
+    setDiffLoading(true);
+    setDiffError("");
+
+    void getWorktreeDiff(worktree.id)
+      .then((value) => {
+        if (!cancelled) {
+          setDiff(value);
+        }
+      })
+      .catch((err) => {
+        if (!cancelled) {
+          setDiff("");
+          setDiffError(getErrorMessage(err));
+        }
+      })
+      .finally(() => {
+        if (!cancelled) {
+          setDiffLoading(false);
+        }
+      });
+
+    return () => {
+      cancelled = true;
+    };
+  }, [tab, worktree?.id, worktree?.status, diff, diffLoading]);
+
   async function handleRetry() {
     if (!ticketId) return;
     setLoading(true);
@@ -214,7 +264,11 @@ export default function TicketDetail() {
       label: "Developer Report",
       disabled: !ticket.developer_report,
     },
-    { key: "diff" as const, label: "Diff", disabled: !diff && !worktree },
+    {
+      key: "diff" as const,
+      label: "Diff",
+      disabled: !worktree || worktree.status !== "Active",
+    },
   ];
 
   return (
@@ -420,7 +474,19 @@ export default function TicketDetail() {
         </div>
       )}
 
-      {tab === "diff" && <DiffViewer diff={diff || ""} />}
+      {tab === "diff" && (
+        <>
+          {diffLoading ? (
+            <div className="p-4 text-sm text-gray-500">Loading diff...</div>
+          ) : diffError ? (
+            <div className={noticeClass("warning")}>
+              Could not load diff: {diffError}
+            </div>
+          ) : (
+            <DiffViewer diff={diff || ""} />
+          )}
+        </>
+      )}
 
       <ConfirmModal
         isOpen={isDeleteWorktreeModalOpen}