Wire up ErrorBoundary, URL session sync, j/k navigation, and refresh

Wrap SessionViewer in an ErrorBoundary so render errors show a
recovery UI instead of a white screen.

Sync the selected session ID with the URL search param (?session=).
On initial load, load the session from the URL if it exists in the
session list. On session change, update the URL via
history.replaceState without triggering navigation.

Add j/k keyboard navigation to step through filtered messages.
Search focus takes precedence over keyboard focus; both reset when
filters or session changes.

Add a refresh button in the sidebar header that calls the new
refreshSessions hook, with a spinning icon while loading.

Pass sensitiveCount to FilterPanel for the new badge display.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/client/app.tsx

@@ -5,8 +5,10 @@ import { FilterPanel } from "./components/FilterPanel";
 import { SearchBar } from "./components/SearchBar";
 import { SearchMinimap } from "./components/SearchMinimap";
 import { ExportButton } from "./components/ExportButton";
+import { ErrorBoundary } from "./components/ErrorBoundary";
 import { useSession } from "./hooks/useSession";
 import { useFilters } from "./hooks/useFilters";
+import { countSensitiveMessages } from "../shared/sensitive-redactor";
 
 
 export function App() {
@@ -16,15 +18,47 @@ export function App() {
     currentSession,
     sessionLoading,
     loadSession,
+    refreshSessions,
   } = useSession();
 
   const filters = useFilters();
 
+  // URL-driven session selection: sync session ID with URL search params
+  const hasRestoredFromUrl = useRef(false);
+
+  // On initial load (once sessions are available), restore session from URL
+  useEffect(() => {
+    if (hasRestoredFromUrl.current || sessionsLoading || sessions.length === 0) return;
+    hasRestoredFromUrl.current = true;
+
+    const params = new URLSearchParams(window.location.search);
+    const sessionId = params.get("session");
+    if (sessionId && sessions.some((s) => s.id === sessionId)) {
+      loadSession(sessionId);
+    }
+  }, [sessionsLoading, sessions, loadSession]);
+
+  // Update URL when session changes
+  useEffect(() => {
+    if (!currentSession) return;
+    const params = new URLSearchParams(window.location.search);
+    if (params.get("session") !== currentSession.id) {
+      params.set("session", currentSession.id);
+      const newUrl = `${window.location.pathname}?${params.toString()}${window.location.hash}`;
+      window.history.replaceState(null, "", newUrl);
+    }
+  }, [currentSession]);
+
   const filteredMessages = useMemo(() => {
     if (!currentSession) return [];
     return filters.filterMessages(currentSession.messages);
   }, [currentSession, filters.filterMessages]);
 
+  const sensitiveCount = useMemo(
+    () => countSensitiveMessages(filteredMessages),
+    [filteredMessages]
+  );
+
   // Track which filtered-message indices match the search query
   const matchIndices = useMemo(() => {
     if (!filters.searchQuery) return [];
@@ -67,6 +101,46 @@ export function App() {
   const focusedMessageIndex =
     currentMatchPosition >= 0 ? matchIndices[currentMatchPosition] : -1;
 
+  // Keyboard navigation: j/k to move between messages
+  const [keyboardFocusIndex, setKeyboardFocusIndex] = useState(-1);
+
+  // Reset keyboard focus when session or filters change
+  useEffect(() => {
+    setKeyboardFocusIndex(-1);
+  }, [filteredMessages]);
+
+  // Combined focus: search focus takes precedence over keyboard focus
+  const activeFocusIndex =
+    focusedMessageIndex >= 0 ? focusedMessageIndex : keyboardFocusIndex;
+
+  useEffect(() => {
+    function handleKeyDown(e: KeyboardEvent) {
+      // Don't intercept when typing in an input
+      if (document.activeElement?.tagName === "INPUT" || document.activeElement?.tagName === "TEXTAREA") {
+        return;
+      }
+
+      if (e.key === "j" && !e.ctrlKey && !e.metaKey) {
+        e.preventDefault();
+        setKeyboardFocusIndex((prev) => {
+          const max = filteredMessages.length - 1;
+          if (max < 0) return -1;
+          return prev < max ? prev + 1 : max;
+        });
+      }
+
+      if (e.key === "k" && !e.ctrlKey && !e.metaKey) {
+        e.preventDefault();
+        setKeyboardFocusIndex((prev) => {
+          if (filteredMessages.length === 0) return -1;
+          return prev > 0 ? prev - 1 : 0;
+        });
+      }
+    }
+    window.addEventListener("keydown", handleKeyDown);
+    return () => window.removeEventListener("keydown", handleKeyDown);
+  }, [filteredMessages.length]);
+
   const visibleUuids = useMemo(
     () => filteredMessages.map((m) => m.uuid),
     [filteredMessages]
@@ -109,9 +183,24 @@ export function App() {
       {/* Sidebar */}
       <div className="w-80 flex-shrink-0 border-r border-border bg-surface-raised flex flex-col">
         <div className="px-5 py-4 border-b border-border" style={{ background: "linear-gradient(180deg, var(--color-surface-overlay) 0%, var(--color-surface-raised) 100%)" }}>
+          <div className="flex items-center justify-between">
             <h1 className="text-heading font-semibold text-foreground tracking-tight">
               Session Viewer
             </h1>
+            <button
+              onClick={refreshSessions}
+              disabled={sessionsLoading}
+              className="flex items-center justify-center w-7 h-7 rounded-md text-foreground-muted hover:text-foreground hover:bg-surface-overlay/60 transition-colors disabled:opacity-40"
+              title="Refresh sessions"
+            >
+              <svg
+                className={`w-4 h-4 ${sessionsLoading ? "animate-spin" : ""}`}
+                fill="none" viewBox="0 0 24 24" stroke="currentColor" strokeWidth={1.5}
+              >
+                <path strokeLinecap="round" strokeLinejoin="round" d="M16.023 9.348h4.992v-.001M2.985 19.644v-4.992m0 0h4.992m-4.993 0l3.181 3.183a8.25 8.25 0 0013.803-3.7M4.031 9.865a8.25 8.25 0 0113.803-3.7l3.181 3.182" />
+              </svg>
+            </button>
+          </div>
           <p className="text-caption text-foreground-muted mt-0.5">
             Browse and export Claude sessions
           </p>
@@ -129,6 +218,7 @@ export function App() {
           onToggle={filters.toggleCategory}
           autoRedactEnabled={filters.autoRedactEnabled}
           onAutoRedactToggle={filters.setAutoRedactEnabled}
+          sensitiveCount={sensitiveCount}
         />
       </div>
 
@@ -184,6 +274,7 @@ export function App() {
         {/* Scroll area wrapper — relative so minimap can position over the right edge */}
         <div className="flex-1 relative min-h-0">
           <div ref={scrollRef} className="h-full overflow-y-auto">
+            <ErrorBoundary>
               <SessionViewer
                 messages={filteredMessages}
                 allMessages={currentSession?.messages || []}
@@ -193,8 +284,9 @@ export function App() {
                 selectedForRedaction={filters.selectedForRedaction}
                 onToggleRedactionSelection={filters.toggleRedactionSelection}
                 autoRedactEnabled={filters.autoRedactEnabled}
-              focusedIndex={focusedMessageIndex}
+                focusedIndex={activeFocusIndex}
               />
+            </ErrorBoundary>
           </div>
           <SearchMinimap
             matchIndices={matchIndices}