feat(ui): remember last visited page per company on company switch

When switching companies via the sidebar rail, dropdown, or keyboard
shortcuts, the app now navigates to the last page visited for that
company instead of staying on the current (now irrelevant) page.
Falls back to /dashboard if no previous page exists.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

ui/src/components/Layout.tsx

@@ -19,6 +19,7 @@ import { usePanel } from "../context/PanelContext";
 import { useCompany } from "../context/CompanyContext";
 import { useSidebar } from "../context/SidebarContext";
 import { useKeyboardShortcuts } from "../hooks/useKeyboardShortcuts";
+import { useCompanyPageMemory } from "../hooks/useCompanyPageMemory";
 import { healthApi } from "../api/health";
 import { queryKeys } from "../lib/queryKeys";
 import { cn } from "../lib/utils";
@@ -58,6 +59,8 @@ export function Layout() {
     [companies, setSelectedCompanyId],
   );
 
+  useCompanyPageMemory();
+
   useKeyboardShortcuts({
     onNewIssue: () => openNewIssue(),
     onToggleSidebar: toggleSidebar,

ui/src/hooks/useCompanyPageMemory.ts

@@ -0,0 +1,58 @@
+import { useEffect, useRef } from "react";
+import { useLocation, useNavigate } from "react-router-dom";
+import { useCompany } from "../context/CompanyContext";
+
+const STORAGE_KEY = "paperclip.companyPaths";
+
+function getCompanyPaths(): Record<string, string> {
+  try {
+    const raw = localStorage.getItem(STORAGE_KEY);
+    if (raw) return JSON.parse(raw);
+  } catch {
+    /* ignore */
+  }
+  return {};
+}
+
+function saveCompanyPath(companyId: string, path: string) {
+  const paths = getCompanyPaths();
+  paths[companyId] = path;
+  localStorage.setItem(STORAGE_KEY, JSON.stringify(paths));
+}
+
+/**
+ * Remembers the last visited page per company and navigates to it on company switch.
+ * Falls back to /dashboard if no page was previously visited for a company.
+ */
+export function useCompanyPageMemory() {
+  const { selectedCompanyId } = useCompany();
+  const location = useLocation();
+  const navigate = useNavigate();
+  const prevCompanyId = useRef<string | null>(selectedCompanyId);
+
+  // Save current path for current company on every location change.
+  // Uses prevCompanyId ref so we save under the correct company even
+  // during the render where selectedCompanyId has already changed.
+  const fullPath = location.pathname + location.search;
+  useEffect(() => {
+    const companyId = prevCompanyId.current;
+    if (companyId) {
+      saveCompanyPath(companyId, fullPath);
+    }
+  }, [fullPath]);
+
+  // Navigate to saved path when company changes
+  useEffect(() => {
+    if (!selectedCompanyId) return;
+
+    if (
+      prevCompanyId.current !== null &&
+      selectedCompanyId !== prevCompanyId.current
+    ) {
+      const paths = getCompanyPaths();
+      const savedPath = paths[selectedCompanyId];
+      navigate(savedPath || "/dashboard", { replace: true });
+    }
+    prevCompanyId.current = selectedCompanyId;
+  }, [selectedCompanyId, navigate]);
+}