feat: show calendars from all logged-in accounts in Pro shell

hooks/use-pro-multi-account-calendars.ts

@@ -0,0 +1,63 @@
+"use client";
+
+import { useEffect, useMemo } from "react";
+import { useAccountStore } from "@/stores/account-store";
+import { useAuthStore } from "@/stores/auth-store";
+import { useCalendarStore, type CalendarAccountClient } from "@/stores/calendar-store";
+import { useSettingsStore } from "@/stores/settings-store";
+import { useIsEmbedded } from "@/hooks/use-is-embedded";
+
+/**
+ * When the Pro shell is the active interface, aggregate calendars from
+ * every connected account so the calendar sidebar lists them all — the
+ * same way [[use-pro-multi-account-mailboxes]] does for mail folders.
+ *
+ * Returns the resolved list of `{ localAccountId, client }` pairs so the
+ * caller (calendar page) can fetch events the same way without
+ * re-deriving the set.
+ */
+export function useProMultiAccountCalendars(start: string | null, end: string | null): {
+  enabled: boolean;
+  accountClients: CalendarAccountClient[];
+} {
+  const isEmbedded = useIsEmbedded();
+  const proInterface = useSettingsStore((s) => s.proInterface);
+  const accounts = useAccountStore((s) => s.accounts);
+  const activeAccountId = useAuthStore((s) => s.activeAccountId);
+  const fetchAllAccountsCalendars = useCalendarStore((s) => s.fetchAllAccountsCalendars);
+  const fetchAllAccountsEvents = useCalendarStore((s) => s.fetchAllAccountsEvents);
+
+  const enabled = proInterface || isEmbedded;
+
+  const accountClients = useMemo(() => {
+    if (!enabled) return [];
+    const getClientForAccount = useAuthStore.getState().getClientForAccount;
+    const pairs: CalendarAccountClient[] = [];
+    for (const account of accounts) {
+      if (!account.isConnected) continue;
+      const client = getClientForAccount(account.id);
+      if (!client || !client.supportsCalendars()) continue;
+      pairs.push({ localAccountId: account.id, client });
+    }
+    return pairs;
+    // accounts identity changes whenever the connected set or login states
+    // change, so this is the only dependency we need.
+  }, [enabled, accounts]);
+
+  // Fetch calendars whenever the set of connected calendar-capable accounts
+  // changes. Skips when there isn't an active account yet (auth still
+  // bootstrapping).
+  useEffect(() => {
+    if (!enabled || !activeAccountId || accountClients.length === 0) return;
+    void fetchAllAccountsCalendars(accountClients, activeAccountId);
+  }, [enabled, activeAccountId, accountClients, fetchAllAccountsCalendars]);
+
+  // Fetch events for the current visible date range across all accounts.
+  useEffect(() => {
+    if (!enabled || !activeAccountId || accountClients.length === 0) return;
+    if (!start || !end) return;
+    void fetchAllAccountsEvents(accountClients, activeAccountId, start, end);
+  }, [enabled, activeAccountId, accountClients, start, end, fetchAllAccountsEvents]);
+
+  return { enabled, accountClients };
+}