Fix mobile account session selection

lib/accounts.ts

@@ -13,6 +13,23 @@ export type SavedAccount = {
   lastUsedAt: number;
 };
 
+function isSavedAccount(value: unknown): value is SavedAccount {
+  if (!value || typeof value !== "object") return false;
+
+  const account = value as Partial<SavedAccount>;
+  return (
+    typeof account.id === "string" &&
+    account.id.length > 0 &&
+    typeof account.instanceUrl === "string" &&
+    account.instanceUrl.length > 0 &&
+    typeof account.userId === "string" &&
+    account.userId.length > 0 &&
+    typeof account.email === "string" &&
+    typeof account.name === "string" &&
+    typeof account.lastUsedAt === "number"
+  );
+}
+
 export function buildAccountId(instanceUrl: string, userId: string) {
   const host = instanceUrl.replace(/^https?:\/\//, "").replace(/\/$/, "");
   return `${host}::${userId}`;
@@ -26,8 +43,8 @@ export async function loadAccounts(): Promise<SavedAccount[]> {
   const raw = await AsyncStorage.getItem(ACCOUNTS_KEY);
   if (!raw) return [];
   try {
-    const parsed = JSON.parse(raw) as SavedAccount[];
-    return Array.isArray(parsed) ? parsed : [];
+    const parsed = JSON.parse(raw) as unknown;
+    return Array.isArray(parsed) ? parsed.filter(isSavedAccount) : [];
   } catch {
     return [];
   }