diff --git a/src/lib/session.ts b/src/lib/session.ts
index 0cbb6ab..bebf3ab 100644
--- a/src/lib/session.ts
+++ b/src/lib/session.ts
@@ -2,6 +2,8 @@ import { eq } from "drizzle-orm";
 import { auth } from "@/lib/auth";
 import { db } from "@/lib/db";
 import { householdMembers, households, users } from "@/modules/_core/schema";
+import { ensureDefaultCalendarsForMembership } from "@/modules/calendar/server/defaults";
+import { ensureDefaultListsForHousehold } from "@/modules/lists/server/defaults";
 
 export interface CurrentSession {
   user: typeof users.$inferSelect;
@@ -25,7 +27,36 @@ export async function getCurrentSession(): Promise<CurrentSession> {
     .where(eq(householdMembers.userId, session.user.id))
     .limit(1);
 
-  if (!row) throw new Error("No household membership");
+  if (row) return row;
 
-  return row;
+  // No membership yet — happens when the household was seeded after the user's
+  // first sign-in (e.g. first deploy). Auto-enroll into the single household.
+  const [household] = await db.select().from(households).limit(1);
+  if (!household) throw new Error("No household membership");
+
+  const [anyMember] = await db
+    .select()
+    .from(householdMembers)
+    .where(eq(householdMembers.householdId, household.id))
+    .limit(1);
+  const role = anyMember ? "member" : "owner";
+
+  await db
+    .insert(householdMembers)
+    .values({ householdId: household.id, userId: session.user.id, role })
+    .onConflictDoNothing();
+
+  await ensureDefaultCalendarsForMembership({ householdId: household.id, userId: session.user.id });
+  await ensureDefaultListsForHousehold(household.id);
+
+  const [fixed] = await db
+    .select({ user: users, household: households, role: householdMembers.role })
+    .from(householdMembers)
+    .innerJoin(users, eq(householdMembers.userId, users.id))
+    .innerJoin(households, eq(householdMembers.householdId, households.id))
+    .where(eq(householdMembers.userId, session.user.id))
+    .limit(1);
+
+  if (!fixed) throw new Error("No household membership");
+  return fixed;
 }