diff --git a/src/http/handlers.ts b/src/http/handlers.ts
index 4f1354a..4bcb3fb 100644
--- a/src/http/handlers.ts
+++ b/src/http/handlers.ts
@@ -89,27 +89,29 @@ export function createBooking(deps: AppDependencies): Handler {
       throw new HttpError(violation.code === 'INVALID_DATE' ? 400 : 422, violation.code, violation.message);
     }
 
-    const sameDay = deps.service.bookingsForCourt(court.id, request.date).filter((b) => b.status === 'confirmed');
-    if (sameDay.some((b) => overlaps({ startHour: b.start_hour, hours: b.hours }, request))) {
-      throw new HttpError(409, 'SLOT_TAKEN', 'La cancha ya está reservada en ese horario.');
-    }
-
-    const priceCents = quotePriceCents({
-      sport: court.sport,
-      date: request.date,
-      startHour: request.startHour,
-      hours: request.hours,
-      plan: member.plan,
-    });
-    const id = deps.service.saveBooking({
-      court_id: court.id,
-      member_id: member.id,
-      date: request.date,
-      start_hour: request.startHour,
-      hours: request.hours,
-      team_name: request.teamName,
-      price_cents: priceCents,
-      created_at: deps.clock.now().toISOString(),
+    const id = deps.service.atomically(() => {
+      const sameDay = deps.service.bookingsForCourt(court.id, request.date).filter((b) => b.status === 'confirmed');
+      if (sameDay.some((b) => overlaps({ startHour: b.start_hour, hours: b.hours }, request))) {
+        throw new HttpError(409, 'SLOT_TAKEN', 'La cancha ya está reservada en ese horario.');
+      }
+
+      const priceCents = quotePriceCents({
+        sport: court.sport,
+        date: request.date,
+        startHour: request.startHour,
+        hours: request.hours,
+        plan: member.plan,
+      });
+      return deps.service.saveBooking({
+        court_id: court.id,
+        member_id: member.id,
+        date: request.date,
+        start_hour: request.startHour,
+        hours: request.hours,
+        team_name: request.teamName,
+        price_cents: priceCents,
+        created_at: deps.clock.now().toISOString(),
+      });
     });
     const booking = toBookingJson(deps.service.findBooking(id)!);
 
diff --git a/src/services/booking-service.ts b/src/services/booking-service.ts
index 55e62cf..1ee0dee 100644
--- a/src/services/booking-service.ts
+++ b/src/services/booking-service.ts
@@ -10,8 +10,10 @@ export class BookingService {
   #courts: CourtRepository;
   #members: MemberRepository;
   #bookings: BookingRepository;
+  #db: DatabaseSync;
 
   constructor(db: DatabaseSync) {
+    this.#db = db;
     this.#courts = new CourtRepository(db);
     this.#members = new MemberRepository(db);
     this.#bookings = new BookingRepository(db);
@@ -56,4 +58,18 @@ export class BookingService {
   markCancelled(id: number, cancelledAt: string): void {
     this.#bookings.updateStatus(id, 'cancelled', cancelledAt);
   }
+
+  // Corre `work` con el lock de escritura tomado desde el principio: entre
+  // la revisión y el guardado ninguna otra conexión puede escribir.
+  atomically<T>(work: () => T): T {
+    this.#db.exec('BEGIN IMMEDIATE');
+    try {
+      const result = work();
+      this.#db.exec('COMMIT');
+      return result;
+    } catch (error) {
+      this.#db.exec('ROLLBACK');
+      throw error;
+    }
+  }
 }
diff --git a/src/store/database.ts b/src/store/database.ts
index c477503..efc5ba7 100644
--- a/src/store/database.ts
+++ b/src/store/database.ts
@@ -38,7 +38,8 @@ const MIGRATIONS: string[] = [
 ];
 
 export function openDatabase(path: string): DatabaseSync {
-  const db = new DatabaseSync(path);
+  // Si otra conexión tiene el lock, esperar hasta 5 s en vez de fallar enseguida.
+  const db = new DatabaseSync(path, { timeout: 5000 });
   // SQLite no revisa las claves foráneas si no se le pide en cada conexión.
   db.exec('PRAGMA foreign_keys = ON');
   migrate(db);