diff --git a/src/aimedb/repo.ts b/src/aimedb/repo.ts
new file mode 100644
index 0000000..3fbda1d
--- /dev/null
+++ b/src/aimedb/repo.ts
@@ -0,0 +1,17 @@
+import { AimeId } from "./model";
+
+export interface CardRepository {
+  lookup(luid: string, now: Date): Promise<AimeId | undefined>;
+
+  register(luid: string, now: Date): Promise<AimeId>;
+}
+
+export interface Repositories {
+  cards(): CardRepository;
+}
+
+export interface Transaction extends Repositories {
+  commit(): Promise<void>;
+
+  rollback(): Promise<void>;
+}