fix: scope generation idempotency per user

packages/db/prisma/migrations/20260311160000_scope_generation_idempotency_per_user/migration.sql

@@ -0,0 +1,4 @@
+DROP INDEX "GenerationRequest_idempotencyKey_key";
+
+CREATE UNIQUE INDEX "GenerationRequest_userId_idempotencyKey_key"
+ON "GenerationRequest"("userId", "idempotencyKey");

packages/db/prisma/schema.prisma

@@ -187,7 +187,7 @@ model GenerationRequest {
   resolutionPreset  String
   batchSize         Int
   imageStrength     Decimal?                @db.Decimal(4, 3)
-  idempotencyKey    String?                 @unique
+  idempotencyKey    String?
   terminalErrorCode String?
   terminalErrorText String?
   requestedAt       DateTime                @default(now())
@@ -200,6 +200,7 @@ model GenerationRequest {
   assets            GeneratedAsset[]
   usageLedgerEntry  UsageLedgerEntry?
 
+  @@unique([userId, idempotencyKey])
   @@index([userId, status, requestedAt])
 }
 

packages/db/src/generation-store.test.ts

@@ -6,10 +6,12 @@ import { createPrismaGenerationStore } from "./generation-store.js";
 
 test("createGenerationRequest rejects an expired active subscription and marks it expired", async () => {
   const database = createGenerationDatabase({
-    subscription: createSubscriptionFixture({
+    subscriptions: [
+      createSubscriptionFixture({
         status: "active",
         currentPeriodEnd: new Date("2026-03-10T11:59:59.000Z"),
       }),
+    ],
   });
   const store = createPrismaGenerationStore(database.client);
 
@@ -29,11 +31,67 @@ test("createGenerationRequest rejects an expired active subscription and marks i
 
   assert.equal(database.calls.subscriptionUpdateMany.length, 1);
   assert.equal(database.calls.generationRequestCreate.length, 0);
-  assert.equal(database.state.subscription?.status, "expired");
+  assert.equal(database.state.subscriptions[0]?.status, "expired");
+});
+
+test("createGenerationRequest scopes idempotency-key reuse per user", async () => {
+  const database = createGenerationDatabase({
+    subscriptions: [
+      createSubscriptionFixture({
+        userId: "user_1",
+        status: "active",
+        currentPeriodEnd: new Date("2026-04-10T11:59:59.000Z"),
+      }),
+      createSubscriptionFixture({
+        id: "subscription_2",
+        userId: "user_2",
+        status: "active",
+        currentPeriodEnd: new Date("2026-04-10T11:59:59.000Z"),
+      }),
+    ],
+    generationRequests: [
+      createGenerationRequestFixture({
+        id: "request_existing",
+        userId: "user_1",
+        idempotencyKey: "shared-key",
+      }),
+    ],
+  });
+  const store = createPrismaGenerationStore(database.client);
+
+  const reused = await createGenerationRequest(store, {
+    userId: "user_1",
+    mode: "text_to_image",
+    providerModel: "nano-banana",
+    prompt: "hello",
+    resolutionPreset: "1024",
+    batchSize: 1,
+    idempotencyKey: "shared-key",
+  });
+
+  assert.equal(reused.reusedExistingRequest, true);
+  assert.equal(reused.request.id, "request_existing");
+
+  const created = await createGenerationRequest(store, {
+    userId: "user_2",
+    mode: "text_to_image",
+    providerModel: "nano-banana",
+    prompt: "hello",
+    resolutionPreset: "1024",
+    batchSize: 1,
+    idempotencyKey: "shared-key",
+  });
+
+  assert.equal(created.reusedExistingRequest, false);
+  assert.equal(created.request.userId, "user_2");
+  assert.equal(created.request.idempotencyKey, "shared-key");
+  assert.equal(database.calls.generationRequestCreate.length, 1);
+  assert.equal(database.state.generationRequests.length, 2);
 });
 
 function createGenerationDatabase(input: {
-  subscription: ReturnType<typeof createSubscriptionFixture> | null;
+  subscriptions: Array<ReturnType<typeof createSubscriptionFixture>>;
+  generationRequests?: Array<ReturnType<typeof createGenerationRequestFixture>>;
 }) {
   const calls = {
     subscriptionUpdateMany: [] as Array<Record<string, unknown>>,
@@ -41,7 +99,8 @@ function createGenerationDatabase(input: {
   };
 
   const state = {
-    subscription: input.subscription,
+    subscriptions: [...input.subscriptions],
+    generationRequests: [...(input.generationRequests ?? [])],
   };
 
   const client = {
@@ -51,15 +110,19 @@ function createGenerationDatabase(input: {
       }: {
         where: { userId: string; status?: "active" };
       }) => {
-        if (!state.subscription || state.subscription.userId !== where.userId) {
+        return (
-          return null;
+          state.subscriptions.find((subscription) => {
+            if (subscription.userId !== where.userId) {
+              return false;
             }
 
-        if (where.status && state.subscription.status !== where.status) {
+            if (where.status && subscription.status !== where.status) {
-          return null;
+              return false;
             }
 
-        return state.subscription;
+            return true;
+          }) ?? null
+        );
       },
       updateMany: async ({
         where,
@@ -70,19 +133,21 @@ function createGenerationDatabase(input: {
       }) => {
         calls.subscriptionUpdateMany.push({ where, data });
 
-        if (
+        let updatedCount = 0;
-          state.subscription &&
+
-          state.subscription.id === where.id &&
+        state.subscriptions = state.subscriptions.map((subscription) => {
-          state.subscription.status === where.status
+          if (subscription.id !== where.id || subscription.status !== where.status) {
-        ) {
+            return subscription;
-          state.subscription = {
-            ...state.subscription,
-            status: data.status,
-          };
-          return { count: 1 };
           }
 
-        return { count: 0 };
+          updatedCount += 1;
+          return {
+            ...subscription,
+            status: data.status,
+          };
+        });
+
+        return { count: updatedCount };
       },
     },
     usageLedgerEntry: {
@@ -95,28 +160,37 @@ function createGenerationDatabase(input: {
     generationRequest: {
       create: async ({ data }: { data: Record<string, unknown> }) => {
         calls.generationRequestCreate.push({ data });
-        return {
+        const request = createGenerationRequestFixture({
-          id: "request_1",
+          id: `request_${state.generationRequests.length + 1}`,
           userId: data.userId as string,
           mode: data.mode as string,
-          status: "queued",
           providerModel: data.providerModel as string,
           prompt: data.prompt as string,
-          sourceImageKey: null,
           resolutionPreset: data.resolutionPreset as string,
           batchSize: data.batchSize as number,
-          imageStrength: null,
+          ...(data.sourceImageKey !== undefined
-          idempotencyKey: null,
+            ? { sourceImageKey: data.sourceImageKey as string }
-          terminalErrorCode: null,
+            : {}),
-          terminalErrorText: null,
+          ...(data.imageStrength !== undefined
-          requestedAt: new Date("2026-03-10T12:00:00.000Z"),
+            ? { imageStrength: data.imageStrength as Prisma.Decimal }
-          startedAt: null,
+            : {}),
-          completedAt: null,
+          ...(data.idempotencyKey !== undefined
-          createdAt: new Date("2026-03-10T12:00:00.000Z"),
+            ? { idempotencyKey: data.idempotencyKey as string }
-          updatedAt: new Date("2026-03-10T12:00:00.000Z"),
+            : {}),
-        };
+        });
+        state.generationRequests.push(request);
+        return request;
       },
-      findFirst: async () => null,
+      findFirst: async ({
+        where,
+      }: {
+        where: { userId: string; idempotencyKey: string };
+      }) =>
+        state.generationRequests.find(
+          (request) =>
+            request.userId === where.userId &&
+            request.idempotencyKey === where.idempotencyKey,
+        ) ?? null,
     },
   } as unknown as Parameters<typeof createPrismaGenerationStore>[0];
 
@@ -128,12 +202,14 @@ function createGenerationDatabase(input: {
 }
 
 function createSubscriptionFixture(input: {
+  id?: string;
+  userId?: string;
   status: "active" | "expired" | "past_due";
   currentPeriodEnd: Date;
 }) {
   return {
-    id: "subscription_1",
+    id: input.id ?? "subscription_1",
-    userId: "user_1",
+    userId: input.userId ?? "user_1",
     planId: "plan_1",
     status: input.status,
     renewsManually: true,
@@ -156,3 +232,38 @@ function createSubscriptionFixture(input: {
     },
   };
 }
+
+function createGenerationRequestFixture(input: {
+  id: string;
+  userId: string;
+  mode?: string;
+  status?: string;
+  providerModel?: string;
+  prompt?: string;
+  sourceImageKey?: string;
+  resolutionPreset?: string;
+  batchSize?: number;
+  imageStrength?: Prisma.Decimal;
+  idempotencyKey?: string;
+}) {
+  return {
+    id: input.id,
+    userId: input.userId,
+    mode: input.mode ?? "text_to_image",
+    status: input.status ?? "queued",
+    providerModel: input.providerModel ?? "nano-banana",
+    prompt: input.prompt ?? "hello",
+    sourceImageKey: input.sourceImageKey ?? null,
+    resolutionPreset: input.resolutionPreset ?? "1024",
+    batchSize: input.batchSize ?? 1,
+    imageStrength: input.imageStrength ?? null,
+    idempotencyKey: input.idempotencyKey ?? null,
+    terminalErrorCode: null,
+    terminalErrorText: null,
+    requestedAt: new Date("2026-03-10T12:00:00.000Z"),
+    startedAt: null,
+    completedAt: null,
+    createdAt: new Date("2026-03-10T12:00:00.000Z"),
+    updatedAt: new Date("2026-03-10T12:00:00.000Z"),
+  };
+}