fix(OUT-3815): return live mapping from handleProductMap on conflict

The initial-save insert uses onConflictDoNothing, so RETURNING omitted rows
skipped on a re-fired/concurrent save and the client could receive []. Always
return getAll() instead; drop the now-unused returningFields param. Add a
regression test covering a repeated initial save.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: SandipBajracharya

src/app/api/quickbooks/product/product.service.ts

@@ -208,10 +208,7 @@ export class ProductService extends BaseService {
    * On intial save, save all flatten products. If mapped, we include and if not, those are excluded
    * On every save after that, we update the record on the basis of productId
    */
-  async handleProductMap(
-    body: ProductMappingSchemaType,
-    returningFields?: (keyof typeof QBProductSync)[],
-  ) {
+  async handleProductMap(body: ProductMappingSchemaType) {
     const { mappingItems, changedItemReference } = body
     const settingService = new SettingService(this.user)
     const setting = await settingService.getOneByPortalId([
@@ -228,22 +225,15 @@ export class ProductService extends BaseService {
               portalId: this.user.workspaceId,
             }
           })
-          // onConflictDoNothing: a re-fired / concurrent initial save would
-          // otherwise violate the (portal_id, product_id) unique index and 500.
-          // where mirrors the partial index predicate so it's the arbiter.
-          const query = this.db
+          // Skip products already saved so a repeated save doesn't error.
+          await this.db
             .insert(QBProductSync)
             .values(formattedPayload)
             .onConflictDoNothing({
               target: [QBProductSync.portalId, QBProductSync.productId],
               where: isNull(QBProductSync.deletedAt),
             })
-          const products = returningFields?.length
-            ? await query.returning(
-                buildReturningFields(QBProductSync, returningFields),
-              )
-            : await query.returning()
-          return products
+          return await this.getAll()
         }
 
         if (changedItemReference.length > 0) {

test/integration/quickbooks/productMap/reFiredInitialSave.test.ts

@@ -0,0 +1,57 @@
+import { describe, it, expect } from 'vitest'
+import { eq } from 'drizzle-orm'
+
+import { db } from '@/db'
+import { QBProductSync } from '@/db/schema/qbProductSync'
+
+import { seedHealthyPortal } from '@test/helpers/seed'
+import { setupProductCreatedTest } from '@test/helpers/productCreatedTestSetup'
+import { postProductMap } from '@test/helpers/productMap'
+
+const PRODUCT_ID = '2cf93cf0-45fa-485f-b584-03c2c38a3999'
+
+describe('POST /api/quickbooks/product/map — repeated initial save', () => {
+  // Reuse the harness for truncate + mock install (mocks auth).
+  setupProductCreatedTest()
+
+  it('returns the saved mapping instead of an empty list when the same initial save is sent twice', async () => {
+    // initialProductSettingMap=false keeps both POSTs on the initial-insert
+    // path, so the second one collides with the (portal_id, product_id) unique
+    // index and is skipped by onConflictDoNothing.
+    await seedHealthyPortal({ setting: { initialProductSettingMap: false } })
+
+    const body = {
+      mappingItems: [
+        {
+          productId: PRODUCT_ID,
+          name: 'Test Product',
+          copilotName: 'Test Product',
+          description: '',
+          qbItemId: '999',
+          qbSyncToken: '0',
+          isExcluded: false,
+        },
+      ],
+      changedItemReference: [],
+    }
+
+    const first = await postProductMap(body)
+    expect(first.status).toBe(200)
+
+    const second = await postProductMap(body)
+    expect(second.status).toBe(200)
+
+    // The re-fired save no-ops on the conflict but must still return the live
+    // mapping, not the [] that a bare RETURNING would yield for skipped rows.
+    const secondMapping = await second.json()
+    expect(secondMapping).toHaveLength(1)
+    expect(secondMapping[0].productId).toBe(PRODUCT_ID)
+
+    // And it must not have created a duplicate row.
+    const rows = await db
+      .select()
+      .from(QBProductSync)
+      .where(eq(QBProductSync.productId, PRODUCT_ID))
+    expect(rows).toHaveLength(1)
+  })
+})