diff --git a/apps/api/src/app/server.js b/apps/api/src/app/server.js
index 5bc630e..9e234fa 100644
--- a/apps/api/src/app/server.js
+++ b/apps/api/src/app/server.js
@@ -198,6 +198,7 @@ async function startServer() {
       imageStorage: createLocalImageStorage(imageStorageRoot),
       imageDerivativeJobRepository,
       inventoryImageRepository,
+      sellerSettingsRepository,
     }),
     listingService: createListingService({
       listingRepository,
diff --git a/apps/api/src/modules/inventory/repositories/inventory-image-repository.js b/apps/api/src/modules/inventory/repositories/inventory-image-repository.js
index db95e80..1ba0c62 100644
--- a/apps/api/src/modules/inventory/repositories/inventory-image-repository.js
+++ b/apps/api/src/modules/inventory/repositories/inventory-image-repository.js
@@ -1,5 +1,6 @@
 import { moveImageInOrder } from '../domain/image-order.js';
 import { and, eq, inArray } from 'drizzle-orm';
+import { createApplicationError } from '../../../shared/errors/application-error.js';
 
 import {
   imageDerivativeJobs,
@@ -24,6 +25,24 @@ export function createInventoryImageRepository(db) {
       return createdImage;
     },
 
+    async createForSellerWithLimit(image, sellerId, maxImages) {
+      return db.transaction(async (tx) => {
+        const [ownedItem] = await tx.select({ id: inventoryItems.id })
+          .from(inventoryItems)
+          .innerJoin(products, eq(products.id, inventoryItems.productId))
+          .where(and(eq(inventoryItems.id, image.inventoryItemId), eq(products.sellerId, sellerId)))
+          .for('update', { of: inventoryItems });
+        if (!ownedItem) return null;
+        const existing = await tx.select({ id: inventoryImages.id }).from(inventoryImages)
+          .where(eq(inventoryImages.inventoryItemId, image.inventoryItemId));
+        if (existing.length >= maxImages) {
+          throw createApplicationError('IMAGE_COUNT_LIMIT_REACHED', 'Maximum images per item reached.', 409);
+        }
+        const [createdImage] = await tx.insert(inventoryImages).values(image).returning();
+        return createdImage;
+      });
+    },
+
     async countByInventoryItemId(inventoryItemId) {
       const rows = await db
         .select({ id: inventoryImages.id })
diff --git a/apps/api/src/modules/inventory/services/inventory-image-service.js b/apps/api/src/modules/inventory/services/inventory-image-service.js
index c6b6fa2..e8e45ab 100644
--- a/apps/api/src/modules/inventory/services/inventory-image-service.js
+++ b/apps/api/src/modules/inventory/services/inventory-image-service.js
@@ -2,13 +2,20 @@ import { validateImageMove } from '../domain/image-order.js';
 import { createApplicationError } from '../../../shared/errors/application-error.js';
 import { normalizeImageAltText, validateImageSortOrder, validateImageSignature, validateInventoryImageMetadata } from '../domain/inventory-image.js';
 
-export function createInventoryImageService({ inventoryImageRepository, imageDerivativeJobRepository, imageStorage, imageInspector }) {
+export function createInventoryImageService({ inventoryImageRepository, imageDerivativeJobRepository, imageStorage, imageInspector, sellerSettingsRepository }) {
   return {
     async create(input) {
       validateInventoryImageMetadata(input);
-      const image = await inventoryImageRepository.createForSeller(
+      const settingsRecord = await sellerSettingsRepository?.findBySellerId(input.sellerId);
+      const maxImages = settingsRecord?.settings?.inventory?.maxImagesPerItem ?? 10;
+      if (!Number.isInteger(maxImages) || maxImages < 1 || maxImages > 100) {
+        throw createApplicationError('IMAGE_COUNT_LIMIT_INVALID', 'Image count limit is invalid.', 500);
+      }
+      const createImage = inventoryImageRepository.createForSellerWithLimit ?? inventoryImageRepository.createForSeller;
+      const image = await createImage.call(inventoryImageRepository,
         { ...input, processingStatus: 'PENDING' },
         input.sellerId,
+        maxImages,
       );
 
       if (!image) {
@@ -99,4 +106,4 @@ async function requireOwnedImage(imagePromise) {
   const image = await imagePromise;
   if (!image) throw imageNotFoundError();
   return image;
-}
\ No newline at end of file
+}
diff --git a/apps/api/tests/application/inventory-image-service.test.js b/apps/api/tests/application/inventory-image-service.test.js
index 64f3741..ccd628c 100644
--- a/apps/api/tests/application/inventory-image-service.test.js
+++ b/apps/api/tests/application/inventory-image-service.test.js
@@ -69,4 +69,21 @@ test('removes stored bytes when metadata persistence fails', async () => {
     (error) => error.code === 'INVENTORY_ITEM_NOT_FOUND',
   );
   assert.deepEqual(deleted, [input.storageKey]);
-});
\ No newline at end of file
+});
+
+test('passes the seller image limit to the atomic repository operation', async () => {
+  let limit;
+  const service = createInventoryImageService({
+    sellerSettingsRepository: { async findBySellerId() { return { settings: { inventory: { maxImagesPerItem: 2 } } }; } },
+    inventoryImageRepository: {
+      async createForSellerWithLimit(image, sellerId, maxImages) {
+        assert.equal(sellerId, 'seller-id');
+        limit = maxImages;
+        return { id: 'image-1', ...image };
+      },
+    },
+  });
+  const image = await service.create({ ...input, data: undefined });
+  assert.equal(image.id, 'image-1');
+  assert.equal(limit, 2);
+});
diff --git a/apps/api/tests/integration/listing-repository.test.js b/apps/api/tests/integration/listing-repository.test.js
index c9ba75b..f94a4d6 100644
--- a/apps/api/tests/integration/listing-repository.test.js
+++ b/apps/api/tests/integration/listing-repository.test.js
@@ -244,6 +244,17 @@ test('persists image metadata only for the owning seller and counts item images'
   );
 });
 
+test('enforces per-item image limits across concurrent inserts', async () => {
+  const { seller, inventoryItem } = await createInventoryFixture();
+  const image = (suffix) => ({ inventoryItemId: inventoryItem.id, storageKey: `inventory/${suffix}.jpg`, originalFilename: `${suffix}.jpg`, mimeType: 'image/jpeg', fileSize: 4, width: 2, height: 2, sortOrder: 0, isPrimary: false, processingStatus: 'PENDING' });
+  const results = await Promise.allSettled([
+    inventoryImageRepository.createForSellerWithLimit(image('a'), seller.id, 1),
+    inventoryImageRepository.createForSellerWithLimit(image('b'), seller.id, 1),
+  ]);
+  assert.equal(results.filter((result) => result.status === 'fulfilled').length, 1);
+  assert.equal(results.filter((result) => result.status === 'rejected' && result.reason.code === 'IMAGE_COUNT_LIMIT_REACHED').length, 1);
+});
+
 test('reads and updates listings only through the owning seller scope', async () => {
   const { seller, category, condition, inventoryItem } = await createInventoryFixture();
 
diff --git a/docs/IMAGES.md b/docs/IMAGES.md
index 42247dc..6ac3f72 100644
--- a/docs/IMAGES.md
+++ b/docs/IMAGES.md
@@ -25,7 +25,7 @@ Support:
 - delete
 - add images later
 
-Image count is configurable.
+Image count is configurable per seller through `inventory.maxImagesPerItem` (default 10). The API enforces this limit atomically while locking the physical inventory item, so concurrent uploads cannot exceed the configured cap.
 
 ## Storage
 
diff --git a/docs/IMPLEMENTATION-STATUS.md b/docs/IMPLEMENTATION-STATUS.md
index 13fd183..bb162b9 100644
--- a/docs/IMPLEMENTATION-STATUS.md
+++ b/docs/IMPLEMENTATION-STATUS.md
@@ -266,6 +266,7 @@ Remaining roadmap areas are approved external provider credentials/adapters, bro
 - Storybook now installs a lightweight router mirroring the app's named routes plus a mobile-viewport-forcing test-runner hook, enabling isolated page stories (including the public catalog) that use `useRoute`/`useRouter` or narrow-viewport CSS breakpoints.
 - The public catalog now has its own Storybook coverage, including an interaction test proving the mobile filter disclosure is keyboard-operable and correctly hides/reveals filter controls via `aria-expanded`. This review also found and fixed a real color-contrast failure in the catalog error-state text.
 - `ListingDetailPage`, `ProductDetailPage`, and `AdminImagePage` now have Storybook coverage. Adding it surfaced and fixed a color-contrast bug shared by all three: the "Back to catalog" link, pagination controls, and the selected image-gallery thumbnail were using the non-text-safe `--color-interactive` token instead of `--color-interactive-text`.
+- Per-item image limits are now enforced atomically for seller image creation and uploads, using `inventory.maxImagesPerItem` (default 10); concurrent inserts are serialized on the physical inventory item and return `IMAGE_COUNT_LIMIT_REACHED` at the configured cap.
 
 ## Local Commands
 
@@ -287,4 +288,4 @@ Then migrate it using its `TEST_DATABASE_URL` value as `DATABASE_URL`, and run i
 
 ## Suggested Resume Prompt
 
-`Read docs/IMPLEMENTATION-STATUS.md and continue the next bounded milestone. Verify the existing baseline first, follow AGENTS.md, and keep the change focused with tests.`
\ No newline at end of file
+`Read docs/IMPLEMENTATION-STATUS.md and continue the next bounded milestone. Verify the existing baseline first, follow AGENTS.md, and keep the change focused with tests.`