diff --git a/apps/api/src/modules/inventory/domain/inventory-image.js b/apps/api/src/modules/inventory/domain/inventory-image.js
new file mode 100644
index 0000000..6e16d41
--- /dev/null
+++ b/apps/api/src/modules/inventory/domain/inventory-image.js
@@ -0,0 +1,31 @@
+import { createApplicationError } from '../../../shared/errors/application-error.js';
+
+const SUPPORTED_MIME_TYPES = new Set(['image/jpeg', 'image/png', 'image/webp']);
+const DEFAULT_MAX_FILE_SIZE = 10 * 1024 * 1024;
+const DEFAULT_MAX_DIMENSION = 10_000;
+
+export function validateInventoryImageMetadata(
+  image,
+  { maxFileSize = DEFAULT_MAX_FILE_SIZE, maxDimension = DEFAULT_MAX_DIMENSION } = {},
+) {
+  if (!SUPPORTED_MIME_TYPES.has(image.mimeType)) {
+    throw createApplicationError('IMAGE_MIME_TYPE_UNSUPPORTED', 'Image MIME type is not supported.', 400);
+  }
+
+  if (!Number.isInteger(image.fileSize) || image.fileSize <= 0 || image.fileSize > maxFileSize) {
+    throw createApplicationError('IMAGE_FILE_TOO_LARGE', 'Image file size is invalid or too large.', 400);
+  }
+
+  if (
+    !Number.isInteger(image.width) ||
+    !Number.isInteger(image.height) ||
+    image.width <= 0 ||
+    image.height <= 0 ||
+    image.width > maxDimension ||
+    image.height > maxDimension
+  ) {
+    throw createApplicationError('IMAGE_DIMENSIONS_INVALID', 'Image dimensions are invalid or too large.', 400);
+  }
+
+  return true;
+}
\ No newline at end of file
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 8332710..5ed9c42 100644
--- a/apps/api/src/modules/inventory/services/inventory-image-service.js
+++ b/apps/api/src/modules/inventory/services/inventory-image-service.js
@@ -1,8 +1,10 @@
 import { createApplicationError } from '../../../shared/errors/application-error.js';
+import { validateInventoryImageMetadata } from '../domain/inventory-image.js';
 
 export function createInventoryImageService({ inventoryImageRepository }) {
   return {
     async create(input) {
+      validateInventoryImageMetadata(input);
       const image = await inventoryImageRepository.createForSeller(
         { ...input, processingStatus: 'PENDING' },
         input.sellerId,
diff --git a/apps/api/tests/domain/inventory-image.test.js b/apps/api/tests/domain/inventory-image.test.js
new file mode 100644
index 0000000..b15816c
--- /dev/null
+++ b/apps/api/tests/domain/inventory-image.test.js
@@ -0,0 +1,30 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+
+import { validateInventoryImageMetadata } from '../../src/modules/inventory/domain/inventory-image.js';
+
+const validImage = {
+  mimeType: 'image/jpeg',
+  fileSize: 12000,
+  width: 1200,
+  height: 900,
+};
+
+test('accepts supported image metadata within configured limits', () => {
+  assert.equal(validateInventoryImageMetadata(validImage), true);
+});
+
+test('rejects unsupported MIME types, oversized files, and oversized dimensions', () => {
+  assert.throws(
+    () => validateInventoryImageMetadata({ ...validImage, mimeType: 'image/gif' }),
+    (error) => error.code === 'IMAGE_MIME_TYPE_UNSUPPORTED',
+  );
+  assert.throws(
+    () => validateInventoryImageMetadata({ ...validImage, fileSize: 11 * 1024 * 1024 }),
+    (error) => error.code === 'IMAGE_FILE_TOO_LARGE',
+  );
+  assert.throws(
+    () => validateInventoryImageMetadata({ ...validImage, width: 10001 }),
+    (error) => error.code === 'IMAGE_DIMENSIONS_INVALID',
+  );
+});
\ No newline at end of file
diff --git a/docs/IMAGES.md b/docs/IMAGES.md
index 8928311..2edf302 100644
--- a/docs/IMAGES.md
+++ b/docs/IMAGES.md
@@ -53,6 +53,11 @@ Validate:
 - image dimensions
 - configured image count
 
+The metadata service currently enforces JPEG, PNG, and WebP MIME types, a
+10 MiB default file-size limit, and a 10,000-pixel maximum width and height.
+Binary signature checks and multipart upload validation remain part of the
+upload transport slice.
+
 Generate:
 - thumbnail
 - medium
diff --git a/docs/IMPLEMENTATION-STATUS.md b/docs/IMPLEMENTATION-STATUS.md
index 5b28f7b..0e9140d 100644
--- a/docs/IMPLEMENTATION-STATUS.md
+++ b/docs/IMPLEMENTATION-STATUS.md
@@ -91,6 +91,7 @@ docker context use orbstack
 - Listing reads are seller-scoped and return only admin listing DTO fields.
 - Item-owned image metadata can be added through a seller-scoped, CSRF-protected admin route; publication uses the persisted image count.
 - `ImageStorage` and a traversal-safe local filesystem adapter are implemented; upload transport, signature validation, and derivative processing remain.
+- Image metadata limits are enforced in the service boundary: supported MIME types, 10 MiB default file size, and 10,000-pixel maximum dimensions.
 
 ### Verified Baseline
 
@@ -101,13 +102,13 @@ docker context use orbstack
 | HTTP | Product and inventory creation, validation, authentication/recovery, CSRF, rate limiting, and session management |
 | Integration | PostgreSQL catalog/session/audit/password recovery persistence and Redis-shared login throttling |
 
-Latest result: `npm test` passed 62 tests; `npm run test:integration` passed 14 tests against OrbStack PostgreSQL and Redis.
+Latest result: `npm test` passed 64 tests; `npm run test:integration` passed 14 tests against OrbStack PostgreSQL and Redis.
 
 ## Next Milestone
 
 Complete the inventory/listing integrity boundary before starting pricing and acquisition.
 
-1. Add upload transport, MIME/signature/size validation, and processing/derivative lifecycle for persisted image metadata.
+1. Add multipart upload transport, binary signature validation, and processing/derivative lifecycle for persisted image metadata.
 2. Begin acquisition and pricing foundations after the listing/image boundary is complete.
 
 Acceptance criteria: listing reads and lifecycle writes preserve seller ownership, CSRF, inventory status, and publication prerequisites.