diff --git a/apps/api/src/modules/inventory/domain/image-order.js b/apps/api/src/modules/inventory/domain/image-order.js
new file mode 100644
index 0000000..f27adad
--- /dev/null
+++ b/apps/api/src/modules/inventory/domain/image-order.js
@@ -0,0 +1,19 @@
+import { createApplicationError } from '../../../shared/errors/application-error.js';
+
+export function validateImageMove(direction) {
+  if (direction !== 'up' && direction !== 'down') {
+    throw createApplicationError('IMAGE_MOVE_INVALID', 'Image move must be up or down.', 400);
+  }
+}
+
+// Input is the persisted display order. Return a reordered copy; boundary moves
+// are no-ops. Persistence assigns contiguous positions after an actual move.
+export function moveImageInOrder(images, imageId, direction) {
+  validateImageMove(direction);
+  const index = images.findIndex((image) => image.id === imageId);
+  const neighbor = index + (direction === 'up' ? -1 : 1);
+  if (index < 0 || neighbor < 0 || neighbor >= images.length) return images;
+  const reordered = [...images];
+  [reordered[index], reordered[neighbor]] = [reordered[neighbor], reordered[index]];
+  return reordered;
+}
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 4e4ddf7..db95e80 100644
--- a/apps/api/src/modules/inventory/repositories/inventory-image-repository.js
+++ b/apps/api/src/modules/inventory/repositories/inventory-image-repository.js
@@ -1,3 +1,4 @@
+import { moveImageInOrder } from '../domain/image-order.js';
 import { and, eq, inArray } from 'drizzle-orm';
 
 import {
@@ -53,10 +54,42 @@ export function createInventoryImageRepository(db) {
           eq(inventoryImages.inventoryItemId, inventoryItemId),
           eq(products.sellerId, sellerId),
         ))
-        .orderBy(inventoryImages.sortOrder)
+        .orderBy(inventoryImages.sortOrder, inventoryImages.createdAt, inventoryImages.id)
         .then((rows) => rows.map(({ image }) => image));
     },
 
+    async moveForSeller(imageId, direction, sellerId) {
+      return db.transaction(async (tx) => {
+        // Lock the owning physical item first, serializing moves within a gallery.
+        const [owned] = await tx
+          .select({ inventoryItemId: inventoryItems.id })
+          .from(inventoryImages)
+          .innerJoin(inventoryItems, eq(inventoryItems.id, inventoryImages.inventoryItemId))
+          .innerJoin(products, eq(products.id, inventoryItems.productId))
+          .where(and(eq(inventoryImages.id, imageId), eq(products.sellerId, sellerId)))
+          .for('update', { of: inventoryItems });
+        if (!owned) return null;
+
+        const images = await tx.select().from(inventoryImages)
+          .where(eq(inventoryImages.inventoryItemId, owned.inventoryItemId))
+          .orderBy(inventoryImages.sortOrder, inventoryImages.createdAt, inventoryImages.id)
+          .for('update');
+        const target = images.find((image) => image.id === imageId);
+        if (!target) return null;
+        const reordered = moveImageInOrder(images, imageId, direction);
+        if (reordered === images) return target;
+        const updatedAt = new Date();
+        for (const [sortOrder, image] of reordered.entries()) {
+          if (image.sortOrder !== sortOrder) {
+            await tx.update(inventoryImages).set({ sortOrder, updatedAt })
+              .where(eq(inventoryImages.id, image.id));
+          }
+        }
+        const [moved] = await tx.select().from(inventoryImages).where(eq(inventoryImages.id, imageId));
+        return moved;
+      });
+    },
+
     async updateOrderForSeller(imageId, sortOrder, sellerId) {
       const owned = await this.findByIdForSeller(imageId, sellerId);
       if (!owned) return null;
@@ -135,7 +168,7 @@ export function createInventoryImageRepository(db) {
           eq(inventoryImages.processingStatus, 'COMPLETED'),
           eq(imageDerivativeJobs.status, 'COMPLETED'),
         ))
-        .orderBy(inventoryImages.sortOrder);
+        .orderBy(inventoryImages.sortOrder, inventoryImages.createdAt, inventoryImages.id);
     },
 
     async findPublicById(imageId) {
diff --git a/apps/api/src/modules/inventory/routes/admin-image-routes.js b/apps/api/src/modules/inventory/routes/admin-image-routes.js
index 4721adf..f1c63a1 100644
--- a/apps/api/src/modules/inventory/routes/admin-image-routes.js
+++ b/apps/api/src/modules/inventory/routes/admin-image-routes.js
@@ -1,5 +1,5 @@
 import { toAdminInventoryImageDto } from '@pokemon-inventory/contracts/image';
-import { createInventoryImageSchema } from '@pokemon-inventory/validation/image';
+import { createInventoryImageSchema, moveInventoryImageSchema } from '@pokemon-inventory/validation/image';
 import { randomUUID } from 'node:crypto';
 
 import { createApplicationError } from '../../../shared/errors/application-error.js';
@@ -98,6 +98,18 @@ export async function registerAdminImageRoutes(app, options) {
     return admin;
   }
 
+  app.post('/images/:id/move', async (request, reply) => {
+    const admin = await authorizeAdminMutation(request);
+    const result = moveInventoryImageSchema.safeParse(request.body);
+    if (!result.success) return validationError(reply, result);
+    const image = await inventoryImageService.move({
+      imageId: request.params.id,
+      direction: result.data.direction,
+      sellerId: admin.sellerId,
+    });
+    return { data: toAdminInventoryImageDto(image) };
+  });
+
   app.patch('/images/:id/order', async (request) => {
     const admin = await authorizeAdminMutation(request);
     const image = await inventoryImageService.updateOrder({
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 7275db3..c3807aa 100644
--- a/apps/api/src/modules/inventory/services/inventory-image-service.js
+++ b/apps/api/src/modules/inventory/services/inventory-image-service.js
@@ -1,3 +1,4 @@
+import { validateImageMove } from '../domain/image-order.js';
 import { createApplicationError } from '../../../shared/errors/application-error.js';
 import { validateImageSignature, validateInventoryImageMetadata } from '../domain/inventory-image.js';
 
@@ -42,6 +43,11 @@ export function createInventoryImageService({ inventoryImageRepository, imageDer
       }
     },
 
+    async move({ imageId, direction, sellerId }) {
+      validateImageMove(direction);
+      return requireOwnedImage(inventoryImageRepository.moveForSeller(imageId, direction, sellerId));
+    },
+
     async updateOrder({ imageId, sortOrder, sellerId }) {
       return requireOwnedImage(inventoryImageRepository.updateOrderForSeller(imageId, sortOrder, sellerId));
     },
diff --git a/apps/api/tests/application/inventory-image-management.test.js b/apps/api/tests/application/inventory-image-management.test.js
index cc3cfbb..e5f54e8 100644
--- a/apps/api/tests/application/inventory-image-management.test.js
+++ b/apps/api/tests/application/inventory-image-management.test.js
@@ -35,3 +35,16 @@ test('manages owned image order, primary state, alt text, retry, and deletion',
   assert.ok(calls.some(([action]) => action === 'delete-job'));
   assert.ok(calls.some(([action]) => action === 'storage-delete'));
 });
+
+test('moves an image through the owned atomic repository operation', async () => {
+  const service = createInventoryImageService({ inventoryImageRepository: {
+    async moveForSeller(id, direction, sellerId) {
+      assert.equal(direction, 'down');
+      assert.equal(sellerId, 'seller-1');
+      return id === 'owned' ? { id, sortOrder: 1 } : null;
+    },
+  } });
+  assert.deepEqual(await service.move({ imageId: 'owned', direction: 'down', sellerId: 'seller-1' }), { id: 'owned', sortOrder: 1 });
+  await assert.rejects(() => service.move({ imageId: 'missing', direction: 'down', sellerId: 'seller-1' }), { code: 'IMAGE_NOT_FOUND' });
+  await assert.rejects(() => service.move({ imageId: 'owned', direction: 'left', sellerId: 'seller-1' }), { code: 'IMAGE_MOVE_INVALID' });
+});
diff --git a/apps/api/tests/domain/image-order.test.js b/apps/api/tests/domain/image-order.test.js
new file mode 100644
index 0000000..caf92e7
--- /dev/null
+++ b/apps/api/tests/domain/image-order.test.js
@@ -0,0 +1,13 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import { moveImageInOrder } from '../../src/modules/inventory/domain/image-order.js';
+
+test('moves one image next to its neighbor without changing the input order', () => {
+  const images = [{ id: 'a' }, { id: 'b' }, { id: 'c' }];
+  assert.deepEqual(moveImageInOrder(images, 'b', 'up').map(({ id }) => id), ['b', 'a', 'c']);
+  assert.deepEqual(moveImageInOrder(images, 'b', 'down').map(({ id }) => id), ['a', 'c', 'b']);
+  assert.deepEqual(images.map(({ id }) => id), ['a', 'b', 'c']);
+  assert.equal(moveImageInOrder(images, 'a', 'up'), images);
+  assert.equal(moveImageInOrder(images, 'c', 'down'), images);
+  assert.throws(() => moveImageInOrder(images, 'a', 'left'), { code: 'IMAGE_MOVE_INVALID' });
+});
diff --git a/apps/api/tests/http/image-move-routes.test.js b/apps/api/tests/http/image-move-routes.test.js
new file mode 100644
index 0000000..d3baca7
--- /dev/null
+++ b/apps/api/tests/http/image-move-routes.test.js
@@ -0,0 +1,33 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import { buildApp } from '../../src/app/build-app.js';
+
+test('validates and authorizes image moves and exposes only the image DTO', async (context) => {
+  const calls = [];
+  const app = buildApp({
+    authenticateAdmin: async () => ({ sellerId: 'seller-1' }),
+    authorizeUnsafeRequest: async () => { calls.push('csrf'); },
+    inventoryImageService: { async move(input) { calls.push(input); return { id: input.imageId, sortOrder: 1, privateData: 'hidden' }; } },
+  });
+  context.after(() => app.close());
+  const response = await app.inject({ method: 'POST', url: '/api/v1/admin/images/image-1/move', payload: { direction: 'down' } });
+  assert.equal(response.statusCode, 200);
+  assert.deepEqual(calls, ['csrf', { imageId: 'image-1', direction: 'down', sellerId: 'seller-1' }]);
+  assert.equal(response.json().data.sortOrder, 1);
+  assert.equal(response.json().data.privateData, undefined);
+  for (const payload of [{}, { direction: 'left' }, { direction: 'up', sellerId: 'other' }]) {
+    assert.equal((await app.inject({ method: 'POST', url: '/api/v1/admin/images/image-1/move', payload })).statusCode, 400);
+  }
+});
+
+test('rejects unauthenticated and CSRF-blocked moves without calling the service', async (context) => {
+  for (const csrf of [false, true]) {
+    const app = buildApp({
+      authenticateAdmin: async () => csrf ? { sellerId: 'seller-1' } : null,
+      authorizeUnsafeRequest: async () => { throw Object.assign(new Error('Forbidden'), { statusCode: 403 }); },
+      inventoryImageService: { async move() { assert.fail('unauthorized move'); } },
+    });
+    context.after(() => app.close());
+    assert.equal((await app.inject({ method: 'POST', url: '/api/v1/admin/images/image-1/move', payload: { direction: 'up' } })).statusCode, csrf ? 403 : 401);
+  }
+});
diff --git a/apps/api/tests/integration/listing-repository.test.js b/apps/api/tests/integration/listing-repository.test.js
index ad49b8b..c9ba75b 100644
--- a/apps/api/tests/integration/listing-repository.test.js
+++ b/apps/api/tests/integration/listing-repository.test.js
@@ -273,3 +273,65 @@ test('reads and updates listings only through the owning seller scope', async ()
   const archivedListing = await listingRepository.updateStatus(createdListing.id, 'ARCHIVED');
   assert.equal(archivedListing.status, 'ARCHIVED');
 });
+
+async function createImageOrderFixture() {
+  const { seller, inventoryItem } = await createInventoryFixture();
+  const images = [];
+  for (let index = 0; index < 3; index += 1) {
+    images.push(await inventoryImageRepository.createForSeller({
+      inventoryItemId: inventoryItem.id, storageKey: `move-${index}.jpg`, originalFilename: `move-${index}.jpg`,
+      mimeType: 'image/jpeg', fileSize: 100, width: 10, height: 10, sortOrder: 0,
+      isPrimary: index === 0,
+    }, seller.id));
+  }
+  return { seller, inventoryItem, images: await inventoryImageRepository.listByInventoryItemForSeller(inventoryItem.id, seller.id) };
+}
+
+test('moves images atomically with tied positions, ownership checks and boundary no-ops', async () => {
+  const { seller, inventoryItem, images } = await createImageOrderFixture();
+  const read = () => inventoryImageRepository.listByInventoryItemForSeller(inventoryItem.id, seller.id);
+  assert.equal(await inventoryImageRepository.moveForSeller(images[0].id, 'down', '00000000-0000-0000-0000-000000000000'), null);
+  assert.equal(await inventoryImageRepository.moveForSeller('00000000-0000-0000-0000-000000000000', 'down', seller.id), null);
+  assert.deepEqual(await read(), images);
+  await inventoryImageRepository.moveForSeller(images[0].id, 'up', seller.id);
+  assert.deepEqual(await read(), images);
+  await inventoryImageRepository.moveForSeller(images[0].id, 'down', seller.id);
+  const moved = await read();
+  assert.deepEqual(moved.map(({ id }) => id), [images[1].id, images[0].id, images[2].id]);
+  assert.deepEqual(moved.map(({ sortOrder }) => sortOrder), [0, 1, 2]);
+  assert.equal(moved.find(({ id }) => id === images[0].id).isPrimary, images[0].isPrimary);
+  await inventoryImageRepository.moveForSeller(images[0].id, 'up', seller.id);
+  assert.deepEqual((await read()).map(({ id }) => id), images.map(({ id }) => id));
+});
+
+test('rolls back every position if an image move fails after its first write', async () => {
+  const { seller, inventoryItem, images } = await createImageOrderFixture();
+  let writes = 0;
+  const failingRepository = createInventoryImageRepository({
+    transaction: (action) => database.db.transaction((tx) => action(new Proxy(tx, {
+      get(target, property) {
+        if (property === 'update') return (...args) => {
+          writes += 1;
+          if (writes === 2) throw new Error('Injected second write failure');
+          return target.update(...args);
+        };
+        const value = target[property];
+        return typeof value === 'function' ? value.bind(target) : value;
+      },
+    }))),
+  });
+  await assert.rejects(() => failingRepository.moveForSeller(images[0].id, 'down', seller.id), /Injected second write failure/);
+  assert.equal(writes, 2);
+  assert.deepEqual(await inventoryImageRepository.listByInventoryItemForSeller(inventoryItem.id, seller.id), images);
+});
+
+test('serializes concurrent moves within the same gallery', async () => {
+  const { seller, inventoryItem, images } = await createImageOrderFixture();
+  await Promise.all([
+    inventoryImageRepository.moveForSeller(images[0].id, 'down', seller.id),
+    inventoryImageRepository.moveForSeller(images[0].id, 'down', seller.id),
+  ]);
+  const result = await inventoryImageRepository.listByInventoryItemForSeller(inventoryItem.id, seller.id);
+  assert.deepEqual(result.map(({ id }) => id), [images[1].id, images[2].id, images[0].id]);
+  assert.deepEqual(result.map(({ sortOrder }) => sortOrder), [0, 1, 2]);
+});
diff --git a/apps/web/src/composables/useAdminImages.js b/apps/web/src/composables/useAdminImages.js
index e470737..7679582 100644
--- a/apps/web/src/composables/useAdminImages.js
+++ b/apps/web/src/composables/useAdminImages.js
@@ -3,7 +3,7 @@ import { ref } from 'vue';
 import {
   deleteImage,
   listAdminImages,
-  reorderImage,
+  moveImage,
   retryImageProcessing,
   setPrimaryImage,
   updateImageAltText,
@@ -76,18 +76,6 @@ export function useAdminImages(inventoryItemId) {
     });
   }
 
-  async function moveImage(imageId, direction) {
-    const ordered = [...images.value].sort((left, right) => left.sortOrder - right.sortOrder);
-    const index = ordered.findIndex((image) => image.id === imageId);
-    const neighborIndex = direction === 'up' ? index - 1 : index + 1;
-    if (index === -1 || neighborIndex < 0 || neighborIndex >= ordered.length) return;
-    const current = ordered[index];
-    const neighbor = ordered[neighborIndex];
-    await apply(async (token) => {
-      await reorderImage(current.id, neighbor.sortOrder, token);
-      await reorderImage(neighbor.id, current.sortOrder, token);
-    });
-  }
 
   return {
     images,
@@ -98,7 +86,7 @@ export function useAdminImages(inventoryItemId) {
     hasLoaded,
     load,
     upload,
-    move: moveImage,
+    move: (imageId, direction) => apply((token) => moveImage(imageId, direction, token)),
     setPrimary: (imageId) => apply((token) => setPrimaryImage(imageId, token)),
     updateAltText: (imageId, altText) => apply((token) => updateImageAltText(imageId, altText, token)),
     retry: (imageId) => apply((token) => retryImageProcessing(imageId, token)),
diff --git a/apps/web/src/pages/AdminImagePage.stories.js b/apps/web/src/pages/AdminImagePage.stories.js
index b7ffc47..7d0b260 100644
--- a/apps/web/src/pages/AdminImagePage.stories.js
+++ b/apps/web/src/pages/AdminImagePage.stories.js
@@ -10,6 +10,7 @@ export default {
     let reads = 0;
     let writes = 0;
     let images = [{ id: 'image-1', altText: 'Front of card', sortOrder: 0, isPrimary: true, processingStatus: 'COMPLETED' }];
+    if (scenario === 'move' || scenario === 'move-error') images.push({ id: 'image-2', altText: 'Back of card', sortOrder: 1, isPrimary: false, processingStatus: 'COMPLETED' });
     const reply = (data) => new Response(JSON.stringify({ data }), { headers: { 'content-type': 'application/json' } });
     const fail = (message) => new Response(JSON.stringify({ error: { message } }), { status: 503 });
     globalThis.fetch = async (url, options = {}) => {
@@ -21,6 +22,15 @@ export default {
         return reply(images);
       }
       writes += 1;
+      if (scenario === 'move' || scenario === 'move-error') {
+        await expect(String(url)).toMatch(/\/images\/image-[12]\/move$/);
+        await expect(options.method).toBe('POST');
+        const { direction } = JSON.parse(options.body);
+        await expect(['up', 'down']).toContain(direction);
+        if (scenario === 'move-error' && writes === 1) return fail('Move failed.');
+        images = [...images].reverse().map((image, sortOrder) => ({ ...image, sortOrder }));
+        return reply(images[0]);
+      }
       if (scenario === 'saving') return new Promise(() => {});
       if (scenario === 'partial-upload' && writes === 2) return fail('Second upload failed.');
       if (options.body instanceof FormData) images = [...images, { id: `uploaded-${writes}`, altText: options.body.get('altText'), sortOrder: images.length, isPrimary: false, processingStatus: 'COMPLETED' }];
@@ -137,3 +147,29 @@ export const PartialUploadFailure = {
     await expect(canvas.getByRole('button', { name: 'front.png' })).toBeVisible();
   },
 };
+
+export const AtomicMove = {
+  parameters: { imageScenario: 'move' },
+  play: async ({ canvasElement }) => {
+    const canvas = within(canvasElement);
+    const down = await canvas.findAllByRole('button', { name: 'Move down' });
+    await userEvent.click(down[0]);
+    await waitFor(() => expect(canvas.getAllByRole('button', { name: /^(Front|Back) of card$/ })[0]).toHaveTextContent('Back of card'));
+    await userEvent.click(canvas.getAllByRole('button', { name: 'Move up' })[1]);
+    await waitFor(() => expect(canvas.getAllByRole('button', { name: /^(Front|Back) of card$/ })[0]).toHaveTextContent('Front of card'));
+    await expect(canvas.getAllByRole('button', { name: 'Move up' })[0]).toBeDisabled();
+    await expect(canvas.getAllByRole('button', { name: 'Move down' })[1]).toBeDisabled();
+  },
+};
+export const FailedAtomicMove = {
+  parameters: { imageScenario: 'move-error' },
+  play: async ({ canvasElement }) => {
+    const canvas = within(canvasElement);
+    await userEvent.click((await canvas.findAllByRole('button', { name: 'Move down' }))[0]);
+    await expect(await canvas.findByRole('alert')).toHaveTextContent('Move failed.');
+    await waitFor(() => expect(canvas.getAllByRole('button', { name: 'Move down' })[0]).toBeEnabled());
+    await expect(canvas.getAllByRole('button', { name: /^(Front|Back) of card$/ })[0]).toHaveTextContent('Front of card');
+    await userEvent.click(canvas.getAllByRole('button', { name: 'Move down' })[0]);
+    await waitFor(() => expect(canvas.getAllByRole('button', { name: /^(Front|Back) of card$/ })[0]).toHaveTextContent('Back of card'));
+  },
+};
diff --git a/apps/web/src/services/admin-image-service.js b/apps/web/src/services/admin-image-service.js
index b96d7e1..493116b 100644
--- a/apps/web/src/services/admin-image-service.js
+++ b/apps/web/src/services/admin-image-service.js
@@ -80,3 +80,11 @@ export async function listAdminImages(inventoryItemId) {
     headers: {},
   });
 }
+
+export function moveImage(imageId, direction, csrfToken) {
+  return request(`/admin/images/${encodeURIComponent(imageId)}/move`, {
+    method: 'POST',
+    headers: { 'x-csrf-token': csrfToken },
+    body: JSON.stringify({ direction }),
+  });
+}
diff --git a/docs/API.md b/docs/API.md
index f5c426c..daee988 100644
--- a/docs/API.md
+++ b/docs/API.md
@@ -197,3 +197,13 @@ Seller contact removal uses the same explicit-empty-string convention:
 whitespace-only strings clear the contact. Omitted contact fields retain their
 saved values. `null` is not a settings input. Public listing/product detail DTOs
 return `null` for empty or absent contacts, so no contact link is rendered.
+
+`POST /api/v1/admin/images/:id/move` accepts exactly `{ "direction": "up" }`
+or `{ "direction": "down" }`. Authentication and session CSRF validation are
+required; ownership comes from the authenticated Seller. The server selects the
+adjacent image within the same physical Inventory Item and commits all resulting
+positions atomically. At the first/last position the corresponding move is a
+successful no-op. Missing/unowned images return `404 IMAGE_NOT_FOUND`; invalid
+bodies return `400 VALIDATION_ERROR`. The response uses the existing admin image
+DTO. The legacy absolute `/order` endpoint remains available, but UI moves use
+this new operation exclusively.
diff --git a/docs/IMAGES.md b/docs/IMAGES.md
index 4c4b734..ac15d26 100644
--- a/docs/IMAGES.md
+++ b/docs/IMAGES.md
@@ -119,3 +119,13 @@ retain the last loaded gallery but disable mutations until an explicit reload
 succeeds. Failed initial loads show a reload action instead of an empty manager.
 Reload restores keyboard focus to the manager or the retry control. Pending
 operations block conflicting writes and uploads, including drag-and-drop.
+
+## Atomic adjacent moves
+
+Move up/down uses one server operation. The repository locks the owning Inventory
+Item and its images, selects current order by `sortOrder`, `createdAt`, then `id`,
+and uses the domain move rule to choose the new order. An actual move assigns
+contiguous zero-based positions, resolving tied legacy/upload positions, within
+one PostgreSQL transaction. Any failure rolls back all changes. Concurrent moves
+within one item serialize; primary selection and image metadata are unchanged.
+Boundary moves are no-ops. No database migration is required.
diff --git a/docs/IMPLEMENTATION-STATUS.md b/docs/IMPLEMENTATION-STATUS.md
index 7adf667..e30954c 100644
--- a/docs/IMPLEMENTATION-STATUS.md
+++ b/docs/IMPLEMENTATION-STATUS.md
@@ -1,6 +1,6 @@
 # Implementation Status
 
-Last updated: 2026-09-10
+Last updated: 2026-09-11
 
 ## Resume Here
 
@@ -120,7 +120,7 @@ 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 |
 
-Verified locally: `npm test` passes 167 tests with no failures (23 domain, 79 application, and 65 HTTP); worker tests, web tests, web build, Storybook build, Storybook interaction/accessibility checks, integration tests, and authenticated E2E workflows also pass when their required local services and credentials are available.
+Verified locally: `npm test` passes 171 tests with no failures (24 domain, 80 application, and 67 HTTP); worker tests, web tests, web build, Storybook build, Storybook interaction/accessibility checks, integration tests, and authenticated E2E workflows also pass when their required local services and credentials are available.
 
 ### Public Seller Description
 
@@ -169,7 +169,7 @@ Verified locally: `npm test` passes 167 tests with no failures (23 domain, 79 ap
 - Storybook covers populated/empty/loading/error states, load retries, create/delete recovery, invalid JSON, pending disabled states, mobile retry and dark-theme recovery.
 - Validation: 167 API tests, 11 web tests, production web build, Storybook build, and 32 Storybook suites / 113 tests. Frontend-only change; API and persistence unchanged.
 
-### Latest Vertical Slice: Image Manager Error Recovery
+### Image Manager Error Recovery
 
 - Loaded images and alt-text drafts survive action failures and refreshes. Initial-load errors offer Reload; refresh errors retain the gallery with writes disabled until reload succeeds.
 - Every action reconciles metadata even on failure, exposing partial multi-upload/reorder success without replaying mutations. Pending actions block overlapping writes and file drops.
@@ -177,7 +177,14 @@ Verified locally: `npm test` passes 167 tests with no failures (23 domain, 79 ap
 - Dark-theme coverage also fixed destructive-button contrast by separating its solid background token from error-text color.
 - Validation: 167 API tests, 11 web tests, production web build, Storybook build, and 32 Storybook suites / 124 tests. No API or persistence changes.
 
-Next bounded slice: atomic image reordering. Move up/down currently sends two separate order updates; failure between them can leave a partial reorder. Add a seller-scoped API operation that updates both positions transactionally, connect the controls to it, and verify rollback and ownership with integration tests.
+### Latest Vertical Slice: Atomic Image Reordering
+
+- Move up/down now calls a single authenticated, CSRF-protected `POST /api/v1/admin/images/:id/move` operation. The server derives the adjacent image from current persisted order.
+- The repository locks the owning Inventory Item and its images, applies the domain move rule, and commits contiguous positions in one transaction. Ties are resolved deterministically; boundary moves are no-ops; primary state is preserved.
+- Tests cover invalid requests, ownership, CSRF, missing images, boundary moves, tied positions, rollback after the first write, concurrent moves, and UI success/failure recovery.
+- Validation: 171 API tests, 26 isolated PostgreSQL/Redis integration tests, 11 web tests, production web build, Storybook build, and 32 Storybook suites / 126 tests. No migration required.
+
+Next bounded slice: image mutation payload validation. The legacy absolute-order and alt-text endpoints currently pass unchecked request fields into the service. Add strict schemas and domain validation for these updates, provide clear UI validation feedback, and test malformed/oversized requests without changing valid image workflows.
 
 ## Next Milestone
 
diff --git a/packages/validation/image.js b/packages/validation/image.js
index cbecde8..7f29edf 100644
--- a/packages/validation/image.js
+++ b/packages/validation/image.js
@@ -10,4 +10,7 @@ export const createInventoryImageSchema = z.object({
   altText: z.string().trim().max(1000).optional(),
   sortOrder: z.int().nonnegative().optional(),
   isPrimary: z.boolean().optional(),
-}).strict();
\ No newline at end of file
+}).strict();
+export const moveInventoryImageSchema = z.object({
+  direction: z.enum(['up', 'down']),
+}).strict();