diff --git a/apps/desktop/src/services/AgentService/infrastructure/attachments/storage.ts b/apps/desktop/src/services/AgentService/infrastructure/attachments/storage.ts
index 735c4906..21e2b617 100644
--- a/apps/desktop/src/services/AgentService/infrastructure/attachments/storage.ts
+++ b/apps/desktop/src/services/AgentService/infrastructure/attachments/storage.ts
@@ -118,6 +118,14 @@ async function buildAttachmentStoragePath(
     return join(shardDir, hash);
 }
 
+async function ensureAttachmentStorageFile(sourcePath: string, targetPath: string): Promise<void> {
+    if (await exists(targetPath)) {
+        return;
+    }
+
+    await copyFile(sourcePath, targetPath);
+}
+
 async function ensureAttachmentRecord(
     type: AttachmentIndex['type'],
     path: string,
@@ -131,13 +139,14 @@ async function ensureAttachmentRecord(
         getFileSize(path),
     ]);
 
+    const targetPath = await buildAttachmentStoragePath(type, hash);
     const existing = await findAttachmentByHash(hash, database);
     if (existing) {
+        await ensureAttachmentStorageFile(path, targetPath);
         return existing;
     }
 
-    const targetPath = await buildAttachmentStoragePath(type, hash);
-    await copyFile(path, targetPath);
+    await ensureAttachmentStorageFile(path, targetPath);
 
     try {
         return await createAttachmentRecord(
diff --git a/apps/desktop/tests/services/AgentService/infrastructure/attachment-storage.test.ts b/apps/desktop/tests/services/AgentService/infrastructure/attachment-storage.test.ts
new file mode 100644
index 00000000..5bb6ebe2
--- /dev/null
+++ b/apps/desktop/tests/services/AgentService/infrastructure/attachment-storage.test.ts
@@ -0,0 +1,176 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+
+import type { AttachmentIndex } from '@/services/AgentService/infrastructure/attachments';
+import { ensurePersistedAttachmentIndex } from '@/services/AgentService/infrastructure/attachments';
+
+const {
+    convertFileSrcMock,
+    copyFileMock,
+    createAttachmentRecordMock,
+    digestMock,
+    existsMock,
+    fetchMock,
+    findAttachmentByHashMock,
+    fullNameMock,
+    getAppDirectoryPathMock,
+    iconMock,
+    joinMock,
+    mkdirMock,
+    randomUUIDMock,
+    sizeMock,
+    writeFileMock,
+} = vi.hoisted(() => ({
+    convertFileSrcMock: vi.fn(),
+    copyFileMock: vi.fn(),
+    createAttachmentRecordMock: vi.fn(),
+    digestMock: vi.fn(),
+    existsMock: vi.fn(),
+    fetchMock: vi.fn(),
+    findAttachmentByHashMock: vi.fn(),
+    fullNameMock: vi.fn(),
+    getAppDirectoryPathMock: vi.fn(),
+    iconMock: vi.fn(),
+    joinMock: vi.fn(),
+    mkdirMock: vi.fn(),
+    randomUUIDMock: vi.fn(),
+    sizeMock: vi.fn(),
+    writeFileMock: vi.fn(),
+}));
+
+vi.mock('@database', () => ({
+    db: {},
+}));
+
+vi.mock('@database/queries', () => ({
+    createAttachmentRecord: createAttachmentRecordMock,
+    findAttachmentByHash: findAttachmentByHashMock,
+}));
+
+vi.mock('@services/NativeService', () => ({
+    native: {
+        paths: {
+            getAppDirectoryPath: getAppDirectoryPathMock,
+        },
+    },
+}));
+
+vi.mock('@tauri-apps/api/core', () => ({
+    convertFileSrc: convertFileSrcMock,
+}));
+
+vi.mock('@tauri-apps/api/path', () => ({
+    join: joinMock,
+}));
+
+vi.mock('@tauri-apps/plugin-fs', () => ({
+    copyFile: copyFileMock,
+    exists: existsMock,
+    mkdir: mkdirMock,
+    writeFile: writeFileMock,
+}));
+
+vi.mock('tauri-plugin-fs-pro-api', () => ({
+    fullName: fullNameMock,
+    icon: iconMock,
+    size: sizeMock,
+}));
+
+function buildDraftAttachment(path = 'C:/source/report.txt'): AttachmentIndex {
+    return {
+        id: 'draft-attachment',
+        type: 'file',
+        path,
+        originPath: path,
+        name: 'report.txt',
+        size: 12,
+        supportStatus: 'supported',
+    };
+}
+
+function expectedCachePath(hash: string): string {
+    return `C:/TouchAI/cache/attachments/files/${hash.slice(0, 3)}/${hash}`;
+}
+
+describe('attachment storage persistence', () => {
+    beforeEach(() => {
+        vi.clearAllMocks();
+
+        const digest = new Uint8Array(32);
+        digest.forEach((_, index) => {
+            digest[index] = index;
+        });
+
+        digestMock.mockResolvedValue(digest.buffer);
+        randomUUIDMock.mockReturnValue('generated-id');
+        vi.stubGlobal('crypto', {
+            randomUUID: randomUUIDMock,
+            subtle: {
+                digest: digestMock,
+            },
+        });
+
+        fetchMock.mockResolvedValue({
+            ok: true,
+            arrayBuffer: async () => new Uint8Array([1, 2, 3]).buffer,
+        });
+        vi.stubGlobal('fetch', fetchMock);
+
+        convertFileSrcMock.mockImplementation((path: string) => `asset://${path}`);
+        getAppDirectoryPathMock.mockResolvedValue('C:/TouchAI/cache');
+        joinMock.mockImplementation(async (...parts: string[]) => parts.join('/'));
+        mkdirMock.mockResolvedValue(undefined);
+        fullNameMock.mockResolvedValue('report.txt');
+        sizeMock.mockResolvedValue(12);
+        iconMock.mockImplementation(async (path: string) => `${path}.ico`);
+        createAttachmentRecordMock.mockRejectedValue(new Error('unexpected insert'));
+    });
+
+    it('restores a missing cache file before reusing an existing hash record', async () => {
+        existsMock.mockResolvedValue(false);
+        findAttachmentByHashMock.mockImplementation(async (hash: string) => ({
+            id: 42,
+            hash,
+            type: 'file',
+            original_name: 'report.txt',
+            origin_path: 'C:/source/report.txt',
+            mime_type: null,
+            size: 12,
+            created_at: '2026-01-01T00:00:00.000Z',
+        }));
+
+        const attachment = buildDraftAttachment();
+        const persisted = await ensurePersistedAttachmentIndex(attachment, {} as never);
+
+        expect(findAttachmentByHashMock).toHaveBeenCalled();
+        const [hash] = findAttachmentByHashMock.mock.calls[0]!;
+        const cachePath = expectedCachePath(hash);
+
+        expect(persisted.id).toBe(42);
+        expect(createAttachmentRecordMock).not.toHaveBeenCalled();
+        expect(copyFileMock).toHaveBeenCalledWith('C:/source/report.txt', cachePath);
+        expect(attachment.attachmentId).toBe(42);
+        expect(attachment.hash).toBe(hash);
+        expect(attachment.path).toBe(cachePath);
+        expect(attachment.preview).toBe(`asset://${cachePath}.ico`);
+    });
+
+    it('does not copy an existing cache file when reusing a hash record', async () => {
+        existsMock.mockResolvedValue(true);
+        findAttachmentByHashMock.mockImplementation(async (hash: string) => ({
+            id: 43,
+            hash,
+            type: 'file',
+            original_name: 'report.txt',
+            origin_path: 'C:/source/report.txt',
+            mime_type: null,
+            size: 12,
+            created_at: '2026-01-01T00:00:00.000Z',
+        }));
+
+        const persisted = await ensurePersistedAttachmentIndex(buildDraftAttachment(), {} as never);
+
+        expect(persisted.id).toBe(43);
+        expect(createAttachmentRecordMock).not.toHaveBeenCalled();
+        expect(copyFileMock).not.toHaveBeenCalled();
+    });
+});