Improve attachment memory safety, downloads, and high-memory alert UX.

Stream large receives to disk with chunk acks to cap renderer RAM, evict
off-screen display blobs, and route exports through a disk-aware download
service. Fix the high-memory dialog (backdrop dismiss, copy, log actions),
allow diagnostics paths in the path jail, and restore persisted image
hydration after reload.

Co-authored-by: Cursor <cursoragent@cursor.com>

toju-app/src/app/domains/attachment/application/services/attachment-persistence.service.spec.ts

@@ -99,7 +99,17 @@ describe('AttachmentPersistenceService', () => {
   });
 
   it('hydrates blob URLs on demand for a single attachment', async () => {
-    const service = createService();
+    const injector = Injector.create({
+      providers: [
+        AttachmentPersistenceService,
+        AttachmentRuntimeStore,
+        { provide: DatabaseService, useValue: database },
+        { provide: AttachmentStorageService, useValue: attachmentStorage },
+        { provide: Store, useValue: { select: () => of('room-1') } }
+      ]
+    });
+    const service = runInInjectionContext(injector, () => injector.get(AttachmentPersistenceService));
+    const runtimeStore = injector.get(AttachmentRuntimeStore);
 
     await service.initFromDatabase();
 
@@ -113,10 +123,12 @@ describe('AttachmentPersistenceService', () => {
       savedPath: '/appdata/photo.png',
       available: false
     };
+    const versionBefore = runtimeStore.updated();
 
     await expect(service.ensureInlineDisplayObjectUrl(attachment)).resolves.toBe(true);
     expect(attachment.available).toBe(true);
     expect(attachment.objectUrl).toMatch(/^blob:/);
+    expect(runtimeStore.updated()).toBeGreaterThan(versionBefore);
     expect(attachmentStorage.getFileSize).toHaveBeenCalledWith('/appdata/photo.png');
     expect(attachmentStorage.readFileChunk).toHaveBeenCalled();
     expect(attachmentStorage.readFile).not.toHaveBeenCalled();
@@ -206,4 +218,49 @@ describe('AttachmentPersistenceService', () => {
     expect(attachmentStorage.readFileChunk).not.toHaveBeenCalled();
     expect(database.saveAttachment).toHaveBeenCalled();
   });
+
+  it('restores host metadata without hydrating media blobs when display hydration is disabled', async () => {
+    const service = createService();
+    const attachment = {
+      id: 'att-1',
+      messageId: 'msg-1',
+      filename: 'photo.png',
+      size: 3,
+      mime: 'image/png',
+      isImage: true,
+      savedPath: '/appdata/photo.png',
+      available: false
+    };
+
+    await expect(service.tryRestoreAttachmentHostOnly(attachment)).resolves.toBe(true);
+
+    expect(attachment.savedPath).toBe('/appdata/photo.png');
+    expect(attachment.objectUrl).toBeUndefined();
+    expect(attachment.available).toBe(false);
+    expect(attachmentStorage.readFileChunk).not.toHaveBeenCalled();
+    expect(attachmentStorage.readFile).not.toHaveBeenCalled();
+  });
+
+  it('revokes display blobs while keeping disk paths for later rehydration', () => {
+    const service = createService();
+    const attachment = {
+      id: 'att-1',
+      messageId: 'msg-1',
+      filename: 'photo.png',
+      size: 3,
+      mime: 'image/png',
+      isImage: true,
+      savedPath: '/appdata/photo.png',
+      available: true,
+      objectUrl: 'blob:http://localhost/abc'
+    };
+    const revokeSpy = vi.spyOn(URL, 'revokeObjectURL').mockImplementation(() => undefined);
+
+    expect(service.revokeAttachmentDisplayBlob(attachment)).toBe(true);
+    expect(attachment.objectUrl).toBeUndefined();
+    expect(attachment.savedPath).toBe('/appdata/photo.png');
+    expect(revokeSpy).toHaveBeenCalledWith('blob:http://localhost/abc');
+
+    revokeSpy.mockRestore();
+  });
 });