feat: implement PI core chat timeline

tests/unit/coding-attachments-facade.test.ts

@@ -0,0 +1,45 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+
+const hostApi = vi.hoisted(() => ({
+  fetch: vi.fn(),
+  fetchBytes: vi.fn(),
+}));
+
+vi.mock('@/lib/host-api', () => ({
+  hostApiFetch: hostApi.fetch,
+  hostApiFetchBytes: hostApi.fetchBytes,
+}));
+
+describe('coding attachment Host facade', () => {
+  beforeEach(() => vi.clearAllMocks());
+
+  it('uploads raw image bytes only when invoked and returns the attachment reference', async () => {
+    const attachment = { attachmentId: 'attachment-1', mime: 'image/png', byteLength: 4 };
+    hostApi.fetch.mockResolvedValueOnce(attachment);
+    const { uploadCodingAttachment } = await import('@/lib/coding-attachments');
+    const file = new File([new Uint8Array([1, 2, 3, 4])], 'pixel.png', { type: 'image/png' });
+
+    await expect(uploadCodingAttachment(file)).resolves.toEqual(attachment);
+    expect(hostApi.fetch).toHaveBeenCalledOnce();
+    const [path, init] = hostApi.fetch.mock.calls[0] as [string, RequestInit];
+    expect(path).toBe('/api/coding/attachments');
+    expect(init).toMatchObject({ method: 'POST', headers: { 'Content-Type': 'image/png' } });
+    expect(Array.from(new Uint8Array(init.body as ArrayBuffer))).toEqual([1, 2, 3, 4]);
+  });
+
+  it('loads an authenticated binary preview without constructing a data URL', async () => {
+    hostApi.fetchBytes.mockResolvedValueOnce({
+      bytes: new Uint8Array([5, 6, 7]),
+      contentType: 'image/webp',
+    });
+    const { loadCodingAttachmentPreview } = await import('@/lib/coding-attachments');
+
+    await expect(loadCodingAttachmentPreview('attachment/a')).resolves.toEqual({
+      bytes: new Uint8Array([5, 6, 7]),
+      mime: 'image/webp',
+    });
+    expect(hostApi.fetchBytes).toHaveBeenCalledWith(
+      '/api/coding/attachments/attachment%2Fa/content',
+    );
+  });
+});