feat: implement PI core chat timeline

electron/main/ipc/host-api-proxy.ts

@@ -43,11 +43,19 @@ export function registerHostApiProxyHandlers(hostApiContext?: HostApiContext): v
       // Inject the per-session auth token so the Host API server accepts this request.
       headers['Authorization'] = `Bearer ${getHostApiToken()}`;
       headers[RENDERER_CAPABILITY_HEADER] = getRendererCapability();
-      let body: string | undefined;
+      let body: string | Uint8Array | undefined;
 
       if (request.body !== undefined && request.body !== null) {
         if (typeof request.body === 'string') {
           body = request.body;
+        } else if (request.body instanceof ArrayBuffer) {
+          body = new Uint8Array(request.body);
+        } else if (ArrayBuffer.isView(request.body)) {
+          body = new Uint8Array(
+            request.body.buffer,
+            request.body.byteOffset,
+            request.body.byteLength,
+          );
         } else {
           body = JSON.stringify(request.body);
         }
@@ -79,7 +87,14 @@ export function registerHostApiProxyHandlers(hostApiContext?: HostApiContext): v
         body,
       });
 
-      const data: { status: number; ok: boolean; json?: unknown; text?: string } = {
+      const data: {
+        status: number;
+        ok: boolean;
+        json?: unknown;
+        text?: string;
+        bytes?: Uint8Array;
+        contentType?: string;
+      } = {
         status: response.status,
         ok: response.ok,
       };
@@ -88,6 +103,9 @@ export function registerHostApiProxyHandlers(hostApiContext?: HostApiContext): v
         const contentType = response.headers.get('content-type') || '';
         if (contentType.includes('application/json')) {
           data.json = await response.json().catch(() => undefined);
+        } else if (contentType.startsWith('image/') || contentType === 'application/octet-stream') {
+          data.bytes = new Uint8Array(await response.arrayBuffer());
+          data.contentType = contentType.split(';', 1)[0]?.trim() || 'application/octet-stream';
         } else {
           data.text = await response.text().catch(() => '');
         }