feat(agent): add authenticated durable uploads to backend and web

web/src/lib/agent-room.ts

@@ -1,4 +1,5 @@
 import type { Message } from "./api";
+import { parseAgentAttachment, type AgentAttachment, type AgentAttachmentCapability } from "./agent-attachments.ts";
 
 export type AgentActivity = {
   state: "idle" | "thinking" | "tool" | "waiting" | "error";
@@ -16,7 +17,7 @@ export type AgentMessagesPage = {
 };
 export type AgentDescriptor = {
   id: string; title: string; model: string; activity: AgentActivity;
-  websocket: string; protocol: string;
+  websocket: string; protocol: string; capabilities?: { attachments?: AgentAttachmentCapability };
 };
 export type AgentReadState = { cursor: string; updatedAt: string | null };
 export type AgentRoomState = {
@@ -126,7 +127,7 @@ export function agentAuthFrame(token: string | null, cursor: string): string {
   return JSON.stringify({ type: "auth", token, after: normalizeAgentCursor(cursor) });
 }
 
-export type AgentSubmission = { id: number; status: "queued" | "placed" | "done" | "unanswered"; messageId: string };
+export type AgentSubmission = { id: number; status: "queued" | "placed" | "done" | "unanswered"; messageId: string; attachmentIds?: string[] };
 export type AgentRoomClientOptions = { baseUrl?: string; token?: () => string | null; fetch?: typeof globalThis.fetch };
 export class AgentRoomClient {
   private readonly baseUrl: string;
@@ -141,7 +142,7 @@ export class AgentRoomClient {
     const headers = new Headers(init.headers);
     const token = this.token();
     if (token) headers.set("Authorization", `Bearer ${token}`);
-    if (init.body !== undefined) headers.set("Content-Type", "application/json");
+    if (init.body !== undefined && !(init.body instanceof FormData)) headers.set("Content-Type", "application/json");
     const response = await this.fetcher(`${this.baseUrl}/v1/agent${path}`, { ...init, headers });
     let value: unknown;
     try { value = await response.json(); }
@@ -160,15 +161,30 @@ export class AgentRoomClient {
   markRead(cursor: string, signal?: AbortSignal): Promise<AgentReadState> {
     return this.request("/read-state", { method: "PUT", body: JSON.stringify({ cursor: normalizeAgentCursor(cursor) }), signal });
   }
-  async submit(content: string, requestId: string): Promise<AgentSubmission> {
-    const receipt = object(await this.request<unknown>("/messages", { method: "POST", body: JSON.stringify({ content, requestId }) }));
+  async submit(content: string, requestId: string, attachments: AgentAttachment[] = []): Promise<AgentSubmission> {
+    const receipt = object(await this.request<unknown>("/messages", { method: "POST", body: JSON.stringify({ content, requestId, ...(attachments.length ? { attachments: attachments.map(({ id }) => ({ id })) } : {}) }) }));
     // An HTTP success alone does not acknowledge delivery. Keep the original
     // outbox receipt key retryable if a proxy or upstream returns malformed data.
     if (!receipt || typeof receipt.id !== "number" || !Number.isSafeInteger(receipt.id) || receipt.id <= 0
       || typeof receipt.status !== "string" || !["queued", "placed", "done", "unanswered"].includes(receipt.status)
-      || receipt.messageId !== `inbound:sybil:${requestId}`) throw new Error("Agent API returned an invalid message receipt. Retry to confirm delivery.");
+      || receipt.messageId !== `inbound:sybil:${requestId}`
+      || (attachments.length && JSON.stringify(receipt.attachmentIds) !== JSON.stringify(attachments.map(file => file.id)))) throw new Error("Agent API returned an invalid message receipt. Retry to confirm delivery.");
     return receipt as AgentSubmission;
   }
+  async upload(file: File, uploadId: string, signal?: AbortSignal): Promise<AgentAttachment> {
+    const body = new FormData(); body.append("uploadId", uploadId); body.append("file", file, file.name);
+    const value = await this.request<{ attachment: unknown }>("/attachments", { method: "POST", body, signal });
+    return parseAgentAttachment(value.attachment);
+  }
+  async download(attachment: AgentAttachment, signal?: AbortSignal): Promise<Blob> {
+    const file = parseAgentAttachment(attachment), headers = new Headers(), token = this.token();
+    if (token) headers.set("Authorization", `Bearer ${token}`);
+    const response = await this.fetcher(`${this.baseUrl}/v1/agent/attachments/${encodeURIComponent(file.id)}/content`, { headers, signal, cache: "no-store", redirect: "error" });
+    if (!response.ok) { const error = await response.json().catch(() => null); throw new Error(error?.message || "Attachment download failed."); }
+    const blob = await response.blob();
+    if (blob.size !== file.sizeBytes || blob.size > 8 * 1024 * 1024) throw new Error("Attachment download was incomplete.");
+    return blob;
+  }
   websocketUrl(pageUrl: string): string {
     const url = new URL(`${this.baseUrl}/v1/agent/ws`, pageUrl);
     url.protocol = url.protocol === "https:" ? "wss:" : "ws:";