feat: add task workflow and asset downloads

lib/server/webhook.ts

@@ -0,0 +1,71 @@
+import { createHmac } from "node:crypto";
+import type { GenerationJob, WebhookLastStatus } from "@/lib/types";
+
+export type JobWebhookPayload = {
+  jobId: string;
+  status: GenerationJob["status"];
+  capability: GenerationJob["capability"];
+  outputAssetIds: string[];
+  error?: GenerationJob["error"];
+  updatedAt: string;
+};
+
+const MAX_WEBHOOK_ATTEMPTS = 3;
+
+export function buildJobWebhookPayload(job: GenerationJob): JobWebhookPayload {
+  return {
+    jobId: job.id,
+    status: job.status,
+    capability: job.capability,
+    outputAssetIds: job.outputAssetIds,
+    error: job.error,
+    updatedAt: job.updatedAt
+  };
+}
+
+export function signWebhookBody(body: string, secret = process.env.ZHINIAN_WEBHOOK_SECRET): string | undefined {
+  if (!secret?.trim()) return undefined;
+  return `sha256=${createHmac("sha256", secret.trim()).update(body).digest("hex")}`;
+}
+
+export async function deliverJobWebhook(job: GenerationJob): Promise<{
+  attempts: number;
+  lastStatus?: WebhookLastStatus;
+}> {
+  if (!job.webhookUrl) return { attempts: job.webhookAttempts || 0 };
+  let attempts = job.webhookAttempts || 0;
+  let lastStatus: WebhookLastStatus | undefined = job.webhookLastStatus;
+  const payload = buildJobWebhookPayload(job);
+  const body = JSON.stringify(payload);
+  const signature = signWebhookBody(body);
+
+  while (attempts < MAX_WEBHOOK_ATTEMPTS) {
+    attempts += 1;
+    const attemptedAt = new Date().toISOString();
+    try {
+      const response = await fetch(job.webhookUrl, {
+        method: "POST",
+        headers: {
+          "Content-Type": "application/json",
+          "User-Agent": "zhinian-aigc-webhook/1.0",
+          ...(signature ? { "X-Zhinian-Signature": signature } : {})
+        },
+        body
+      });
+      lastStatus = {
+        ok: response.ok,
+        status: response.status,
+        attemptedAt
+      };
+      if (response.ok) break;
+    } catch (error) {
+      lastStatus = {
+        ok: false,
+        error: error instanceof Error ? error.message : String(error),
+        attemptedAt
+      };
+    }
+  }
+
+  return { attempts, lastStatus };
+}