feat: add task workflow and asset downloads

app/api/v1/jobs/[id]/cancel/route.ts

@@ -0,0 +1,26 @@
+import { clearGenerationJobLock, getGenerationJob, updateGenerationJob } from "@/lib/server/data-store";
+import { jsonError, jsonOk } from "@/lib/server/api";
+import { authenticatePublicApiRequest } from "@/lib/server/public-api-auth";
+import { publicApiError } from "@/lib/server/public-api-response";
+
+export const runtime = "nodejs";
+
+export async function POST(request: Request, context: { params: Promise<{ id: string }> }) {
+  try {
+    const client = authenticatePublicApiRequest(request);
+    const { id } = await context.params;
+    const job = await getGenerationJob(id);
+    if (!job || job.externalClientId !== client.id) return jsonError("Job not found.", 404);
+    if (["succeeded", "failed", "expired", "cancelled"].includes(job.status)) {
+      return jsonOk({ job });
+    }
+    await updateGenerationJob(id, {
+      status: "cancelled",
+      completedAt: new Date().toISOString()
+    });
+    const cancelled = await clearGenerationJobLock(id);
+    return jsonOk({ job: cancelled });
+  } catch (error) {
+    return publicApiError(error);
+  }
+}