feat: expose tenant-safe dataset describe route

app/api/0pt/datasets/[datasetId]/route.ts

@@ -0,0 +1,27 @@
+import { NextRequest, NextResponse } from "next/server";
+
+import { assertTenantMatchesVerified } from "@/src/http/tenant-guard";
+import { siaxErrorResponse } from "@/src/http/siax-error-response";
+import { SiaxError } from "@/src/platform/errors";
+import { datasetService } from "@/src/services/datasets";
+
+export async function GET(
+  request: NextRequest,
+  { params }: { params: Promise<{ datasetId: string }> },
+) {
+  try {
+    const { datasetId } = await params;
+    const tenantId = new URL(request.url).searchParams.get("tenant_id")?.trim();
+    if (!tenantId) throw new SiaxError("INVALID_REQUEST", "0pt.dataset", "tenant_id is required");
+    const guard = assertTenantMatchesVerified(request, tenantId);
+    if (guard) return guard;
+
+    const dataset = await datasetService.getDataset(datasetId);
+    if (dataset.tenant_id !== tenantId) {
+      throw new SiaxError("NOT_FOUND", "0pt.dataset", `dataset ${datasetId} not found`);
+    }
+    return NextResponse.json(dataset);
+  } catch (error: unknown) {
+    return siaxErrorResponse(error);
+  }
+}