fix: handle BigInt serialization in REST API v1 detail endpoints (#53)

GET /api/v1/pipelines/:id and /api/v1/nodes/:id return 500 because
NodePipelineStatus contains BigInt fields (eventsIn, eventsOut, etc.)
that JSON.stringify cannot serialize. Adds a jsonResponse() helper
using a custom replacer to convert BigInts to numbers.

Author: TerrifiedBug

src/app/api/v1/_lib/api-handler.ts

@@ -6,6 +6,18 @@ import {
   type ServiceAccountContext,
 } from "@/server/middleware/api-auth";
 
+/** BigInt-safe NextResponse.json() — converts BigInts to numbers before serialization. */
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
+export function jsonResponse(data: any, init?: { status?: number }) {
+  const body = JSON.stringify(data, (_key, value) =>
+    typeof value === "bigint" ? Number(value) : value,
+  );
+  return new NextResponse(body, {
+    status: init?.status ?? 200,
+    headers: { "Content-Type": "application/json" },
+  });
+}
+
 const TRPC_TO_HTTP: Record<string, number> = {
   NOT_FOUND: 404,
   BAD_REQUEST: 400,

src/app/api/v1/nodes/[id]/route.ts

@@ -1,6 +1,6 @@
 import { NextResponse } from "next/server";
 import { prisma } from "@/lib/prisma";
-import { apiRoute } from "../../_lib/api-handler";
+import { apiRoute, jsonResponse } from "../../_lib/api-handler";
 
 export const GET = apiRoute("nodes.read", async (_req, ctx, params) => {
   const id = params?.id;
@@ -41,5 +41,5 @@ export const GET = apiRoute("nodes.read", async (_req, ctx, params) => {
     return NextResponse.json({ error: "Node not found" }, { status: 404 });
   }
 
-  return NextResponse.json({ node });
+  return jsonResponse({ node });
 });

src/app/api/v1/pipelines/[id]/route.ts

@@ -1,6 +1,6 @@
 import { NextResponse } from "next/server";
 import { prisma } from "@/lib/prisma";
-import { apiRoute } from "../../_lib/api-handler";
+import { apiRoute, jsonResponse } from "../../_lib/api-handler";
 
 export const GET = apiRoute("pipelines.read", async (_req, ctx, params) => {
   const id = params?.id;
@@ -58,5 +58,5 @@ export const GET = apiRoute("pipelines.read", async (_req, ctx, params) => {
     );
   }
 
-  return NextResponse.json({ pipeline });
+  return jsonResponse({ pipeline });
 });