fix(next-js): disable health check during build phase

Author: NathanFlurry

packages/rivetkit/src/client/client.ts

@@ -4,6 +4,7 @@ import type { Encoding } from "@/actor/protocol/serde";
 import type { ManagerDriver } from "@/driver-helpers/mod";
 import type { ActorQuery } from "@/manager/protocol/query";
 import type { Registry } from "@/registry/mod";
+import { getEnvUniversal } from "@/utils";
 import type { ActorActionFunction } from "./actor-common";
 import {
 	type ActorConn,
@@ -170,6 +171,14 @@ export class ClientRaw {
 	 * Creates an instance of Client.
 	 */
 	public constructor(driver: ManagerDriver, config: ClientConfig) {
+		// Disable health check if in Next.js build phase since there is no `/metadata` endpoint
+		//
+		// See https://github.com/vercel/next.js/blob/5e6b008b561caf2710ab7be63320a3d549474a5b/packages/next/shared/lib/constants.ts#L19-L23
+		if (getEnvUniversal("NEXT_PHASE") === "phase-production-build") {
+			logger().info("detected next.js build phase, disabling health check");
+			config.disableHealthCheck = true;
+		}
+
 		this.#driver = driver;
 
 		this.#encodingKind = config.encoding ?? "bare";