From 2b600fd4b7d2ffed053709a7ba7b4424d91b641a Mon Sep 17 00:00:00 2001
From: Sree Narayanan <sreeaadhi07@gmail.com>
Date: Wed, 2 Sep 2026 00:33:22 +0400
Subject: [PATCH] fix(rivetkit): preserve engine bind defaults

---
 .../rivetkit/src/registry/config/index.ts      |  8 ++++----
 .../tests/registry-constructor.test.ts         | 18 ++++++++++++++++++
 2 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/rivetkit-typescript/packages/rivetkit/src/registry/config/index.ts b/rivetkit-typescript/packages/rivetkit/src/registry/config/index.ts
index 60843f6e22..6d65c14849 100644
--- a/rivetkit-typescript/packages/rivetkit/src/registry/config/index.ts
+++ b/rivetkit-typescript/packages/rivetkit/src/registry/config/index.ts
@@ -225,7 +225,7 @@ export const RegistryConfigSchema = z
 		engineHost: z
 			.string()
 			.optional()
-			.default(() => getRivetRunEngineHost() ?? ENGINE_HOST),
+			.transform((value) => value ?? getRivetRunEngineHost()),
 		/**
 		 * @experimental
 		 *
@@ -237,7 +237,7 @@ export const RegistryConfigSchema = z
 			.min(1)
 			.max(65_535)
 			.optional()
-			.default(() => getRivetRunEnginePort() ?? ENGINE_PORT),
+			.transform((value) => value ?? getRivetRunEnginePort()),
 		/** @experimental */
 		engineVersion: z
 			.string()
@@ -347,8 +347,8 @@ export const RegistryConfigSchema = z
 
 		// Flatten the endpoint and apply defaults for namespace/token.
 		const localEngineEndpoint = buildEngineEndpoint(
-			config.engineHost,
-			config.enginePort,
+			config.engineHost ?? ENGINE_HOST,
+			config.enginePort ?? ENGINE_PORT,
 		);
 		const endpoint = config.startEngine
 			? localEngineEndpoint
diff --git a/rivetkit-typescript/packages/rivetkit/tests/registry-constructor.test.ts b/rivetkit-typescript/packages/rivetkit/tests/registry-constructor.test.ts
index 314bd9d328..c40a0aca85 100644
--- a/rivetkit-typescript/packages/rivetkit/tests/registry-constructor.test.ts
+++ b/rivetkit-typescript/packages/rivetkit/tests/registry-constructor.test.ts
@@ -108,6 +108,24 @@ describe("Registry constructor", () => {
 		expect(config.publicEndpoint).toBe("http://127.0.0.1:7655");
 	});
 
+	test("does not override the bind address for an explicit engine endpoint", async () => {
+		const config = RegistryConfigSchema.parse({
+			use: {
+				test: testActor,
+			},
+			startEngine: false,
+			endpoint: "http://127.0.0.1:7656",
+		});
+
+		const serveConfig = await buildServeConfig(config);
+
+		expect(new URL(serveConfig.endpoint).origin).toBe(
+			"http://127.0.0.1:7656",
+		);
+		expect(serveConfig.engineHost).toBeUndefined();
+		expect(serveConfig.enginePort).toBeUndefined();
+	});
+
 	test("keeps endpoint separate from spawned local engine config", () => {
 		const result = RegistryConfigSchema.safeParse({
 			use: {