diff --git a/packages/rivetkit/package.json b/packages/rivetkit/package.json
index b03b2e34a..41479af3c 100644
--- a/packages/rivetkit/package.json
+++ b/packages/rivetkit/package.json
@@ -163,7 +163,7 @@
     "@bare-ts/lib": "~0.3.0",
     "@hono/standard-validator": "^0.1.3",
     "@hono/zod-openapi": "^0.19.10",
-    "@rivetkit/engine-runner": "https://pkg.pr.new/rivet-dev/engine/@rivetkit/engine-runner@f594631",
+    "@rivetkit/engine-runner": "https://pkg.pr.new/rivet-dev/engine/@rivetkit/engine-runner@03e3532",
     "@rivetkit/fast-json-patch": "^3.1.2",
     "cbor-x": "^1.6.0",
     "hono": "^4.7.0",
diff --git a/packages/rivetkit/src/drivers/engine/actor-driver.ts b/packages/rivetkit/src/drivers/engine/actor-driver.ts
index 0dae41616..755166901 100644
--- a/packages/rivetkit/src/drivers/engine/actor-driver.ts
+++ b/packages/rivetkit/src/drivers/engine/actor-driver.ts
@@ -411,9 +411,9 @@ export class EngineActorDriver implements ActorDriver {
 
 		return streamSSE(c, async (stream) => {
 			// Runner id should be set if the runner started
-			const runnerId = this.#runner.runnerId;
-			invariant(runnerId, "runnerId not set");
-			stream.writeSSE({ data: runnerId });
+			const payload = this.#runner.getServerlessInitPacket();
+			invariant(payload, "runnerId not set");
+			stream.writeSSE({ data: payload });
 
 			return this.#runnerStopped.promise;
 		});
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index ec1d0e5fd..6f6dfc66a 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -1131,8 +1131,8 @@ importers:
         specifier: ^0.19.10
         version: 0.19.10(hono@4.9.8)(zod@3.25.76)
       '@rivetkit/engine-runner':
-        specifier: https://pkg.pr.new/rivet-dev/engine/@rivetkit/engine-runner@f594631
-        version: https://pkg.pr.new/rivet-dev/engine/@rivetkit/engine-runner@f594631(bufferutil@4.0.9)
+        specifier: https://pkg.pr.new/rivet-dev/engine/@rivetkit/engine-runner@03e3532
+        version: https://pkg.pr.new/rivet-dev/engine/@rivetkit/engine-runner@03e3532(bufferutil@4.0.9)
       '@rivetkit/fast-json-patch':
         specifier: ^3.1.2
         version: 3.1.2
@@ -2499,13 +2499,13 @@ packages:
   '@polka/url@1.0.0-next.29':
     resolution: {integrity: sha512-wwQAWhWSuHaag8c4q/KN/vCoeOJYshAIvMQwD4GpSb3OiZklFfvAgmj0VCBBImRpuF/aFgIRzllXlVX93Jevww==}
 
-  '@rivetkit/engine-runner-protocol@https://pkg.pr.new/rivet-dev/engine/@rivetkit/engine-runner-protocol@f5946317869fd2a1f81694074e867cffbb94c178':
-    resolution: {tarball: https://pkg.pr.new/rivet-dev/engine/@rivetkit/engine-runner-protocol@f5946317869fd2a1f81694074e867cffbb94c178}
-    version: 25.7.1
+  '@rivetkit/engine-runner-protocol@https://pkg.pr.new/rivet-dev/engine/@rivetkit/engine-runner-protocol@03e3532bf8291753196247ecf667a3e4e7955133':
+    resolution: {tarball: https://pkg.pr.new/rivet-dev/engine/@rivetkit/engine-runner-protocol@03e3532bf8291753196247ecf667a3e4e7955133}
+    version: 25.7.2
 
-  '@rivetkit/engine-runner@https://pkg.pr.new/rivet-dev/engine/@rivetkit/engine-runner@f594631':
-    resolution: {tarball: https://pkg.pr.new/rivet-dev/engine/@rivetkit/engine-runner@f594631}
-    version: 25.7.1
+  '@rivetkit/engine-runner@https://pkg.pr.new/rivet-dev/engine/@rivetkit/engine-runner@03e3532':
+    resolution: {tarball: https://pkg.pr.new/rivet-dev/engine/@rivetkit/engine-runner@03e3532}
+    version: 25.7.2
 
   '@rivetkit/fast-json-patch@3.1.2':
     resolution: {integrity: sha512-CtA50xgsSSzICQduF/NDShPRzvucnNvsW/lQO0WgMTT1XAj9Lfae4pm7r3llFwilgG+9iq76Hv1LUqNy72v6yw==}
@@ -5780,13 +5780,13 @@ snapshots:
 
   '@polka/url@1.0.0-next.29': {}
 
-  '@rivetkit/engine-runner-protocol@https://pkg.pr.new/rivet-dev/engine/@rivetkit/engine-runner-protocol@f5946317869fd2a1f81694074e867cffbb94c178':
+  '@rivetkit/engine-runner-protocol@https://pkg.pr.new/rivet-dev/engine/@rivetkit/engine-runner-protocol@03e3532bf8291753196247ecf667a3e4e7955133':
     dependencies:
       '@bare-ts/lib': 0.4.0
 
-  '@rivetkit/engine-runner@https://pkg.pr.new/rivet-dev/engine/@rivetkit/engine-runner@f594631(bufferutil@4.0.9)':
+  '@rivetkit/engine-runner@https://pkg.pr.new/rivet-dev/engine/@rivetkit/engine-runner@03e3532(bufferutil@4.0.9)':
     dependencies:
-      '@rivetkit/engine-runner-protocol': https://pkg.pr.new/rivet-dev/engine/@rivetkit/engine-runner-protocol@f5946317869fd2a1f81694074e867cffbb94c178
+      '@rivetkit/engine-runner-protocol': https://pkg.pr.new/rivet-dev/engine/@rivetkit/engine-runner-protocol@03e3532bf8291753196247ecf667a3e4e7955133
       pino: 9.9.5
       uuid: 12.0.0
       ws: 8.18.3(bufferutil@4.0.9)