fix(rivetkit): expose client actor metadata

CLAUDE.md

@@ -24,6 +24,7 @@ Design constraints, invariants, and reference commands for the Rivet monorepo. F
 
 - Avoid raw `f64` fields in vbare protocol schemas that use hashable maps; generated Rust derives `Eq`/`Hash`, so encode floats as fixed bytes or an ordered wrapper.
 - Version converters must manually map fields between versions; never use serialize-deserialize round trips such as `transcode_version` or `serde_bare::to_vec` plus `from_slice`.
+- RivetKit client/server protocol compatibility assumes the server/runtime is newer than the client; clients send their latest request protocol version, and servers handle older-client compatibility and negotiation.
 
 When talking about "Rivet Actors" make sure to capitalize "Rivet Actor" as a proper noun and lowercase "actor" as a generic noun.
 

rivetkit-asyncapi/asyncapi.json

@@ -123,6 +123,33 @@
                               "type": "null"
                             }
                           ]
+                        },
+                        "actor": {
+                          "type": "object",
+                          "properties": {
+                            "actorId": {
+                              "type": "string"
+                            },
+                            "generation": {
+                              "anyOf": [
+                                {
+                                  "type": "number"
+                                },
+                                {
+                                  "type": "integer",
+                                  "format": "int64"
+                                }
+                              ]
+                            },
+                            "key": {
+                              "type": "string"
+                            }
+                          },
+                          "required": [
+                            "actorId",
+                            "generation"
+                          ],
+                          "additionalProperties": false
                         }
                       },
                       "required": [
@@ -421,6 +448,33 @@
                 "type": "null"
               }
             ]
+          },
+          "actor": {
+            "type": "object",
+            "properties": {
+              "actorId": {
+                "type": "string"
+              },
+              "generation": {
+                "anyOf": [
+                  {
+                    "type": "number"
+                  },
+                  {
+                    "type": "integer",
+                    "format": "int64"
+                  }
+                ]
+              },
+              "key": {
+                "type": "string"
+              }
+            },
+            "required": [
+              "actorId",
+              "generation"
+            ],
+            "additionalProperties": false
           }
         },
         "required": [

rivetkit-typescript/packages/rivetkit/src/client/actor-conn.ts

@@ -216,6 +216,9 @@ export class ActorConnRaw {
 		this.#encoding = encoding;
 		this.#actorResolutionState = actorResolutionState;
 		this.#gatewayOptions = resolveActorGatewayOptions(gatewayOptions);
+		if ("getForId" in actorResolutionState) {
+			this.#actorId = actorResolutionState.getForId.actorId;
+		}
 		this.#readyPromise = promiseWithResolvers((reason) =>
 			logger().warn({
 				msg: "unhandled ready promise rejection",

rivetkit-typescript/packages/rivetkit/tests/driver/actor-conn.test.ts

@@ -100,6 +100,20 @@ describeDriverMatrix("Actor Conn", (driverTestConfig) => {
 				await connection.dispose();
 			});
 
+			test("should expose actorId after connection init", async (c) => {
+				const { client } = await setupDriverTest(c, driverTestConfig);
+
+				const handle = client.counter.getOrCreate([
+					"test-conn-actor-id",
+				]);
+				const connection = handle.connect();
+
+				await connection.ready;
+				expect(connection.actorId).toBe(await handle.resolve());
+
+				await connection.dispose();
+			});
+
 			test("should connect using (await create()).connect()", async (c) => {
 				const { client } = await setupDriverTest(c, driverTestConfig);