fix: update to @agentclientprotocol/sdk 2.2.0 (#1491)

Moves to ACP schema v1.28.0 and v2.0.0-alpha.11.

- v2 dropped JSON-RPC batching, so `AnyWireMessage` is gone. The test
harnesses use `AnyMessage`, and a request id can now be `null` in the
types.
- The v2 elicitation schema now requires `properties`. A forwarded MCP
schema without them, such as `{ "type": "object" }`, gets an empty map,
so clients on SDK 2.2.0 don't reject it.

Runtime changes that come with the SDK and need no agent code:
- The SDK handles a repeated `initialize`, rejects batches, and rejects
messages sent before initialization. A failed `initialize` now leaves
the connection open.
- v2 `usage_update.cost` is now a patch field, where omitted means
unchanged. The agent sends `cost` only on the result update, so the
client keeps showing the last cost during a turn.

Follow-up PRs for the spec changes in this range are stacked on this
branch.

package-lock.json

@@ -9,7 +9,7 @@
       "version": "0.99.1",
       "license": "Apache-2.0",
       "dependencies": {
-        "@agentclientprotocol/sdk": "2.1.0",
+        "@agentclientprotocol/sdk": "2.2.0",
         "@anthropic-ai/claude-agent-sdk": "0.3.312",
         "diff": "9.0.0",
         "zod": "4.6.7"
@@ -38,9 +38,9 @@
       }
     },
     "node_modules/@agentclientprotocol/sdk": {
-      "version": "2.1.0",
-      "resolved": "https://registry.npmjs.org/@agentclientprotocol/sdk/-/sdk-2.1.0.tgz",
-      "integrity": "sha512-IuKjJmHLPzbmbg26eK9Jopd8AVxgLuu8fX114YzYAU6tLYclCo2DUzLL4vbCpYGr9mzvs2T0kigE3ZCueL06tg==",
+      "version": "2.2.0",
+      "resolved": "https://registry.npmjs.org/@agentclientprotocol/sdk/-/sdk-2.2.0.tgz",
+      "integrity": "sha512-o1+eDQVb05yzPY+5v54awHyONU1oeLsbLVavkwrMQaZDuJDh/38pQiXJS4ix4d6QA3Y4bU0lHFRjwg99KKKSaQ==",
       "license": "Apache-2.0",
       "peerDependencies": {
         "@modelcontextprotocol/server": "^2.4.0",

package.json

@@ -65,7 +65,7 @@
     "node": ">=22"
   },
   "dependencies": {
-    "@agentclientprotocol/sdk": "2.1.0",
+    "@agentclientprotocol/sdk": "2.2.0",
     "@anthropic-ai/claude-agent-sdk": "0.3.312",
     "diff": "9.0.0",
     "zod": "4.6.7"

src/elicitation.ts

@@ -377,7 +377,9 @@ export function applyAskElicitationResponse(
 /**
  * Coerce an arbitrary MCP `requestedSchema` into an ACP `ElicitationSchema`.
  * The two are structurally compatible JSON Schemas; we just guarantee the
- * `type: "object"` discriminator is present.
+ * `type: "object"` discriminator and a `properties` map are present. The v2
+ * schema requires both, so a client on SDK 2.2.0 or later rejects an MCP
+ * schema such as `{ type: "object" }` that has no `properties`.
  */
 function normalizeElicitationSchema(
   schema: Record<string, unknown> | undefined,
@@ -385,7 +387,8 @@ function normalizeElicitationSchema(
   if (!schema || typeof schema !== "object") {
     return { type: "object", properties: {} };
   }
-  return { ...(schema as ElicitationSchema), type: "object" };
+  const { properties } = schema as Partial<ElicitationSchema>;
+  return { ...(schema as ElicitationSchema), type: "object", properties: properties ?? {} };
 }
 
 /**

src/tests/acp-scenarios/harness.ts

@@ -500,21 +500,17 @@ export async function runScenarioV2(
   const idles: unknown[] = [];
   const failures: string[] = [];
 
-  const each = (message: v2.AnyWireMessage) =>
-    (Array.isArray(message) ? message : [message]) as Record<string, any>[];
-  const toAgent = new TransformStream<v2.AnyWireMessage, v2.AnyWireMessage>({
+  const toAgent = new TransformStream<v2.AnyMessage, v2.AnyMessage>({
     transform(message, controller) {
-      for (const m of each(message)) {
-        if ("method" in m && "id" in m) methodsOfClientRequests.set(m.id, m.method);
+      if ("method" in message && "id" in message && message.id !== null) {
+        methodsOfClientRequests.set(message.id, message.method);
       }
       controller.enqueue(message);
     },
   });
-  const toClient = new TransformStream<v2.AnyWireMessage, v2.AnyWireMessage>({
+  const toClient = new TransformStream<v2.AnyMessage, v2.AnyMessage>({
     transform(message, controller) {
-      for (const m of each(message)) {
-        if (recording) raw.push(wireRecord(m, methodsOfClientRequests));
-      }
+      if (recording) raw.push(wireRecord(message, methodsOfClientRequests));
       controller.enqueue(message);
     },
   });

src/tests/acp-v2.test.ts

@@ -162,8 +162,8 @@ afterEach(async () => {
 
 /** Connects a fresh router to a client, and returns the client end of the stream. */
 function connectRouter(protocols?: AcpProtocols): v2.Stream {
-  const toAgent = new TransformStream<v2.AnyWireMessage, v2.AnyWireMessage>();
-  const toClient = new TransformStream<v2.AnyWireMessage, v2.AnyWireMessage>();
+  const toAgent = new TransformStream<v2.AnyMessage, v2.AnyMessage>();
+  const toClient = new TransformStream<v2.AnyMessage, v2.AnyMessage>();
   acpProtocolRouter(undefined, (agent) => agents.push(agent), protocols).connect({
     readable: toAgent.readable,
     writable: toClient.writable,
@@ -333,11 +333,11 @@ describe("ACP protocol routing", () => {
       params: { protocolVersion: v2.PROTOCOL_VERSION, info: V2_CLIENT_INFO, capabilities: {} },
     });
     const reader = stream.readable.getReader();
-    let response: v2.AnyWireMessage | undefined;
+    let response: v2.AnyMessage | undefined;
     while (!response) {
       const { value, done } = await reader.read();
       if (done) break;
-      if (!Array.isArray(value) && "id" in value && value.id === 1) response = value;
+      if ("id" in value && value.id === 1) response = value;
     }
     await writer.close();
 

src/tests/elicitation.test.ts

@@ -60,6 +60,19 @@ describe("mcpElicitationToCreateRequest", () => {
     });
   });
 
+  it("adds an empty properties map when the MCP schema has none", () => {
+    const request: ElicitationRequest = {
+      serverName: "server",
+      message: "Confirm?",
+      mode: "form",
+      requestedSchema: { type: "object" },
+    };
+
+    const result = mcpElicitationToCreateRequest(request, SESSION_ID);
+
+    expect(result).toMatchObject({ requestedSchema: { type: "object", properties: {} } });
+  });
+
   it("maps a url-mode request and preserves the elicitation id", () => {
     const request: ElicitationRequest = {
       serverName: "server",

src/tests/provider-session-configuration.test.ts

@@ -750,8 +750,8 @@ describe("provider updates preserve session configuration", { timeout: 10_000 },
 
   it("publishes the restored configuration through the v2 protocol router", async () => {
     await agent.dispose();
-    const toAgent = new TransformStream<v2.AnyWireMessage, v2.AnyWireMessage>();
-    const toClient = new TransformStream<v2.AnyWireMessage, v2.AnyWireMessage>();
+    const toAgent = new TransformStream<v2.AnyMessage, v2.AnyMessage>();
+    const toClient = new TransformStream<v2.AnyMessage, v2.AnyMessage>();
     acpProtocolRouter({ log() {}, error() {} }, (created) => (agent = created)).connect({
       readable: toAgent.readable,
       writable: toClient.writable,