Add SDK support for agent selection and session compact APIs

SteveSandersonMS · Copilot · SteveSandersonMS · commit b7fccbc8925f · 2026-02-24T23:28:47.000Z
Co-Authored-By: Copilot &lt;223556219+Copilot@users.noreply.github.com&gt;
diff --git a/nodejs/src/generated/rpc.ts b/nodejs/src/generated/rpc.ts
@@ -314,6 +314,122 @@ export interface SessionFleetStartParams {
   prompt?: string;
 }
 
+export interface SessionAgentListResult {
+  /**
+   * Available custom agents
+   */
+  agents: {
+    /**
+     * Unique identifier of the custom agent
+     */
+    name: string;
+    /**
+     * Human-readable display name
+     */
+    displayName: string;
+    /**
+     * Description of the agent's purpose
+     */
+    description: string;
+  }[];
+}
+
+export interface SessionAgentListParams {
+  /**
+   * Target session identifier
+   */
+  sessionId: string;
+}
+
+export interface SessionAgentGetCurrentResult {
+  /**
+   * Currently selected custom agent, or null if using the default agent
+   */
+  agent: {
+    /**
+     * Unique identifier of the custom agent
+     */
+    name: string;
+    /**
+     * Human-readable display name
+     */
+    displayName: string;
+    /**
+     * Description of the agent's purpose
+     */
+    description: string;
+  } | null;
+}
+
+export interface SessionAgentGetCurrentParams {
+  /**
+   * Target session identifier
+   */
+  sessionId: string;
+}
+
+export interface SessionAgentSelectResult {
+  /**
+   * The newly selected custom agent
+   */
+  agent: {
+    /**
+     * Unique identifier of the custom agent
+     */
+    name: string;
+    /**
+     * Human-readable display name
+     */
+    displayName: string;
+    /**
+     * Description of the agent's purpose
+     */
+    description: string;
+  };
+}
+
+export interface SessionAgentSelectParams {
+  /**
+   * Target session identifier
+   */
+  sessionId: string;
+  /**
+   * Name of the custom agent to select
+   */
+  name: string;
+}
+
+export interface SessionAgentDeselectResult {}
+
+export interface SessionAgentDeselectParams {
+  /**
+   * Target session identifier
+   */
+  sessionId: string;
+}
+
+export interface SessionCompactionCompactResult {
+  /**
+   * Whether compaction completed successfully
+   */
+  success: boolean;
+  /**
+   * Number of tokens freed by compaction
+   */
+  tokensRemoved: number;
+  /**
+   * Number of messages removed during compaction
+   */
+  messagesRemoved: number;
+}
+
+export interface SessionCompactionCompactParams {
+  /**
+   * Target session identifier
+   */
+  sessionId: string;
+}
+
 /** Create typed server-scoped RPC methods (no session required). */
 export function createServerRpc(connection: MessageConnection) {
     return {
@@ -369,5 +485,19 @@ export function createSessionRpc(connection: MessageConnection, sessionId: strin
             start: async (params: Omit<SessionFleetStartParams, "sessionId">): Promise<SessionFleetStartResult> =>
                 connection.sendRequest("session.fleet.start", { sessionId, ...params }),
         },
+        agent: {
+            list: async (): Promise<SessionAgentListResult> =>
+                connection.sendRequest("session.agent.list", { sessionId }),
+            getCurrent: async (): Promise<SessionAgentGetCurrentResult> =>
+                connection.sendRequest("session.agent.getCurrent", { sessionId }),
+            select: async (params: Omit<SessionAgentSelectParams, "sessionId">): Promise<SessionAgentSelectResult> =>
+                connection.sendRequest("session.agent.select", { sessionId, ...params }),
+            deselect: async (): Promise<SessionAgentDeselectResult> =>
+                connection.sendRequest("session.agent.deselect", { sessionId }),
+        },
+        compaction: {
+            compact: async (): Promise<SessionCompactionCompactResult> =>
+                connection.sendRequest("session.compaction.compact", { sessionId }),
+        },
     };
 }
diff --git a/nodejs/test/e2e/agent_and_compact_rpc.test.ts b/nodejs/test/e2e/agent_and_compact_rpc.test.ts
@@ -0,0 +1,136 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *--------------------------------------------------------------------------------------------*/
+
+import { describe, expect, it } from "vitest";
+import type { CustomAgentConfig } from "../../src/index.js";
+import { createSdkTestContext } from "./harness/sdkTestContext.js";
+
+describe("Agent Selection RPC", async () => {
+    const { copilotClient: client } = await createSdkTestContext();
+
+    it("should list available custom agents", async () => {
+        const customAgents: CustomAgentConfig[] = [
+            {
+                name: "test-agent",
+                displayName: "Test Agent",
+                description: "A test agent",
+                prompt: "You are a test agent.",
+            },
+            {
+                name: "another-agent",
+                displayName: "Another Agent",
+                description: "Another test agent",
+                prompt: "You are another agent.",
+            },
+        ];
+
+        const session = await client.createSession({ customAgents });
+
+        const result = await session.rpc.agent.list();
+        expect(result.agents).toBeDefined();
+        expect(Array.isArray(result.agents)).toBe(true);
+        expect(result.agents.length).toBe(2);
+        expect(result.agents[0].name).toBe("test-agent");
+        expect(result.agents[0].displayName).toBe("Test Agent");
+        expect(result.agents[0].description).toBe("A test agent");
+        expect(result.agents[1].name).toBe("another-agent");
+
+        await session.destroy();
+    });
+
+    it("should return null when no agent is selected", async () => {
+        const customAgents: CustomAgentConfig[] = [
+            {
+                name: "test-agent",
+                displayName: "Test Agent",
+                description: "A test agent",
+                prompt: "You are a test agent.",
+            },
+        ];
+
+        const session = await client.createSession({ customAgents });
+
+        const result = await session.rpc.agent.getCurrent();
+        expect(result.agent).toBeNull();
+
+        await session.destroy();
+    });
+
+    it("should select and get current agent", async () => {
+        const customAgents: CustomAgentConfig[] = [
+            {
+                name: "test-agent",
+                displayName: "Test Agent",
+                description: "A test agent",
+                prompt: "You are a test agent.",
+            },
+        ];
+
+        const session = await client.createSession({ customAgents });
+
+        // Select the agent
+        const selectResult = await session.rpc.agent.select({ name: "test-agent" });
+        expect(selectResult.agent).toBeDefined();
+        expect(selectResult.agent.name).toBe("test-agent");
+        expect(selectResult.agent.displayName).toBe("Test Agent");
+
+        // Verify getCurrent returns the selected agent
+        const currentResult = await session.rpc.agent.getCurrent();
+        expect(currentResult.agent).not.toBeNull();
+        expect(currentResult.agent!.name).toBe("test-agent");
+
+        await session.destroy();
+    });
+
+    it("should deselect current agent", async () => {
+        const customAgents: CustomAgentConfig[] = [
+            {
+                name: "test-agent",
+                displayName: "Test Agent",
+                description: "A test agent",
+                prompt: "You are a test agent.",
+            },
+        ];
+
+        const session = await client.createSession({ customAgents });
+
+        // Select then deselect
+        await session.rpc.agent.select({ name: "test-agent" });
+        await session.rpc.agent.deselect();
+
+        // Verify no agent is selected
+        const currentResult = await session.rpc.agent.getCurrent();
+        expect(currentResult.agent).toBeNull();
+
+        await session.destroy();
+    });
+
+    it("should return empty list when no custom agents configured", async () => {
+        const session = await client.createSession();
+
+        const result = await session.rpc.agent.list();
+        expect(result.agents).toEqual([]);
+
+        await session.destroy();
+    });
+});
+
+describe("Session Compact RPC", async () => {
+    const { copilotClient: client } = await createSdkTestContext();
+
+    it("should compact session history after messages", async () => {
+        const session = await client.createSession();
+
+        // Send a message to create some history
+        await session.sendAndWait({ prompt: "What is 2+2?" });
+
+        // Compact the session
+        const result = await session.rpc.compaction.compact();
+        expect(typeof result.success).toBe("boolean");
+        expect(typeof result.tokensRemoved).toBe("number");
+        expect(typeof result.messagesRemoved).toBe("number");
+
+        await session.destroy();
+    }, 60000);
+});
diff --git a/test/harness/replayingCapiProxy.ts b/test/harness/replayingCapiProxy.ts
@@ -632,6 +632,7 @@ function normalizeUserMessage(content: string): string {
   return content
     .replace(/<current_datetime>.*?<\/current_datetime>/g, "")
     .replace(/<reminder>[\s\S]*?<\/reminder>/g, "")
+    .replace(/Please create a detailed summary of the conversation so far\. The history is being compacted[\s\S]*/, "${compaction_prompt}")
     .trim();
 }
 
diff --git a/test/snapshots/agent_and_compact_rpc/should_compact_session_history_after_messages.yaml b/test/snapshots/agent_and_compact_rpc/should_compact_session_history_after_messages.yaml
@@ -0,0 +1,80 @@
+models:
+  - claude-sonnet-4.5
+conversations:
+  - messages:
+      - role: system
+        content: ${system}
+      - role: user
+        content: What is 2+2?
+      - role: assistant
+        content: 2+2 = 4
+      - role: user
+        content: ${compaction_prompt}
+      - role: assistant
+        content: >-
+          <overview>
+
+          The user asked a simple arithmetic question ("What is 2+2?") which was answered directly (4). No technical
+          work, code changes, or file modifications were requested or performed. This appears to be a minimal test or
+          verification exchange before any substantive work begins.
+
+          </overview>
+
+
+          <history>
+
+          1. The user asked "What is 2+2?"
+             - Provided the answer: 4
+             - No follow-up actions were needed
+          </history>
+
+
+          <work_done>
+
+          No work has been performed. No files were created, modified, or deleted. This was purely an informational
+          exchange with no code changes or system modifications.
+
+
+          Current state:
+
+          - Working directory: ${workdir}
+
+          - Not a git repository
+
+          - No files have been accessed or modified
+
+          - No todos or plan have been created
+
+          </work_done>
+
+
+          <technical_details>
+
+          - Environment is Windows (Windows_NT), requiring backslash path separators
+
+          - Session workspace available for artifacts (e.g., plan.md)
+
+          - SQL database available but not yet initialized (no tables created)
+
+          - Available tools: git, curl, gh
+
+          - No technical work has been performed yet, so no technical details have been discovered
+
+          </technical_details>
+
+
+          <important_files>
+
+          No files have been accessed or modified during this conversation.
+
+          </important_files>
+
+
+          <next_steps>
+
+          No work is currently in progress. Awaiting user's next request for any substantive task.
+
+          </next_steps>
+
+
+          <checkpoint_title>Simple arithmetic question answered</checkpoint_title>
diff --git a/test/snapshots/compaction/should_trigger_compaction_with_low_threshold_and_emit_events.yaml b/test/snapshots/compaction/should_trigger_compaction_with_low_threshold_and_emit_events.yaml

Original file line number	Diff line number	Diff line change
`@@ -632,6 +632,7 @@ function normalizeUserMessage(content: string): string {`
`632`	`632`	`return content`
`633`	`633`	`.replace(/<current_datetime>.*?<\/current_datetime>/g, "")`
`634`	`634`	`.replace(/<reminder>[\s\S]*?<\/reminder>/g, "")`
	`635`	`+ .replace(/Please create a detailed summary of the conversation so far\. The history is being compacted[\s\S]*/, "${compaction_prompt}")`
`635`	`636`	`.trim();`
`636`	`637`	`}`
`637`	`638`