feat: Add experimental session delete support (#682)

- **Update Agent Client Protocol SDK to 0.22.0**
- **feat: Add session delete support**

package-lock.json

@@ -9,7 +9,7 @@
       "version": "0.35.0",
       "license": "Apache-2.0",
       "dependencies": {
-        "@agentclientprotocol/sdk": "0.21.1",
+        "@agentclientprotocol/sdk": "0.22.0",
         "@anthropic-ai/claude-agent-sdk": "0.3.143",
         "zod": "^3.25.0 || ^4.0.0"
       },
@@ -32,9 +32,9 @@
       }
     },
     "node_modules/@agentclientprotocol/sdk": {
-      "version": "0.21.1",
-      "resolved": "https://registry.npmjs.org/@agentclientprotocol/sdk/-/sdk-0.21.1.tgz",
-      "integrity": "sha512-ZTLH+o9QxcZDLX/9ww+W7C2iExnXFM+vD/uGFVSlR61Kzj9FaxUqBC6Rv/kwgA7qVWYUEI9c5ZNqCuO9PM4rKg==",
+      "version": "0.22.0",
+      "resolved": "https://registry.npmjs.org/@agentclientprotocol/sdk/-/sdk-0.22.0.tgz",
+      "integrity": "sha512-mnkpiuEfGm7/snhWbrRhe3Hk+WDDjv7U2N/Ql0XiThl9zg7T984dPH8Tich4wlBQnaaXTV4Fl5OQSe2pa9hoFA==",
       "license": "Apache-2.0",
       "peerDependencies": {
         "zod": "^3.25.0 || ^4.0.0"

package.json

@@ -60,7 +60,7 @@
   "author": "Zed Industries",
   "license": "Apache-2.0",
   "dependencies": {
-    "@agentclientprotocol/sdk": "0.21.1",
+    "@agentclientprotocol/sdk": "0.22.0",
     "@anthropic-ai/claude-agent-sdk": "0.3.143",
     "zod": "^3.25.0 || ^4.0.0"
   },

src/acp-agent.ts

@@ -37,6 +37,8 @@ import {
   SetSessionModeResponse,
   CloseSessionRequest,
   CloseSessionResponse,
+  DeleteSessionRequest,
+  DeleteSessionResponse,
   TerminalHandle,
   TerminalOutputResponse,
   WriteTextFileRequest,
@@ -45,6 +47,7 @@ import {
 } from "@agentclientprotocol/sdk";
 import {
   CanUseTool,
+  deleteSession,
   getSessionMessages,
   listSessions,
   McpServerConfig,
@@ -629,6 +632,7 @@ export class ClaudeAcpAgent implements Agent {
           list: {},
           resume: {},
           close: {},
+          delete: {},
         },
       },
       agentInfo: {
@@ -1297,6 +1301,16 @@ export class ClaudeAcpAgent implements Agent {
     return {};
   }
 
+  async unstable_deleteSession(params: DeleteSessionRequest): Promise<DeleteSessionResponse> {
+    // Tear down any active in-memory state first so the on-disk file isn't
+    // recreated by an outstanding query writing to it.
+    if (this.sessions[params.sessionId]) {
+      await this.teardownSession(params.sessionId);
+    }
+    await deleteSession(params.sessionId);
+    return {};
+  }
+
   async unstable_setSessionModel(
     params: SetSessionModelRequest,
   ): Promise<SetSessionModelResponse | void> {
@@ -1834,7 +1848,7 @@ export class ClaudeAcpAgent implements Agent {
               ? Object.fromEntries(server.headers.map((e) => [e.name, e.value]))
               : undefined,
           };
-        } else {
+        } else if (!("type" in server)) {
           // Stdio type MCP server (with or without explicit type field)
           mcpServers[server.name] = {
             type: "stdio",

src/tests/acp-agent.test.ts

@@ -1,4 +1,4 @@
-import { describe, it, expect, beforeAll, afterAll, vi } from "vitest";
+import { describe, it, expect, beforeAll, beforeEach, afterAll, vi } from "vitest";
 import { spawn, spawnSync } from "child_process";
 import {
   Agent,
@@ -35,8 +35,16 @@ import {
   type SDKMessageFilter,
 } from "../acp-agent.js";
 import { Pushable } from "../utils.js";
-import { query, SDKAssistantMessage } from "@anthropic-ai/claude-agent-sdk";
+import { deleteSession, query, SDKAssistantMessage } from "@anthropic-ai/claude-agent-sdk";
 import { randomUUID } from "crypto";
+
+vi.mock("@anthropic-ai/claude-agent-sdk", async (importOriginal) => {
+  const actual = await importOriginal<typeof import("@anthropic-ai/claude-agent-sdk")>();
+  return {
+    ...actual,
+    deleteSession: vi.fn(),
+  };
+});
 import type {
   BetaToolResultBlockParam,
   BetaToolSearchToolResultBlockParam,
@@ -1888,6 +1896,94 @@ describe("session/close", () => {
   });
 });
 
+describe("session/delete", () => {
+  function createMockAgent() {
+    const mockClient = {
+      sessionUpdate: async () => {},
+    } as unknown as AgentSideConnection;
+    return new ClaudeAcpAgent(mockClient, { log: () => {}, error: () => {} });
+  }
+
+  function injectSession(agent: ClaudeAcpAgent, sessionId: string) {
+    function* empty() {}
+    const gen = Object.assign(empty(), { interrupt: vi.fn(), close: vi.fn() });
+    agent.sessions[sessionId] = {
+      query: gen as any,
+      input: new Pushable(),
+      cancelled: false,
+      cwd: "/test",
+      sessionFingerprint: JSON.stringify({ cwd: "/test", mcpServers: [] }),
+      modes: { currentModeId: "default", availableModes: [] },
+      models: { currentModelId: "default", availableModels: [] },
+      modelInfos: [],
+      settingsManager: { dispose: vi.fn() } as any,
+      accumulatedUsage: {
+        inputTokens: 0,
+        outputTokens: 0,
+        cachedReadTokens: 0,
+        cachedWriteTokens: 0,
+      },
+      configOptions: [],
+      promptRunning: false,
+      pendingMessages: new Map(),
+      nextPendingOrder: 0,
+      abortController: new AbortController(),
+      emitRawSDKMessages: false,
+      contextWindowSize: 200000,
+      taskState: new Map(),
+    };
+    return agent.sessions[sessionId]!;
+  }
+
+  beforeEach(() => {
+    vi.mocked(deleteSession).mockReset();
+    vi.mocked(deleteSession).mockResolvedValue(undefined);
+  });
+
+  it("tears down the active session and deletes it from disk", async () => {
+    const agent = createMockAgent();
+    const session = injectSession(agent, "session-1");
+
+    const result = await agent.unstable_deleteSession({ sessionId: "session-1" });
+
+    expect(result).toEqual({});
+    expect(agent.sessions["session-1"]).toBeUndefined();
+    expect(session.query.interrupt).toHaveBeenCalled();
+    expect(session.settingsManager.dispose).toHaveBeenCalled();
+    expect(session.abortController.signal.aborted).toBe(true);
+    expect(deleteSession).toHaveBeenCalledWith("session-1");
+  });
+
+  it("deletes a session from disk that is not currently active", async () => {
+    const agent = createMockAgent();
+
+    const result = await agent.unstable_deleteSession({ sessionId: "not-active" });
+
+    expect(result).toEqual({});
+    expect(deleteSession).toHaveBeenCalledWith("not-active");
+  });
+
+  it("propagates errors from the SDK delete call", async () => {
+    const agent = createMockAgent();
+    vi.mocked(deleteSession).mockRejectedValueOnce(new Error("Session not found on disk"));
+
+    await expect(agent.unstable_deleteSession({ sessionId: "missing" })).rejects.toThrow(
+      "Session not found on disk",
+    );
+  });
+
+  it("does not affect other sessions when deleting one", async () => {
+    const agent = createMockAgent();
+    injectSession(agent, "session-a");
+    injectSession(agent, "session-b");
+
+    await agent.unstable_deleteSession({ sessionId: "session-a" });
+
+    expect(agent.sessions["session-a"]).toBeUndefined();
+    expect(agent.sessions["session-b"]).toBeDefined();
+  });
+});
+
 describe("getOrCreateSession param change detection", () => {
   function createMockAgent() {
     const mockClient = {