Fix incorrect stop reason after tool call rejection (#153)

We were mapping tool call rejections to actual "refusals" which isn't
quite right in ACP.

Also filters out more of these status messages that Claude is returning.

.github/workflows/publish.yml

@@ -4,7 +4,7 @@ on:
     tags:
       - "v*.*.*"
 jobs:
-  build:
+  publish-npm:
     runs-on: ubuntu-latest
     environment: release # Optional: for enhanced security
     permissions:
@@ -22,3 +22,15 @@ jobs:
       - run: npm ci
       - run: npm run build
       - run: npm publish
+  release:
+    runs-on: ubuntu-latest
+    needs: [publish-npm]
+    permissions:
+      contents: write
+    steps:
+      - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8
+      - name: Create Release
+        id: create_release
+        uses: softprops/action-gh-release@6da8fa9354ddfdc4aeace5fc48d7f679b5214090
+        with:
+          draft: true

.gitignore

@@ -1,2 +1,3 @@
 node_modules
 dist
+.DS_Store

CHANGELOG.md

@@ -1,5 +1,72 @@
 # Changelog
 
+## 0.10.2
+
+- Fix incorrect stop reason for tool call refusals
+
+## 0.10.1
+
+- Add additional structured metadata to tool calls
+- Update to @anthropic-ai/claude-agent-sdk@v0.1.37
+
+## 0.10.0
+
+- Update to @anthropic-ai/claude-agent-sdk@v0.1.30
+- Use `canUseTool` callback instead of launching an HTTP MCP server for permission checks.
+
+## 0.9.0
+
+- Support slash commands coming from MCP servers (Prompts)
+
+## 0.8.0
+
+- Revert changes to filename for cli entrypoint
+- Provide library entrypoint via lib.ts
+
+## 0.7.0
+
+- Allow importing from this package as a library in addition to running it as a CLI. Allows for easier integration into existing node applications.
+- Update to @anthropic-ai/claude-agent-sdk@v0.1.27
+
+## 0.6.10
+
+- Provide `agentInfo` on initialization response.
+- Update to @agentclientprotocol/sdk@0.5.1
+- Fix crash when receiving a hook_response event
+- Fix for invalid locations when read call has no path
+
+## 0.6.9
+
+- Update to @anthropic-ai/claude-agent-sdk@v0.1.26
+- Update to @agentclientprotocol/sdk@0.5.0
+
+## 0.6.8
+
+- Fix for duplicate tokens appearing in thread with streaming enabled
+- Update to @anthropic-ai/claude-agent-sdk@v0.1.23
+- Update to @agentclientprotocol/sdk@0.4.9
+
+## 0.6.7
+
+- Fix for invalid plan input from the model introduced in latest agent-sdk
+
+## 0.6.6
+
+- Do not enable bypassPermissions mode if in root/sudo mode, because Claude Code will not start
+
+## 0.6.5
+
+- Fix for duplicated text content after streaming
+
+## 0.6.4
+
+- Support streaming partial messages!
+- Update to @anthropic-ai/claude-agent-sdk@v0.1.21
+
+## 0.6.3
+
+- Fix issue where slash commands were loaded before initialization was complete.
+
 ## 0.6.2
 
 - Fix bug where mode selection would sometimes fire before initialization was complete.

docs/RELEASES.md

@@ -0,0 +1,24 @@
+## How to publish a new release
+
+1. Create a new branch prep-vX.X.X
+
+```sh
+git checkout -b prep-vX.X.X
+```
+
+2. Bump the version in package.json
+
+```sh
+npm version vX.X.X
+```
+
+3. Add a new entry in CHANGELOG.md
+4. Create a PR for `prev-vX.X.X` & merge it
+5. Create tag and push it
+
+```sh
+git tag vX.X.X
+git push origin vX.X.X
+```
+
+6. Paste CHANGELOG into release notes and publish the version on GitHub

package.json

@@ -3,12 +3,12 @@
   "publishConfig": {
     "access": "public"
   },
+  "version": "0.10.2",
+  "description": "An ACP-compatible coding agent powered by the Claude Code SDK (TypeScript)",
+  "main": "dist/lib.js",
   "bin": {
     "claude-code-acp": "./dist/index.js"
   },
-  "version": "0.6.2",
-  "description": "An ACP-compatible coding agent powered by the Claude Code SDK (TypeScript)",
-  "main": "dist/index.js",
   "type": "module",
   "files": [
     "dist/",
@@ -51,30 +51,26 @@
   "author": "Zed Industries",
   "license": "Apache-2.0",
   "dependencies": {
-    "@agentclientprotocol/sdk": "0.4.8",
-    "@anthropic-ai/claude-agent-sdk": "0.1.19",
-    "@anthropic-ai/claude-code": "2.0.19",
-    "@modelcontextprotocol/sdk": "1.20.0",
+    "@agentclientprotocol/sdk": "0.5.1",
+    "@anthropic-ai/claude-agent-sdk": "0.1.37",
+    "@anthropic-ai/claude-code": "2.0.37",
+    "@modelcontextprotocol/sdk": "1.21.1",
     "diff": "8.0.2",
-    "express": "5.1.0",
-    "minimist": "1.2.8",
     "uuid": "13.0.0"
   },
   "devDependencies": {
-    "@anthropic-ai/sdk": "^0.66.0",
-    "@types/express": "5.0.3",
-    "@types/minimist": "1.2.5",
-    "@types/node": "24.8.0",
+    "@anthropic-ai/sdk": "0.68.0",
+    "@types/node": "24.10.1",
     "@types/uuid": "10.0.0",
-    "@typescript-eslint/eslint-plugin": "8.46.1",
-    "@typescript-eslint/parser": "8.46.1",
-    "@vitest/ui": "3.2.4",
-    "eslint": "9.37.0",
+    "@typescript-eslint/eslint-plugin": "8.46.4",
+    "@typescript-eslint/parser": "8.46.4",
+    "@vitest/ui": "4.0.8",
+    "eslint": "9.39.1",
     "eslint-config-prettier": "10.1.8",
-    "globals": "16.4.0",
+    "globals": "16.5.0",
     "prettier": "3.6.2",
     "ts-node": "10.9.2",
     "typescript": "5.9.3",
-    "vitest": "3.2.4"
+    "vitest": "4.0.8"
   }
 }

src/acp-agent.ts

@@ -26,14 +26,14 @@ import {
   WriteTextFileResponse,
 } from "@agentclientprotocol/sdk";
 import {
+  CanUseTool,
   McpServerConfig,
   Options,
   PermissionMode,
   Query,
   query,
-  SDKAssistantMessage,
+  SDKPartialAssistantMessage,
   SDKUserMessage,
-  SDKUserMessageReplay,
 } from "@anthropic-ai/claude-agent-sdk";
 import * as fs from "node:fs";
 import * as path from "node:path";
@@ -41,19 +41,18 @@ import * as os from "node:os";
 import { v7 as uuidv7 } from "uuid";
 import { nodeToWebReadable, nodeToWebWritable, Pushable, unreachable } from "./utils.js";
 import { SessionNotification } from "@agentclientprotocol/sdk";
-import {
-  createMcpServer,
-  createPermissionMcpServer,
-  PERMISSION_TOOL_NAME,
-  toolNames,
-} from "./mcp-server.js";
-import { AddressInfo } from "node:net";
+import { createMcpServer, EDIT_TOOL_NAMES, toolNames } from "./mcp-server.js";
 import {
   toolInfoFromToolUse,
   planEntries,
   toolUpdateFromToolResult,
   ClaudePlanEntry,
+  registerHookCallback,
+  postToolUseHook,
 } from "./tools.js";
+import { ContentBlockParam } from "@anthropic-ai/sdk/resources";
+import { BetaContentBlock, BetaRawContentBlockDelta } from "@anthropic-ai/sdk/resources/beta.mjs";
+import packageJson from "../package.json" with { type: "json" };
 
 type Session = {
   query: Query;
@@ -73,12 +72,30 @@ type BackgroundTerminal =
       pendingOutput: TerminalOutputResponse;
     };
 
+/**
+ * Extra metadata that the agent provides for each tool_call / tool_update update, under the `_meta.claudeCode` key.
+ */
+export type ToolUpdateMeta = {
+  /* The name of the tool that was used in Claude Code. */
+  toolName: string;
+  /* The structured output provided by Claude Code. */
+  toolResponse?: unknown;
+};
+
 type ToolUseCache = {
-  [key: string]: { type: "tool_use"; id: string; name: string; input: any };
+  [key: string]: {
+    type: "tool_use" | "server_tool_use" | "mcp_tool_use";
+    id: string;
+    name: string;
+    input: any;
+  };
 };
 
 const DEFAULT_MODEL_ID = "default";
 
+// Bypass Permissions doesn't work if we are a root/sudo user
+const IS_ROOT = (process.geteuid?.() ?? process.getuid?.()) === 0;
+
 // Implement the ACP Agent interface
 export class ClaudeAcpAgent implements Agent {
   sessions: {
@@ -99,9 +116,31 @@ export class ClaudeAcpAgent implements Agent {
 
   async initialize(request: InitializeRequest): Promise<InitializeResponse> {
     this.clientCapabilities = request.clientCapabilities;
+
+    // Default authMethod
+    const authMethod: any = {
+      description: "Run `claude /login` in the terminal",
+      name: "Log in with Claude Code",
+      id: "claude-login",
+    };
+
+    // If client supports terminal-auth capability, use that instead.
+    if (request.clientCapabilities?._meta?.["terminal-auth"] === true) {
+      const cliPath = import.meta
+        .resolve("@anthropic-ai/claude-agent-sdk/cli.js")
+        .replace("file://", "");
+
+      authMethod._meta = {
+        "terminal-auth": {
+          command: "node",
+          args: [cliPath, "/login"],
+          label: "Claude Code Login",
+        },
+      };
+    }
+
     return {
       protocolVersion: 1,
-      // todo!()
       agentCapabilities: {
         promptCapabilities: {
           image: true,
@@ -112,13 +151,12 @@ export class ClaudeAcpAgent implements Agent {
           sse: true,
         },
       },
-      authMethods: [
-        {
-          description: "Run `claude /login` in the terminal",
-          name: "Log in with Claude Code",
-          id: "claude-login",
-        },
-      ],
+      agentInfo: {
+        name: packageJson.name,
+        title: "Claude Code",
+        version: packageJson.version,
+      },
+      authMethods: [authMethod],
     };
   }
   async newSession(params: NewSessionRequest): Promise<NewSessionResponse> {
@@ -163,17 +201,6 @@ export class ClaudeAcpAgent implements Agent {
       instance: server,
     };
 
-    // Ideally replace with `canUseTool`
-    const permissionServer = await createPermissionMcpServer(this, sessionId);
-    const address = permissionServer.address() as AddressInfo;
-    mcpServers["acpPermission"] = {
-      type: "http",
-      url: "http://127.0.0.1:" + address.port + "/mcp",
-      headers: {
-        "x-acp-proxy-session-id": sessionId,
-      },
-    };
-
     let systemPrompt: Options["systemPrompt"] = { type: "preset", preset: "claude_code" };
     if (params._meta?.systemPrompt) {
       const customPrompt = params._meta.systemPrompt;
@@ -188,15 +215,19 @@ export class ClaudeAcpAgent implements Agent {
       }
     }
 
+    const permissionMode = "default";
+
     const options: Options = {
       cwd: params.cwd,
+      includePartialMessages: true,
       mcpServers,
       systemPrompt,
       settingSources: ["user", "project", "local"],
-      // If we want bypassPermissions to be an option, we have to start the session with it on.
-      // We change it immediately back to default below before returning the session.
-      permissionMode: "bypassPermissions",
-      permissionPromptToolName: PERMISSION_TOOL_NAME,
+      // If we want bypassPermissions to be an option, we have to allow it here.
+      // But it doesn't work in root mode, so we only activate it if it will work.
+      allowDangerouslySkipPermissions: !IS_ROOT,
+      permissionMode,
+      canUseTool: this.canUseTool(sessionId),
       stderr: (err) => console.error(err),
       // note: although not documented by the types, passing an absolute path
       // here works to find zed's managed node version.
@@ -204,6 +235,13 @@ export class ClaudeAcpAgent implements Agent {
       ...(process.env.CLAUDE_CODE_EXECUTABLE && {
         pathToClaudeCodeExecutable: process.env.CLAUDE_CODE_EXECUTABLE,
       }),
+      hooks: {
+        PostToolUse: [
+          {
+            hooks: [postToolUseHook],
+          },
+        ],
+      },
     };
 
     const allowedTools = [];
@@ -231,10 +269,7 @@ export class ClaudeAcpAgent implements Agent {
       prompt: input,
       options,
     });
-    const models = await getAvailableModels(q);
-    const permissionMode = "default";
-    // Change it back to default
-    await q.setPermissionMode(permissionMode);
+
     this.sessions[sessionId] = {
       query: q,
       input: input,
@@ -242,7 +277,11 @@ export class ClaudeAcpAgent implements Agent {
       permissionMode,
     };
 
-    getAvailableSlashCommands(q).then((availableCommands) => {
+    const availableCommands = await getAvailableSlashCommands(q);
+    const models = await getAvailableModels(q);
+
+    // Needs to happen after we return the session
+    setTimeout(() => {
       this.client.sessionUpdate({
         sessionId,
         update: {
@@ -250,35 +289,40 @@ export class ClaudeAcpAgent implements Agent {
           availableCommands,
         },
       });
-    });
+    }, 0);
+
+    const availableModes = [
+      {
+        id: "default",
+        name: "Always Ask",
+        description: "Prompts for permission on first use of each tool",
+      },
+      {
+        id: "acceptEdits",
+        name: "Accept Edits",
+        description: "Automatically accepts file edit permissions for the session",
+      },
+      {
+        id: "plan",
+        name: "Plan Mode",
+        description: "Claude can analyze but not modify files or execute commands",
+      },
+    ];
+    // Only works in non-root mode
+    if (!IS_ROOT) {
+      availableModes.push({
+        id: "bypassPermissions",
+        name: "Bypass Permissions",
+        description: "Skips all permission prompts",
+      });
+    }
 
     return {
       sessionId,
       models,
       modes: {
         currentModeId: permissionMode,
-        availableModes: [
-          {
-            id: "default",
-            name: "Always Ask",
-            description: "Prompts for permission on first use of each tool",
-          },
-          {
-            id: "acceptEdits",
-            name: "Accept Edits",
-            description: "Automatically accepts file edit permissions for the session",
-          },
-          {
-            id: "bypassPermissions",
-            name: "Bypass Permissions",
-            description: "Skips all permission prompts",
-          },
-          {
-            id: "plan",
-            name: "Plan Mode",
-            description: "Claude can analyze but not modify files or execute commands",
-          },
-        ],
+        availableModes,
       },
     };
   }
@@ -311,9 +355,12 @@ export class ClaudeAcpAgent implements Agent {
             case "init":
               break;
             case "compact_boundary":
+            case "hook_response":
+            case "status":
+              // Todo: process via status api: https://docs.claude.com/en/docs/claude-code/hooks#hook-output
               break;
             default:
-              unreachable(message as never);
+              unreachable(message);
           }
           break;
         case "result": {
@@ -330,12 +377,26 @@ export class ClaudeAcpAgent implements Agent {
               return { stopReason: "end_turn" };
             }
             case "error_during_execution":
-              return { stopReason: "refusal" };
+              return { stopReason: "end_turn" };
+            case "error_max_budget_usd":
             case "error_max_turns":
               return { stopReason: "max_turn_requests" };
             default:
-              return { stopReason: "refusal" };
+              unreachable(message);
           }
+          break;
+        }
+        case "stream_event": {
+          for (const notification of streamEventToAcpNotifications(
+            message,
+            params.sessionId,
+            this.toolUseCache,
+            this.fileContentCache,
+            this.client,
+          )) {
+            await this.client.sessionUpdate(notification);
+          }
+          break;
         }
         case "user":
         case "assistant": {
@@ -361,7 +422,13 @@ export class ClaudeAcpAgent implements Agent {
             break;
           }
           // Skip these user messages for now, since they seem to just be messages we don't want in the feed
-          if (message.type === "user" && typeof message.message.content === "string") {
+          if (
+            message.type === "user" &&
+            (typeof message.message.content === "string" ||
+              (Array.isArray(message.message.content) &&
+                message.message.content.length === 1 &&
+                message.message.content[0].type === "text"))
+          ) {
             break;
           }
 
@@ -376,18 +443,30 @@ export class ClaudeAcpAgent implements Agent {
             throw RequestError.authRequired();
           }
 
+          const content =
+            message.type === "assistant"
+              ? // Handled by stream events above
+                message.message.content.filter((item) => !["text", "thinking"].includes(item.type))
+              : message.message.content;
+
           for (const notification of toAcpNotifications(
-            message,
+            content,
+            message.message.role,
             params.sessionId,
             this.toolUseCache,
             this.fileContentCache,
+            this.client,
           )) {
             await this.client.sessionUpdate(notification);
           }
           break;
         }
+        case "tool_progress":
+          break;
+        case "auth_status":
+          break;
         default:
-          unreachable(message as never);
+          unreachable(message);
       }
     }
     throw new Error("Session did not end in result");
@@ -446,6 +525,126 @@ export class ClaudeAcpAgent implements Agent {
     this.fileContentCache[params.path] = params.content;
     return response;
   }
+
+  canUseTool(sessionId: string): CanUseTool {
+    return async (toolName, toolInput, { suggestions, toolUseID }) => {
+      const session = this.sessions[sessionId];
+      if (!session) {
+        return {
+          behavior: "deny",
+          message: "Session not found",
+          interrupt: true,
+        };
+      }
+
+      if (toolName === "ExitPlanMode") {
+        const response = await this.client.requestPermission({
+          options: [
+            {
+              kind: "allow_always",
+              name: "Yes, and auto-accept edits",
+              optionId: "acceptEdits",
+            },
+            { kind: "allow_once", name: "Yes, and manually approve edits", optionId: "default" },
+            { kind: "reject_once", name: "No, keep planning", optionId: "plan" },
+          ],
+          sessionId,
+          toolCall: {
+            toolCallId: toolUseID,
+            rawInput: toolInput,
+          },
+        });
+
+        if (
+          response.outcome?.outcome === "selected" &&
+          (response.outcome.optionId === "default" || response.outcome.optionId === "acceptEdits")
+        ) {
+          session.permissionMode = response.outcome.optionId;
+          await this.client.sessionUpdate({
+            sessionId,
+            update: {
+              sessionUpdate: "current_mode_update",
+              currentModeId: response.outcome.optionId,
+            },
+          });
+
+          return {
+            behavior: "allow",
+            updatedInput: toolInput,
+            updatedPermissions: suggestions ?? [
+              { type: "setMode", mode: response.outcome.optionId, destination: "session" },
+            ],
+          };
+        } else {
+          return {
+            behavior: "deny",
+            message: "User rejected request to exit plan mode.",
+            interrupt: true,
+          };
+        }
+      }
+
+      if (
+        session.permissionMode === "bypassPermissions" ||
+        (session.permissionMode === "acceptEdits" && EDIT_TOOL_NAMES.includes(toolName))
+      ) {
+        return {
+          behavior: "allow",
+          updatedInput: toolInput,
+          updatedPermissions: suggestions ?? [
+            { type: "addRules", rules: [{ toolName }], behavior: "allow", destination: "session" },
+          ],
+        };
+      }
+
+      const response = await this.client.requestPermission({
+        options: [
+          {
+            kind: "allow_always",
+            name: "Always Allow",
+            optionId: "allow_always",
+          },
+          { kind: "allow_once", name: "Allow", optionId: "allow" },
+          { kind: "reject_once", name: "Reject", optionId: "reject" },
+        ],
+        sessionId,
+        toolCall: {
+          toolCallId: toolUseID,
+          rawInput: toolInput,
+        },
+      });
+      if (
+        response.outcome?.outcome === "selected" &&
+        (response.outcome.optionId === "allow" || response.outcome.optionId === "allow_always")
+      ) {
+        // If Claude Code has suggestions, it will update their settings already
+        if (response.outcome.optionId === "allow_always") {
+          return {
+            behavior: "allow",
+            updatedInput: toolInput,
+            updatedPermissions: suggestions ?? [
+              {
+                type: "addRules",
+                rules: [{ toolName }],
+                behavior: "allow",
+                destination: "session",
+              },
+            ],
+          };
+        }
+        return {
+          behavior: "allow",
+          updatedInput: toolInput,
+        };
+      } else {
+        return {
+          behavior: "deny",
+          message: "User refused permission to run tool",
+          interrupt: true,
+        };
+      }
+    };
+  }
 }
 
 async function getAvailableModels(query: Query): Promise<SessionModelState> {
@@ -470,54 +669,30 @@ async function getAvailableModels(query: Query): Promise<SessionModelState> {
 
 async function getAvailableSlashCommands(query: Query): Promise<AvailableCommand[]> {
   const UNSUPPORTED_COMMANDS = [
-    "add-dir",
-    "agents", // Modal
-    "bashes", // Modal
-    "bug", // Modal
-    "clear", // Escape Codes
-    "config", // Modal
-    "context", // Escape Codes
-    "cost", // Escape Codes
-    "doctor", // Escape Codes
-    "exit",
-    "export", // Modal
-    "help", // Modal
-    "hooks", // Modal
-    "ide", // Modal
-    "install-github-app", // Modal
+    "context",
+    "cost",
     "login",
     "logout",
-    "memory",
-    "mcp",
-    "migrate-installer", // Modal
-    "model", // Not supported via SDK?
-    "output-style", // Modal
-    "output-style:new", // Modal
-    "permissions", // Modal
-    "privacy-settings",
-    "release-notes", // Escape Codes
-    "resume",
-    "status", // Not supported via SDK?
-    "statusline", // Not needed
-    "terminal-setup", // Not needed
-    "todos", // Escape Codes
-    "vim", // Not needed
+    "output-style:new",
+    "release-notes",
+    "todos",
   ];
   const commands = await query.supportedCommands();
 
   return commands
     .map((command) => {
       const input = command.argumentHint ? { hint: command.argumentHint } : null;
+      let name = command.name;
+      if (command.name.endsWith(" (MCP)")) {
+        name = `mcp:${name.replace(" (MCP)", "")}`;
+      }
       return {
-        name: command.name,
+        name,
         description: command.description || "",
         input,
       };
     })
-    .filter(
-      (command: AvailableCommand) =>
-        !(command.name.match(/\(MCP\)/) || UNSUPPORTED_COMMANDS.includes(command.name)),
-    );
+    .filter((command: AvailableCommand) => !UNSUPPORTED_COMMANDS.includes(command.name));
 }
 
 function formatUriAsLink(uri: string): string {
@@ -537,15 +712,23 @@ function formatUriAsLink(uri: string): string {
   }
 }
 
-function promptToClaude(prompt: PromptRequest): SDKUserMessage {
+export function promptToClaude(prompt: PromptRequest): SDKUserMessage {
   const content: any[] = [];
   const context: any[] = [];
 
   for (const chunk of prompt.prompt) {
     switch (chunk.type) {
-      case "text":
-        content.push({ type: "text", text: chunk.text });
+      case "text": {
+        let text = chunk.text;
+        // change /mcp:server:command args -> /server:command (MCP) args
+        const mcpMatch = text.match(/^\/mcp:([^:\s]+):(\S+)(\s+.*)?$/);
+        if (mcpMatch) {
+          const [, server, command, args] = mcpMatch;
+          text = `/${server}:${command} (MCP)${args || ""}`;
+        }
+        content.push({ type: "text", text });
         break;
+      }
       case "resource_link": {
         const formattedUri = formatUriAsLink(chunk.uri);
         content.push({
@@ -613,20 +796,19 @@ function promptToClaude(prompt: PromptRequest): SDKUserMessage {
  * Only handles text, image, and thinking chunks for now.
  */
 export function toAcpNotifications(
-  message: SDKAssistantMessage | SDKUserMessage | SDKUserMessageReplay,
+  content: string | ContentBlockParam[] | BetaContentBlock[] | BetaRawContentBlockDelta[],
+  role: "assistant" | "user",
   sessionId: string,
   toolUseCache: ToolUseCache,
   fileContentCache: { [key: string]: string },
+  client: AgentSideConnection,
 ): SessionNotification[] {
-  const content = message.message.content;
-
   if (typeof content === "string") {
     return [
       {
         sessionId,
         update: {
-          sessionUpdate:
-            message.type === "assistant" ? "agent_message_chunk" : "user_message_chunk",
+          sessionUpdate: role === "assistant" ? "agent_message_chunk" : "user_message_chunk",
           content: {
             type: "text",
             text: content,
@@ -642,9 +824,9 @@ export function toAcpNotifications(
     let update: SessionNotification["update"] | null = null;
     switch (chunk.type) {
       case "text":
+      case "text_delta":
         update = {
-          sessionUpdate:
-            message.type === "assistant" ? "agent_message_chunk" : "user_message_chunk",
+          sessionUpdate: role === "assistant" ? "agent_message_chunk" : "user_message_chunk",
           content: {
             type: "text",
             text: chunk.text,
@@ -653,8 +835,7 @@ export function toAcpNotifications(
         break;
       case "image":
         update = {
-          sessionUpdate:
-            message.type === "assistant" ? "agent_message_chunk" : "user_message_chunk",
+          sessionUpdate: role === "assistant" ? "agent_message_chunk" : "user_message_chunk",
           content: {
             type: "image",
             data: chunk.source.type === "base64" ? chunk.source.data : "",
@@ -664,6 +845,7 @@ export function toAcpNotifications(
         };
         break;
       case "thinking":
+      case "thinking_delta":
         update = {
           sessionUpdate: "agent_thought_chunk",
           content: {
@@ -673,13 +855,45 @@ export function toAcpNotifications(
         };
         break;
       case "tool_use":
+      case "server_tool_use":
+      case "mcp_tool_use": {
         toolUseCache[chunk.id] = chunk;
         if (chunk.name === "TodoWrite") {
-          update = {
-            sessionUpdate: "plan",
-            entries: planEntries(chunk.input as { todos: ClaudePlanEntry[] }),
-          };
+          // @ts-expect-error - sometimes input is empty object
+          if (Array.isArray(chunk.input.todos)) {
+            update = {
+              sessionUpdate: "plan",
+              entries: planEntries(chunk.input as { todos: ClaudePlanEntry[] }),
+            };
+          }
         } else {
+          // Register hook callback to receive the structured output from the hook
+          registerHookCallback(chunk.id, {
+            onPostToolUseHook: async (toolUseId, toolInput, toolResponse) => {
+              const toolUse = toolUseCache[toolUseId];
+              if (toolUse) {
+                const update: SessionNotification["update"] = {
+                  _meta: {
+                    claudeCode: {
+                      toolResponse,
+                      toolName: toolUse.name,
+                    } satisfies ToolUpdateMeta,
+                  },
+                  toolCallId: toolUseId,
+                  sessionUpdate: "tool_call_update",
+                };
+                await client.sessionUpdate({
+                  sessionId,
+                  update,
+                });
+              } else {
+                console.error(
+                  `[claude-code-acp] Got a tool response for tool use that wasn't tracked: ${toolUseId}`,
+                );
+              }
+            },
+          });
+
           let rawInput;
           try {
             rawInput = JSON.parse(JSON.stringify(chunk.input));
@@ -687,6 +901,11 @@ export function toAcpNotifications(
             // ignore if we can't turn it to JSON
           }
           update = {
+            _meta: {
+              claudeCode: {
+                toolName: chunk.name,
+              } satisfies ToolUpdateMeta,
+            },
             toolCallId: chunk.id,
             sessionUpdate: "tool_call",
             rawInput,
@@ -695,8 +914,15 @@ export function toAcpNotifications(
           };
         }
         break;
+      }
 
-      case "tool_result": {
+      case "tool_result":
+      case "web_fetch_tool_result":
+      case "web_search_tool_result":
+      case "code_execution_tool_result":
+      case "bash_code_execution_tool_result":
+      case "text_editor_code_execution_tool_result":
+      case "mcp_tool_result": {
         const toolUse = toolUseCache[chunk.tool_use_id];
         if (!toolUse) {
           console.error(
@@ -707,17 +933,31 @@ export function toAcpNotifications(
 
         if (toolUse.name !== "TodoWrite") {
           update = {
+            _meta: {
+              claudeCode: {
+                toolName: toolUse.name,
+              } satisfies ToolUpdateMeta,
+            },
             toolCallId: chunk.tool_use_id,
             sessionUpdate: "tool_call_update",
-            status: chunk.is_error ? "failed" : "completed",
+            status: "is_error" in chunk && chunk.is_error ? "failed" : "completed",
             ...toolUpdateFromToolResult(chunk, toolUseCache[chunk.tool_use_id]),
           };
         }
         break;
       }
 
+      case "document":
+      case "search_result":
+      case "redacted_thinking":
+      case "input_json_delta":
+      case "citations_delta":
+      case "signature_delta":
+      case "container_upload":
+        break;
+
       default:
-        throw new Error("unhandled chunk type: " + chunk.type);
+        unreachable(chunk);
     }
     if (update) {
       output.push({ sessionId, update });
@@ -727,6 +967,45 @@ export function toAcpNotifications(
   return output;
 }
 
+export function streamEventToAcpNotifications(
+  message: SDKPartialAssistantMessage,
+  sessionId: string,
+  toolUseCache: ToolUseCache,
+  fileContentCache: { [key: string]: string },
+  client: AgentSideConnection,
+): SessionNotification[] {
+  const event = message.event;
+  switch (event.type) {
+    case "content_block_start":
+      return toAcpNotifications(
+        [event.content_block],
+        "assistant",
+        sessionId,
+        toolUseCache,
+        fileContentCache,
+        client,
+      );
+    case "content_block_delta":
+      return toAcpNotifications(
+        [event.delta],
+        "assistant",
+        sessionId,
+        toolUseCache,
+        fileContentCache,
+        client,
+      );
+    // No content
+    case "message_start":
+    case "message_delta":
+    case "message_stop":
+    case "content_block_stop":
+      return [];
+
+    default:
+      unreachable(event);
+  }
+}
+
 export function runAcp() {
   const input = nodeToWebWritable(process.stdout);
   const output = nodeToWebReadable(process.stdin);

src/index.ts

@@ -19,7 +19,7 @@ process.on("unhandledRejection", (reason, promise) => {
   console.error("Unhandled Rejection at:", promise, "reason:", reason);
 });
 
-import { runAcp as runAcp } from "./acp-agent.js";
+import { runAcp } from "./acp-agent.js";
 runAcp();
 
 // Keep process alive

src/lib.ts

@@ -0,0 +1,21 @@
+// Export the main agent class and utilities for library usage
+export {
+  ClaudeAcpAgent,
+  runAcp,
+  toAcpNotifications,
+  streamEventToAcpNotifications,
+  type ToolUpdateMeta,
+} from "./acp-agent.js";
+export {
+  loadManagedSettings,
+  applyEnvironmentSettings,
+  nodeToWebReadable,
+  nodeToWebWritable,
+  Pushable,
+  unreachable,
+} from "./utils.js";
+export { createMcpServer, toolNames } from "./mcp-server.js";
+export { toolInfoFromToolUse, planEntries, toolUpdateFromToolResult } from "./tools.js";
+
+// Export types
+export type { ClaudePlanEntry } from "./tools.js";

src/mcp-server.ts

@@ -1,15 +1,10 @@
-import express from "express";
-
 import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
-import { StreamableHTTPServerTransport } from "@modelcontextprotocol/sdk/server/streamableHttp.js";
 import { z } from "zod";
-import { Server } from "node:http";
 import { ClaudeAcpAgent } from "./acp-agent.js";
 import { ClientCapabilities, TerminalOutputResponse } from "@agentclientprotocol/sdk";
 import * as diff from "diff";
 
 import { sleep, unreachable, extractLinesWithByteLimit } from "./utils.js";
-import { PermissionResult } from "@anthropic-ai/claude-agent-sdk";
 
 export const SYSTEM_REMINDER = `
 
@@ -38,7 +33,7 @@ export const toolNames = {
   bashOutput: SERVER_PREFIX + unqualifiedToolNames.bashOutput,
 };
 
-const editToolNames = [toolNames.edit, toolNames.write];
+export const EDIT_TOOL_NAMES = [toolNames.edit, toolNames.write];
 
 export function createMcpServer(
   agent: ClaudeAcpAgent,
@@ -578,189 +573,6 @@ In sessions with ${toolNames.killShell} always use it instead of KillShell.`,
   return server;
 }
 
-const UNQUALIFIED_PERMISSION_TOOL_NAME = "permission";
-const PERMISSION_SERVER_PREFIX = "mcp__acpPermission__";
-export const PERMISSION_TOOL_NAME = PERMISSION_SERVER_PREFIX + UNQUALIFIED_PERMISSION_TOOL_NAME;
-
-/**
- * Separate permission tool. Needs to be an HTTP server for now, because Claude Code doesn't
- * support permission tools via SDK servers.
- * Ideally it moves to the `canUseTool` callback in the future.
- */
-export function createPermissionMcpServer(
-  agent: ClaudeAcpAgent,
-  sessionId: string,
-): Promise<Server> {
-  const server = new McpServer(
-    { name: "acpPermission", version: "1.0.0" },
-    { capabilities: { tools: {} } },
-  );
-
-  const alwaysAllowedTools: { [key: string]: boolean } = {};
-  server.registerTool(
-    UNQUALIFIED_PERMISSION_TOOL_NAME,
-    {
-      title: "Permission Tool",
-      description: "Used to request tool permissions",
-      inputSchema: {
-        tool_name: z.string(),
-        input: z.any(),
-        tool_use_id: z.string().optional(),
-      },
-    },
-    async (input) => {
-      const result = await canUseTool(input);
-
-      return {
-        content: [{ type: "text", text: JSON.stringify(result) }],
-      };
-    },
-  );
-
-  async function canUseTool(input: {
-    tool_use_id?: string;
-    tool_name: string;
-    input?: any;
-  }): Promise<PermissionResult> {
-    const session = agent.sessions[sessionId];
-    if (!session) {
-      return {
-        behavior: "deny",
-        message: "Session not found",
-      };
-    }
-
-    if (input.tool_name === "ExitPlanMode") {
-      const response = await agent.client.requestPermission({
-        options: [
-          {
-            kind: "allow_always",
-            name: "Yes, and auto-accept edits",
-            optionId: "acceptEdits",
-          },
-          { kind: "allow_once", name: "Yes, and manually approve edits", optionId: "default" },
-          { kind: "reject_once", name: "No, keep planning", optionId: "plan" },
-        ],
-        sessionId,
-        toolCall: {
-          toolCallId: input.tool_use_id!,
-          rawInput: input.input,
-        },
-      });
-
-      if (
-        response.outcome?.outcome === "selected" &&
-        (response.outcome.optionId === "default" || response.outcome.optionId === "acceptEdits")
-      ) {
-        session.permissionMode = response.outcome.optionId;
-        await agent.client.sessionUpdate({
-          sessionId,
-          update: {
-            sessionUpdate: "current_mode_update",
-            currentModeId: response.outcome.optionId,
-          },
-        });
-
-        return {
-          behavior: "allow",
-          updatedInput: input.input,
-          updatedPermissions: [
-            { type: "setMode", mode: response.outcome.optionId, destination: "session" },
-          ],
-        };
-      } else {
-        return {
-          behavior: "deny",
-          message: "User rejected request to exit plan mode.",
-        };
-      }
-    }
-
-    if (
-      session.permissionMode === "bypassPermissions" ||
-      (session.permissionMode === "acceptEdits" && editToolNames.includes(input.tool_name)) ||
-      alwaysAllowedTools[input.tool_name]
-    ) {
-      return {
-        behavior: "allow",
-        updatedInput: input.input,
-      };
-    }
-
-    const response = await agent.client.requestPermission({
-      options: [
-        {
-          kind: "allow_always",
-          name: "Always Allow",
-          optionId: "allow_always",
-        },
-        { kind: "allow_once", name: "Allow", optionId: "allow" },
-        { kind: "reject_once", name: "Reject", optionId: "reject" },
-      ],
-      sessionId,
-      toolCall: {
-        toolCallId: input.tool_use_id!,
-        rawInput: input.input,
-      },
-    });
-    if (
-      response.outcome?.outcome === "selected" &&
-      (response.outcome.optionId === "allow" || response.outcome.optionId === "allow_always")
-    ) {
-      if (response.outcome.optionId === "allow_always") {
-        alwaysAllowedTools[input.tool_name] = true;
-      }
-      return {
-        behavior: "allow",
-        updatedInput: input.input,
-      };
-    } else {
-      return {
-        behavior: "deny",
-        message: "User refused permission to run tool",
-      };
-    }
-  }
-
-  const app = express();
-  app.use(express.json());
-
-  app.post("/mcp", async (req, res) => {
-    try {
-      const transport: StreamableHTTPServerTransport = new StreamableHTTPServerTransport({
-        sessionIdGenerator: undefined,
-      });
-      res.on("close", () => {
-        transport.close();
-        server.close();
-      });
-      await server.connect(transport);
-      await transport.handleRequest(req, res, req.body);
-    } catch (error) {
-      if (!res.headersSent) {
-        res.status(500).json({
-          jsonrpc: "2.0",
-          error: {
-            code: -32603,
-            message: `Internal server error: ${error}`,
-          },
-          id: null,
-        });
-      }
-    }
-  });
-
-  return new Promise((resolve, reject) => {
-    const listener = app.listen(0, "127.0.0.1", (error) => {
-      if (error) {
-        reject(error);
-        return;
-      }
-      resolve(listener);
-    });
-  });
-}
-
 function stripCommonPrefix(a: string, b: string): string {
   let i = 0;
   while (i < a.length && i < b.length && a[i] === b[i]) {

src/tests/acp-agent.test.ts

@@ -2,6 +2,7 @@ import { describe, it, expect, beforeAll, afterAll } from "vitest";
 import { spawn, spawnSync } from "child_process";
 import {
   Agent,
+  AgentSideConnection,
   AvailableCommand,
   Client,
   ClientSideConnection,
@@ -17,7 +18,7 @@ import {
 } from "@agentclientprotocol/sdk";
 import { nodeToWebWritable, nodeToWebReadable } from "../utils.js";
 import { markdownEscape, toolInfoFromToolUse, toolUpdateFromToolResult } from "../tools.js";
-import { toAcpNotifications } from "../acp-agent.js";
+import { toAcpNotifications, promptToClaude } from "../acp-agent.js";
 import { query, SDKAssistantMessage } from "@anthropic-ai/claude-agent-sdk";
 
 describe.skipIf(!process.env.RUN_INTEGRATION_TESTS)("ACP subprocess integration", () => {
@@ -649,7 +650,16 @@ describe("tool conversions", () => {
       session_id: "d056596f-e328-41e9-badd-b07122ae5227",
       uuid: "b7c3330c-de8f-4bba-ac53-68c7f76ffeb5",
     };
-    expect(toAcpNotifications(received, "test", {}, {})).toStrictEqual([
+    expect(
+      toAcpNotifications(
+        received.message.content,
+        received.message.role,
+        "test",
+        {},
+        {},
+        {} as AgentSideConnection,
+      ),
+    ).toStrictEqual([
       {
         sessionId: "test",
         update: {
@@ -781,6 +791,44 @@ describe("escape markdown", () => {
   });
 });
 
+describe("prompt conversion", () => {
+  it("should not change built-in slash commands", () => {
+    const message = promptToClaude({
+      sessionId: "test",
+      prompt: [
+        {
+          type: "text",
+          text: "/compact args",
+        },
+      ],
+    });
+    expect(message.message.content).toEqual([
+      {
+        text: "/compact args",
+        type: "text",
+      },
+    ]);
+  });
+
+  it("should remove MCP prefix from MCP slash commands", () => {
+    const message = promptToClaude({
+      sessionId: "test",
+      prompt: [
+        {
+          type: "text",
+          text: "/mcp:server:name args",
+        },
+      ],
+    });
+    expect(message.message.content).toEqual([
+      {
+        text: "/server:name (MCP) args",
+        type: "text",
+      },
+    ]);
+  });
+});
+
 describe("SDK behavior", () => {
   it.skipIf(!process.env.RUN_INTEGRATION_TESTS)(
     "query has a 'default' model",

src/tools.ts

@@ -1,6 +1,15 @@
 import { PlanEntry, ToolCallContent, ToolCallLocation, ToolKind } from "@agentclientprotocol/sdk";
 import { replaceAndCalculateLocation, SYSTEM_REMINDER, toolNames } from "./mcp-server.js";
-import { ToolResultBlockParam } from "@anthropic-ai/sdk/resources";
+import { ToolResultBlockParam, WebSearchToolResultBlockParam } from "@anthropic-ai/sdk/resources";
+import {
+  BetaBashCodeExecutionToolResultBlockParam,
+  BetaCodeExecutionToolResultBlockParam,
+  BetaRequestMCPToolResultBlockParam,
+  BetaTextEditorCodeExecutionToolResultBlockParam,
+  BetaWebFetchToolResultBlockParam,
+  BetaWebSearchToolResultBlockParam,
+} from "@anthropic-ai/sdk/resources/beta.mjs";
+import { HookCallback } from "@anthropic-ai/claude-agent-sdk";
 
 interface ToolInfo {
   title: string;
@@ -105,12 +114,14 @@ export function toolInfoFromToolUse(
       return {
         title: "Read " + (input.file_path ?? "File") + limit,
         kind: "read",
-        locations: [
-          {
-            path: input.file_path,
-            line: input.offset ?? 0,
-          },
-        ],
+        locations: input.file_path
+          ? [
+              {
+                path: input.file_path,
+                line: input.offset ?? 0,
+              },
+            ]
+          : [],
         content: [],
       };
     }
@@ -336,7 +347,7 @@ export function toolInfoFromToolUse(
 
     case "TodoWrite":
       return {
-        title: input?.todos
+        title: Array.isArray(input?.todos)
           ? `Update TODOs: ${input.todos.map((todo: any) => todo.content).join(", ")}`
           : "Update TODOs",
         kind: "think",
@@ -385,7 +396,15 @@ export function toolInfoFromToolUse(
 }
 
 export function toolUpdateFromToolResult(
-  toolResult: ToolResultBlockParam,
+  toolResult:
+    | ToolResultBlockParam
+    | BetaWebSearchToolResultBlockParam
+    | BetaWebFetchToolResultBlockParam
+    | WebSearchToolResultBlockParam
+    | BetaCodeExecutionToolResultBlockParam
+    | BetaBashCodeExecutionToolResultBlockParam
+    | BetaTextEditorCodeExecutionToolResultBlockParam
+    | BetaRequestMCPToolResultBlockParam,
   toolUse: any | undefined,
 ): ToolUpdate {
   switch (toolUse?.name) {
@@ -425,7 +444,12 @@ export function toolUpdateFromToolResult(
     case toolNames.edit:
     case toolNames.write:
     case "Write": {
-      if (toolResult.is_error && toolResult.content && toolResult.content.length > 0) {
+      if (
+        "is_error" in toolResult &&
+        toolResult.is_error &&
+        toolResult.content &&
+        toolResult.content.length > 0
+      ) {
         // Only return errors
         return toAcpContentUpdate(toolResult.content, true);
       }
@@ -451,7 +475,10 @@ export function toolUpdateFromToolResult(
     case "WebSearch":
     case "Other":
     default: {
-      return toAcpContentUpdate(toolResult.content, toolResult.is_error);
+      return toAcpContentUpdate(
+        toolResult.content,
+        "is_error" in toolResult ? toolResult.is_error : false,
+      );
     }
   }
 }
@@ -512,3 +539,50 @@ export function markdownEscape(text: string): string {
   }
   return escape + "\n" + text + (text.endsWith("\n") ? "" : "\n") + escape;
 }
+
+/* A global variable to store callbacks that should be executed when receiving hooks from Claude Code */
+const toolUseCallbacks: {
+  [toolUseId: string]: {
+    onPostToolUseHook?: (
+      toolUseID: string,
+      toolInput: unknown,
+      toolResponse: unknown,
+    ) => Promise<void>;
+  };
+} = {};
+
+/* Setup callbacks that will be called when receiving hooks from Claude Code */
+export const registerHookCallback = (
+  toolUseID: string,
+  {
+    onPostToolUseHook,
+  }: {
+    onPostToolUseHook?: (
+      toolUseID: string,
+      toolInput: unknown,
+      toolResponse: unknown,
+    ) => Promise<void>;
+  },
+) => {
+  toolUseCallbacks[toolUseID] = {
+    onPostToolUseHook,
+  };
+};
+
+/* A callback for Claude Code that is called when receiving a PostToolUse hook */
+export const postToolUseHook: HookCallback = async (
+  input: any,
+  toolUseID: string | undefined,
+): Promise<{ continue: boolean }> => {
+  if (input.hook_event_name === "PostToolUse" && toolUseID) {
+    const onPostToolUseHook = toolUseCallbacks[toolUseID]?.onPostToolUseHook;
+    if (onPostToolUseHook) {
+      await onPostToolUseHook(toolUseID, input.tool_input, input.tool_response);
+      delete toolUseCallbacks[toolUseID]; // Cleanup after execution
+    } else {
+      console.error(`No onPostToolUseHook found for tool use ID: ${toolUseID}`);
+      delete toolUseCallbacks[toolUseID];
+    }
+  }
+  return { continue: true };
+};

src/utils.ts

@@ -76,7 +76,13 @@ export function nodeToWebReadable(nodeStream: Readable): ReadableStream<Uint8Arr
 }
 
 export function unreachable(value: never): never {
-  throw new Error(`Unexpected case: ${value}`);
+  let valueAsString;
+  try {
+    valueAsString = JSON.stringify(value);
+  } catch {
+    valueAsString = value;
+  }
+  throw new Error(`Unexpected case: ${valueAsString}`);
 }
 
 export function sleep(time: number): Promise<void> {