> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/agentclientprotocol/typescript-sdk/llms.txt
> Use this file to discover all available pages before exploring further.

# Schema Constants

> Protocol constants and method names

The schema module exports important constants for working with the Agent Client Protocol.

## Protocol Version

### PROTOCOL\_VERSION

The current version of the Agent Client Protocol.

```typescript theme={null}
export const PROTOCOL_VERSION = 1;
```

Use this constant when initializing a connection:

```typescript theme={null}
import { PROTOCOL_VERSION } from '@agentclientprotocol/sdk/schema';

const response = await conn.initialize({
  protocolVersion: PROTOCOL_VERSION,
  clientCapabilities: { /* ... */ },
  clientInfo: {
    name: 'my-client',
    version: '1.0.0'
  }
});
```

## Method Name Constants

The SDK exports constants for all protocol method names. These ensure type safety and prevent typos when working with method names directly.

### AGENT\_METHODS

Method names for requests sent to agents (client-to-agent).

```typescript theme={null}
export const AGENT_METHODS = {
  authenticate: "authenticate",
  initialize: "initialize",
  session_cancel: "session/cancel",
  session_fork: "session/fork",
  session_list: "session/list",
  session_load: "session/load",
  session_new: "session/new",
  session_prompt: "session/prompt",
  session_resume: "session/resume",
  session_set_config_option: "session/set_config_option",
  session_set_mode: "session/set_mode",
  session_set_model: "session/set_model",
  session_stop: "session/stop",
} as const;
```

#### Usage Example

```typescript theme={null}
import { AGENT_METHODS } from '@agentclientprotocol/sdk/schema';

// Using with custom request handling
const request = {
  id: '1',
  method: AGENT_METHODS.session_prompt,
  params: { /* ... */ }
};
```

#### Method Descriptions

* **`authenticate`**: Authenticate with the agent
* **`initialize`**: Initialize the connection
* **`session_cancel`**: Cancel ongoing session operations
* **`session_fork`**: Fork an existing session (UNSTABLE)
* **`session_list`**: List available sessions (UNSTABLE)
* **`session_load`**: Load an existing session
* **`session_new`**: Create a new session
* **`session_prompt`**: Send a prompt to the session
* **`session_resume`**: Resume a stopped session (UNSTABLE)
* **`session_set_config_option`**: Update a configuration option
* **`session_set_mode`**: Change the session mode
* **`session_set_model`**: Change the session model (UNSTABLE)
* **`session_stop`**: Stop a running session (UNSTABLE)

### CLIENT\_METHODS

Method names for requests sent to clients (agent-to-client).

```typescript theme={null}
export const CLIENT_METHODS = {
  fs_read_text_file: "fs/read_text_file",
  fs_write_text_file: "fs/write_text_file",
  session_request_permission: "session/request_permission",
  session_update: "session/update",
  terminal_create: "terminal/create",
  terminal_kill: "terminal/kill",
  terminal_output: "terminal/output",
  terminal_release: "terminal/release",
  terminal_wait_for_exit: "terminal/wait_for_exit",
} as const;
```

#### Usage Example

```typescript theme={null}
import { CLIENT_METHODS } from '@agentclientprotocol/sdk/schema';

// Register handler for file read requests
conn.onRequest(CLIENT_METHODS.fs_read_text_file, async (request) => {
  const { path } = request.params;
  const content = await fs.readFile(path, 'utf-8');
  return { content };
});
```

#### Method Descriptions

**File System Methods:**

* **`fs_read_text_file`**: Read a text file from the file system
* **`fs_write_text_file`**: Write a text file to the file system

**Session Methods:**

* **`session_request_permission`**: Request user permission for an operation
* **`session_update`**: Stream session updates (notification)

**Terminal Methods:**

* **`terminal_create`**: Create a new terminal
* **`terminal_kill`**: Kill a terminal process
* **`terminal_output`**: Get terminal output
* **`terminal_release`**: Release a terminal
* **`terminal_wait_for_exit`**: Wait for terminal to exit

## Type Safety

All method constant objects are defined with `as const` to ensure type safety:

```typescript theme={null}
// Type is inferred as the literal string "session/prompt"
const method = AGENT_METHODS.session_prompt;

// TypeScript will catch typos
const invalid = AGENT_METHODS.sesion_prompt; // Error: Property does not exist
```

## Working with Custom Methods

While the protocol defines standard methods, you can also use custom extension methods:

```typescript theme={null}
import { AGENT_METHODS } from '@agentclientprotocol/sdk/schema';

// Standard method
await conn.request({
  method: AGENT_METHODS.session_prompt,
  params: { /* ... */ }
});

// Custom extension method
await conn.request({
  method: 'x-custom/my-method',
  params: { /* ... */ }
});
```

Custom methods should be prefixed with `x-` to avoid conflicts with future protocol additions.

## Notification Methods

Some methods are notifications (one-way messages) rather than requests:

```typescript theme={null}
import { CLIENT_METHODS } from '@agentclientprotocol/sdk/schema';

// session_update is a notification method
conn.onNotification(CLIENT_METHODS.session_update, (notification) => {
  console.log('Session update:', notification.params);
});
```

Notifications:

* Don't expect a response
* Don't have a request ID
* Are used for streaming updates

## Method Naming Convention

The protocol uses a consistent naming pattern:

* Method names use lowercase with slashes: `noun/verb`
* Constants use underscores: `noun_verb`
* TypeScript types use PascalCase: `VerbNounRequest`/`VerbNounResponse`

Examples:

| Protocol Method     | Constant            | Request Type            | Response Type            |
| ------------------- | ------------------- | ----------------------- | ------------------------ |
| `session/new`       | `session_new`       | `NewSessionRequest`     | `NewSessionResponse`     |
| `session/prompt`    | `session_prompt`    | `PromptRequest`         | `PromptResponse`         |
| `terminal/create`   | `terminal_create`   | `CreateTerminalRequest` | `CreateTerminalResponse` |
| `fs/read_text_file` | `fs_read_text_file` | `ReadTextFileRequest`   | `ReadTextFileResponse`   |