Struct AgentConfig 

pub struct AgentConfig {
    pub base_url: Option<String>,
    pub api_key: Option<String>,
    pub model: Option<String>,
    pub small_fast_model: Option<String>,
    pub max_thinking_tokens: Option<u32>,
}

Agent configuration loaded from environment variables and settings files

Configuration priority (highest to lowest):

1. Environment variables (e.g., ANTHROPIC_MODEL)
2. Settings files - Top-level fields (e.g., model)
3. Settings files - env object (e.g., env.ANTHROPIC_MODEL)
4. Defaults

Settings files are loaded from:

• ~/.claude/settings.json (user settings)
• <project_dir>/.claude/settings.json (project settings)
• <project_dir>/.claude/settings.local.json (local settings)

Supports configuring alternative AI model providers (e.g., domestic providers in China) through environment variables or settings files.

Fields

base_url: Option<String>

Anthropic API base URL Environment variable: ANTHROPIC_BASE_URL Settings field: apiBaseUrl

api_key: Option<String>

API key for authentication Environment variable: ANTHROPIC_API_KEY (preferred) or ANTHROPIC_AUTH_TOKEN (legacy) Note: Not supported in settings files for security reasons

model: Option<String>

Primary model name Environment variable: ANTHROPIC_MODEL Settings field: model

small_fast_model: Option<String>

Small/fast model name (fallback) Environment variable: ANTHROPIC_SMALL_FAST_MODEL Settings field: smallFastModel

max_thinking_tokens: Option<u32>

Maximum tokens for thinking blocks (extended thinking mode)

Can be set via:

• Environment variable: MAX_THINKING_TOKENS
• Settings field: alwaysThinkingEnabled (sets to default 20000)
• Settings env object: env.MAX_THINKING_TOKENS

When alwaysThinkingEnabled is true in settings, this defaults to 20000. Typical values: 4096, 8000, 16000, 20000

Implementations

impl AgentConfig

pub fn new() -> Self

Create a new empty configuration

pub fn from_env() -> Self

Load configuration from environment variables

Reads the following environment variables:

• ANTHROPIC_BASE_URL: API base URL
• ANTHROPIC_API_KEY: API key (preferred)
• ANTHROPIC_AUTH_TOKEN: Auth token (legacy, fallback if API_KEY not set)
• ANTHROPIC_MODEL: Primary model name
• ANTHROPIC_SMALL_FAST_MODEL: Small/fast model name
• MAX_THINKING_TOKENS: Maximum tokens for thinking blocks

pub fn from_settings_or_env(project_dir: &Path) -> Self

Load configuration from settings files and environment variables

Configuration priority (highest to lowest):

1. Environment variables (e.g., ANTHROPIC_MODEL)
2. Settings files - Top-level fields (e.g., model)
3. Settings files - env object (e.g., env.ANTHROPIC_MODEL)
4. Defaults (including alwaysThinkingEnabled → default MAX_THINKING_TOKENS)

Settings files are loaded in this order (later ones override earlier):

• ~/.claude/settings.json (user settings)
• <project_dir>/.claude/settings.json (project settings)
• <project_dir>/.claude/settings.local.json (local settings)

Arguments

• project_dir - The project working directory

Example settings.json

Using top-level fields:

{
  "model": "claude-opus-4-20250514",
  "smallFastModel": "claude-haiku-4-20250514",
  "apiBaseUrl": "https://api.anthropic.com"
}

Using env object (compatible with Claude Code CLI):

{
  "env": {
    "ANTHROPIC_MODEL": "claude-opus-4-20250514",
    "ANTHROPIC_SMALL_FAST_MODEL": "claude-haiku-4-20250514",
    "ANTHROPIC_BASE_URL": "https://api.anthropic.com"
  }
}

Enabling extended thinking mode with alwaysThinkingEnabled:

{
  "model": "claude-sonnet-4-20250514",
  "alwaysThinkingEnabled": true
}

This will set MAX_THINKING_TOKENS to 20000 by default. You can still override it with the MAX_THINKING_TOKENS environment variable.

pub fn is_configured(&self) -> bool

Check if any configuration is set

pub fn to_env_vars(&self) -> HashMap<String, String>

Get environment variables to pass to Claude Code CLI

Returns a HashMap of environment variable names and values that should be passed to the subprocess.

pub fn masked_api_key(&self) -> Option<String>

Get a masked version of the API key for logging

Shows first 4 and last 4 characters with the middle masked by asterisks. For example: sk-ant-api03-xxx... becomes sk-a***xxx

Returns None if no API key is set.

pub fn apply_to_options(&self, options: &mut ClaudeAgentOptions)

Apply configuration to ClaudeAgentOptions

Sets the model and environment variables on the options.

Trait Implementations

impl Clone for AgentConfig

fn clone(&self) -> AgentConfig

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for AgentConfig

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for AgentConfig

fn default() -> AgentConfig

Returns the “default value” for a type.