claude-agent-sdk-python/CHANGELOG.md

Changelog

0.1.0

Introducing the Claude Agent SDK! The Claude Code SDK has been renamed to better reflect its capabilities for building AI agents across all domains, not just coding.

Breaking Changes

Type Name Changes

• ClaudeCodeOptions renamed to ClaudeAgentOptions: The options type has been renamed to match the new SDK branding. Update all imports and type references:

  # Before
  from claude_agent_sdk import query, ClaudeCodeOptions
  options = ClaudeCodeOptions(...)
  
  # After
  from claude_agent_sdk import query, ClaudeAgentOptions
  options = ClaudeAgentOptions(...)
  

System Prompt Changes

• Merged prompt options: The custom_system_prompt and append_system_prompt fields have been merged into a single system_prompt field for simpler configuration
• No default system prompt: The Claude Code system prompt is no longer included by default, giving you full control over agent behavior. To use the Claude Code system prompt, explicitly set:

  system_prompt={"type": "preset", "preset": "claude_code"}
  

Settings Isolation

• No filesystem settings by default: Settings files (settings.json, CLAUDE.md), slash commands, and subagents are no longer loaded automatically. This ensures SDK applications have predictable behavior independent of local filesystem configurations
• Explicit settings control: Use the new setting_sources field to specify which settings locations to load: ["user", "project", "local"]

For full migration instructions, see our migration guide.

New Features

• Programmatic subagents: Subagents can now be defined inline in code using the agents option, enabling dynamic agent creation without filesystem dependencies. Learn more
• Session forking: Resume sessions with the new fork_session option to branch conversations and explore different approaches from the same starting point. Learn more
• Granular settings control: The setting_sources option gives you fine-grained control over which filesystem settings to load, improving isolation for CI/CD, testing, and production deployments

Documentation

• Comprehensive documentation now available in the API Guide
• New guides for Custom Tools, Permissions, Session Management, and more
• Complete Python API reference

0.0.22

• Introduce custom tools, implemented as in-process MCP servers.
• Introduce hooks.
• Update internal Transport class to lower-level interface.
• ClaudeSDKClient can no longer be run in different async contexts.

0.0.19

• Add ClaudeCodeOptions.add_dirs for --add-dir
• Fix ClaudeCodeSDK hanging when MCP servers log to Claude Code stderr

0.0.18

• Add ClaudeCodeOptions.settings for --settings

0.0.17

• Remove dependency on asyncio for Trio compatibility

0.0.16

• Introduce ClaudeSDKClient for bidirectional streaming conversation
• Support Message input, not just string prompts, in query()
• Raise explicit error if the cwd does not exist

0.0.14

• Add safety limits to Claude Code CLI stderr reading
• Improve handling of output JSON messages split across multiple stream reads

0.0.13

• Update MCP (Model Context Protocol) types to align with Claude Code expectations
• Fix multi-line buffering issue
• Rename cost_usd to total_cost_usd in API responses
• Fix optional cost fields handling