## Summary
Adds comprehensive support for tool permission callbacks and hook
callbacks to the Python SDK, enabling fine-grained control over tool
execution and custom event handling.
## Key Changes
- **Tool Permission Callbacks**: Control which tools Claude can use and
modify their inputs
- type with async support
- with suggestions from CLI
- for structured responses
- **Hook Callbacks**: React to events in the Claude workflow
- type for event handlers
- for conditional hook execution
- Support for tool_use_start, tool_use_end events
- **Integration**: Full plumbing through ClaudeCodeOptions → Client →
Query
- **Examples**: Comprehensive example showing permission control
patterns
- **Tests**: Coverage for all callback scenarios
## Implementation Details
- Callbacks are registered during initialization phase
- Control protocol handles can_use_tool and hook_callback requests
- Backwards compatible with dict returns for tool permissions
- Proper error handling and type safety throughout
Builds on top of #139's control protocol implementation.
---------
Co-authored-by: Dickson Tsai <dickson@anthropic.com>
## Summary
Adds in-process SDK MCP server support to the Python SDK, building on
the control protocol from #139.
**Note: Targets `dickson/control` branch (PR #139), not `main`.**
## Key Changes
- Added `@tool` decorator and `create_sdk_mcp_server()` API for defining
in-process MCP servers
- SDK MCP servers run directly in the Python process (no subprocess
overhead)
- Moved SDK MCP handling from Transport to Query class for proper
architectural layering
- Added `McpSdkServerConfig` type and integrated with control protocol
## Example
```python
from claude_code_sdk import tool, create_sdk_mcp_server
@tool("greet", "Greet a user", {"name": str})
async def greet_user(args):
return {"content": [{"type": "text", "text": f"Hello, {args['name']}!"}]}
server = create_sdk_mcp_server(name="my-tools", tools=[greet_user])
options = ClaudeCodeOptions(mcp_servers={"tools": server})
```
## Testing
- Added integration tests in `test_sdk_mcp_integration.py`
- Added example calculator server in `examples/mcp_calculator.py`
---------
Co-authored-by: Dickson Tsai <dickson@anthropic.com>
Co-authored-by: Ashwin Bhat <ashwin@anthropic.com>
Co-authored-by: Claude <noreply@anthropic.com>
## Summary
This PR implements control protocol support in the Python SDK, aligning
it with the TypeScript implementation pattern. The refactor introduces a
Query + Transport separation to enable bidirectional communication
between the SDK and CLI.
## Motivation
The previous Python SDK implementation used a high-level abstraction in
the Transport ABC (`send_request`/`receive_messages`) that couldn't
handle bidirectional communication. This prevented support for:
- Control messages from CLI to SDK that need responses
- Hooks implementation
- Dynamic permission mode changes
- SDK MCP servers
## Changes
### Core Architecture Refactor
1. **New Query Class** (`src/claude_code_sdk/_internal/query.py`)
- Manages control protocol on top of Transport
- Handles control request/response routing
- Manages initialization handshake with timeout
- Supports hook callbacks and tool permission callbacks
- Implements message streaming
2. **Refactored Transport ABC**
(`src/claude_code_sdk/_internal/transport/__init__.py`)
- Changed from high-level (`send_request`/`receive_messages`) to
low-level (`write`/`read_messages`) interface
- Now handles raw I/O instead of protocol logic
- Aligns with TypeScript ProcessTransport pattern
3. **Updated SubprocessCLITransport**
(`src/claude_code_sdk/_internal/transport/subprocess_cli.py`)
- Simplified to focus on raw message streaming
- Removed protocol logic (moved to Query)
- Improved cleanup and error handling
4. **Enhanced ClaudeSDKClient** (`src/claude_code_sdk/client.py`)
- Now uses Query for control protocol
- Supports initialization messages
- Better error handling for control protocol failures
### Control Protocol Features
- **Initialization handshake**: SDK sends initialize request, CLI
responds with supported commands
- **Control message types**:
- `initialize`: Establish bidirectional connection
- `interrupt`: Cancel ongoing operations
- `set_permission_mode`: Change permission mode dynamically
- **Timeout handling**: 60-second timeout for initialization to handle
CLI versions without control support
### Examples
Updated `examples/streaming_mode.py` to demonstrate control protocol
initialization and error handling.
## Testing
- Tested with current CLI (no control protocol support yet) - gracefully
falls back
- Verified backward compatibility with existing `query()` function
- Tested initialization timeout handling
- Verified proper cleanup on errors
## Design Alignment
This implementation closely follows the TypeScript reference:
- `src/core/Query.ts` → `src/claude_code_sdk/_internal/query.py`
- `src/transport/ProcessTransport.ts` →
`src/claude_code_sdk/_internal/transport/subprocess_cli.py`
- `src/entrypoints/sdk.ts` → `src/claude_code_sdk/client.py`
## Next Steps
Once the CLI implements the control protocol handler, this will enable:
- Hooks support
- Dynamic permission mode changes
- SDK MCP servers
- Improved error recovery
🤖 Generated with [Claude Code](https://claude.ai/code)
---------
Co-authored-by: Ashwin Bhat <ashwin@anthropic.com>
Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: Kashyap Murali <kashyap@anthropic.com>
## Key changes
- Adds env field to `ClaudeCodeOptions`, allowing custom env vars to cli
- Updates tests and examples
## Motivation
Bringing Python SDK to feature parity with TS SDK, which supports custom
env vars
## Notes
- Environment variables are merged in order: system env → user env → SDK
required vars
- This implementation seems slightly more robust than the TypeScript
version, which can exclude OS envs vars if a user passes a minimal env
object
- Some linting changes seem to have been picked up
## Summary
Fixes an issue where `thinking` content blocks in Claude Code responses
were not being parsed, resulting in empty `AssistantMessage` content
arrays.
## Changes
- Added `ThinkingBlock` dataclass to handle thinking content with
`thinking` and `signature` fields
- Updated client parsing logic in `_internal/client.py` to recognize and
create `ThinkingBlock` instances
- Added comprehensive test coverage for thinking block functionality
## Before
```python
# Claude Code response with thinking block resulted in:
AssistantMessage(content=[]) # Empty content!
```
## After
```python
# Now correctly parses to:
AssistantMessage(content=[
ThinkingBlock(thinking="...", signature="...")
])
```
Fixes#27
---------
Co-authored-by: Dickson Tsai <dickson@anthropic.com>
`claude`'s `--mcp-config` takes either a JSON file or string, so support
this in `ClaudeCodeOptions`
```
--mcp-config <file or string> Load MCP servers from a JSON file or string
```
---------
Co-authored-by: claude[bot] <209825114+claude[bot]@users.noreply.github.com>
Co-authored-by: Sam Fu <shunfu@users.noreply.github.com>
## Summary
- Adds `extra_args` field to `ClaudeCodeOptions` to support passing
arbitrary CLI flags
- Enables forward compatibility with future CLI flags without requiring
SDK updates
- Supports both valued flags (`--flag value`) and boolean flags
(`--flag`)
## Changes
- Add `extra_args: dict[str, str | None]` field to `ClaudeCodeOptions`
- Implement logic in `SubprocessCLITransport` to handle extra args:
- `None` values create boolean flags (e.g., `{"verbose": None}` →
`--verbose`)
- String values create flags with arguments (e.g., `{"output": "json"}`
→ `--output json`)
- Add comprehensive tests for the new functionality
## Test plan
- [x] Added unit tests for settings file path handling
- [x] Added unit tests for settings JSON object handling
- [x] Added unit tests for extra_args with both valued and boolean flags
- [x] All tests pass (`python -m pytest tests/`)
- [x] Type checking passes (`python -m mypy src/`)
🤖 Generated with [Claude Code](https://claude.ai/code)
Co-authored-by: Claude <noreply@anthropic.com>
The test was checking source code for specific strings rather than
testing behavior. The existing subprocess tests already verify the
functionality works correctly.
Remove anyio.create_task_group() from receive_messages() to fix the
RuntimeError "Attempted to exit cancel scope in a different task than
it was entered in" when using the SDK with FastAPI's SSE streaming.
The issue occurred because FastAPI can move async generators between
different asyncio tasks during the streaming lifecycle, which conflicts
with anyio's cancel scope tracking.
Changes:
- Remove task group usage from receive_messages()
- Read stderr sequentially after stdout completes
- Add test to ensure no task groups are used
- Fix existing test expectation for buffer overflow
This is a minimal fix that maintains compatibility while solving the
core issue. The trade-off is that stderr is read after stdout instead
of concurrently, but this is unlikely to cause issues in practice.
🤖 Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: Claude <noreply@anthropic.com>
Removed redundant comments that simply restate what the code is doing.
Kept only comments that provide valuable context or explain complex behavior.
🤖 Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: Claude <noreply@anthropic.com>
Adds buffering to accumulate incomplete JSON messages that are split
across multiple stream reads due to asyncio's 64KB default buffer limit.
- Implement 1MB buffer to accumulate partial JSON
- Clear buffer on successful parse or size limit exceeded
- Add comprehensive tests for split JSON scenarios
Fixes CLIJSONDecodeError when reading large minified JSON files.
🤖 Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: Claude <noreply@anthropic.com>
- Fixed quotes to use double quotes consistently
- Adjusted line breaks per ruff formatter rules
- No functional changes
🤖 Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: Claude <noreply@anthropic.com>
- Fixed formatting in test_subprocess_buffering.py
- No functional changes, only code style improvements
🤖 Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: Claude <noreply@anthropic.com>
- Convert async test to use anyio.run() pattern consistent with other tests
- Remove unused CLIJSONDecodeError import
- Add tests for JSON with embedded newlines
- Add tests for multiple newlines between objects
- All tests passing
🤖 Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: Claude <noreply@anthropic.com>
- Remove cost_usd field from test expectations
- Update to use total_cost_usd instead of total_cost
- All 30 tests now pass
🤖 Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: Claude <noreply@anthropic.com>
