Problem

HookJSONOutput is defined in types.py and used as the return type for HookCallback:

 HookCallback = Callable[ [dict[str, Any], str | None, HookContext], Awaitable[HookJSONOutput], ] 

However, HookJSONOutput is not exported in init.py, which causes type checking issues when implementing hook callbacks.

Current Workaround

Users need to either:

1. Import from the private module: from claude_agent_sdk.types import HookJSONOutput
2. Define their own TypedDict matching the structure
3. Use dict[str, Any] and lose type safety

Example Code

from claude_agent_sdk import HookContext

HookJSONOutput is not available

 async def my_hook( input_data: dict[str, Any], tool_use_id: str | None, context: HookContext, ) -> HookJSONOutput: # Type error: HookJSONOutput not found return {"decision": "block", "systemMessage": "Not allowed"} 

Suggested Fix

Add HookJSONOutput to the all list in init.py:

 __all__ = [ # ... existing exports "HookCallback", "HookContext", "HookMatcher", "HookJSONOutput", # Add this # ... ]