# plugins/framework/observability.py
from typing import Protocol, Optional
from contextvars import ContextVar

current_trace_id: ContextVar[Optional[str]] = ContextVar("current_trace_id", default=None)

class ObservabilityProvider(Protocol):
    """Interface for observability - host application implements this."""
    def start_trace(self, name: str, **kwargs) -> Optional[str]: ...
    def end_trace(self, trace_id: str, **kwargs) -> None: ...

class NullObservability:
    """Default no-op implementation for standalone operation."""
    def start_trace(self, name: str, **kwargs) -> None:
        return None
    def end_trace(self, trace_id: str, **kwargs) -> None:
        pass