Protocol API

Core public objects:

Object	Use
Tactic	Typed callable boundary.
TacticInfo	Name, schemas, refs, capabilities, examples, metadata.
CallContext	Request id, trace id, metadata, caller context.
TacticEvent	Streaming/status/error event envelope.
TacticResolver	Resolve refs to local or remote tactics.

Input/output types should be Pydantic-schema-compatible. BaseModel is the cleanest path, but simple JSON-compatible annotations and supported Pydantic types can also work.