Crate behest_context 

Layered context traits for the behest agent runtime.

Inspired by ADK-Rust’s ReadonlyContext → CallbackContext → InvocationContext hierarchy, this module defines progressively richer context interfaces that give agents, tools, hooks, and memory operations access to exactly the capabilities they need — no more, no less.

Hierarchy

ReadonlyContext         (identity: invocation_id, session_id, user_id, app_name)
  ├── SessionContext    (+ session state, session store)
  │     ├── RunContext  (+ run_id, cancellation, deadline, event sink, budget)
  │     │     └── ToolContext (+ tool_call, emit_progress, search_memory)
  │     └── MemoryContext (+ active_window, demote, compact)
  └── HookContext       (+ current_state, snapshot)

Design constraints

• Each layer adds specific, well-defined capabilities.
• Context does not become a “global service locator” — each trait is narrowly scoped to what the consumer needs.
• Tool can access session info and stream progress, but cannot access internal runtime state.
• Every trait has clear ownership and lifetime semantics.

Structs

AppContext

Application-level context: global configuration and identity.

EventSink

A sink for emitting events during a run.

HookContextImpl

Hook context implementation for observing run state.

MemoryContextImpl

Memory context implementation with active window management.

MemoryEntry

An entry retrieved from long-term memory.

RunBudget

Tracks the token budget for a single run.

RunContextImpl

Run-level context with cancellation, deadline, event sink, and budget.

RunSnapshot

A snapshot of the current run state for audit and replay.

SessionContextImpl

Session-level context with mutable state.

SessionState

A key-value state store scoped to a single session.

ToolContextImpl

Tool execution context.

Traits

HookContext

Context available to hooks observing the system.

MemoryContext

Context for memory operations (demotion, compaction).

ReadonlyContext

The minimum context available to any participant in the system.

RunContext

Context available during a single run invocation.

SessionContext

Context available during a session’s lifetime.

ToolContext

Context for tool execution.