Provides `DictMixin`, a generic dataclass-to-dict converter with attribute access and nesting support. Demonstrates a clean, reusable pattern for serializing Pydantic-like objects without external dependencies. Could be extracted into any Python project needing structured data conversion.

Defines `MiddlewareBase`, an abstract class implementing the onion pattern for agent lifecycle hooks (`on_reply`, `on_reasoning`, `on_acting`, etc.). Composable, non-invasive, and easily extracted into any framework needing a pipeline of cross-cutting concerns (logging, tracing, permissions).

In-memory implementation of `MessageBusBase`, providing publish/subscribe, queues, distributed locks, and a registry for session-to-bus mapping. Clean async interface with comprehensive error handling. Could be extracted as a standalone lightweight event bus for any asyncio application.

Defines `ToolBase` with Pydantic input schema, permission checking (`check_permissions`), streaming chunk support (`ToolChunk`), and concurrency safety flags. Demonstrates a robust pattern for exposing agent-callable functions with safety and streaming. Could be reused in any LLM agent framework.

Implements a projector pattern for mirroring events from one session to another (e.g., subagent HITL results to team leader). Uses message bus registry and lifecycle hooks. Clean separation of concerns, extractable into any event-driven system requiring cross-session state synchronization.