MiddlewareHook#

Build extensions, choose hooks, and manage request-scoped state. See the guide.

class zett_agent.extensions.base.MiddlewareHook[source]#

Wrap provider requests and local tool handlers for one extension.

Every AgentExtension inherits these hooks. Extensions form an onion in their existing priority order: the first extension is outermost and the last extension is closest to the provider or tool handler.

One extension instance may serve concurrent sessions and parallel tool calls. Keep request-local data in local variables or on context, not mutable instance attributes without synchronization.

async on_model_request(context, request, call_next)[source]#

Wrap one provider request and its complete streamed response.

Pass request (or a dataclass replacement) to call_next. The default closes the inner stream so cancellation reaches the provider.

Parameters:
Return type:

AsyncIterator[ModelEvent]

async on_tool_call(context, call, call_next)[source]#

Wrap one registered local tool handler and return its ToolResult.

An extension may adjust call.arguments, return without calling the next layer, transform its result, or raise into normal tool-failure handling.

Parameters:
Return type:

ToolResult