Module interface 

Engine Interface Abstractions

This module defines the contract between the agent engine and external consumers (TUI, servers, CLI tools, etc.).

Architecture

The interface is message-based and transport-agnostic:

Consumer          Interface           Engine
   │                                    │
   │◄─────── EventSink ────────────────│  (events out)
   │                                    │
   │─────── InputSource ──────────────►│  (input in)
   │                                    │
   │◄────── PermissionRegistry ───────►│  (request/response)

Components

• EventSink - Receives events from the engine (text, tools, errors)
• InputSource - Provides input to the engine (user messages, commands)
• PermissionPolicy - Automatic handling of permission requests

Built-in Implementations

• ChannelEventSink - Channel-backed sink (default, used by TUI)
• ChannelInputSource - Channel-backed source (default, used by TUI)
• [StdoutEventSink] - Simple stdout sink for CLI tools
• AutoApprovePolicy - Auto-approve all permissions (headless/trusted)
• DenyAllPolicy - Deny all permissions (sandboxed)
• InteractivePolicy - Always ask user (default for TUI)

Structs

AutoApprovePolicy

Auto-approve all permission requests.

ChannelEventSink

Event sink backed by an async channel.

ChannelInputSource

Input source backed by an async channel.

DenyAllPolicy

Deny all permission requests.

InteractivePolicy

Interactive policy - always ask the user.

SendError

Error when sending an event fails.

SimpleEventSink

Simple event sink that prints to stdout.

Enums

PolicyDecision

Decision from a permission policy.

Traits

EventSink

Receives events from the agent engine and delivers them to a consumer.

InputSource

Provides input from a consumer to the agent engine.

PermissionPolicy

Policy for handling permission requests.