Crate adk_plugin 

adk-plugin

Plugin system for ADK-Rust agents.

This crate provides a plugin architecture similar to adk-go’s plugin package, allowing you to extend agent behavior through callbacks at various lifecycle points.

Overview

Plugins can hook into:

• Run lifecycle: Before/after the entire agent run
• User messages: Modify or inspect user input
• Events: Modify or inspect agent events
• Agent callbacks: Before/after agent execution
• Model callbacks: Before/after LLM calls
• Tool callbacks: Before/after tool execution

Quick Start

Using PluginConfig directly

use adk_plugin::{Plugin, PluginConfig, PluginManager};

// Create a logging plugin via PluginConfig
let logging_plugin = Plugin::new(PluginConfig {
    name: "logging".to_string(),
    on_user_message: Some(Box::new(|ctx, content| {
        Box::pin(async move {
            println!("User said: {:?}", content);
            Ok(None) // Don't modify
        })
    })),
    on_event: Some(Box::new(|ctx, event| {
        Box::pin(async move {
            println!("Event: {:?}", event);
            Ok(None) // Don't modify
        })
    })),
    ..Default::default()
});

Using PluginBuilder

use adk_plugin::{PluginBuilder, PluginManager};

// Create the same plugin via the builder API
let logging_plugin = PluginBuilder::new("logging")
    .on_user_message(Box::new(|ctx, content| {
        Box::pin(async move {
            println!("User said: {:?}", content);
            Ok(None)
        })
    }))
    .on_event(Box::new(|ctx, event| {
        Box::pin(async move {
            println!("Event: {:?}", event);
            Ok(None)
        })
    }))
    .build();

// Use with Runner
let manager = PluginManager::new(vec![logging_plugin]);

Re-exports

pub use adapted_plugin::AdaptedPlugin;

Modules

adapted_plugin

Adapter wrapping a legacy closure-based Plugin as an EnhancedPlugin.

Structs

EnhancedPluginManager

Manages enhanced plugins with priority-based pipeline execution.

Plugin

A Plugin bundles related callbacks for extending agent behavior.

PluginBuilder

Builder for creating plugins with a fluent API.

PluginConfig

Configuration for creating a Plugin.

PluginContext

A type-safe, concurrent key-value store for plugin shared state.

PluginManager

Manages a collection of plugins and coordinates callback execution.

PluginManagerConfig

Configuration for the PluginManager.

Enums

AfterModelCallResult

Result from an after_model_call hook invocation.

AfterToolCallResult

Result from an after_tool_call hook invocation.

BeforeModelCallResult

Result from a before_model_call hook invocation.

BeforeToolCallResult

Result from a before_tool_call hook invocation.

Traits

EnhancedPlugin

Enhanced plugin trait with fine-grained hooks and default no-op implementations.

Functions

collect_metrics

Helper to create a metrics collection callback.

log_events

Helper to create a simple logging callback for events.

log_user_messages

Helper to create a simple logging callback for user messages.

Type Aliases

AfterRunCallback

Callback invoked after the agent run completes.

BeforeRunCallback

Callback invoked before the agent run starts.

OnEventCallback

Callback invoked for each event generated by the agent.

OnModelErrorCallback

Callback invoked when a model error occurs.

OnToolErrorCallback

Callback invoked when a tool execution fails (after retries are exhausted).

OnUserMessageCallback

Callback invoked when a user message is received.