TodoListMiddleware

Injects task-planning state into the agent's context by maintaining a shared todo list. Use this when your agent performs multi-step operations and you want it to track progress across model calls.

Constructor

use synaptic::middleware::TodoListMiddleware;

let mw = TodoListMiddleware::new();

Managing Tasks

The middleware provides async methods to add and complete tasks programmatically:

let mw = TodoListMiddleware::new();

// Add tasks before or during agent execution
let id1 = mw.add("Research competitor pricing").await;
let id2 = mw.add("Draft summary report").await;

// Mark tasks as done
mw.complete(id1).await;

// Inspect current state
let items = mw.items().await;

Each task gets a unique auto-incrementing ID. Tasks have an id, task (description), and done (completion status).

Usage with `create_agent`

use std::sync::Arc;
use synaptic::graph::{create_agent, AgentOptions};
use synaptic::middleware::TodoListMiddleware;

let todo = Arc::new(TodoListMiddleware::new());
todo.add("Gather user requirements").await;
todo.add("Generate implementation plan").await;
todo.add("Write code").await;

let options = AgentOptions {
    middleware: vec![todo.clone()],
    ..Default::default()
};

let graph = create_agent(model, tools, options)?;

How It Works

Lifecycle hook: before_model
Before each model call, the middleware checks the current todo list.
If the list is non-empty, it inserts a system message at the beginning of the request's message list containing the formatted task list.
The model sees the current state of all tasks, including which ones are done.

The injected message looks like:

Current TODO list:
  [ ] #1: Gather user requirements
  [x] #2: Generate implementation plan
  [ ] #3: Write code

This gives the model awareness of the overall plan and progress, enabling it to work through tasks methodically. You can call complete() from tool implementations or external code to update progress between agent steps.

Example: Tool-driven Task Completion

Combine with a custom tool that marks tasks as done:

let todo = Arc::new(TodoListMiddleware::new());
todo.add("Fetch data from API").await;
todo.add("Transform data").await;
todo.add("Save results").await;

// The agent sees the todo list in its context and can
// reason about which tasks remain. Your tools can call
// todo.complete(id) when they finish their work.

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