HTN Decomposition Guide

Hierarchy Levels

The HTN system decomposes tasks through four levels:

Level	Description	Example
portfolio	Strategic workspace tasks	”Improve portfolio health”
project	Project-scoped tasks	”Stabilize CI pipeline”
domain	Domain-specific tasks	”Restart failing service”
action	Primitive executable actions	”Set service.status = healthy”

Defining Tasks

Primitive Actions

import { action } from "../src/planner/action.ts";

const restart = action("restart", "restart-service")
  .level("action")
  .requireEquals("service.status", "down")
  .set({ "service.status": "healthy" })
  .cost(2)
  .build();

Composite Tasks

import type { CompositeTask } from "../src/planner/types.ts";

const fixService: CompositeTask = {
  id: "fix-service",
  name: "Fix Service",
  level: "domain",
  precondition: (state) => state["service.status"] === "down",
  decompose: (state) => ["restart", "verify-health"],
};

Building the Task Network

import { TaskNetwork } from "../src/planner/task-network.ts";

const network = new TaskNetwork();
network.addPrimitiveAction(restart);
network.addPrimitiveAction(verifyHealth);
network.addCompositeTask(fixService);

Running Decomposition

import { HTNDecomposer } from "../src/planner/htn-decomposer.ts";

const decomposer = new HTNDecomposer(network);
const result = decomposer.decompose("fix-service", currentState);

if (result.success) {
  // result.actions contains ordered primitive actions
}