2nd/10_Wiki/Topics/AI_and_ML/Goal-Oriented-Action-Planning.md

id, title, category, status, canonical_id, aliases, duplicate_of, source_trust_level, confidence_score, verification_status, tags, raw_sources, last_reinforced, github_commit, tech_stack

id	title	category	status	canonical_id	aliases	duplicate_of	source_trust_level	confidence_score	verification_status	tags	raw_sources	last_reinforced	github_commit	tech_stack
wiki-2026-0508-goal-oriented-action-planning	Goal-Oriented Action Planning (GOAP)	10_Wiki/Topics	verified	self	GOAP action planning F.E.A.R AI STRIPS HTN behavior tree alternative	none	A	0.92	applied	game-ai planning goap strips htn action-planning npc		2026-05-10	pending	language applicable_to C# / C++ / Python Game AI Planning NPC

Goal-Oriented Action Planning (GOAP)

매 한 줄

"매 NPC 의 goal 의 의 의 action sequence 의 plan". F.E.A.R. (Monolith 2005) 매 famous. 매 STRIPS-derived. 매 modern alternative: 매 behavior tree, HTN, utility AI. 매 LLM 의 action plan 의 also similar.

매 핵심

매 component

• Goal: 매 desired world state.
• Action: 매 (precondition, effect, cost).
• Planner: 매 A* search 의 의 의 actions.
• WorldState: 매 current facts.

매 vs alternatives

• FSM: 매 hardcoded transitions.
• Behavior Tree: 매 reactive, designer-friendly.
• GOAP: 매 emergent, dynamic plan.
• HTN: 매 hierarchical task decompose.
• Utility AI: 매 score actions.

매 응용

1. Game AI (FPS, RTS).
2. Robotics planning.
3. NPC complex behavior.
4. Strategy game.
5. LLM agent (similar pattern).

💻 패턴

Action definition

@dataclass
class Action:
    name: str
    cost: float
    preconditions: dict  # 매 state requirements
    effects: dict  # 매 state changes
    
    def can_run(self, world_state):
        return all(world_state.get(k) == v for k, v in self.preconditions.items())
    
    def apply(self, world_state):
        new = world_state.copy()
        new.update(self.effects)
        return new

Goal definition

@dataclass
class Goal:
    name: str
    desired_state: dict
    priority: float
    
    def is_satisfied(self, world_state):
        return all(world_state.get(k) == v for k, v in self.desired_state.items())

A* planner

import heapq

def goap_plan(world_state, goal, actions):
    queue = [(0, world_state, [])]
    visited = set()
    
    while queue:
        cost, state, path = heapq.heappop(queue)
        state_key = frozenset(state.items())
        if state_key in visited: continue
        visited.add(state_key)
        
        if goal.is_satisfied(state): return path
        
        for action in actions:
            if action.can_run(state):
                new_state = action.apply(state)
                heuristic = compute_heuristic(new_state, goal)
                heapq.heappush(queue, (cost + action.cost + heuristic, new_state, path + [action]))
    
    return None  # 매 no plan

Heuristic (number of unsatisfied goal facts)

def compute_heuristic(state, goal):
    return sum(1 for k, v in goal.desired_state.items() if state.get(k) != v)

Example: combat AI

ACTIONS = [
    Action('reload', cost=1, preconditions={'has_weapon': True, 'has_ammo': True}, effects={'weapon_loaded': True}),
    Action('grab_ammo', cost=2, preconditions={'near_ammo': True}, effects={'has_ammo': True}),
    Action('fire', cost=1, preconditions={'weapon_loaded': True, 'enemy_visible': True}, effects={'enemy_dead': True, 'weapon_loaded': False}),
    Action('take_cover', cost=3, preconditions={'cover_available': True}, effects={'in_cover': True}),
]

GOAL_KILL = Goal('kill_enemy', {'enemy_dead': True}, priority=1.0)

world = {'has_weapon': True, 'has_ammo': False, 'near_ammo': True, 'enemy_visible': True, 'cover_available': True}
plan = goap_plan(world, GOAL_KILL, ACTIONS)
# 매 → [grab_ammo, reload, fire]

Reactive replanning

class GOAPAgent:
    def __init__(self, actions):
        self.actions = actions
        self.current_plan = []
        self.current_goal = None
    
    def update(self, world_state):
        # 매 select goal
        goals = self.evaluate_goals(world_state)
        new_goal = max(goals, key=lambda g: g.priority)
        
        # 매 replan if goal changed or plan invalid
        if new_goal != self.current_goal or not self.plan_valid(world_state):
            self.current_plan = goap_plan(world_state, new_goal, self.actions)
            self.current_goal = new_goal
        
        if self.current_plan:
            return self.current_plan.pop(0)
        return None

Cost dynamic adjustment

def dynamic_cost(action, world_state):
    base = action.cost
    if action.name == 'fire' and world_state['low_ammo']: return base * 3
    if action.name == 'take_cover' and world_state['health'] < 30: return base * 0.3
    return base

HTN (Hierarchical Task Network)

class Task:
    def __init__(self, name, methods):
        self.name = name; self.methods = methods  # 매 list of decomposition

class Method:
    def __init__(self, preconditions, subtasks):
        self.preconditions = preconditions; self.subtasks = subtasks

# 매 decompose top task → primitive actions

Behavior Tree (alternative)

class Selector:
    def tick(self):
        for child in self.children:
            if child.tick() == 'success': return 'success'
        return 'fail'

class Sequence:
    def tick(self):
        for child in self.children:
            if child.tick() != 'success': return 'fail'
        return 'success'

# 매 attack tree
attack = Sequence([HasAmmo(), HasWeapon(), Selector([Fire(), Reload()])])

Utility AI (alternative)

def utility_decide(actions, world_state):
    scores = []
    for action in actions:
        if not action.can_run(world_state): continue
        score = sum(consider.score(world_state) for consider in action.considerations)
        scores.append((action, score))
    return max(scores, key=lambda x: x[1])[0]

LLM agent (similar pattern)

def llm_plan(goal, world_state, available_tools, llm):
    prompt = f"""You are a planner. Goal: {goal}
Current state: {world_state}
Tools: {available_tools}

Output a plan (JSON list of tool invocations) to achieve the goal."""
    return json.loads(llm.generate(prompt))

Plan visualization

def visualize_plan(plan, world_state):
    state = world_state.copy()
    for i, action in enumerate(plan):
        print(f'{i+1}. {action.name} (cost {action.cost})')
        state = action.apply(state)
    print(f'Final state: {state}')

매 결정 기준

상황	Approach
Complex emergent NPC	GOAP
Designer-driven	Behavior Tree
Hierarchical task	HTN
Score-based	Utility AI
Modern flexible	LLM agent
Simple	FSM

기본값: 매 GOAP for emergent + 매 BT for reactive + 매 HTN for hierarchical + 매 LLM for flexible/data-rich.

🔗 Graph

• 부모: Planning
• 변형: Behavior-Tree · HTN
• 응용: F.E.A.R-AI
• Adjacent: STRIPS · Drama Management Systems · Foundation-Models

🤖 LLM 활용

언제: 매 game NPC. 매 robot planning. 언제 X: 매 simple linear behavior.

❌ 안티패턴

• Plan once + execute blind: 매 dynamic world fail.
• Action explosion: 매 search slow.
• No replanning: 매 stale.
• GOAP for trivial NPC: 매 over-engineer.

🧪 검증 / 중복

• Verified (F.E.A.R AI postmortem, Orkin, GOAP literature).
• 신뢰도 A.

🕓 Changelog

날짜	변경
2026-04-20	Auto
2026-05-08	Phase 1
2026-05-10	Manual cleanup — GOAP + 매 A* / BT / HTN / utility / LLM agent code