Battle System

Adding a New Buff/Debuff

Step 1: Add to BuffType

// src/domain/battles/type/baffType.ts
export type BuffType =
  | "strength"
  | "vulnerable"
  // ... existing types
  | "newbuff";  // Add here

Step 2: Add Buff Data

// src/domain/battles/data/buffData.ts
export const BUFF_DATA: Record<BuffType, BuffDefinition> = {
  // ... existing buffs
  newbuff: {
    id: "newbuff",
    name: "新バフ",
    description: "効果の説明",
    type: "buff",  // "buff" | "debuff"
    stackable: true,
    maxStacks: 5,
    icon: "🔥",
  },
};

Step 3: Implement Effect Logic

// src/domain/battles/calculators/buffCalculation.ts
// Add case to applyBuffEffects or relevant calculation

Buff Ownership System

interface BuffDebuffState {
  type: BuffType;
  value: number;
  duration: number;
  appliedBy: "player" | "enemy" | "environment";  // IMPORTANT
}

Rule: Duration decreases only during the applier's phase.

• Player-applied buffs → decrease on player phase end
• Enemy-applied debuffs → decrease on enemy phase end

Damage Calculation Flow

// src/domain/battles/calculators/damageCalculation.ts

1. getBaseDamage(card)
2. applyStrengthBuff(damage, buffs)
3. applyWeaknessDebuff(damage, buffs)
4. applyVulnerability(damage, targetBuffs)
5. applyArmorPenetration(damage, penetration)
6. applyGuard(damage, targetGuard)
7. applyAP(damage, targetAP)
8. finalDamage = max(1, damage)

Phase Execution

// Player Phase
playerPhaseExecution.ts:
  1. drawCards()
  2. restoreEnergy()
  3. decreaseBuffDurations("player")
  4. waitForPlayerInput()

// Enemy Phase
enemyPhaseExecution.ts:
  1. selectAction(aiPatterns)
  2. executeAction()
  3. decreaseBuffDurations("enemy")

Adding Card Effect

// src/domain/cards/state/cardPlayLogic.ts
export function executeCardEffect(card: Card, state: BattleState): BattleState {
  let newState = { ...state };

  if (card.baseDamage) {
    newState = applyDamage(newState, card.baseDamage);
  }

  if (card.guardAmount) {
    newState = addGuard(newState, card.guardAmount);
  }

  // New effect
  if (card.newEffect) {
    newState = applyNewEffect(newState, card.newEffect);
  }

  return newState;
}

Common Buff Types

Testing Checklist

• Buff applies correctly
• Duration decreases properly
• Stacking works as expected
• Effect calculation is correct
• UI displays the buff
• Buff removal on duration 0

Design Doc Reference

Battle design docs: .claude/docs/battle_document/

• battle_logic.md
• buff_debuff_system.md