feat(vf): add WitherFightConfig and WitherTarget to Boss

core/include/vf/Boss.h

@@ -158,3 +158,131 @@ public:
     DragonFight(DragonFight&&) = delete;
     DragonFight& operator=(DragonFight&&) = delete;
 
+    BossTickReport tick(const DragonPlayerInput& input);
+
+    const BossState& state() const { return boss; }
+    const DragonFightConfig& settings() const { return cfg; }
+    const std::vector<CrystalNode>& crystals() const { return pillarCrystals; }
+    int aliveCrystalCount() const;
+    // Taken from the End generator: the fight orbits and perches on the real
+    // exit portal column, not on an invented origin.
+    Vec3 portalCenter() const { return portal; }
+
+    bool exitPortalOpen() const { return portalOpen; }
+    bool dragonEggDropped() const { return eggDropped; }
+    Vec3i eggPosition() const { return eggCell; }
+
+    const BehaviorTree& brain() const { return tree; }
+    const BehaviorContext& context() const { return ctx; }
+
+    // Writes the reward the fight earned: the real End exit portal from
+    // EndGen. Refuses while the dragon still lives.
+    bool placeVictoryStructures(World& world, const EndGenerator& end) const;
+
+private:
+    void buildTree();
+    int resolvePlayerShot(const DragonPlayerInput& input);
+    void applyPlayerMelee(const DragonPlayerInput& input);
+    float applyCrystalHealing();
+
+    DragonFightConfig cfg;
+    BossState boss;
+    std::vector<CrystalNode> pillarCrystals;
+    BehaviorTree tree;
+    BehaviorContext ctx;
+    DragonPlayerInput lastInput;
+    Vec3 portal;
+    Vec3i eggCell;
+    bool portalOpen = false;
+    bool eggDropped = false;
+    float damageThisTick = 0.0f;
+};
+
+struct WitherFightConfig {
+    float maxHealth = 300.0f;
+    int summonTicks = 220;
+    float summonBlastRadius = 8.0f;
+    float summonBlastDamage = 12.0f;
+    float armorThreshold = 0.5f;
+    float projectileDamage = 5.0f;
+    float projectileRange = 32.0f;
+    int projectileCooldownTicks = 20;
+    int minionCooldownTicks = 100;
+    int maxMinions = 3;
+    float minionSpawnRange = 6.0f;
+    float armoredRegenPerTick = 0.06f;
+    float moveStep = 0.35f;
+    float minTargetDistance = 6.0f;
+};
+
+struct WitherTarget {
+    Vec3 position;
+    float health = 20.0f;
+    bool alive = true;
+};
+
+struct BossMinion {
+    Vec3 position;
+    float health = 6.0f;
+    bool alive = true;
+    long long spawnedTick = 0;
+};
+
+struct WitherHit {
+    float amount = 0.0f;
+    bool projectile = false;
+};
+
+// The block pattern that calls the wither: a soul sand T topped with three
+// heads, readable along either horizontal axis.
+Block witherBaseBlock();
+Block witherHeadBlock();
+bool witherPatternAt(const World& world, const Vec3i& baseCell, bool alongX);
+bool findWitherPattern(const World& world, const Vec3i& baseCell, bool& outAlongX);
+void consumeWitherPattern(World& world, const Vec3i& baseCell, bool alongX);
+
+// Summons out of a block pattern, blasts everything around it on arrival, then
+// hunts the nearest living target. Below half health it armours up: projectiles
+// stop landing entirely and it starts regenerating and calling minions.
+class WitherFight {
+public:
+    explicit WitherFight(uint32_t seed, const WitherFightConfig& config = {});
+
+    WitherFight(const WitherFight&) = delete;
+    WitherFight& operator=(const WitherFight&) = delete;
+    WitherFight(WitherFight&&) = delete;
+    WitherFight& operator=(WitherFight&&) = delete;
+
+    void begin(const Vec3& spawnPosition);
+    // Consumes the pattern in the world and starts the fight at its centre.
+    bool summonFromWorld(World& world, const Vec3i& baseCell);
+
+    BossTickReport tick(const std::vector<WitherHit>& incoming,
+                        std::vector<WitherTarget>& targets);
+
+    const BossState& state() const { return boss; }
+    const WitherFightConfig& settings() const { return cfg; }
+    const std::vector<BossMinion>& minions() const { return summoned; }
+    bool armored() const { return boss.phase == BossPhase::Armored; }
+    int aliveMinionCount() const;
+
+    const BehaviorTree& brain() const { return tree; }
+    const BehaviorContext& context() const { return ctx; }
+
+private:
+    void buildTree();
+    float applyIncoming(const std::vector<WitherHit>& incoming);
+    int nearestAliveTarget() const;
+
+    WitherFightConfig cfg;
+    BossState boss;
+    std::vector<BossMinion> summoned;
+    BehaviorTree tree;
+    BehaviorContext ctx;
+    std::vector<WitherTarget>* activeTargets = nullptr;
+    float damageThisTick = 0.0f;
+    float healedThisTick = 0.0f;
+    int minionsThisTick = 0;
+};
+
+} // namespace vf