XP

src/common/rpg/components/cooldown.ts

@@ -0,0 +1,41 @@
+import { component } from "../core/registry";
+import { Component } from "../core/world";
+import { action, variable } from "../utils/decorators";
+
+@component
+export class Cooldown extends Component<{
+    remaining: number;
+    duration: number;
+}> {
+    constructor(duration: number) {
+        super({ remaining: duration, duration });
+    }
+
+    @variable('.')
+    get ready(): boolean {
+        return this.state.remaining <= 0;
+    }
+
+    @action
+    reset(duration?: number): void {
+        if (duration != null) this.state.duration = duration;
+        this.state.remaining = this.state.duration;
+    }
+
+    @action
+    clear(): void {
+        if (this.state.remaining <= 0) return;
+        this.state.remaining = 0;
+        this.emit('ready');
+    }
+
+    @action
+    update(dt: number): void {
+        if (this.state.remaining <= 0) return;
+        this.state.remaining -= dt;
+        if (this.state.remaining <= 0) {
+            this.state.remaining = 0;
+            this.emit('ready');
+        }
+    }
+}

src/common/rpg/components/effect.ts

@@ -0,0 +1,83 @@
+import { component } from "../core/registry";
+import { Component, type EvalContext } from "../core/world";
+import { evaluateCondition } from "../utils/conditions";
+import { action, variable } from "../utils/decorators";
+import { Stat } from "./stat";
+
+@component
+export class Effect extends Component<{
+    targetStat: string;   // component key, e.g. 'health'
+    targetField: 'value' | 'max' | 'min';
+    delta: number;
+    duration: number | null;   // null = permanent until removed
+    remaining: number | null;  // countdown in seconds; null for condition-based/permanent
+    condition: string | null;  // keep effect while true; remove when it becomes false
+}> {
+    /** True while the effect's delta is applied to the target stat. */
+    @variable('.') active: boolean = false;
+
+    constructor(
+        targetStat: string,
+        delta: number,
+        targetField?: 'value' | 'max' | 'min',
+        duration?: number,
+        condition?: string,
+    ) {
+        super({
+            targetStat,
+            targetField: targetField ?? 'value',
+            delta,
+            duration: duration ?? null,
+            remaining: duration ?? null,
+            condition: condition ?? null,
+        });
+    }
+
+    override onAdd(): void {
+        const stat = this.entity.get(Stat, this.state.targetStat);
+        if (stat) {
+            stat.applyModifier(this.state.delta, this.state.targetField);
+        }
+        this.active = true;
+    }
+
+    override onRemove(): void {
+        const stat = this.entity.get(Stat, this.state.targetStat);
+        if (stat) {
+            stat.removeModifier(this.state.delta, this.state.targetField);
+        }
+        this.active = false;
+    }
+
+    @action
+    reset(duration?: number): void {
+        if (duration != null) {
+            this.state.duration = duration;
+        }
+        this.state.remaining = this.state.duration;
+        this.active = true;
+    }
+
+    /** Mark as expired. EffectSystem will remove the component, which reverses the delta. */
+    @action
+    clear(): void {
+        this.state.remaining = 0;
+        this.active = false;
+        this.emit('expired');
+    }
+
+    update(dt: number, ctx?: EvalContext): void {
+        if (this.state.remaining != null) {
+            this.state.remaining -= dt;
+            if (this.state.remaining <= 0) {
+                this.state.remaining = 0;
+                this.clear();
+            }
+        } else if (this.state.condition != null) {
+            if (!evaluateCondition(this.state.condition, ctx ?? this.context)) {
+                this.clear();
+            }
+        }
+        // permanent effect (no duration, no condition): nothing to do
+    }
+}

src/common/rpg/components/equipment.ts

@@ -0,0 +1,164 @@
+import { component } from "../core/registry";
+import { Component, COMPONENT_STATE } from "../core/world";
+import { action } from "../utils/decorators";
+import type { RPGVariables } from "../types";
+import { Effect } from "./effect";
+
+// ── Equippable ────────────────────────────────────────────────────────────────
+
+interface EquippableState {
+    slotType: string;  // e.g. 'weapon', 'armor', 'accessory'
+}
+
+/**
+ * Add to an item entity to make it equippable.
+ * `slotType` must match the target slot's type; slots with no type accept anything.
+ */
+@component
+export class Equippable extends Component<EquippableState> {
+    constructor(slotType: string) {
+        super({ slotType });
+    }
+
+    get slotType(): string { return this.state.slotType; }
+}
+
+// ── Equipment ─────────────────────────────────────────────────────────────────
+
+interface SlotRecord {
+    slotName: string;
+    type: string | null;       // null = generic (accepts any Equippable)
+    itemId: string | null;
+    appliedEffectKeys: string[];
+}
+
+interface EquipmentState {
+    slots: SlotRecord[];
+}
+
+export type SlotInput =
+    | string                                    // generic slot
+    | { slotName: string; type?: string };      // typed slot
+
+@component
+export class Equipment extends Component<EquipmentState> {
+    #cachedVars: RPGVariables | null = null;
+
+    constructor(slots: SlotInput[]) {
+        super({
+            slots: slots.map(s => {
+                const slotName = typeof s === 'string' ? s : s.slotName;
+                const type = typeof s === 'object' && s.type ? s.type : null;
+                return { slotName, type, itemId: null, appliedEffectKeys: [] };
+            }),
+        });
+    }
+
+    #slot(slotName: string): SlotRecord | undefined {
+        return this.state.slots.find(s => s.slotName === slotName);
+    }
+
+    /** ItemId in the named slot, or null if empty. */
+    getItem(slotName: string): string | null {
+        return this.#slot(slotName)?.itemId ?? null;
+    }
+
+    /**
+     * Find the first empty slot compatible with `slotType`.
+     * Typed slots that match take priority over generic (untyped) slots.
+     * Returns `null` if no compatible empty slot exists.
+     */
+    findCompatibleSlot(slotType: string): string | null {
+        let genericFallback: string | null = null;
+        for (const slot of this.state.slots) {
+            if (slot.itemId !== null) continue;
+            if (slot.type === null) { genericFallback ??= slot.slotName; continue; }
+            if (slot.type === slotType) return slot.slotName;
+        }
+        return genericFallback;
+    }
+
+    /** All currently equipped `{ slotName, itemId }` pairs. */
+    getEquipped(): { slotName: string; itemId: string }[] {
+        return this.state.slots
+            .filter((s): s is SlotRecord & { itemId: string } => s.itemId !== null)
+            .map(({ slotName, itemId }) => ({ slotName, itemId }));
+    }
+
+    /**
+     * Equip an item into a named slot.
+     *
+     * - The item entity must have an `Equippable` component.
+     * - If the slot has a type, `Equippable.slotType` must match.
+     * - If the slot is occupied the existing item is unequipped first.
+     * - All `Effect` components on the item entity are cloned onto the owner.
+     */
+    @action
+    equip({ slotName, itemId }: { slotName: string; itemId: string }): boolean {
+        const slot = this.#slot(slotName);
+        if (!slot) return false;
+
+        const itemEntity = this.entity.world.getEntity(itemId);
+        if (!itemEntity) return false;
+
+        const equippable = itemEntity.get(Equippable);
+        if (!equippable) return false;
+
+        if (slot.type !== null && equippable.slotType !== slot.type) return false;
+
+        this.unequip(slotName);
+
+        slot.itemId = itemId;
+        this.#cachedVars = null;
+
+        for (const [key, component] of itemEntity) {
+            if (!(component instanceof Effect)) continue;
+            const clone = Object.create(Effect.prototype) as Effect;
+            (clone as unknown as { state: unknown }).state =
+                structuredClone(component[COMPONENT_STATE]());
+            const effectKey = `__equip_${slotName}_${key}`;
+            this.entity.add(effectKey, clone);
+            slot.appliedEffectKeys.push(effectKey);
+        }
+
+        this.emit('equip', { slotName, itemId });
+        return true;
+    }
+
+    /**
+     * Remove the item from a named slot, reversing all stat effects.
+     * Returns `false` if the slot is empty or does not exist.
+     */
+    @action
+    unequip(slotName: string): boolean {
+        const slot = this.#slot(slotName);
+        if (!slot || slot.itemId === null) return false;
+
+        const itemId = slot.itemId;
+        this.#removeEffects(slot);
+        slot.itemId = null;
+        this.#cachedVars = null;
+
+        this.emit('unequip', { slotName, itemId });
+        return true;
+    }
+
+    #removeEffects(slot: SlotRecord): void {
+        for (const key of slot.appliedEffectKeys) {
+            this.entity.remove(key);
+        }
+        slot.appliedEffectKeys = [];
+    }
+
+    override getVariables(): RPGVariables {
+        if (this.#cachedVars) return this.#cachedVars;
+
+        const result: RPGVariables = {};
+        for (const { slotName, itemId } of this.state.slots) {
+            result[slotName] = itemId ?? '';
+        }
+        this.#cachedVars = result;
+
+        return result;
+    }
+}

src/common/rpg/components/experience.ts

@@ -0,0 +1,69 @@
+import { component } from "../core/registry";
+import { Component } from "../core/world";
+import { action, variable } from "../utils/decorators";
+
+/**
+ * How much XP is required to advance from level N to N+1.
+ *
+ * - `number[]`  — explicit table; `values[0]` = XP for level 1→2.
+ *   Max level = `values.length + 1`. Past the end the entity is at max level.
+ * - `{ base, factor }` — geometric: XP[N] = floor(base * factor^(N-1)).
+ *   No max level.
+ */
+export type ThresholdSpec = number[] | { base: number; factor: number };
+
+function xpForStep(spec: ThresholdSpec, level: number): number | null {
+    if (Array.isArray(spec)) {
+        const idx = level - 1;
+        return idx < spec.length ? spec[idx] : null;
+    }
+    return Math.floor(spec.base * Math.pow(spec.factor, level - 1));
+}
+
+@component
+export class Experience extends Component<{
+    xp: number;
+    level: number;
+    xpAtLevel: number;  // total XP accumulated when current level was reached
+    spec: ThresholdSpec;
+}> {
+    constructor(spec: ThresholdSpec) {
+        super({ xp: 0, level: 1, xpAtLevel: 0, spec });
+    }
+
+    /** Current level, starting at 1. Primary variable for conditions: `experience >= 5`. */
+    @variable get level(): number { return this.state.level; }
+
+    /** Total accumulated XP (never resets). */
+    @variable('.') get xp(): number { return this.state.xp; }
+
+    /** XP accumulated within the current level. */
+    @variable get xpInLevel(): number { return this.state.xp - this.state.xpAtLevel; }
+
+    /** XP remaining until the next level, or `null` at max level. */
+    get xpToNext(): number | null {
+        const needed = xpForStep(this.state.spec, this.state.level);
+        return needed === null ? null : needed - this.xpInLevel;
+    }
+
+    /** Progress toward the next level as a 0–1 fraction. `1` at max level. */
+    @variable get progress(): number {
+        const needed = xpForStep(this.state.spec, this.state.level);
+        if (needed === null) return 1;
+        return Math.min(this.xpInLevel / needed, 1);
+    }
+
+    /** Add XP and emit `'levelup'` with `{ level, prev }` for each level gained. */
+    @action
+    award(xp: number): void {
+        this.state.xp += xp;
+        while (true) {
+            const needed = xpForStep(this.state.spec, this.state.level);
+            if (needed === null) break;
+            if (this.xpInLevel < needed) break;
+            this.state.xpAtLevel += needed;
+            const prev = this.state.level++;
+            this.emit('levelup', { level: this.state.level, prev });
+        }
+    }
+}

src/common/rpg/components/inventory.ts

@@ -3,6 +3,7 @@ import { action } from "../utils/decorators";
 import { Component, type EvalContext } from "../core/world";
 import { component } from "../core/registry";
 import { Stackable, Usable } from "./item";
+import { Equipment, Equippable } from "./equipment";
 import { resolveVariables } from "../utils/variables";
 
 interface SlotRecord {
@@ -12,6 +13,8 @@ interface SlotRecord {
 }
 
 interface InventoryState {
+    infinite: boolean;
+    nextSlotId: number;  // auto-increment counter for infinite mode
     slots: SlotRecord[];
 }
 
@@ -19,14 +22,34 @@ interface InventoryState {
 export class Inventory extends Component<InventoryState> {
     #cachedVars: RPGVariables | null = null;
 
-    constructor(slotDefs: Array<InventorySlotInput>) {
+    /** Infinite inventory — grows on demand, no slot cap. */
-        super({
+    constructor();
-            slots: slotDefs.map(def => {
+    /** N generic slots, each limited only by item maxStack. */
-                const slotId = typeof def === 'object' ? def.slotId : def;
+    constructor(count: number);
-                const limit = typeof def === 'object' ? def.limit : undefined;
+    /** Named slots with optional per-slot stack limits (original behaviour). */
-                return { slotId, limit, contents: null };
+    constructor(slots: InventorySlotInput[]);
-            }),
+    constructor(input?: number | InventorySlotInput[]) {
-        });
+        if (input === undefined) {
+            super({ infinite: true, nextSlotId: 0, slots: [] });
+        } else if (typeof input === 'number') {
+            super({
+                infinite: false,
+                nextSlotId: 0,
+                slots: Array.from({ length: input }, (_, i) => ({
+                    slotId: i, limit: undefined, contents: null,
+                })),
+            });
+        } else {
+            super({
+                infinite: false,
+                nextSlotId: 0,
+                slots: input.map(def => {
+                    const slotId = typeof def === 'object' ? def.slotId : def;
+                    const limit = typeof def === 'object' ? def.limit : undefined;
+                    return { slotId, limit, contents: null };
+                }),
+            });
+        }
     }
 
     #slot(slotId: SlotId): SlotRecord | undefined {
@@ -56,6 +79,7 @@ export class Inventory extends Component<InventoryState> {
             return false;
         }
 
+        // ── Direct slot ───────────────────────────────────────────────────────
         if (slotId !== undefined) {
             const slot = this.#slot(slotId);
             if (!slot) return false;
@@ -65,45 +89,70 @@ export class Inventory extends Component<InventoryState> {
             return true;
         }
 
-        // Two-phase: pre-check then apply
+        // ── Finite inventory: two-phase (check → apply) ───────────────────────
-        let remaining = amount;
+        if (!this.state.infinite) {
-        for (const slot of this.state.slots) {
+            let canFit = 0;
-            if (slot.contents === null || slot.contents.itemId === itemId) {
+            for (const slot of this.state.slots) {
-                remaining -= Math.min(this.#roomFor(slot, itemId), remaining);
+                if (slot.contents === null || slot.contents.itemId === itemId)
-                if (remaining === 0) break;
+                    canFit += this.#roomFor(slot, itemId);
             }
-        }
+            if (canFit < amount) return false;
-        if (remaining > 0) return false;
 
-        // Apply — fill existing slots for this item first, then empty ones
+            let remaining = amount;
-        remaining = amount;
+            const slotIds: SlotId[] = [];
+            for (const slot of this.state.slots) {
+                if (slot.contents?.itemId === itemId && remaining > 0) {
+                    const take = Math.min(this.#roomFor(slot, itemId), remaining);
+                    slot.contents!.amount += take;
+                    remaining -= take;
+                    slotIds.push(slot.slotId);
+                }
+            }
+            for (const slot of this.state.slots) {
+                if (slot.contents === null && remaining > 0) {
+                    const take = Math.min(this.#capFor(slot, itemId), remaining);
+                    slot.contents = { itemId, amount: take };
+                    remaining -= take;
+                    slotIds.push(slot.slotId);
+                }
+            }
+            this.emit('add', { itemId, amount, slotIds });
+            return true;
+        }
+
+        // ── Infinite inventory: fill existing slots, then grow ─────────────────
+        let remaining = amount;
         const slotIds: SlotId[] = [];
+
         for (const slot of this.state.slots) {
-            if (slot.contents?.itemId === itemId) {
+            if (slot.contents?.itemId === itemId && remaining > 0) {
                 const take = Math.min(this.#roomFor(slot, itemId), remaining);
-                slot.contents.amount += take;
+                if (take > 0) {
-                remaining -= take;
+                    slot.contents!.amount += take;
-                slotIds.push(slot.slotId);
+                    remaining -= take;
-                if (remaining === 0) {
+                    slotIds.push(slot.slotId);
-                    this.emit('add', { itemId, amount, slotIds });
-                    return true;
                 }
             }
         }
         for (const slot of this.state.slots) {
-            if (slot.contents === null) {
+            if (slot.contents === null && remaining > 0) {
                 const take = Math.min(this.#capFor(slot, itemId), remaining);
                 slot.contents = { itemId, amount: take };
                 remaining -= take;
                 slotIds.push(slot.slotId);
-                if (remaining === 0) {
-                    this.emit('add', { itemId, amount, slotIds });
-                    return true;
-                }
             }
         }
+        while (remaining > 0) {
+            const newSlot: SlotRecord = { slotId: this.state.nextSlotId++, limit: undefined, contents: null };
+            this.state.slots.push(newSlot);
+            const take = Math.min(this.#capFor(newSlot, itemId), remaining);
+            newSlot.contents = { itemId, amount: take };
+            remaining -= take;
+            slotIds.push(newSlot.slotId);
+        }
 
-        return remaining === 0;
+        this.emit('add', { itemId, amount, slotIds });
+        return true;
     }
 
     @action
@@ -127,27 +176,71 @@ export class Inventory extends Component<InventoryState> {
         let remaining = amount;
         const slotIds: SlotId[] = [];
         for (const slot of this.state.slots) {
-            if (slot.contents?.itemId === itemId) {
+            if (slot.contents?.itemId === itemId && remaining > 0) {
                 const take = Math.min(slot.contents.amount, remaining);
                 slot.contents.amount -= take;
                 if (slot.contents.amount === 0) slot.contents = null;
                 remaining -= take;
                 slotIds.push(slot.slotId);
-                if (remaining === 0) {
-                    this.emit('remove', { itemId, amount, slotIds });
-                    return true;
-                }
             }
         }
 
-        return false;
+        this.emit('remove', { itemId, amount, slotIds });
+        return true;
     }
 
+    /**
+     * Equip an item from this inventory onto the entity's `Equipment` component.
+     * `slotId` specifies which inventory slot to equip from (otherwise any slot is used).
+     * `slotName` specifies the equipment body slot (otherwise auto-detected by item type).
+     */
     @action
-    async use(itemId?: string, ctx?: EvalContext): Promise<boolean> {
+    equip(arg: string | { itemId?: string; slotId?: SlotId; slotName?: string }): boolean {
-        if (!itemId) return false;
+        const resolved = this.#resolveItem(arg);
+        if (!resolved) return false;
+        const { itemId, slotId } = resolved;
+        const slotName = typeof arg === 'object' ? arg.slotName : undefined;
 
-        if (this.getAmount(itemId) === 0) {
+        if (this.getAmount(itemId, slotId) === 0) {
+            console.warn(`[Inventory] equip: item '${itemId}' not in inventory`);
+            return false;
+        }
+
+        const equipment = this.entity.get(Equipment);
+        if (!equipment) {
+            console.warn(`[Inventory] equip: entity has no Equipment component`);
+            return false;
+        }
+
+        let resolvedSlot = slotName;
+        if (resolvedSlot === undefined) {
+            const equippable = this.entity.world.getEntity(itemId)?.get(Equippable);
+            if (!equippable) {
+                console.warn(`[Inventory] equip: item '${itemId}' has no Equippable component`);
+                return false;
+            }
+            const found = equipment.findCompatibleSlot(equippable.slotType);
+            if (!found) {
+                console.warn(`[Inventory] equip: no compatible slot for '${itemId}'`);
+                return false;
+            }
+            resolvedSlot = found;
+        }
+
+        return equipment.equip({ slotName: resolvedSlot, itemId });
+    }
+
+    /**
+     * Use an item from this inventory.
+     * `slotId` specifies which inventory slot to use from (otherwise any slot is used).
+     */
+    @action
+    async use(arg?: string | { itemId?: string; slotId?: SlotId }, ctx?: EvalContext): Promise<boolean> {
+        const resolved = this.#resolveItem(arg);
+        if (!resolved) return false;
+        const { itemId, slotId } = resolved;
+
+        if (this.getAmount(itemId, slotId) === 0) {
             console.warn(`[Inventory] use: item '${itemId}' not in inventory`);
             return false;
         }
@@ -164,13 +257,29 @@ export class Inventory extends Component<InventoryState> {
             return false;
         }
 
-        if (usable.consumeOnUse) {
+        if (usable.consumeOnUse) this.remove({ itemId, amount: 1, slotId });
-            this.remove({ itemId, amount: 1 });
+
+        await usable.use(ctx ?? this.context);
+        return true;
+    }
+
+    /** Resolve an item reference, deriving `itemId` from slot contents if only `slotId` is given. */
+    #resolveItem(arg?: string | { itemId?: string; slotId?: SlotId }): { itemId: string; slotId?: SlotId } | null {
+        if (!arg) return null;
+        if (typeof arg === 'string') return { itemId: arg };
+
+        if (arg.slotId !== undefined) {
+            const contents = this.getSlotContents(arg.slotId);
+            if (!contents) return null;
+            if (arg.itemId && contents.itemId !== arg.itemId) return null;
+            return { itemId: contents.itemId, slotId: arg.slotId };
         }
 
-        const resolvedCtx = ctx ?? { self: this.entity, world: this.entity.world };
+        return arg.itemId ? { itemId: arg.itemId } : null;
-        await usable.use(resolvedCtx);
+    }
-        return true;
+
+    getSlotContents(slotId: SlotId): { itemId: string; amount: number } | null {
+        return this.#slot(slotId)?.contents ?? null;
     }
 
     getAmount(itemId: string, slotId?: SlotId): number {

src/common/rpg/components/stat.ts

@@ -3,7 +3,8 @@ import { Component } from "../core/world";
 import { component } from "../core/registry";
 
 interface StatState {
-    value: number;
+    base: number;
+    modifierSums: { value: number; max: number; min: number };
     max: number | undefined;
     min: number | undefined;
 }
@@ -11,47 +12,67 @@ interface StatState {
 @component
 export class Stat extends Component<StatState> {
     constructor(value: number, max?: number, min?: number) {
-        super({ value, max, min });
+        super({ base: value, modifierSums: { value: 0, max: 0, min: 0 }, max, min });
     }
 
-    @variable('.') get value(): number { return this.state.value; }
+    @variable('.') get value(): number {
-    @variable get max(): number | undefined { return this.state.max; }
+        const effMin = this.min;
-    @variable get min(): number | undefined { return this.state.min; }
+        const effMax = this.max;
+        let v = this.state.base + this.state.modifierSums.value;
+        if (effMin != null) v = Math.max(effMin, v);
+        if (effMax != null) v = Math.min(v, effMax);
+        return v;
+    }
+
+    @variable get base(): number { return this.state.base; }
+    @variable get max(): number | undefined {
+        return this.state.max != null ? this.state.max + this.state.modifierSums.max : undefined;
+    }
+    @variable get min(): number | undefined {
+        return this.state.min != null ? this.state.min + this.state.modifierSums.min : undefined;
+    }
 
     @action
     update(amount: number) {
-        this.set(this.state.value + amount);
+        this.set(this.state.base + amount);
     }
 
     @action
     set(value: number) {
-        const prev = this.state.value;
+        const prev = this.value;
-        this.state.value = value;
+        this.state.base = value;
-        if (this.state.min != null) {
+        const next = this.value;
-            this.state.value = Math.max(this.state.min, this.state.value);
+        if (prev !== next) {
-        }
+            this.emit('set', { prev, value: next });
-        if (this.state.max != null) {
-            this.state.value = Math.min(this.state.value, this.state.max);
-        }
-        if (prev !== this.state.value) {
-            this.emit('set', { prev, value: this.state.value });
         }
     }
 
-    get current(): number {
+    applyModifier(delta: number, field: 'value' | 'max' | 'min' = 'value'): void {
-        return this.state.value;
+        const prev = this.value;
+        this.state.modifierSums[field] += delta;
+        const next = this.value;
+        if (prev !== next) this.emit('set', { prev, value: next });
     }
+
+    removeModifier(delta: number, field: 'value' | 'max' | 'min' = 'value'): void {
+        this.applyModifier(-delta, field);
+    }
+
+    get current(): number { return this.value; }
 }
 
 @component
 export class Health extends Stat {
-    constructor(value: number, max?: number, min = 0) {
-        super(value, max, min);
-    }
-
     @action
     kill() {
         this.set(0);
         this.emit('killed');
     }
 }
+
+@component
+export class Defense extends Stat { }
+
+@component
+export class Damage extends Stat { }
+

src/common/rpg/systems/cooldownSystem.ts

@@ -0,0 +1,10 @@
+import { Cooldown } from "../components/cooldown";
+import { System, type World } from "../core/world";
+
+export class CooldownSystem extends System {
+    override update(world: World, dt: number): void {
+        for (const [, , cooldown] of world.query(Cooldown)) {
+            cooldown.update(dt);
+        }
+    }
+}

src/common/rpg/systems/effectSystem.ts

@@ -0,0 +1,19 @@
+import { Effect } from "../components/effect";
+import { System, type Entity, type World } from "../core/world";
+
+export class EffectSystem extends System {
+    override update(world: World, dt: number): void {
+        const expired: [Entity, string][] = [];
+
+        for (const [entity, key, effect] of world.query(Effect)) {
+            effect.update(dt, entity.context);
+            if (!effect.active) {
+                expired.push([entity, key]);
+            }
+        }
+
+        for (const [entity, key] of expired) {
+            entity.remove(key);
+        }
+    }
+}