refactor: replace number health with Health value object in MagicalObject

- MagicalObject: internal #health and #maxHealth now Health type
- HealingObject: constructor, create, and heal use Health value object
- MagicalWeapon: constructor, create, and use use Health value object
- DamageDealer and Healer interfaces: health: number -> health: Health
- magical-objects.spec.ts: all assertions use .health.value
- Run npm run checks: 0 errors, 70 tests passing

.pi/extensions/yak-mode-gate.ts

@@ -1,18 +1,19 @@
-import type { ExtensionAPI } from "@earendil-works/pi-coding-agent";
-import { isToolCallEventType } from "@earendil-works/pi-coding-agent";
+import type { ExtensionAPI } from '@earendil-works/pi-coding-agent';
+import { isToolCallEventType } from '@earendil-works/pi-coding-agent';
 
 export default function (pi: ExtensionAPI) {
-  pi.on("tool_call", async (event, ctx) => {
-    if (!isToolCallEventType("bash", event)) return;
+  pi.on('tool_call', async (event, ctx) => {
+    if (!isToolCallEventType('bash', event)) return;
 
-    const cmd = event.input.command || "";
-    const isYxCommand = cmd.includes("yx ");
+    const cmd = event.input.command || '';
+    const isYxCommand = cmd.includes('yx ');
 
     // Allow yaks in interactive mode, block in print mode (sub-agents)
-    if (isYxCommand && ctx.mode === "print") {
+    if (isYxCommand && ctx.mode === 'print') {
       return {
         block: true,
-        reason: "yx commands are disabled in print mode. Sub-agents must focus on domain work only.",
+        reason:
+          'yx commands are disabled in print mode. Sub-agents must focus on domain work only.',
       };
     }
   });

.pi/skills/yak-tasks/SKILL.md

@@ -18,6 +18,7 @@ Coordinate sub-agent work using the `yx` CLI. The main agent creates tasks and d
 ## Running Sub-Agents
 
 Sub-agents execute in print mode and are **hard-blocked from using `yx` commands** (see `.pi/extensions/yak-mode-gate.ts`). They receive:
+
 - The yak's `.context.md` (task description)
 - `AGENTS.md` (project conventions)
 - Domain files to work on
@@ -43,6 +44,7 @@ cat .yaks/<task-id>/.state
 ```
 
 States:
+
 - `pending` — not yet started
 - `in-progress` — being worked on
 - `done` — completed
@@ -54,6 +56,7 @@ yx done <task-id>
 ```
 
 Always verify before marking done:
+
 ```bash
 # 1. Check state
 cat .yaks/<task-id>/.state
@@ -68,6 +71,7 @@ npm run checks
 ## Sub-Agent Communication
 
 Sub-agents can read yak state files directly (no yx CLI needed):
+
 ```bash
 cat .yaks/<task-id>/.name    # task name
 cat .yaks/<task-id>/.state   # current state

README.md

@@ -51,13 +51,13 @@ The TypeScript implementation embraces functional patterns:
 
 All five user stories are implemented and verified:
 
-| Story | Topic | Status |
-|-------|-------|--------|
-| 1 | Character Creation & Damage | ✅ Done |
-| 2 | Levels | ✅ Done |
-| 3 | Factions | ✅ Done |
-| 4 | Magical Objects | ✅ Done |
-| 5 | Changing Level | ✅ Done |
+| Story | Topic                       | Status  |
+| ----- | --------------------------- | ------- |
+| 1     | Character Creation & Damage | ✅ Done |
+| 2     | Levels                      | ✅ Done |
+| 3     | Factions                    | ✅ Done |
+| 4     | Magical Objects             | ✅ Done |
+| 5     | Changing Level              | ✅ Done |
 
 **70 tests passing** across 6 spec files.
 

eslint/no-primitive-value-properties.js

@@ -4,9 +4,7 @@ import { join, parse } from 'node:path';
 const VALUE_OBJECTS_DIR = join(import.meta.dirname, '..', 'src', 'value-objects');
 
 function discoverValueObjects() {
-  const files = readdirSync(VALUE_OBJECTS_DIR).filter(
-    (f) => f.endsWith('.ts') && f !== 'index.ts',
-  );
+  const files = readdirSync(VALUE_OBJECTS_DIR).filter((f) => f.endsWith('.ts') && f !== 'index.ts');
   return files.map((f) => parse(f).name);
 }
 

src/magical-objects.spec.ts

@@ -38,7 +38,7 @@ describe('Magical Objects', () => {
             const target = Character.create({ name: 'goblin', level: Level.create(1) });
             const weapon = MagicalWeapon.create({ damage, maxHealth: weaponHP, owner: attacker });
             const result = attacker.useWeapon(weapon, target);
-            return result.weapon.health === weaponHP - 1;
+            return result.weapon.health.value === weaponHP - 1;
           },
         ),
       );
@@ -86,11 +86,11 @@ describe('Magical Objects', () => {
             // Kill the attacker using a separate killer
             const killer = Character.create({ name: 'boss', level: Level.create(1) });
             const deadAttacker = killer.dealDamage(attacker, 10000);
-            const weaponHPBefore = weapon.health;
+            const weaponHPBefore = weapon.health.value;
             const targetHealthBefore = target.health.value;
             const result = deadAttacker.useWeapon(weapon, target);
             return (
-              result.weapon.health === weaponHPBefore &&
+              result.weapon.health.value === weaponHPBefore &&
               result.target.health.value === targetHealthBefore
             );
           },
@@ -110,11 +110,11 @@ describe('Magical Objects', () => {
             const thief = Character.create({ name: 'thief', level: Level.create(1) });
             const target = Character.create({ name: 'goblin', level: Level.create(1) });
             const weapon = MagicalWeapon.create({ damage, maxHealth: weaponHP, owner });
-            const weaponHPBefore = weapon.health;
+            const weaponHPBefore = weapon.health.value;
             const targetHealthBefore = target.health.value;
             const result = thief.useWeapon(weapon, target);
             return (
-              result.weapon.health === weaponHPBefore &&
+              result.weapon.health.value === weaponHPBefore &&
               result.target.health.value === targetHealthBefore
             );
           },
@@ -136,7 +136,9 @@ describe('Magical Objects', () => {
           const targetHealthBefore = firstUse.target.health.value;
           // Try to use again on the destroyed weapon
           const result = owner.useWeapon(destroyedWeapon, firstUse.target);
-          return result.weapon.health === 0 && result.target.health.value === targetHealthBefore;
+          return (
+            result.weapon.health.value === 0 && result.target.health.value === targetHealthBefore
+          );
         }),
       );
     });
@@ -203,7 +205,7 @@ describe('Magical Objects', () => {
             });
             const object = HealingObject.create({ maxHealth: objectHP, currentHealth: objectHP });
             const result = character.useHealingObject(object, healAmount);
-            return result.object.health === objectHP - healAmount;
+            return result.object.health.value === objectHP - healAmount;
           },
         ),
       );
@@ -255,11 +257,11 @@ describe('Magical Objects', () => {
           // Kill the character using a separate killer
           const killer = Character.create({ name: 'boss', level: Level.create(1) });
           const deadCharacter = killer.dealDamage(character, 10000);
-          const objectHPBefore = object.health;
+          const objectHPBefore = object.health.value;
           const characterHealthBefore = deadCharacter.health.value;
           const result = deadCharacter.useHealingObject(object, 100);
           return (
-            result.object.health === objectHPBefore &&
+            result.object.health.value === objectHPBefore &&
             result.character.health.value === characterHealthBefore
           );
         }),
@@ -287,7 +289,8 @@ describe('Magical Objects', () => {
           // Try to use again on the destroyed object
           const result = healedCharacter.useHealingObject(destroyedObject, 100);
           return (
-            result.object.health === 0 && result.character.health.value === characterHealthBefore
+            result.object.health.value === 0 &&
+            result.character.health.value === characterHealthBefore
           );
         }),
       );
@@ -305,7 +308,7 @@ describe('Magical Objects', () => {
             const target = Character.create({ name: 'goblin', level: Level.create(1) });
             const weapon = MagicalWeapon.create({ damage, maxHealth: weaponHP, owner: attacker });
             const result = attacker.useWeapon(weapon, target);
-            return result.weapon.health >= 0;
+            return result.weapon.health.value >= 0;
           },
         ),
       );
@@ -320,7 +323,7 @@ describe('Magical Objects', () => {
             const character = Character.create({ name: 'hero', level: Level.create(1) });
             const object = HealingObject.create({ maxHealth: objectHP, currentHealth: objectHP });
             const result = character.useHealingObject(object, healAmount);
-            return result.object.health >= 0;
+            return result.object.health.value >= 0;
           },
         ),
       );
@@ -336,7 +339,7 @@ describe('Magical Objects', () => {
             const target = Character.create({ name: 'goblin', level: Level.create(1) });
             const weapon = MagicalWeapon.create({ damage, maxHealth: weaponHP, owner: attacker });
             const result = attacker.useWeapon(weapon, target);
-            return result.weapon.health <= weaponHP;
+            return result.weapon.health.value <= weaponHP;
           },
         ),
       );
@@ -351,7 +354,7 @@ describe('Magical Objects', () => {
             const character = Character.create({ name: 'hero', level: Level.create(1) });
             const object = HealingObject.create({ maxHealth: objectHP, currentHealth: objectHP });
             const result = character.useHealingObject(object, healAmount);
-            return result.object.health <= objectHP;
+            return result.object.health.value <= objectHP;
           },
         ),
       );

src/magical-objects/HealingObject.ts

@@ -7,14 +7,15 @@
  */
 
 import { Character } from '../characters/Character.ts';
+import { Health } from '../value-objects/Health.ts';
 import { Level } from '../value-objects/Level.ts';
 import { MagicalObject } from './MagicalObject.ts';
 import type { Healer } from './magical-object-types.ts';
 
 export class HealingObject extends MagicalObject implements Healer {
   private constructor(
-    health: number,
-    maxHealth: number,
+    health: Health,
+    maxHealth: Health,
     status: { readonly kind: 'alive' } | { readonly kind: 'destroyed' },
   ) {
     super(health, maxHealth, status);
@@ -32,7 +33,7 @@ export class HealingObject extends MagicalObject implements Healer {
     if (currentHealth > maxHealth) throw new Error('CurrentHealth cannot exceed maxHealth');
     const status =
       currentHealth === 0 ? { kind: 'destroyed' as const } : { kind: 'alive' as const };
-    return new HealingObject(currentHealth, maxHealth, status);
+    return new HealingObject(Health.create(currentHealth), Health.create(maxHealth), status);
   }
 
   /** Use this object to heal a character. Returns updated object and character. */
@@ -44,7 +45,7 @@ export class HealingObject extends MagicalObject implements Healer {
     // Negative amount is invalid
     if (amount < 0) throw new Error('Heal amount must be non-negative');
     // Calculate actual heal amount: min of requested, object remaining, character headroom
-    const objectRemaining = this.health;
+    const objectRemaining = this.health.value;
     const characterMax = Level.maxHealthForLevel(character.level.value);
     const characterHeadroom = characterMax - character.health.value;
     const actualHeal = Math.min(amount, objectRemaining, characterHeadroom);
@@ -53,7 +54,7 @@ export class HealingObject extends MagicalObject implements Healer {
       return { object: this, character };
     }
     // Create updated object
-    const newObjectHealth = this.health - actualHeal;
+    const newObjectHealth = this.health.value - actualHeal;
     const newObjectStatus =
       newObjectHealth === 0 ? { kind: 'destroyed' as const } : { kind: 'alive' as const };
     // Create updated character
@@ -64,7 +65,7 @@ export class HealingObject extends MagicalObject implements Healer {
       health: newCharacterHealth,
     });
     return {
-      object: new HealingObject(newObjectHealth, this.maxHealth, newObjectStatus),
+      object: new HealingObject(Health.create(newObjectHealth), this.maxHealth, newObjectStatus),
       character: newCharacter,
     };
   }

src/magical-objects/MagicalObject.ts

@@ -7,24 +7,26 @@
  * - Status derived from health (0 = destroyed, > 0 = alive)
  */
 
+import { Health } from '../value-objects/Health.ts';
+
 export type MagicalObjectStatus = { readonly kind: 'alive' } | { readonly kind: 'destroyed' };
 
 export class MagicalObject {
-  readonly #health: number;
-  readonly #maxHealth: number;
+  readonly #health: Health;
+  readonly #maxHealth: Health;
   readonly #status: MagicalObjectStatus;
 
-  protected constructor(health: number, maxHealth: number, status: MagicalObjectStatus) {
+  protected constructor(health: Health, maxHealth: Health, status: MagicalObjectStatus) {
     this.#health = health;
     this.#maxHealth = maxHealth;
     this.#status = status;
   }
 
-  get health(): number {
+  get health(): Health {
     return this.#health;
   }
 
-  get maxHealth(): number {
+  get maxHealth(): Health {
     return this.#maxHealth;
   }
 
@@ -35,7 +37,7 @@ export class MagicalObject {
   /** Create a destroyed object (health = 0). */
   static createDestroyed(maxHealth: number): MagicalObject {
     if (maxHealth < 0) throw new Error('MaxHealth cannot be negative');
-    return new MagicalObject(0, maxHealth, { kind: 'destroyed' });
+    return new MagicalObject(Health.create(0), Health.create(maxHealth), { kind: 'destroyed' });
   }
 
   /** Check if this object is alive. */

src/magical-objects/MagicalWeapon.ts

@@ -6,6 +6,7 @@
  * - Damage is non-negative
  */
 import { Character } from '../characters/Character.ts';
+import { Health } from '../value-objects/Health.ts';
 import { MagicalObject } from './MagicalObject.ts';
 import type { DamageDealer } from './magical-object-types.ts';
 
@@ -14,8 +15,8 @@ export class MagicalWeapon extends MagicalObject implements DamageDealer {
   readonly #owner: Character;
 
   private constructor(
-    health: number,
-    maxHealth: number,
+    health: Health,
+    maxHealth: Health,
     status: { readonly kind: 'alive' } | { readonly kind: 'destroyed' },
     damage: number,
     owner: Character,
@@ -36,7 +37,13 @@ export class MagicalWeapon extends MagicalObject implements DamageDealer {
   }): MagicalWeapon {
     if (maxHealth < 0) throw new Error('MaxHealth cannot be negative');
     if (damage < 0) throw new Error('Damage cannot be negative');
-    return new MagicalWeapon(maxHealth, maxHealth, { kind: 'alive' }, damage, owner);
+    return new MagicalWeapon(
+      Health.create(maxHealth),
+      Health.create(maxHealth),
+      { kind: 'alive' },
+      damage,
+      owner,
+    );
   }
 
   get damage(): number {
@@ -63,12 +70,12 @@ export class MagicalWeapon extends MagicalObject implements DamageDealer {
       status: newTargetStatus,
     });
     // Reduce weapon health by 1
-    const newWeaponHealth = this.health - 1;
+    const newWeaponHealth = this.health.value - 1;
     const newWeaponStatus =
       newWeaponHealth === 0 ? { kind: 'destroyed' as const } : { kind: 'alive' as const };
     return {
       weapon: new MagicalWeapon(
-        newWeaponHealth,
+        Health.create(newWeaponHealth),
         this.maxHealth,
         newWeaponStatus,
         this.#damage,

src/magical-objects/magical-object-types.ts

@@ -6,19 +6,20 @@
  * so Character can depend on abstractions rather than concrete classes.
  */
 import type { Character } from '../characters/Character.ts';
+import type { Health } from '../value-objects/Health.ts';
 import type { MagicalObjectStatus } from './MagicalObject.ts';
 
 /** A magical object that deals damage — from Character's point of view */
 export interface DamageDealer {
   readonly owner: Character;
-  readonly health: number;
+  readonly health: Health;
   readonly status: MagicalObjectStatus;
   use(target: Character): { weapon: DamageDealer; target: Character };
 }
 
 /** A magical object that heals — from Character's point of view */
 export interface Healer {
-  readonly health: number;
+  readonly health: Health;
   readonly status: MagicalObjectStatus;
   heal(character: Character, amount: number): { object: Healer; character: Character };
 }