feat(api): add inventory API (GET /api/inventory)

apps/api/src/inventory/inventory.controller.ts

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+import { Controller, Get } from '@nestjs/common';
+import { DEMO_CHARACTER_ID } from '../demo/demo-character.constants';
+import { InventoryResponseDto, InventoryService } from './inventory.service';
+
+@Controller('inventory')
+export class InventoryController {
+  constructor(private readonly inventoryService: InventoryService) {}
+
+  @Get()
+  getInventory(): Promise<InventoryResponseDto> {
+    return this.inventoryService.getInventory(DEMO_CHARACTER_ID);
+  }
+}

apps/api/src/inventory/inventory.module.ts

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+import { Module } from '@nestjs/common';
+import { TypeOrmModule } from '@nestjs/typeorm';
+import { CharacterEquipment } from '../equipment/entities/character-equipment.entity';
+import { CharacterItem } from '../items/entities/character-item.entity';
+import { InventoryController } from './inventory.controller';
+import { InventoryService } from './inventory.service';
+
+@Module({
+  imports: [TypeOrmModule.forFeature([CharacterItem, CharacterEquipment])],
+  controllers: [InventoryController],
+  providers: [InventoryService],
+})
+export class InventoryModule {}

apps/api/src/inventory/inventory.service.spec.ts

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+import { Repository } from 'typeorm';
+import { CharacterEquipment } from '../equipment/entities/character-equipment.entity';
+import { CharacterItem } from '../items/entities/character-item.entity';
+import { EquipmentSlot } from '../items/equipment-slot.enum';
+import { ItemRarity } from '../items/item-rarity.enum';
+import { ItemType } from '../items/item-type.enum';
+import { InventoryService } from './inventory.service';
+
+const CHARACTER_ID = 'character-1';
+
+function characterItem(overrides: Partial<CharacterItem> = {}): CharacterItem {
+  return {
+    id: 'item-1',
+    characterId: CHARACTER_ID,
+    itemDefinitionId: 'def-1',
+    quantity: 1,
+    createdAt: new Date('2026-08-18T09:00:00.000Z'),
+    updatedAt: new Date('2026-08-18T09:00:00.000Z'),
+    itemDefinition: {
+      key: 'worn-short-sword',
+      name: 'Abgenutztes Kurzschwert',
+      rarity: ItemRarity.COMMON,
+      type: ItemType.WEAPON,
+      equipmentSlot: EquipmentSlot.WEAPON,
+      requiredLevel: 1,
+      weaponDamage: 8,
+      bonusAttack: 0,
+      bonusHp: 0,
+      bonusArmor: 0,
+      iconPath: '/images/items/worn-short-sword.png',
+    },
+    ...overrides,
+  } as CharacterItem;
+}
+
+describe('InventoryService', () => {
+  it('returns only the current character\'s items with definition data, quantity, and equipped state', async () => {
+    const items = [
+      characterItem({ id: 'item-1', quantity: 1 }),
+      characterItem({ id: 'item-2', quantity: 3, itemDefinitionId: 'def-2' }),
+    ];
+    const characterItems = {
+      find: jest.fn().mockResolvedValue(items),
+    } as unknown as Repository<CharacterItem>;
+    const equipment = {
+      find: jest.fn().mockResolvedValue([
+        { characterItemId: 'item-1', slot: EquipmentSlot.WEAPON } as CharacterEquipment,
+      ]),
+    } as unknown as Repository<CharacterEquipment>;
+    const service = new InventoryService(characterItems, equipment);
+
+    const result = await service.getInventory(CHARACTER_ID);
+
+    expect(characterItems.find).toHaveBeenCalledWith({
+      where: { characterId: CHARACTER_ID },
+      relations: { itemDefinition: true },
+      order: { createdAt: 'ASC' },
+    });
+    expect(result.items).toEqual([
+      {
+        id: 'item-1',
+        quantity: 1,
+        equipped: true,
+        item: {
+          key: 'worn-short-sword',
+          name: 'Abgenutztes Kurzschwert',
+          rarity: 'COMMON',
+          equipmentSlot: 'WEAPON',
+          requiredLevel: 1,
+          weaponDamage: 8,
+          bonusAttack: 0,
+          bonusHp: 0,
+          bonusArmor: 0,
+          iconPath: '/images/items/worn-short-sword.png',
+        },
+      },
+      {
+        id: 'item-2',
+        quantity: 3,
+        equipped: false,
+        item: expect.objectContaining({ key: 'worn-short-sword' }),
+      },
+    ]);
+  });
+
+  it('returns an empty list when the character owns nothing', async () => {
+    const characterItems = {
+      find: jest.fn().mockResolvedValue([]),
+    } as unknown as Repository<CharacterItem>;
+    const equipment = {
+      find: jest.fn().mockResolvedValue([]),
+    } as unknown as Repository<CharacterEquipment>;
+    const service = new InventoryService(characterItems, equipment);
+
+    await expect(service.getInventory(CHARACTER_ID)).resolves.toEqual({ items: [] });
+  });
+});

apps/api/src/inventory/inventory.service.ts

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+import { Injectable } from '@nestjs/common';
+import { InjectRepository } from '@nestjs/typeorm';
+import { Repository } from 'typeorm';
+import { CharacterEquipment } from '../equipment/entities/character-equipment.entity';
+import { CharacterItem } from '../items/entities/character-item.entity';
+import { EquipmentSlot } from '../items/equipment-slot.enum';
+import { ItemRarity } from '../items/item-rarity.enum';
+
+export interface InventoryItemDto {
+  id: string;
+  quantity: number;
+  equipped: boolean;
+  item: {
+    key: string;
+    name: string;
+    rarity: ItemRarity;
+    equipmentSlot: EquipmentSlot | null;
+    requiredLevel: number;
+    weaponDamage: number;
+    bonusAttack: number;
+    bonusHp: number;
+    bonusArmor: number;
+    iconPath: string;
+  };
+}
+
+export interface InventoryResponseDto {
+  items: InventoryItemDto[];
+}
+
+@Injectable()
+export class InventoryService {
+  constructor(
+    @InjectRepository(CharacterItem)
+    private readonly characterItems: Repository<CharacterItem>,
+    @InjectRepository(CharacterEquipment)
+    private readonly equipment: Repository<CharacterEquipment>,
+  ) {}
+
+  async getInventory(characterId: string): Promise<InventoryResponseDto> {
+    const [items, equipped] = await Promise.all([
+      this.characterItems.find({
+        where: { characterId },
+        relations: { itemDefinition: true },
+        order: { createdAt: 'ASC' },
+      }),
+      this.equipment.find({ where: { characterId } }),
+    ]);
+    const equippedIds = new Set(equipped.map((row) => row.characterItemId));
+
+    return {
+      items: items.map((characterItem) => ({
+        id: characterItem.id,
+        quantity: characterItem.quantity,
+        equipped: equippedIds.has(characterItem.id),
+        item: {
+          key: characterItem.itemDefinition.key,
+          name: characterItem.itemDefinition.name,
+          rarity: characterItem.itemDefinition.rarity,
+          equipmentSlot: characterItem.itemDefinition.equipmentSlot,
+          requiredLevel: characterItem.itemDefinition.requiredLevel,
+          weaponDamage: characterItem.itemDefinition.weaponDamage,
+          bonusAttack: characterItem.itemDefinition.bonusAttack,
+          bonusHp: characterItem.itemDefinition.bonusHp,
+          bonusArmor: characterItem.itemDefinition.bonusArmor,
+          iconPath: characterItem.itemDefinition.iconPath,
+        },
+      })),
+    };
+  }
+}