test(web): cover the same-slot equipped-item filter in InventoryPageComponent

The equippedItemInSelectedSlot computed is the riskiest logic this
component owns, but every existing test mocked selectedItem() as null,
so the slot-matching branch never ran and a regression to "any equipped
item" would have gone unnoticed. Adds a test with three items across two
slots that asserts the detail panel receives the same-slot equipped item,
not just any equipped item.

apps/web/src/app/features/inventory/inventory-page.component.spec.ts

@@ -1,8 +1,10 @@
 import { signal } from '@angular/core';
 import { TestBed } from '@angular/core/testing';
+import { By } from '@angular/platform-browser';
 import { vi } from 'vitest';
-import type { CharacterResponse, EquipmentResponse, InventoryResponse } from '../../core/api/game-api.models';
+import type { CharacterResponse, EquipmentResponse, InventoryItem, InventoryResponse } from '../../core/api/game-api.models';
 import { WorldStore } from '../world/world.store';
+import { InventoryDetailPanelComponent } from './inventory-detail-panel.component';
 import { InventoryPageComponent } from './inventory-page.component';
 import { InventoryStore } from './inventory.store';
 
@@ -70,17 +72,23 @@ const character: CharacterResponse = {
   currentLocation: { id: 'loc-1', key: 'south-gate', name: 'Südtor' },
 };
 
-async function setup() {
+interface SetupOptions {
+  inventoryData?: InventoryResponse;
+  selectedItemId?: string | null;
+  selectedItem?: InventoryItem | null;
+}
+
+async function setup(options: SetupOptions = {}) {
   const inventoryStore = {
-    inventory: signal(inventory),
+    inventory: signal(options.inventoryData ?? inventory),
     equipment: signal(equipment),
-    selectedItemId: signal<string | null>(null),
+    selectedItemId: signal<string | null>(options.selectedItemId ?? null),
     loading: signal(false),
     equipping: signal(false),
     error: signal<string | null>(null),
     load: vi.fn(() => Promise.resolve()),
     selectItem: vi.fn(),
-    selectedItem: vi.fn(() => null),
+    selectedItem: vi.fn(() => options.selectedItem ?? null),
     equip: vi.fn(() => Promise.resolve()),
   };
   const worldStore = { character: signal(character) };
@@ -140,4 +148,44 @@ describe('InventoryPageComponent', () => {
     expect(text).toContain('6');
     expect(text).toContain('8');
   });
+
+  it('passes the equipped item from the SAME slot as the selection — not just any equipped item — to the detail panel', async () => {
+    // item-helm (HEAD, equipped) is placed before item-sword (WEAPON, equipped) so that a
+    // regression which drops the equipmentSlot match (i.e. "find the first equipped item")
+    // would surface item-helm instead of item-sword, and this test would fail.
+    const threeItemInventory: InventoryResponse = {
+      items: [
+        {
+          id: 'item-helm',
+          quantity: 1,
+          equipped: true,
+          item: {
+            key: 'iron-helm',
+            name: 'Eiserner Helm',
+            rarity: 'COMMON',
+            equipmentSlot: 'HEAD',
+            requiredLevel: 1,
+            weaponDamage: 0,
+            bonusAttack: 0,
+            bonusHp: 5,
+            bonusArmor: 2,
+            iconPath: '/images/items/iron-helm.png',
+          },
+        },
+        inventory.items[0], // item-sword, WEAPON, equipped
+        inventory.items[1], // item-blade, WEAPON, not equipped — this is the selection
+      ],
+    };
+
+    const { fixture } = await setup({
+      inventoryData: threeItemInventory,
+      selectedItemId: 'item-blade',
+      selectedItem: threeItemInventory.items[2],
+    });
+
+    const panel = fixture.debugElement.query(By.directive(InventoryDetailPanelComponent))
+      .componentInstance as InventoryDetailPanelComponent;
+
+    expect(panel.equippedItemInSlot()?.id).toBe('item-sword');
+  });
 });