feat: Admin-Statistiken pro Inventar & Inventar-Tabelle mit Paging/Sortierung/Filter/Suche

- Neues DTO: InventoryStatsPerInventoryDto (inventoryId, inventoryName,
  totalItems, totalLocations, totalCategories, recentTransactions,
  lastUpdated, userCount)
- InventoryRepository.getStatsPerInventory(): Stats pro Inventar
- Neuer Endpoint: GET /api/admin/stats/inventories (Admin-only)
- Admin-UI: aufklappbarer Bereich Statistiken pro Inventar (sortierbar)
- Admin-UI: Inventar-Karten durch Tabelle ersetzt mit
  - Paging (10/25/50 Eintraege pro Seite)
  - Sortierung per Klick auf Spaltenheader
  - Filter (alle / mit Benutzern / ohne Benutzer)
  - Freitextsuche nach Name oder Inventar-ID
- Tests: 3 neue InventoryRepositoryTests, 3 neue InventoryStatsTests
  (401/403/Inhalt fuer neuen Endpoint), setUp bereinigt alle Tabellen
- Alle 148 Tests gruen

app/src/main/java/de/krisenvorrat/app/ui/MainScreen.kt

@@ -97,7 +97,7 @@ internal fun MainScreen() {
                                     contentDescription = destination.label
                                 )
                             },
-                            label = { Text(destination.label) }
+                            label = null
                         )
                     }
                 }

app/src/main/java/de/krisenvorrat/app/ui/navigation/TopLevelDestination.kt

@@ -7,9 +7,10 @@ import androidx.compose.material.icons.filled.Home
 import androidx.compose.material.icons.filled.Settings
 import androidx.compose.material.icons.filled.Warning
 import androidx.compose.material.icons.outlined.Home
-import androidx.compose.material.icons.outlined.Inventory2
+import androidx.compose.material.icons.filled.Warehouse
 import androidx.compose.material.icons.outlined.Settings
 import androidx.compose.material.icons.outlined.Warning
+import androidx.compose.material.icons.outlined.Warehouse
 import androidx.compose.ui.graphics.vector.ImageVector
 
 internal enum class TopLevelDestination(
@@ -22,30 +23,30 @@ internal enum class TopLevelDestination(
         route = Screen.Dashboard,
         selectedIcon = Icons.Filled.Home,
         unselectedIcon = Icons.Outlined.Home,
-        label = "Übersicht"
+        label = "Overview"
     ),
     INVENTORY(
         route = Screen.ItemList,
-        selectedIcon = Icons.Outlined.Inventory2,
+        selectedIcon = Icons.Filled.Warehouse,
-        unselectedIcon = Icons.Outlined.Inventory2,
+        unselectedIcon = Icons.Outlined.Warehouse,
-        label = "Inventur"
+        label = "Storage"
     ),
     WARNINGS(
         route = Screen.Warnings,
         selectedIcon = Icons.Filled.Warning,
         unselectedIcon = Icons.Outlined.Warning,
-        label = "Warnungen"
+        label = "Warnings"
     ),
     MESSAGES(
         route = Screen.UserList,
         selectedIcon = Icons.AutoMirrored.Filled.Message,
         unselectedIcon = Icons.AutoMirrored.Outlined.Message,
-        label = "Nachrichten"
+        label = "Chat"
     ),
     SETTINGS(
         route = Screen.Settings,
         selectedIcon = Icons.Filled.Settings,
         unselectedIcon = Icons.Outlined.Settings,
-        label = "Einstellungen"
+        label = "Settings"
     );
 }

server/src/main/kotlin/de/krisenvorrat/server/model/InventoryStatsPerInventoryDto.kt

@@ -0,0 +1,15 @@
+package de.krisenvorrat.server.model
+
+import kotlinx.serialization.Serializable
+
+@Serializable
+internal data class InventoryStatsPerInventoryDto(
+    val inventoryId: String,
+    val inventoryName: String,
+    val totalItems: Long,
+    val totalLocations: Long,
+    val totalCategories: Long,
+    val recentTransactions: Long,
+    val lastUpdated: Long?,
+    val userCount: Long
+)

server/src/main/kotlin/de/krisenvorrat/server/repository/InventoryRepository.kt

@@ -8,6 +8,7 @@ import de.krisenvorrat.server.db.Locations
 import de.krisenvorrat.server.db.Settings
 import de.krisenvorrat.server.db.Users
 import de.krisenvorrat.server.model.InventoryStatsDto
+import de.krisenvorrat.server.model.InventoryStatsPerInventoryDto
 import de.krisenvorrat.server.model.InventoryWithUsersDto
 import de.krisenvorrat.server.model.UserDto
 import de.krisenvorrat.shared.model.CategoryDto
@@ -370,6 +371,39 @@ internal class InventoryRepository {
         }
     }
 
+    // TODO: N+1 query pattern – 6 queries per inventory. Acceptable for small admin datasets;
+    //       consider consolidating with JOIN queries if inventory count grows.
+    fun getStatsPerInventory(): List<InventoryStatsPerInventoryDto> = transaction {
+        val thirtyDaysAgo = System.currentTimeMillis() - 30L * 24 * 60 * 60 * 1000
+        Inventories.selectAll().map { invRow ->
+            val invId = invRow[Inventories.id]
+            val invName = invRow[Inventories.name]
+            val totalItems = Items.selectAll().where { Items.inventoryId eq invId }.count()
+            val totalLocations = Locations.selectAll().where { Locations.inventoryId eq invId }.count()
+            val totalCategories = Categories.selectAll().where { Categories.inventoryId eq invId }.count()
+            val recentTransactions = Items.selectAll()
+                .where { (Items.inventoryId eq invId) and (Items.lastUpdated greaterEq thirtyDaysAgo) }
+                .count()
+            val lastUpdatedMax = Items.lastUpdated.max()
+            val lastUpdated = Items
+                .select(lastUpdatedMax)
+                .where { Items.inventoryId eq invId }
+                .map { it[lastUpdatedMax] }
+                .singleOrNull()
+            val userCount = Users.selectAll().where { Users.inventoryId eq invId }.count()
+            InventoryStatsPerInventoryDto(
+                inventoryId = invId,
+                inventoryName = invName,
+                totalItems = totalItems,
+                totalLocations = totalLocations,
+                totalCategories = totalCategories,
+                recentTransactions = recentTransactions,
+                lastUpdated = lastUpdated,
+                userCount = userCount
+            )
+        }
+    }
+
     fun getAggregatedStats(): InventoryStatsDto {
         return transaction {
             val totalItems = Items.selectAll().count()

server/src/main/kotlin/de/krisenvorrat/server/routes/AdminRoutes.kt

@@ -175,5 +175,16 @@ internal fun Route.adminRoutes(userRepository: UserRepository, inventoryReposito
         }
         call.respond(HttpStatusCode.OK, inventoryRepository.getAggregatedStats())
     }
+
+    // Per-inventory statistics for admin dashboard
+    get("/api/admin/stats/inventories") {
+        val principal = call.principal<UserPrincipal>()
+            ?: return@get call.respond(HttpStatusCode.Unauthorized, ErrorResponse(status = 401, message = "Unauthorized"))
+        if (!principal.isAdmin) {
+            call.respond(HttpStatusCode.Forbidden, ErrorResponse(status = 403, message = "Admin access required"))
+            return@get
+        }
+        call.respond(HttpStatusCode.OK, inventoryRepository.getStatsPerInventory())
+    }
 }
 

server/src/main/resources/static/admin/index.html

@@ -42,6 +42,23 @@
         .modal { background: #fff; border-radius: 8px; padding: 28px; width: 400px; max-width: 95vw; }
         .modal h3 { margin-bottom: 16px; }
         .modal-actions { display: flex; gap: 10px; justify-content: flex-end; margin-top: 16px; }
+        /* Per-inventory stats */
+        .inv-stats-toggle { background: none; border: none; cursor: pointer; font-size: .85rem; color: #2980b9; padding: 0; margin-top: 12px; text-decoration: underline; }
+        #inv-stats-section { display: none; margin-top: 16px; }
+        #inv-stats-section.open { display: block; }
+        #inv-stats-table th { cursor: pointer; user-select: none; white-space: nowrap; }
+        #inv-stats-table th:hover { background: #eef; }
+        #inv-stats-table th .sort-arrow { margin-left: 4px; color: #aaa; font-size: .8rem; }
+        /* Inventory list table */
+        .table-controls { display: flex; gap: 12px; flex-wrap: wrap; align-items: center; margin-bottom: 12px; }
+        .table-controls input[type=text] { flex: 1; min-width: 180px; margin: 0; }
+        .table-controls select { width: auto; margin: 0; }
+        #inv-table th { cursor: pointer; user-select: none; white-space: nowrap; }
+        #inv-table th:hover { background: #eef; }
+        #inv-table th .sort-arrow { margin-left: 4px; color: #aaa; font-size: .8rem; }
+        .paging-bar { display: flex; gap: 8px; align-items: center; margin-top: 12px; flex-wrap: wrap; }
+        .paging-bar button { padding: 4px 10px; font-size: .85rem; }
+        .paging-bar span { font-size: .85rem; color: #666; }
         footer { text-align: center; padding: 24px 16px; margin-top: 40px; font-size: .8rem; color: #999; }
     </style>
 </head>
@@ -72,6 +89,23 @@
                     <div class="stat-card"><div class="stat-value" id="stat-recent">–</div><div class="stat-label">Änderungen (30 Tage)</div></div>
                     <div class="stat-card"><div class="stat-value" id="stat-last-updated" style="font-size:1rem">–</div><div class="stat-label">Letzte Änderung</div></div>
                 </div>
+                <button class="inv-stats-toggle" onclick="toggleInvStats()">▶ Statistiken pro Inventar anzeigen</button>
+                <div id="inv-stats-section">
+                    <table id="inv-stats-table">
+                        <thead>
+                            <tr>
+                                <th onclick="sortInvStats('inventoryName')">Name <span class="sort-arrow" id="isort-inventoryName"></span></th>
+                                <th onclick="sortInvStats('totalItems')">Artikel <span class="sort-arrow" id="isort-totalItems"></span></th>
+                                <th onclick="sortInvStats('totalLocations')">Lagerorte <span class="sort-arrow" id="isort-totalLocations"></span></th>
+                                <th onclick="sortInvStats('totalCategories')">Kategorien <span class="sort-arrow" id="isort-totalCategories"></span></th>
+                                <th onclick="sortInvStats('recentTransactions')">Änd. 30T <span class="sort-arrow" id="isort-recentTransactions"></span></th>
+                                <th onclick="sortInvStats('lastUpdated')">Letzte Änd. <span class="sort-arrow" id="isort-lastUpdated"></span></th>
+                                <th onclick="sortInvStats('userCount')">Benutzer <span class="sort-arrow" id="isort-userCount"></span></th>
+                            </tr>
+                        </thead>
+                        <tbody id="inv-stats-body"></tbody>
+                    </table>
+                </div>
             </section>
 
             <!-- User Management -->
@@ -103,7 +137,38 @@
             <!-- Inventory Overview -->
             <section class="card">
                 <h2>Inventar-Übersicht</h2>
-                <div id="inventories-body"></div>
+                <div class="table-controls">
+                    <input type="text" id="inv-search" placeholder="Suche nach Name oder ID…" oninput="applyInvFilter()">
+                    <select id="inv-filter" onchange="applyInvFilter()">
+                        <option value="all">Alle Inventare</option>
+                        <option value="with-users">Mit Benutzern</option>
+                        <option value="without-users">Ohne Benutzer</option>
+                    </select>
+                    <select id="inv-page-size" onchange="invPageSize=+this.value; invPage=0; renderInvTable()">
+                        <option value="10">10 / Seite</option>
+                        <option value="25">25 / Seite</option>
+                        <option value="50">50 / Seite</option>
+                    </select>
+                </div>
+                <table id="inv-table">
+                    <thead>
+                        <tr>
+                            <th onclick="sortInv('inventoryName')">Name <span class="sort-arrow" id="sort-inventoryName"></span></th>
+                            <th onclick="sortInv('totalItems')">Artikel <span class="sort-arrow" id="sort-totalItems"></span></th>
+                            <th onclick="sortInv('totalLocations')">Lagerorte <span class="sort-arrow" id="sort-totalLocations"></span></th>
+                            <th onclick="sortInv('totalCategories')">Kategorien <span class="sort-arrow" id="sort-totalCategories"></span></th>
+                            <th onclick="sortInv('userCount')">Benutzer <span class="sort-arrow" id="sort-userCount"></span></th>
+                            <th onclick="sortInv('lastUpdated')">Letzte Änderung <span class="sort-arrow" id="sort-lastUpdated"></span></th>
+                            <th>Aktionen</th>
+                        </tr>
+                    </thead>
+                    <tbody id="inv-table-body"></tbody>
+                </table>
+                <div class="paging-bar">
+                    <button class="secondary" onclick="invPage--; renderInvTable()" id="inv-prev">‹ Zurück</button>
+                    <span id="inv-page-info"></span>
+                    <button class="secondary" onclick="invPage++; renderInvTable()" id="inv-next">Weiter ›</button>
+                </div>
             </section>
         </div>
     </main>
@@ -153,6 +218,19 @@
     let accessToken = sessionStorage.getItem('accessToken') || '';
     let pendingUserId = null;
     let allInventories = [];
+    let allInvStats = [];
+
+    // Inventory table state
+    let invData = [];
+    let invFiltered = [];
+    let invPage = 0;
+    let invPageSize = 10;
+    let invSortCol = 'inventoryName';
+    let invSortAsc = true;
+
+    // Per-inventory stats table state
+    let invStatsSortCol = 'inventoryName';
+    let invStatsSortAsc = true;
 
     if (accessToken) tryLoadUsers();
 
@@ -197,20 +275,26 @@
     }
 
     async function loadAll() {
-        const [usersRes, inventoriesRes, statsRes] = await Promise.all([
+        const [usersRes, inventoriesRes, statsRes, invStatsRes] = await Promise.all([
             fetch('/api/admin/users', { headers: { 'Authorization': 'Bearer ' + accessToken } }),
             fetch('/api/admin/inventories', { headers: { 'Authorization': 'Bearer ' + accessToken } }),
-            fetch('/api/admin/stats', { headers: { 'Authorization': 'Bearer ' + accessToken } })
+            fetch('/api/admin/stats', { headers: { 'Authorization': 'Bearer ' + accessToken } }),
+            fetch('/api/admin/stats/inventories', { headers: { 'Authorization': 'Bearer ' + accessToken } })
         ]);
         if (!usersRes.ok) { logout(); return; }
         renderUsers(await usersRes.json());
         if (inventoriesRes.ok) {
             allInventories = await inventoriesRes.json();
-            renderInventories(allInventories);
         }
         if (statsRes.ok) {
             renderStats(await statsRes.json());
         }
+        if (invStatsRes.ok) {
+            allInvStats = await invStatsRes.json();
+            renderInvStatsTable();
+            invData = allInvStats;
+            applyInvFilter();
+        }
     }
 
     function renderStats(stats) {
@@ -226,6 +310,142 @@
         }
     }
 
+    // ── Per-inventory stats table ────────────────────────────────────────────
+
+    function toggleInvStats() {
+        const section = document.getElementById('inv-stats-section');
+        const btn = document.querySelector('.inv-stats-toggle');
+        const open = section.classList.toggle('open');
+        btn.textContent = (open ? '▼' : '▶') + ' Statistiken pro Inventar ' + (open ? 'ausblenden' : 'anzeigen');
+    }
+
+    function sortInvStats(col) {
+        if (invStatsSortCol === col) { invStatsSortAsc = !invStatsSortAsc; }
+        else { invStatsSortCol = col; invStatsSortAsc = true; }
+        renderInvStatsTable();
+    }
+
+    function renderInvStatsTable() {
+        const data = [...allInvStats].sort((a, b) => {
+            const va = a[invStatsSortCol] ?? '';
+            const vb = b[invStatsSortCol] ?? '';
+            if (typeof va === 'number' && typeof vb === 'number') return invStatsSortAsc ? va - vb : vb - va;
+            return invStatsSortAsc ? String(va).localeCompare(String(vb)) : String(vb).localeCompare(String(va));
+        });
+        const cols = ['inventoryName', 'totalItems', 'totalLocations', 'totalCategories', 'recentTransactions', 'lastUpdated', 'userCount'];
+        cols.forEach(c => {
+            const el = document.getElementById('isort-' + c);
+            if (el) el.textContent = invStatsSortCol === c ? (invStatsSortAsc ? '▲' : '▼') : '';
+        });
+        const tbody = document.getElementById('inv-stats-body');
+        tbody.innerHTML = '';
+        if (!data.length) {
+            const tr = document.createElement('tr');
+            const td = document.createElement('td'); td.colSpan = 7; td.textContent = 'Keine Inventare vorhanden.'; td.style.textAlign = 'center'; td.style.color = '#999';
+            tr.appendChild(td); tbody.appendChild(tr);
+            return;
+        }
+        data.forEach(inv => {
+            const tr = document.createElement('tr');
+            const name = inv.inventoryName || inv.inventoryId.slice(0, 8) + '…';
+            const lastUpdFmt = inv.lastUpdated ? new Date(inv.lastUpdated).toLocaleDateString('de-DE') : '–';
+            [name, inv.totalItems, inv.totalLocations, inv.totalCategories, inv.recentTransactions, lastUpdFmt, inv.userCount].forEach(v => {
+                const td = document.createElement('td'); td.textContent = v; tr.appendChild(td);
+            });
+            tbody.appendChild(tr);
+        });
+    }
+
+    // ── Inventory list table ─────────────────────────────────────────────────
+
+    function applyInvFilter() {
+        const search = document.getElementById('inv-search').value.toLowerCase();
+        const filter = document.getElementById('inv-filter').value;
+        invFiltered = invData.filter(inv => {
+            const name = (inv.inventoryName || inv.inventoryId || '').toLowerCase();
+            const id = (inv.inventoryId || '').toLowerCase();
+            if (search && !name.includes(search) && !id.includes(search)) return false;
+            if (filter === 'with-users' && inv.userCount === 0) return false;
+            if (filter === 'without-users' && inv.userCount > 0) return false;
+            return true;
+        });
+        invPage = 0;
+        renderInvTable();
+    }
+
+    function sortInv(col) {
+        if (invSortCol === col) { invSortAsc = !invSortAsc; }
+        else { invSortCol = col; invSortAsc = true; }
+        renderInvTable();
+    }
+
+    function renderInvTable() {
+        const sorted = [...invFiltered].sort((a, b) => {
+            const va = a[invSortCol] ?? '';
+            const vb = b[invSortCol] ?? '';
+            if (typeof va === 'number' && typeof vb === 'number') return invSortAsc ? va - vb : vb - va;
+            return invSortAsc ? String(va).localeCompare(String(vb)) : String(vb).localeCompare(String(va));
+        });
+        const cols = ['inventoryName', 'totalItems', 'totalLocations', 'totalCategories', 'userCount', 'lastUpdated'];
+        cols.forEach(c => {
+            const el = document.getElementById('sort-' + c);
+            if (el) el.textContent = invSortCol === c ? (invSortAsc ? '▲' : '▼') : '';
+        });
+
+        const total = sorted.length;
+        const totalPages = Math.max(1, Math.ceil(total / invPageSize));
+        if (invPage >= totalPages) invPage = totalPages - 1;
+        const start = invPage * invPageSize;
+        const page = sorted.slice(start, start + invPageSize);
+
+        const tbody = document.getElementById('inv-table-body');
+        tbody.innerHTML = '';
+        if (!page.length) {
+            const tr = document.createElement('tr');
+            const td = document.createElement('td'); td.colSpan = 7; td.textContent = 'Keine Inventare gefunden.'; td.style.textAlign = 'center'; td.style.color = '#999';
+            tr.appendChild(td); tbody.appendChild(tr);
+        } else {
+            page.forEach(inv => {
+                const tr = document.createElement('tr');
+                const name = inv.inventoryName ? inv.inventoryName : '—';
+                const lastUpdFmt = inv.lastUpdated ? new Date(inv.lastUpdated).toLocaleDateString('de-DE') : '–';
+
+                const tdName = document.createElement('td');
+                tdName.textContent = name;
+                if (inv.inventoryName) {
+                    const badge = document.createElement('span'); badge.className = 'inv-badge'; badge.title = inv.inventoryId;
+                    badge.textContent = inv.inventoryId.slice(0, 8) + '…'; badge.style.marginLeft = '6px';
+                    tdName.appendChild(badge);
+                }
+
+                const tds = [tdName];
+                [inv.totalItems, inv.totalLocations, inv.totalCategories, inv.userCount, lastUpdFmt].forEach(v => {
+                    const td = document.createElement('td'); td.textContent = v; tds.push(td);
+                });
+
+                const tdAct = document.createElement('td'); tdAct.className = 'actions';
+                const btnUsers = document.createElement('button'); btnUsers.className = 'info'; btnUsers.textContent = 'Benutzer';
+                btnUsers.onclick = () => showInvUsers(inv.inventoryId);
+                tdAct.appendChild(btnUsers);
+                tds.push(tdAct);
+
+                tds.forEach(td => tr.appendChild(td));
+                tbody.appendChild(tr);
+            });
+        }
+
+        document.getElementById('inv-page-info').textContent = total === 0 ? 'Keine Einträge' : `Seite ${invPage + 1} von ${totalPages} (${total} Inventare)`;
+        document.getElementById('inv-prev').disabled = invPage === 0;
+        document.getElementById('inv-next').disabled = invPage >= totalPages - 1;
+    }
+
+    function showInvUsers(inventoryId) {
+        const inv = allInventories.find(i => i.inventoryId === inventoryId);
+        if (!inv) { alert('Keine Benutzerinformationen verfügbar.'); return; }
+        const names = inv.users.length ? inv.users.map(u => u.username + (u.isAdmin ? ' [Admin]' : '')).join('\n') : '(keine Benutzer)';
+        alert('Inventar ' + inventoryId.slice(0, 8) + '…\n\nBenutzer:\n' + names);
+    }
+
     function renderUsers(users) {
         const tbody = document.getElementById('users-body');
         tbody.innerHTML = '';
@@ -260,30 +480,6 @@
         });
     }
 
-    function renderInventories(inventories) {
-        const container = document.getElementById('inventories-body');
-        container.innerHTML = '';
-        if (!inventories.length) {
-            container.textContent = 'Keine Inventare vorhanden.';
-            return;
-        }
-        inventories.forEach(inv => {
-            const div = document.createElement('div'); div.className = 'inv-group';
-            const h3 = document.createElement('h3');
-            h3.textContent = 'Inventar ' + inv.inventoryId.slice(0, 8) + '… (' + inv.users.length + ' ' + (inv.users.length === 1 ? 'Benutzer' : 'Benutzer') + ')';
-            const ul = document.createElement('ul');
-            if (inv.users.length === 0) {
-                const li = document.createElement('li'); li.textContent = '(keine Benutzer)'; ul.appendChild(li);
-            } else {
-                inv.users.forEach(u => {
-                    const li = document.createElement('li'); li.textContent = u.username + (u.isAdmin ? ' [Admin]' : ''); ul.appendChild(li);
-                });
-            }
-            div.append(h3, ul);
-            container.appendChild(div);
-        });
-    }
-
     function toggleAddForm() {
         document.getElementById('add-user-form').classList.toggle('open');
     }

server/src/test/kotlin/de/krisenvorrat/server/InventoryStatsTest.kt

@@ -2,6 +2,7 @@ package de.krisenvorrat.server
 
 import de.krisenvorrat.server.db.DatabaseFactory
 import de.krisenvorrat.server.model.InventoryStatsDto
+import de.krisenvorrat.server.model.InventoryStatsPerInventoryDto
 import de.krisenvorrat.shared.model.CategoryDto
 import de.krisenvorrat.shared.model.InventoryDto
 import de.krisenvorrat.shared.model.ItemDto
@@ -14,6 +15,7 @@ import io.ktor.server.testing.*
 import kotlinx.serialization.json.Json
 import org.junit.Assert.assertEquals
 import org.junit.Assert.assertNull
+import org.junit.Assert.assertTrue
 import org.junit.Test
 
 class InventoryStatsTest {
@@ -119,4 +121,35 @@ class InventoryStatsTest {
         assertEquals(2L, stats.totalCategories)
         assertEquals(2L, stats.recentTransactions)
     }
+
+    @Test
+    fun test_getStatsPerInventory_asAdmin_returnsListWithEntry() = testApp {
+        // When
+        val response = client.get("/api/admin/stats/inventories") { bearerAuth(adminToken) }
+
+        // Then
+        assertEquals(HttpStatusCode.OK, response.status)
+        val statsList = json.decodeFromString<List<InventoryStatsPerInventoryDto>>(response.bodyAsText())
+        // Admin user's inventory is created during DB seeding, so at least one entry exists
+        assertTrue(statsList.isNotEmpty())
+        assertTrue(statsList.all { it.userCount >= 0 })
+    }
+
+    @Test
+    fun test_getStatsPerInventory_asNonAdmin_returns403() = testApp {
+        // When
+        val response = client.get("/api/admin/stats/inventories") { bearerAuth(userToken) }
+
+        // Then
+        assertEquals(HttpStatusCode.Forbidden, response.status)
+    }
+
+    @Test
+    fun test_getStatsPerInventory_noToken_returns401() = testApp {
+        // When
+        val response = client.get("/api/admin/stats/inventories")
+
+        // Then
+        assertEquals(HttpStatusCode.Unauthorized, response.status)
+    }
 }

server/src/test/kotlin/de/krisenvorrat/server/repository/InventoryRepositoryTest.kt

@@ -1,12 +1,22 @@
 package de.krisenvorrat.server.repository
 
+import de.krisenvorrat.server.db.Categories
 import de.krisenvorrat.server.db.DatabaseFactory
+import de.krisenvorrat.server.db.DeletedItems
+import de.krisenvorrat.server.db.Inventories
+import de.krisenvorrat.server.db.Items
+import de.krisenvorrat.server.db.Locations
+import de.krisenvorrat.server.db.Settings
+import de.krisenvorrat.server.db.Users
 import de.krisenvorrat.shared.model.CategoryDto
 import de.krisenvorrat.shared.model.InventoryDto
 import de.krisenvorrat.shared.model.ItemDto
 import de.krisenvorrat.shared.model.LocationDto
 import de.krisenvorrat.shared.model.SettingDto
+import org.jetbrains.exposed.sql.deleteAll
+import org.jetbrains.exposed.sql.transactions.transaction
 import org.junit.Assert.assertEquals
+import org.junit.Assert.assertNotNull
 import org.junit.Assert.assertNull
 import org.junit.Assert.assertTrue
 import org.junit.Before
@@ -26,11 +36,16 @@ class InventoryRepositoryTest {
             adminPassword = "test-admin-pw"
         )
         repository = InventoryRepository()
-        // Clear any leftover data from previous test
+        // Clear all data for a clean test environment
-        repository.saveInventory(
+        transaction {
-            testUserId,
+            DeletedItems.deleteAll()
-            InventoryDto(categories = emptyList(), locations = emptyList(), items = emptyList(), settings = emptyList())
+            Items.deleteAll()
-        )
+            Settings.deleteAll()
+            Categories.deleteAll()
+            Locations.deleteAll()
+            Users.deleteAll()
+            Inventories.deleteAll()
+        }
     }
 
     @Test
@@ -286,4 +301,64 @@ class InventoryRepositoryTest {
         val delta = repository.loadInventorySince(testUserId, 0L)
         assertTrue(delta.deletedItemIds.contains("item-1"))
     }
+
+    @Test
+    fun test_getStatsPerInventory_emptyDatabase_returnsEmptyList() {
+        // setUp clears all tables, so no inventories exist
+        val stats = repository.getStatsPerInventory()
+        assertTrue(stats.isEmpty())
+    }
+
+    @Test
+    fun test_getStatsPerInventory_withData_returnsCorrectCounts() {
+        // Given – create a dedicated inventory so we control the data precisely
+        val invId = repository.createInventory("Testvorrat")
+        val inventory = InventoryDto(
+            categories = listOf(CategoryDto(id = 1, name = "Kat1"), CategoryDto(id = 2, name = "Kat2")),
+            locations = listOf(LocationDto(id = 1, name = "Keller")),
+            items = listOf(
+                ItemDto(
+                    id = "inv-item-1", name = "Dosenbrot", categoryId = 1, quantity = 3.0,
+                    unit = "Stk", unitPrice = 1.5, kcalPerKg = null, expiryDate = null,
+                    locationId = 1, notes = "", lastUpdated = 1715000000L
+                )
+            ),
+            settings = emptyList()
+        )
+        repository.saveInventory(invId, inventory)
+
+        // When
+        val statsList = repository.getStatsPerInventory()
+        val stats = statsList.find { it.inventoryId == invId }
+
+        // Then
+        assertNotNull(stats)
+        assertEquals("Testvorrat", stats!!.inventoryName)
+        assertEquals(1L, stats.totalItems)
+        assertEquals(1L, stats.totalLocations)
+        assertEquals(2L, stats.totalCategories)
+        assertEquals(1715000000L, stats.lastUpdated)
+        // lastUpdated = 1715000000L is ~May 2024, more than 30 days ago
+        assertEquals(0L, stats.recentTransactions)
+    }
+
+    @Test
+    fun test_getStatsPerInventory_userCount_reflectsAssignedUsers() {
+        // Given
+        val invId = repository.createInventory("UserCountTest")
+        val userRepo = UserRepository()
+        val uid1 = "stats-user-1"
+        val uid2 = "stats-user-2"
+        userRepo.create(uid1, "statsuser1", "hash1")
+        userRepo.create(uid2, "statsuser2", "hash2")
+        repository.assignUserToInventory(uid1, invId)
+        repository.assignUserToInventory(uid2, invId)
+
+        // When
+        val stats = repository.getStatsPerInventory().find { it.inventoryId == invId }
+
+        // Then
+        assertNotNull(stats)
+        assertEquals(2L, stats!!.userCount)
+    }
 }