feat: add GET /history/recent endpoint for cross-list activity

src/main/java/de/zendric/app/xpensely_server/controller/ExpenseListController.java

@@ -15,6 +15,7 @@ import org.springframework.web.server.ResponseStatusException;
 
 import de.zendric.app.xpensely_server.model.*;
 import de.zendric.app.xpensely_server.model.DTO.HistoryPageDto;
+import de.zendric.app.xpensely_server.model.DTO.RecentHistoryEntryDto;
 import de.zendric.app.xpensely_server.security.AuthenticatedUserResolver;
 import de.zendric.app.xpensely_server.services.CategoryService;
 import de.zendric.app.xpensely_server.services.ExpenseListService;
@@ -194,6 +195,14 @@ public class ExpenseListController {
         return ResponseEntity.ok(historyService.getHistory(id, page, size));
     }
 
+    @GetMapping("/history/recent")
+    public ResponseEntity<List<RecentHistoryEntryDto>> getRecentHistory(
+            @RequestParam(defaultValue = "4") int limit,
+            Authentication authentication) {
+        AppUser user = authenticatedUserResolver.resolveCurrentUser(authentication);
+        return ResponseEntity.ok(historyService.getRecentForUser(user, limit));
+    }
+
     private void assertOwner(AppUser authenticated, ExpenseList list) {
         if (!list.getOwner().getId().equals(authenticated.getId()))
             throw new ResponseStatusException(HttpStatus.FORBIDDEN);

src/main/java/de/zendric/app/xpensely_server/model/DTO/RecentHistoryEntryDto.java

@@ -0,0 +1,12 @@
+package de.zendric.app.xpensely_server.model.DTO;
+
+import java.time.LocalDateTime;
+
+public record RecentHistoryEntryDto(
+        String type,
+        String actorUsername,
+        String expenseTitle,
+        LocalDateTime timestamp,
+        Long listId,
+        String listName) {
+}

src/main/java/de/zendric/app/xpensely_server/repo/ExpenseHistoryRepository.java

@@ -13,6 +13,9 @@ public interface ExpenseHistoryRepository extends JpaRepository<ExpenseHistoryEn
 
     Page<ExpenseHistoryEntry> findByExpenseListIdOrderByTimestampDescIdDesc(Long expenseListId, Pageable pageable);
 
+    Page<ExpenseHistoryEntry> findByExpenseListOwnerIdOrExpenseListSharedWithIdOrderByTimestampDescIdDesc(
+            Long ownerId, Long sharedWithId, Pageable pageable);
+
     @Query("select h.expenseId from ExpenseHistoryEntry h")
     List<Long> findAllExpenseIds();
 

src/main/java/de/zendric/app/xpensely_server/services/HistoryService.java

@@ -17,6 +17,7 @@ import tools.jackson.databind.ObjectMapper;
 import de.zendric.app.xpensely_server.model.AppUser;
 import de.zendric.app.xpensely_server.model.DTO.HistoryEntryDto;
 import de.zendric.app.xpensely_server.model.DTO.HistoryPageDto;
+import de.zendric.app.xpensely_server.model.DTO.RecentHistoryEntryDto;
 import de.zendric.app.xpensely_server.model.Expense;
 import de.zendric.app.xpensely_server.model.ExpenseHistoryEntry;
 import de.zendric.app.xpensely_server.model.ExpenseList;
@@ -104,6 +105,23 @@ public class HistoryService {
         return new HistoryPageDto(entries, result.hasNext());
     }
 
+    @Transactional(readOnly = true)
+    public List<RecentHistoryEntryDto> getRecentForUser(AppUser user, int limit) {
+        int cappedLimit = Math.min(Math.max(limit, 1), 20);
+        Page<ExpenseHistoryEntry> result = historyRepository
+                .findByExpenseListOwnerIdOrExpenseListSharedWithIdOrderByTimestampDescIdDesc(
+                        user.getId(), user.getId(), PageRequest.of(0, cappedLimit));
+        return result.getContent().stream()
+                .map(e -> new RecentHistoryEntryDto(
+                        e.getType().name(),
+                        e.getActor() == null ? null : e.getActor().getUsername(),
+                        e.getExpenseTitle(),
+                        e.getTimestamp(),
+                        e.getExpenseList().getId(),
+                        e.getExpenseList().getName()))
+                .toList();
+    }
+
     private HistoryEntryDto toDto(ExpenseHistoryEntry entry) {
         List<FieldChange> changes = List.of();
         if (entry.getChanges() != null) {

src/test/java/de/zendric/app/xpensely_Server/controller/ExpenseListControllerTest.java

@@ -3,6 +3,7 @@ package de.zendric.app.xpensely_Server.controller;
 import de.zendric.app.xpensely_server.controller.ExpenseListController;
 import de.zendric.app.xpensely_server.model.AppUser;
 import de.zendric.app.xpensely_server.model.DTO.HistoryPageDto;
+import de.zendric.app.xpensely_server.model.DTO.RecentHistoryEntryDto;
 import de.zendric.app.xpensely_server.model.Expense;
 import de.zendric.app.xpensely_server.model.ExpenseList;
 import de.zendric.app.xpensely_server.security.AuthenticatedUserResolver;
@@ -370,4 +371,49 @@ class ExpenseListControllerTest {
         mockMvc.perform(get("/api/expenselist/99/history"))
                 .andExpect(status().isNotFound());
     }
+
+    // --- Recent history endpoint ---
+
+    @Test
+    void getRecentHistory_returnsArrayWithListInfo() throws Exception {
+        AppUser user = new AppUser(); user.setId(1L); user.setUsername("alice");
+        when(authenticatedUserResolver.resolveCurrentUser(any())).thenReturn(user);
+        when(historyService.getRecentForUser(user, 4)).thenReturn(List.of(
+                new RecentHistoryEntryDto("UPDATED", "alice", "Groceries",
+                        LocalDateTime.of(2026, 7, 6, 12, 0), 10L, "Trip to Rome")));
+
+        mockMvc.perform(get("/api/expenselist/history/recent"))
+                .andExpect(status().isOk())
+                .andExpect(jsonPath("$[0].type").value("UPDATED"))
+                .andExpect(jsonPath("$[0].actorUsername").value("alice"))
+                .andExpect(jsonPath("$[0].expenseTitle").value("Groceries"))
+                .andExpect(jsonPath("$[0].listId").value(10))
+                .andExpect(jsonPath("$[0].listName").value("Trip to Rome"));
+    }
+
+    @Test
+    void getRecentHistory_passesLimitParam() throws Exception {
+        AppUser user = new AppUser(); user.setId(1L);
+        when(authenticatedUserResolver.resolveCurrentUser(any())).thenReturn(user);
+        when(historyService.getRecentForUser(user, 10)).thenReturn(List.of());
+
+        mockMvc.perform(get("/api/expenselist/history/recent").param("limit", "10"))
+                .andExpect(status().isOk())
+                .andExpect(jsonPath("$").isEmpty());
+    }
+
+    @Test
+    void getRecentHistory_doesNotClashWithPerListHistoryRoute() throws Exception {
+        // /api/expenselist/1/history must still hit the per-list handler.
+        AppUser owner = new AppUser(); owner.setId(1L); owner.setUsername("alice");
+        ExpenseList list = new ExpenseList(); list.setId(1L); list.setOwner(owner);
+        when(expenseListService.findById(1L)).thenReturn(Optional.of(list));
+        when(authenticatedUserResolver.resolveCurrentUser(any())).thenReturn(owner);
+        when(historyService.getHistory(1L, 0, 30))
+                .thenReturn(new HistoryPageDto(List.of(), false));
+
+        mockMvc.perform(get("/api/expenselist/1/history"))
+                .andExpect(status().isOk())
+                .andExpect(jsonPath("$.entries").isArray());
+    }
 }

src/test/java/de/zendric/app/xpensely_Server/services/HistoryServiceTest.java

@@ -18,6 +18,7 @@ import tools.jackson.databind.ObjectMapper;
 
 import de.zendric.app.xpensely_server.model.AppUser;
 import de.zendric.app.xpensely_server.model.DTO.HistoryPageDto;
+import de.zendric.app.xpensely_server.model.DTO.RecentHistoryEntryDto;
 import de.zendric.app.xpensely_server.model.Expense;
 import de.zendric.app.xpensely_server.model.ExpenseHistoryEntry;
 import de.zendric.app.xpensely_server.model.ExpenseList;
@@ -206,4 +207,75 @@ class HistoryServiceTest {
 
         assertThat(page.entries().get(0).changes()).isEmpty();
     }
+
+    private ExpenseHistoryEntry historyEntry(Long id, ExpenseList list, AppUser actor,
+            HistoryEntryType type, String title, java.time.LocalDateTime timestamp) {
+        ExpenseHistoryEntry e = new ExpenseHistoryEntry();
+        e.setId(id);
+        e.setExpenseList(list);
+        e.setActor(actor);
+        e.setType(type);
+        e.setExpenseTitle(title);
+        e.setTimestamp(timestamp);
+        return e;
+    }
+
+    @Test
+    void getRecentForUser_mapsEntriesWithListIdAndName() {
+        AppUser alice = user(1L, "alice");
+        ExpenseList list = new ExpenseList();
+        list.setId(10L);
+        list.setName("Trip to Rome");
+        ExpenseHistoryEntry entry = historyEntry(100L, list, alice,
+                HistoryEntryType.UPDATED, "Groceries", java.time.LocalDateTime.of(2026, 7, 6, 12, 0));
+
+        when(historyRepository
+                .findByExpenseListOwnerIdOrExpenseListSharedWithIdOrderByTimestampDescIdDesc(
+                        eq(1L), eq(1L), any(Pageable.class)))
+                .thenReturn(new PageImpl<>(List.of(entry)));
+
+        List<RecentHistoryEntryDto> result = service.getRecentForUser(alice, 4);
+
+        assertThat(result).containsExactly(new RecentHistoryEntryDto(
+                "UPDATED", "alice", "Groceries",
+                java.time.LocalDateTime.of(2026, 7, 6, 12, 0), 10L, "Trip to Rome"));
+    }
+
+    @Test
+    void getRecentForUser_nullActor_mapsToNullUsername() {
+        AppUser alice = user(1L, "alice");
+        ExpenseList list = new ExpenseList();
+        list.setId(10L);
+        list.setName("Trip to Rome");
+        ExpenseHistoryEntry entry = historyEntry(100L, list, null,
+                HistoryEntryType.CREATED, "Taxi", java.time.LocalDateTime.of(2026, 7, 6, 12, 0));
+
+        when(historyRepository
+                .findByExpenseListOwnerIdOrExpenseListSharedWithIdOrderByTimestampDescIdDesc(
+                        eq(1L), eq(1L), any(Pageable.class)))
+                .thenReturn(new PageImpl<>(List.of(entry)));
+
+        List<RecentHistoryEntryDto> result = service.getRecentForUser(alice, 4);
+
+        assertThat(result.get(0).actorUsername()).isNull();
+    }
+
+    @Test
+    void getRecentForUser_clampsLimitBetween1And20() {
+        AppUser alice = user(1L, "alice");
+        when(historyRepository
+                .findByExpenseListOwnerIdOrExpenseListSharedWithIdOrderByTimestampDescIdDesc(
+                        eq(1L), eq(1L), any(Pageable.class)))
+                .thenReturn(new PageImpl<>(List.of()));
+
+        service.getRecentForUser(alice, 500);
+        verify(historyRepository)
+                .findByExpenseListOwnerIdOrExpenseListSharedWithIdOrderByTimestampDescIdDesc(
+                        1L, 1L, PageRequest.of(0, 20));
+
+        service.getRecentForUser(alice, 0);
+        verify(historyRepository)
+                .findByExpenseListOwnerIdOrExpenseListSharedWithIdOrderByTimestampDescIdDesc(
+                        1L, 1L, PageRequest.of(0, 1));
+    }
 }