Remove docs from tracking

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docs/superpowers/specs/2026-05-04-security-hardening-design.md

@@ -1,166 +0,0 @@
-# Security Hardening Design — XpenselyServer
-**Date:** 2026-05-04  
-**Scope:** Input validation, authorization enforcement, rate limiting
-
----
-
-## Problem Statement
-
-The XpenselyServer has three security gaps:
-
-1. **No input validation** — request bodies are accepted without any field constraints, allowing null fields, negative amounts, oversized strings, and malformed data to reach the database layer.
-2. **Authorization bypass** — every endpoint trusts caller-supplied user IDs from query params or request bodies rather than the authenticated JWT. Any authenticated user can read or destroy another user's expense lists.
-3. **No rate limiting** — no protection against brute-force or abuse of sensitive endpoints (invite generation, account creation, invite acceptance).
-
----
-
-## Section 1 — Input Validation
-
-### Dependency
-Add `spring-boot-starter-validation` to `pom.xml`.
-
-### Request Model Constraints
-
-**`AppUserCreateRequest`**
-- `username`: `@NotBlank @Size(min=3, max=30) @Pattern(regexp="^[a-zA-Z0-9_.-]+$")`
-- `googleId`: `@NotBlank`
-
-**`ExpenseInput`**
-- `title`: `@NotBlank @Size(max=100)`
-- `owner`: `@NotBlank`
-- `amount`: `@NotNull @DecimalMin("0.01")`
-- `date`: `@NotNull`
-- `category`: `@NotBlank`
-
-**`ExpenseChangeRequest`** — same constraints as `ExpenseInput` for the corresponding fields.
-
-**`InviteRequest`**
-- `inviteCode`: `@NotBlank @Size(min=6, max=6)`
-- `userId` field removed (derived from JWT — see Section 2)
-
-### Controller Changes
-Add `@Valid` to every `@RequestBody` parameter in `AppUserController` and `ExpenseListController`.
-
-### Error Handling
-Add a `@ControllerAdvice` class `GlobalExceptionHandler` that:
-- Catches `MethodArgumentNotValidException` → returns `400 Bad Request` with a map of `{ field: errorMessage }` pairs
-- Catches `IllegalArgumentException` → returns `400 Bad Request` with the exception message
-
-This replaces the current pattern of returning `500 INTERNAL_SERVER_ERROR` or `417 EXPECTATION_FAILED` for validation failures.
-
-### Cleanup
-Remove the stray `@Id` and `@GeneratedValue` JPA annotations from `ExpenseInput` — it is a DTO, not an entity.
-
----
-
-## Section 2 — Authorization Model
-
-### Core Principle
-Stop trusting caller-supplied user IDs. Derive the authenticated user from the JWT on every request.
-
-### New Component: `AuthenticatedUserResolver`
-A `@Component` with a single method:
-```java
-AppUser resolveCurrentUser(Authentication auth)
-```
-- Extracts the `sub` claim (Google ID) from the JWT
-- Calls `UserService.getUserByGoogleId(sub)` to return the `AppUser`
-- Throws `ResponseStatusException(403)` if no user is found for the JWT subject
-
-### Endpoint Changes
-
-| Endpoint | Change |
-|---|---|
-| `GET /api/expenselist/all` | **Removed** — no legitimate non-admin use case |
-| `GET /api/expenselist/byUser?userId=X` | **Replaced** by `GET /api/expenselist/mine` — returns lists for the JWT user, no param |
-| `GET /api/expenselist/byUsername?username=X` | **Removed** — redundant with `/mine` |
-| `GET /api/expenselist/byId?id=X` | **Guard added** — 403 if authenticated user is neither owner nor sharedWith |
-| `DELETE /api/expenselist/{id}` | **Guard added** — 403 if authenticated user is not the owner |
-| `POST /api/expenselist/{id}/add` | **Guard added** — 403 if authenticated user is not owner or sharedWith |
-| `PUT /api/expenselist/{id}/update` | **Guard added** — 403 if authenticated user is not owner or sharedWith |
-| `DELETE /api/expenselist/{id}/delete` | **Guard added** — 403 if authenticated user is not owner or sharedWith |
-| `POST /api/expenselist/{listId}/invite` | **Guard added** — 403 if authenticated user is not the owner |
-| `POST /api/expenselist/accept-invite` | **`userId` removed from body** — derived from JWT instead |
-| `GET /api/users?id=X` | **Guard added** — 403 if id doesn't match JWT user's id |
-| `GET /api/users/byGoogleId?id=X` | **Guard added** — 403 if id doesn't match JWT sub |
-| `DELETE /api/users?id=X` | **Guard added** — 403 if id doesn't match JWT user's id |
-
-### Ownership Check Helper
-Each guard is implemented as a private method in its controller (2–3 lines):
-```java
-private void assertOwner(AppUser authenticated, ExpenseList list) {
-    if (!list.getOwner().getId().equals(authenticated.getId()))
-        throw new ResponseStatusException(HttpStatus.FORBIDDEN);
-}
-
-private void assertMember(AppUser authenticated, ExpenseList list) {
-    boolean isOwner = list.getOwner().getId().equals(authenticated.getId());
-    boolean isShared = list.getSharedWith() != null && list.getSharedWith().getId().equals(authenticated.getId());
-    if (!isOwner && !isShared)
-        throw new ResponseStatusException(HttpStatus.FORBIDDEN);
-}
-```
-
-### Test Profile
-The `@Profile("test")` security chain in `SecurityConfig` is untouched. Existing tests continue to work without authentication.
-
----
-
-## Section 3 — Rate Limiting
-
-### Dependency
-Add `bucket4j-core` to `pom.xml`. In-memory storage — no external cache needed for single-instance deployment.
-
-### Implementation
-A `RateLimitFilter` extending `OncePerRequestFilter`, registered as a `@Component` with `@Profile("!test")`:
-
-- **Key for authenticated requests:** JWT `sub` claim (per-user bucket)
-- **Key for unauthenticated requests:** remote IP address (pre-auth fallback)
-- Buckets stored in a `ConcurrentHashMap<String, Bucket>`
-
-### Limits
-
-| Endpoint pattern | Limit |
-|---|---|
-| All endpoints (default) | 60 requests / minute |
-| `POST /api/expenselist/*/invite` | 5 requests / minute |
-| `POST /api/expenselist/accept-invite` | 10 requests / minute |
-| `POST /api/users/createUser` | 3 requests / minute |
-
-Sensitive endpoints get their own per-user bucket independent of the general bucket.
-
-### Response
-When a bucket is exhausted: `429 Too Many Requests` with a `Retry-After: <seconds>` header indicating time until refill.
-
----
-
-## Architecture Summary
-
-```
-Request
-  └── RateLimitFilter (per-user/IP buckets)
-        └── SecurityFilterChain (JWT validation)
-              └── Controller
-                    ├── @Valid on @RequestBody → GlobalExceptionHandler on failure
-                    ├── AuthenticatedUserResolver → AppUser from JWT sub
-                    └── assertOwner / assertMember → 403 on violation
-```
-
-No new service layer is introduced. The authorization checks are lightweight and local to each controller method.
-
----
-
-## Files Affected
-
-| File | Change |
-|---|---|
-| `pom.xml` | Add `spring-boot-starter-validation`, `bucket4j-core` |
-| `model/AppUserCreateRequest.java` | Add validation annotations |
-| `model/ExpenseInput.java` | Add validation annotations, remove JPA annotations |
-| `model/ExpenseChangeRequest.java` | Add validation annotations |
-| `model/InviteRequest.java` | Add validation annotations, remove `userId` field |
-| `controller/AppUserController.java` | Add `@Valid`, ownership guards, use `AuthenticatedUserResolver` |
-| `controller/ExpenseListController.java` | Add `@Valid`, ownership guards, remove/rename endpoints, use `AuthenticatedUserResolver` |
-| `security/AuthenticatedUserResolver.java` | **New** — resolves JWT sub to `AppUser` |
-| `security/RateLimitFilter.java` | **New** — per-user/IP rate limiting |
-| `controller/GlobalExceptionHandler.java` | **New** — structured 400/403 error responses |

src/main/java/de/zendric/app/xpensely_server/model/Exception/ResourceNotFoundException.java

@@ -0,0 +1,11 @@
+package de.zendric.app.xpensely_server.model.Exception;
+
+import org.springframework.http.HttpStatus;
+import org.springframework.web.bind.annotation.ResponseStatus;
+
+@ResponseStatus(HttpStatus.NOT_FOUND)
+public class ResourceNotFoundException extends RuntimeException {
+    public ResourceNotFoundException(String message) {
+        super(message);
+    }
+}

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

@@ -3,13 +3,22 @@ package de.zendric.app.xpensely_server.repo;
 import java.util.List;
 
 import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.repository.query.Param;
 import org.springframework.stereotype.Repository;
 
 import de.zendric.app.xpensely_server.model.ExpenseList;
 
 @Repository
 public interface ExpenseListRepository extends JpaRepository<ExpenseList, Long> {
+
     List<ExpenseList> findByOwnerId(Long ownerId);
 
     ExpenseList findByInviteCode(String inviteCode);
+
+    @Query("SELECT el FROM ExpenseList el WHERE el.owner.id = :userId OR el.sharedWith.id = :userId")
+    List<ExpenseList> findByOwnerIdOrSharedWithId(@Param("userId") Long userId);
+
+    @Query("SELECT el FROM ExpenseList el WHERE el.owner.username = :username OR el.sharedWith.username = :username")
+    List<ExpenseList> findByOwnerUsernameOrSharedWithUsername(@Param("username") String username);
 }

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

@@ -1,37 +1,29 @@
 package de.zendric.app.xpensely_server.services;
 
 import java.time.LocalDateTime;
-import java.util.ArrayList;
-import java.util.HashSet;
 import java.util.List;
 import java.util.Optional;
 import java.util.UUID;
 
-import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
-import de.zendric.app.xpensely_server.model.AppUser;
 import de.zendric.app.xpensely_server.model.Expense;
 import de.zendric.app.xpensely_server.model.ExpenseList;
+import de.zendric.app.xpensely_server.model.Exception.ResourceNotFoundException;
 import de.zendric.app.xpensely_server.model.XpenselyCustomCategory;
 import de.zendric.app.xpensely_server.repo.ExpenseListRepository;
 import de.zendric.app.xpensely_server.repo.ExpenseRepository;
 import de.zendric.app.xpensely_server.repo.XpenselyCustomCategoryRepository;
-import jakarta.persistence.EntityManager;
 
 @Service
 @Transactional
 public class ExpenseListService {
 
-    private ExpenseListRepository repository;
+    private final ExpenseListRepository repository;
     private final ExpenseRepository expenseRepository;
-    private XpenselyCustomCategoryRepository customCategoryRepository;
+    private final XpenselyCustomCategoryRepository customCategoryRepository;
 
-    @Autowired
-    private EntityManager entityManager;
-
-    @Autowired
     public ExpenseListService(ExpenseListRepository repository, ExpenseRepository expenseRepository,
             XpenselyCustomCategoryRepository customCategoryRepository) {
         this.repository = repository;
@@ -68,67 +60,24 @@ public class ExpenseListService {
     }
 
     public List<ExpenseList> findByUserId(Long id) {
-        List<ExpenseList> allLists = repository.findAll();
-        List<ExpenseList> userSpecificList = new ArrayList<>();
-        for (ExpenseList expenseList : allLists) {
-            AppUser sharedWith = expenseList.getSharedWith();
-
-            if (expenseList.getOwner().getId().equals(id)) {
-                userSpecificList.add(expenseList);
-            } else {
-                if (sharedWith != null && sharedWith.getId().equals(id)) {
-                    userSpecificList.add(expenseList);
-                }
-            }
-        }
-        return userSpecificList;
+        return repository.findByOwnerIdOrSharedWithId(id);
     }
 
     public List<ExpenseList> findByUsername(String username) {
-        List<ExpenseList> allLists = repository.findAll();
-        List<ExpenseList> userSpecificList = new ArrayList<>();
-        for (ExpenseList expenseList : allLists) {
-            AppUser sharedWith = expenseList.getSharedWith();
-
-            if (expenseList.getOwner().getUsername().equals(username)) {
-                userSpecificList.add(expenseList);
-            } else {
-                if (sharedWith != null && sharedWith.getUsername().equals(username)) {
-                    userSpecificList.add(expenseList);
-                }
-            }
-        }
-        return userSpecificList;
-
+        return repository.findByOwnerUsernameOrSharedWithUsername(username);
     }
 
     public Expense addExpenseToList(Long expenseListId, Expense expense) {
-        // find expenseList
         ExpenseList expenseList = repository.findById(expenseListId)
-                .orElseThrow(() -> new RuntimeException("ExpenseList not found with id: " + expenseListId));
-        // get all added expenses
-        HashSet<Long> existingId = new HashSet<>();
-        for (Expense e : expenseList.getExpenses()) {
-            existingId.add(e.getId());
-        }
-        // add the new expense
+                .orElseThrow(() -> new ResourceNotFoundException("ExpenseList not found with id: " + expenseListId));
         expenseList.addExpense(expense);
-        // save
         repository.save(expenseList);
-
-        Expense newExpense = new Expense();
-        for (Expense e : expenseList.getExpenses()) {
-            if (!existingId.contains(e.getId())) {
-                newExpense = e;
-                break;
-            }
-        }
-        return newExpense;
+        return expense;
     }
 
     public void deleteExpenseFromList(Long expenseListId, Long expenseId) {
         ExpenseList expenseList = repository.findById(expenseListId)
-                .orElseThrow(() -> new RuntimeException("ExpenseList not found with id: " + expenseListId));
+                .orElseThrow(() -> new ResourceNotFoundException("ExpenseList not found with id: " + expenseListId));
         Expense expenseToRemove = null;
         for (Expense expense : expenseList.getExpenses()) {
             if (expense.getId().equals(expenseId)) {
@@ -139,14 +88,14 @@ public class ExpenseListService {
         if (expenseToRemove != null) {
             expenseList.removeExpense(expenseToRemove);
         } else {
-            throw new RuntimeException("Expense not found with id: " + expenseId);
+            throw new ResourceNotFoundException("Expense not found with id: " + expenseId);
         }
         repository.save(expenseList);
     }
 
     public String generateInviteCode(Long listId) {
         ExpenseList list = repository.findById(listId)
-                .orElseThrow(() -> new RuntimeException("List not found"));
+                .orElseThrow(() -> new ResourceNotFoundException("List not found"));
         String inviteCode;
         if (list.getInviteCode() == null || list.getInviteCodeExpiration().isBefore(LocalDateTime.now())) {
 
@@ -168,7 +117,7 @@ public class ExpenseListService {
 
     public Expense updateExpense(Long expenseListId, Expense updatedExpense) {
         ExpenseList expenseList = repository.findById(expenseListId)
-                .orElseThrow(() -> new IllegalArgumentException("ExpenseList not found"));
+                .orElseThrow(() -> new ResourceNotFoundException("ExpenseList not found with id: " + expenseListId));
 
         if (!expenseList.getExpenses().stream()
                 .anyMatch(expense -> expense.getId().equals(updatedExpense.getId()))) {
@@ -176,7 +125,7 @@ public class ExpenseListService {
         }
 
         Expense existingExpense = expenseRepository.findById(updatedExpense.getId())
-                .orElseThrow(() -> new IllegalArgumentException("Expense not found"));
+                .orElseThrow(() -> new ResourceNotFoundException("Expense not found with id: " + updatedExpense.getId()));
         existingExpense.setTitle(updatedExpense.getTitle());
         existingExpense.setAmount(updatedExpense.getAmount());
         existingExpense.setPersonalUseAmount(updatedExpense.getPersonalUseAmount());
@@ -191,7 +140,7 @@ public class ExpenseListService {
     // TODO implement API for this
     public XpenselyCustomCategory addCustomCategory(Long expenseListId, XpenselyCustomCategory customCategory) {
         ExpenseList expenseList = repository.findById(expenseListId)
-                .orElseThrow(() -> new RuntimeException("Expense List not found"));
+                .orElseThrow(() -> new ResourceNotFoundException("Expense List not found"));
         customCategory.setExpenseList(expenseList);
 
         return customCategoryRepository.save(customCategory);
@@ -200,9 +149,9 @@ public class ExpenseListService {
     // TODO implement API for this
     public void deleteCustomCategory(Long expenseListId, Long categoryId) {
         XpenselyCustomCategory category = customCategoryRepository.findById(categoryId)
-                .orElseThrow(() -> new RuntimeException("Custom Category not found"));
+                .orElseThrow(() -> new ResourceNotFoundException("Custom Category not found"));
         if (!category.getExpenseList().getId().equals(expenseListId)) {
-            throw new RuntimeException("Category does not belong to the specified Expense List");
+            throw new IllegalArgumentException("Category does not belong to the specified Expense List");
         }
         customCategoryRepository.delete(category);
     }

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

@@ -1,11 +1,11 @@
 package de.zendric.app.xpensely_server.services;
 
 import java.util.List;
-import java.util.Optional;
 
 import org.springframework.stereotype.Service;
 
 import de.zendric.app.xpensely_server.model.AppUser;
+import de.zendric.app.xpensely_server.model.Exception.ResourceNotFoundException;
 import de.zendric.app.xpensely_server.model.Exception.UsernameAlreadyExistsException;
 import de.zendric.app.xpensely_server.repo.UserRepository;
 
@@ -29,36 +29,24 @@ public class UserService {
     }
 
     public AppUser getUser(Long id) {
-        Optional<AppUser> user = userRepository.findById(id);
-        if (user.isPresent()) {
-            return user.get();
-        } else
-            return null;
+        return userRepository.findById(id)
+                .orElseThrow(() -> new ResourceNotFoundException("User not found with id: " + id));
     }
 
     public AppUser deleteUserById(Long id) {
-        Optional<AppUser> user = userRepository.findById(id);
-        if (user.isPresent()) {
+        AppUser user = userRepository.findById(id)
+                .orElseThrow(() -> new ResourceNotFoundException("User not found with id: " + id));
         userRepository.deleteById(id);
-            return user.get();
-        } else
-            return null;
+        return user;
     }
 
     public AppUser getUserByName(String username) {
-        Optional<AppUser> optUser = userRepository.findByUsername(username);
-        if (optUser.isPresent()) {
-            return optUser.get();
-        } else
-            return null;
+        return userRepository.findByUsername(username)
+                .orElseThrow(() -> new ResourceNotFoundException("User not found: " + username));
     }
 
     public AppUser getUserByGoogleId(String id) {
-        Optional<AppUser> optUser = userRepository.findByGoogleId(id);
-        if (optUser.isPresent()) {
-            return optUser.get();
-        } else
-            return null;
+        return userRepository.findByGoogleId(id)
+                .orElseThrow(() -> new ResourceNotFoundException("User not found with Google ID: " + id));
     }
-
 }

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

@@ -0,0 +1,57 @@
+package de.zendric.app.xpensely_Server.services;
+
+import de.zendric.app.xpensely_server.model.AppUser;
+import de.zendric.app.xpensely_server.model.ExpenseList;
+import de.zendric.app.xpensely_server.repo.ExpenseListRepository;
+import de.zendric.app.xpensely_server.repo.ExpenseRepository;
+import de.zendric.app.xpensely_server.repo.XpenselyCustomCategoryRepository;
+import de.zendric.app.xpensely_server.services.ExpenseListService;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.InjectMocks;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+
+import java.util.List;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+import static org.mockito.Mockito.never;
+
+@ExtendWith(MockitoExtension.class)
+class ExpenseListServiceTest {
+
+    @Mock ExpenseListRepository repository;
+    @Mock ExpenseRepository expenseRepository;
+    @Mock XpenselyCustomCategoryRepository customCategoryRepository;
+
+    @InjectMocks
+    ExpenseListService service;
+
+    @Test
+    void findByUserId_usesRepositoryQuery_notFindAll() {
+        AppUser owner = new AppUser(); owner.setId(1L);
+        ExpenseList list = new ExpenseList(); list.setId(10L); list.setOwner(owner);
+        when(repository.findByOwnerIdOrSharedWithId(1L)).thenReturn(List.of(list));
+
+        List<ExpenseList> result = service.findByUserId(1L);
+
+        assertThat(result).hasSize(1);
+        verify(repository).findByOwnerIdOrSharedWithId(1L);
+        verify(repository, never()).findAll();
+    }
+
+    @Test
+    void findByUsername_usesRepositoryQuery_notFindAll() {
+        AppUser owner = new AppUser(); owner.setId(1L); owner.setUsername("alice");
+        ExpenseList list = new ExpenseList(); list.setId(10L); list.setOwner(owner);
+        when(repository.findByOwnerUsernameOrSharedWithUsername("alice")).thenReturn(List.of(list));
+
+        List<ExpenseList> result = service.findByUsername("alice");
+
+        assertThat(result).hasSize(1);
+        verify(repository).findByOwnerUsernameOrSharedWithUsername("alice");
+        verify(repository, never()).findAll();
+    }
+}

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

@@ -0,0 +1,75 @@
+package de.zendric.app.xpensely_Server.services;
+
+import de.zendric.app.xpensely_server.model.AppUser;
+import de.zendric.app.xpensely_server.model.Exception.ResourceNotFoundException;
+import de.zendric.app.xpensely_server.repo.UserRepository;
+import de.zendric.app.xpensely_server.services.UserService;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.InjectMocks;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+
+import java.util.Optional;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.mockito.Mockito.when;
+
+@ExtendWith(MockitoExtension.class)
+class UserServiceTest {
+
+    @Mock
+    UserRepository userRepository;
+
+    @InjectMocks
+    UserService userService;
+
+    @Test
+    void getUserByName_throwsResourceNotFound_whenUserMissing() {
+        when(userRepository.findByUsername("ghost")).thenReturn(Optional.empty());
+
+        assertThatThrownBy(() -> userService.getUserByName("ghost"))
+                .isInstanceOf(ResourceNotFoundException.class)
+                .hasMessageContaining("ghost");
+    }
+
+    @Test
+    void getUserByName_returnsUser_whenFound() {
+        AppUser user = new AppUser();
+        user.setId(1L);
+        user.setUsername("alice");
+        when(userRepository.findByUsername("alice")).thenReturn(Optional.of(user));
+
+        AppUser result = userService.getUserByName("alice");
+
+        assertThat(result.getUsername()).isEqualTo("alice");
+    }
+
+    @Test
+    void getUser_throwsResourceNotFound_whenIdMissing() {
+        when(userRepository.findById(99L)).thenReturn(Optional.empty());
+
+        assertThatThrownBy(() -> userService.getUser(99L))
+                .isInstanceOf(ResourceNotFoundException.class)
+                .hasMessageContaining("99");
+    }
+
+    @Test
+    void deleteUserById_throwsResourceNotFound_whenIdMissing() {
+        when(userRepository.findById(99L)).thenReturn(Optional.empty());
+
+        assertThatThrownBy(() -> userService.deleteUserById(99L))
+                .isInstanceOf(ResourceNotFoundException.class)
+                .hasMessageContaining("99");
+    }
+
+    @Test
+    void getUserByGoogleId_throwsResourceNotFound_whenMissing() {
+        when(userRepository.findByGoogleId("gid-404")).thenReturn(Optional.empty());
+
+        assertThatThrownBy(() -> userService.getUserByGoogleId("gid-404"))
+                .isInstanceOf(ResourceNotFoundException.class)
+                .hasMessageContaining("gid-404");
+    }
+}