fix(library): sync again after a Steam ID change and keep library on empty result

An empty Steam answer (error, private profile, wrong ID) was stored as OK and
soft-deleted the whole library. It is now FAILED, keeps the library and is
retried after 15 minutes (app.library.failed-retry-minutes).

The automatic sync now also runs when the Steam ID in the token differs from
the stored one, and removes the games of the previous Steam account.

src/main/java/core_service/modules/library/service/LibrarySyncService.java

@@ -27,19 +27,22 @@ public class LibrarySyncService {
     @Value("${app.library.running-stale-minutes:5}")
     private long runningStaleMinutes;
 
+    @Value("${app.library.failed-retry-minutes:15}")
+    private long failedRetryMinutes;
+
     /**
-     * Trigger sync only if data is older than TTL. Cheap gate check on caller thread,
-     * actual sync runs async via worker.
+     * Trigger sync only if data is older than TTL or was synced for another Steam ID.
+     * Cheap gate check on caller thread, actual sync runs async via worker.
      */
     public void syncIfStale(Long userId, String steamId) {
         UserSteamSync sync = userSteamSyncRepository.findById(userId).orElse(null);
-        if (sync != null && !isStale(sync)) {
-            return;
-        }
         if (sync != null && isAlreadyRunning(sync)) {
             log.debug("Sync already running for user {}", userId);
             return;
         }
+        if (sync != null && steamId.equals(sync.getSteamId()) && !isStale(sync)) {
+            return;
+        }
         worker.runSync(userId, steamId);
     }
 
@@ -62,7 +65,10 @@ public class LibrarySyncService {
 
     private boolean isStale(UserSteamSync sync) {
         if (sync.getLastSyncedAt() == null) return true;
-        return sync.getLastSyncedAt().isBefore(Instant.now().minus(Duration.ofHours(syncTtlHours)));
+        Duration maxAge = sync.getLastSyncStatus() == UserSteamSync.Status.FAILED
+                ? Duration.ofMinutes(failedRetryMinutes)
+                : Duration.ofHours(syncTtlHours);
+        return sync.getLastSyncedAt().isBefore(Instant.now().minus(maxAge));
     }
 
     private boolean isAlreadyRunning(UserSteamSync sync) {

src/main/java/core_service/modules/library/service/LibrarySyncWorker.java

@@ -3,6 +3,7 @@ package core_service.modules.library.service;
 import core_service.modules.library.domain.SteamGame;
 import core_service.modules.library.domain.UserGame;
 import core_service.modules.library.domain.UserGameId;
+import core_service.modules.library.domain.UserSteamSync;
 import core_service.modules.library.repo.SteamGameRepository;
 import core_service.modules.library.repo.UserGameRepository;
 import core_service.modules.library.repo.UserSteamSyncRepository;
@@ -43,6 +44,9 @@ public class LibrarySyncWorker {
     @Transactional
     public void runSync(Long userId, String steamId) {
         Instant runningStaleBefore = Instant.now().minus(Duration.ofMinutes(runningStaleMinutes));
+        String previousSteamId = userSteamSyncRepository.findById(userId)
+                .map(UserSteamSync::getSteamId)
+                .orElse(null);
         int claimed = userSteamSyncRepository.tryClaimRun(userId, steamId, runningStaleBefore);
         if (claimed == 0) {
             log.info("Sync skipped for user {} — another run already in flight", userId);
@@ -52,8 +56,17 @@ public class LibrarySyncWorker {
         Instant syncStartedAt = Instant.now();
         Status finalStatus = Status.FAILED;
         try {
+            if (previousSteamId != null && !previousSteamId.equals(steamId)) {
+                // The old games belong to the previous Steam account. The upserts below restore the games this account also owns.
+                userGameRepository.softDeleteMissingSince(userId, syncStartedAt, Instant.now());
+            }
             List<SteamOwnedGamesResponse.Game> games = steamApiService.getOwnedGames(steamId);
             log.info("Sync user={} fetched {} games from Steam", userId, games.size());
+            if (games.isEmpty()) {
+                // Steam errors and a private "Game details" setting also end here. A soft-delete would wipe the library.
+                log.warn("Sync user={} got no games for SteamID {}", userId, steamId);
+                return;
+            }
 
             for (SteamOwnedGamesResponse.Game g : games) {
                 if (g.appid() == null) continue;

src/test/java/core_service/modules/library/service/LibrarySyncServiceTest.java

@@ -0,0 +1,104 @@
+package core_service.modules.library.service;
+
+import core_service.modules.library.domain.UserSteamSync;
+import core_service.modules.library.repo.UserSteamSyncRepository;
+import core_service.shared.test.AbstractUnitTest;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.mockito.InjectMocks;
+import org.mockito.Mock;
+import org.springframework.test.util.ReflectionTestUtils;
+
+import java.time.Duration;
+import java.time.Instant;
+import java.util.Optional;
+
+import static org.mockito.ArgumentMatchers.anyLong;
+import static org.mockito.ArgumentMatchers.anyString;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+class LibrarySyncServiceTest extends AbstractUnitTest {
+
+    private static final long USER_ID = 1L;
+    private static final String STEAM_ID = "76561198005679788";
+
+    @Mock
+    private UserSteamSyncRepository userSteamSyncRepository;
+
+    @Mock
+    private LibrarySyncWorker worker;
+
+    @InjectMocks
+    private LibrarySyncService syncService;
+
+    @BeforeEach
+    void setUp() {
+        ReflectionTestUtils.setField(syncService, "syncTtlHours", 24L);
+        ReflectionTestUtils.setField(syncService, "forceSyncCooldownSeconds", 60L);
+        ReflectionTestUtils.setField(syncService, "runningStaleMinutes", 5L);
+        ReflectionTestUtils.setField(syncService, "failedRetryMinutes", 15L);
+    }
+
+    private void givenSync(String steamId, UserSteamSync.Status status, Duration age) {
+        UserSteamSync sync = new UserSteamSync(USER_ID, steamId);
+        sync.setLastSyncStatus(status);
+        sync.setLastSyncedAt(Instant.now().minus(age));
+        when(userSteamSyncRepository.findById(USER_ID)).thenReturn(Optional.of(sync));
+    }
+
+    @Test
+    void syncIfStale_NoSyncYet_Runs() {
+        when(userSteamSyncRepository.findById(USER_ID)).thenReturn(Optional.empty());
+
+        syncService.syncIfStale(USER_ID, STEAM_ID);
+
+        verify(worker).runSync(USER_ID, STEAM_ID);
+    }
+
+    @Test
+    void syncIfStale_FreshOkSync_Skips() {
+        givenSync(STEAM_ID, UserSteamSync.Status.OK, Duration.ofMinutes(10));
+
+        syncService.syncIfStale(USER_ID, STEAM_ID);
+
+        verify(worker, never()).runSync(anyLong(), anyString());
+    }
+
+    @Test
+    void syncIfStale_FreshSyncForOtherSteamId_Runs() {
+        givenSync("76561198005679790", UserSteamSync.Status.OK, Duration.ofMinutes(10));
+
+        syncService.syncIfStale(USER_ID, STEAM_ID);
+
+        verify(worker).runSync(USER_ID, STEAM_ID);
+    }
+
+    @Test
+    void syncIfStale_FailedSyncAfterRetryInterval_Runs() {
+        givenSync(STEAM_ID, UserSteamSync.Status.FAILED, Duration.ofMinutes(16));
+
+        syncService.syncIfStale(USER_ID, STEAM_ID);
+
+        verify(worker).runSync(USER_ID, STEAM_ID);
+    }
+
+    @Test
+    void syncIfStale_FailedSyncWithinRetryInterval_Skips() {
+        givenSync(STEAM_ID, UserSteamSync.Status.FAILED, Duration.ofMinutes(5));
+
+        syncService.syncIfStale(USER_ID, STEAM_ID);
+
+        verify(worker, never()).runSync(anyLong(), anyString());
+    }
+
+    @Test
+    void syncIfStale_RunningForOtherSteamId_Skips() {
+        givenSync("76561198005679790", UserSteamSync.Status.RUNNING, Duration.ofSeconds(10));
+
+        syncService.syncIfStale(USER_ID, STEAM_ID);
+
+        verify(worker, never()).runSync(anyLong(), anyString());
+    }
+}

src/test/java/core_service/modules/library/service/LibrarySyncWorkerTest.java

@@ -0,0 +1,92 @@
+package core_service.modules.library.service;
+
+import core_service.modules.library.domain.UserSteamSync;
+import core_service.modules.library.repo.SteamGameRepository;
+import core_service.modules.library.repo.UserGameRepository;
+import core_service.modules.library.repo.UserSteamSyncRepository;
+import core_service.modules.steam_adapter.api.dto.response.SteamOwnedGamesResponse;
+import core_service.modules.steam_adapter.service.SteamApiService;
+import core_service.shared.test.AbstractUnitTest;
+import org.junit.jupiter.api.Test;
+import org.mockito.InjectMocks;
+import org.mockito.Mock;
+
+import java.util.List;
+import java.util.Optional;
+
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.anyLong;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+class LibrarySyncWorkerTest extends AbstractUnitTest {
+
+    private static final long USER_ID = 1L;
+    private static final String STEAM_ID = "76561198005679788";
+
+    @Mock
+    private SteamApiService steamApiService;
+
+    @Mock
+    private SteamGameRepository steamGameRepository;
+
+    @Mock
+    private UserGameRepository userGameRepository;
+
+    @Mock
+    private UserSteamSyncRepository userSteamSyncRepository;
+
+    @InjectMocks
+    private LibrarySyncWorker worker;
+
+    @Test
+    void runSync_EmptySteamResult_MarksFailedAndKeepsLibrary() {
+        when(userSteamSyncRepository.tryClaimRun(eq(USER_ID), eq(STEAM_ID), any())).thenReturn(1);
+        when(steamApiService.getOwnedGames(STEAM_ID)).thenReturn(List.of());
+
+        worker.runSync(USER_ID, STEAM_ID);
+
+        verify(userGameRepository, never()).softDeleteMissingSince(anyLong(), any(), any());
+        verify(userSteamSyncRepository).markFinished(eq(USER_ID), eq("FAILED"), any());
+    }
+
+    @Test
+    void runSync_EmptyResultForNewSteamId_RemovesOldLibrary() {
+        when(userSteamSyncRepository.findById(USER_ID))
+                .thenReturn(Optional.of(new UserSteamSync(USER_ID, "76561198005679790")));
+        when(userSteamSyncRepository.tryClaimRun(eq(USER_ID), eq(STEAM_ID), any())).thenReturn(1);
+        when(steamApiService.getOwnedGames(STEAM_ID)).thenReturn(List.of());
+
+        worker.runSync(USER_ID, STEAM_ID);
+
+        verify(userGameRepository).softDeleteMissingSince(eq(USER_ID), any(), any());
+        verify(userSteamSyncRepository).markFinished(eq(USER_ID), eq("FAILED"), any());
+    }
+
+    @Test
+    void runSync_SteamErrorForNewSteamId_RemovesOldLibrary() {
+        when(userSteamSyncRepository.findById(USER_ID))
+                .thenReturn(Optional.of(new UserSteamSync(USER_ID, "76561198005679790")));
+        when(userSteamSyncRepository.tryClaimRun(eq(USER_ID), eq(STEAM_ID), any())).thenReturn(1);
+        when(steamApiService.getOwnedGames(STEAM_ID)).thenThrow(new IllegalStateException("Steam down"));
+
+        worker.runSync(USER_ID, STEAM_ID);
+
+        verify(userGameRepository).softDeleteMissingSince(eq(USER_ID), any(), any());
+        verify(userSteamSyncRepository).markFinished(eq(USER_ID), eq("FAILED"), any());
+    }
+
+    @Test
+    void runSync_WithGames_MarksOk() {
+        when(userSteamSyncRepository.tryClaimRun(eq(USER_ID), eq(STEAM_ID), any())).thenReturn(1);
+        when(steamApiService.getOwnedGames(STEAM_ID)).thenReturn(List.of(
+                new SteamOwnedGamesResponse.Game(220, "Half-Life 2", 0, "icon", true)));
+
+        worker.runSync(USER_ID, STEAM_ID);
+
+        verify(userGameRepository).softDeleteMissingSince(eq(USER_ID), any(), any());
+        verify(userSteamSyncRepository).markFinished(eq(USER_ID), eq("OK"), any());
+    }
+}