Slideshow toolbar, unsave from library, fix async error handling

- Add Favorite/Save/Unsave buttons to slideshow mode toolbar
- Add "Unsave from Library" to grid and preview right-click menus
- Fix silent exception swallowing in persistent event loop
- Fix closeEvent race condition with async thread join

booru_viewer/gui/app.py

@@ -217,7 +217,15 @@ class BooruApp(QMainWindow):
         self._status.showMessage(f"Error: {e}")
 
     def _run_async(self, coro_func, *args):
-        asyncio.run_coroutine_threadsafe(coro_func(*args), self._async_loop)
+        future = asyncio.run_coroutine_threadsafe(coro_func(*args), self._async_loop)
+        future.add_done_callback(self._on_async_done)
+
+    @staticmethod
+    def _on_async_done(future):
+        try:
+            future.result()
+        except Exception as e:
+            log.error(f"Async worker failed: {e}")
 
     def _setup_ui(self) -> None:
         central = QWidget()
@@ -303,6 +311,7 @@ class BooruApp(QMainWindow):
         self._preview.open_in_browser.connect(self._open_preview_in_browser)
         self._preview.favorite_requested.connect(self._favorite_from_preview)
         self._preview.save_to_folder.connect(self._save_from_preview)
+        self._preview.unsave_requested.connect(self._unsave_from_preview)
         self._preview.navigate.connect(self._navigate_preview)
         self._preview.fullscreen_requested.connect(self._open_fullscreen_preview)
         self._preview.set_folders_callback(self._db.get_folders)
@@ -841,6 +850,26 @@ class BooruApp(QMainWindow):
                 self._db.add_folder(folder)
             self._save_to_library(self._posts[idx], target)
 
+    def _unsave_from_preview(self) -> None:
+        idx = self._grid.selected_index
+        if 0 <= idx < len(self._posts):
+            post = self._posts[idx]
+            from ..core.cache import delete_from_library
+            site_id = self._site_combo.currentData()
+            folder = None
+            if site_id:
+                favs = self._db.get_favorites(site_id=site_id)
+                for f in favs:
+                    if f.post_id == post.id and f.folder:
+                        folder = f.folder
+                        break
+            if delete_from_library(post.id, folder):
+                self._status.showMessage(f"Removed #{post.id} from library")
+                if 0 <= idx < len(self._grid._thumbs):
+                    self._grid._thumbs[idx].set_saved_locally(False)
+            else:
+                self._status.showMessage(f"#{post.id} not in library")
+
     def _open_fullscreen_preview(self) -> None:
         path = self._preview._current_path
         if not path:
@@ -851,6 +880,9 @@ class BooruApp(QMainWindow):
         cols = self._grid._flow.columns
         self._fullscreen_window = FullscreenPreview(grid_cols=cols, parent=self)
         self._fullscreen_window.navigate.connect(self._navigate_fullscreen)
+        self._fullscreen_window.favorite_requested.connect(self._favorite_from_preview)
+        self._fullscreen_window.save_requested.connect(lambda: self._save_from_preview(""))
+        self._fullscreen_window.unsave_requested.connect(self._unsave_from_preview)
         self._fullscreen_window.destroyed.connect(self._on_fullscreen_closed)
         self._fullscreen_window.set_media(path, self._preview._info_label.text())
 
@@ -893,6 +925,7 @@ class BooruApp(QMainWindow):
         save_lib_menu.addSeparator()
         save_lib_new = save_lib_menu.addAction("+ New Folder...")
 
+        unsave_lib = menu.addAction("Unsave from Library")
         copy_url = menu.addAction("Copy Image URL")
         copy_tags = menu.addAction("Copy Tags")
         menu.addSeparator()
@@ -922,6 +955,22 @@ class BooruApp(QMainWindow):
                 self._save_to_library(post, name.strip())
         elif id(action) in save_lib_folders:
             self._save_to_library(post, save_lib_folders[id(action)])
+        elif action == unsave_lib:
+            from ..core.cache import delete_from_library
+            site_id = self._site_combo.currentData()
+            folder = None
+            if site_id:
+                favs = self._db.get_favorites(site_id=site_id)
+                for f in favs:
+                    if f.post_id == post.id and f.folder:
+                        folder = f.folder
+                        break
+            if delete_from_library(post.id, folder):
+                self._status.showMessage(f"Removed #{post.id} from library")
+                if 0 <= index < len(self._grid._thumbs):
+                    self._grid._thumbs[index].set_saved_locally(False)
+            else:
+                self._status.showMessage(f"#{post.id} not in library")
         elif action == copy_url:
             QApplication.clipboard().setText(post.file_url)
             self._status.showMessage("URL copied")
@@ -1376,6 +1425,7 @@ class BooruApp(QMainWindow):
 
     def closeEvent(self, event) -> None:
         self._async_loop.call_soon_threadsafe(self._async_loop.stop)
+        self._async_thread.join(timeout=2)
         if self._db.get_setting_bool("clear_cache_on_exit"):
             from ..core.cache import clear_cache
             clear_cache(clear_images=True, clear_thumbnails=True)

booru_viewer/gui/preview.py

@@ -25,15 +25,50 @@ def _is_video(path: str) -> bool:
 class FullscreenPreview(QMainWindow):
     """Fullscreen media viewer with navigation — images, GIFs, and video."""
 
-    navigate = Signal(int)  # -1 = prev, +1 = next
+    navigate = Signal(int)  # direction: -1/+1 for left/right, -cols/+cols for up/down
+    favorite_requested = Signal()
+    save_requested = Signal()
+    unsave_requested = Signal()
 
     def __init__(self, grid_cols: int = 3, parent=None) -> None:
         super().__init__(parent, Qt.WindowType.Window)
         self.setWindowTitle("booru-viewer — Fullscreen")
         self._grid_cols = grid_cols
 
+        central = QWidget()
+        main_layout = QVBoxLayout(central)
+        main_layout.setContentsMargins(0, 0, 0, 0)
+        main_layout.setSpacing(0)
+
+        # Top toolbar
+        toolbar = QHBoxLayout()
+        toolbar.setContentsMargins(8, 4, 8, 4)
+
+        self._fav_btn = QPushButton("Favorite")
+        self._fav_btn.setFixedWidth(80)
+        self._fav_btn.clicked.connect(self.favorite_requested)
+        toolbar.addWidget(self._fav_btn)
+
+        self._save_btn = QPushButton("Save")
+        self._save_btn.setFixedWidth(60)
+        self._save_btn.clicked.connect(self.save_requested)
+        toolbar.addWidget(self._save_btn)
+
+        self._unsave_btn = QPushButton("Unsave")
+        self._unsave_btn.setFixedWidth(70)
+        self._unsave_btn.clicked.connect(self.unsave_requested)
+        toolbar.addWidget(self._unsave_btn)
+
+        toolbar.addStretch()
+
+        self._info_label = QLabel()
+        toolbar.addWidget(self._info_label)
+
+        main_layout.addLayout(toolbar)
+
+        # Media stack
         self._stack = QStackedWidget()
-        self.setCentralWidget(self._stack)
+        main_layout.addWidget(self._stack, stretch=1)
 
         self._viewer = ImageViewer()
         self._viewer.close_requested.connect(self.close)
@@ -42,11 +77,14 @@ class FullscreenPreview(QMainWindow):
         self._video = VideoPlayer()
         self._stack.addWidget(self._video)
 
+        self.setCentralWidget(central)
+
         from PySide6.QtWidgets import QApplication
         QApplication.instance().installEventFilter(self)
         self.showFullScreen()
 
     def set_media(self, path: str, info: str = "") -> None:
+        self._info_label.setText(info)
         ext = Path(path).suffix.lower()
         if _is_video(path):
             self._viewer.clear()
@@ -402,6 +440,7 @@ class ImagePreview(QWidget):
     open_in_default = Signal()
     open_in_browser = Signal()
     save_to_folder = Signal(str)
+    unsave_requested = Signal()
     favorite_requested = Signal()
     navigate = Signal(int)  # -1 = prev, +1 = next
     fullscreen_requested = Signal()
@@ -511,6 +550,9 @@ class ImagePreview(QWidget):
         if self._stack.currentIndex() == 0:
             reset_action = menu.addAction("Reset View")
 
+        menu.addSeparator()
+        unsave_action = menu.addAction("Unsave from Library")
+
         slideshow_action = None
         if self._current_path:
             slideshow_action = menu.addAction("Slideshow Mode")
@@ -539,6 +581,8 @@ class ImagePreview(QWidget):
         elif action == reset_action:
             self._image_viewer._fit_to_view()
             self._image_viewer.update()
+        elif action == unsave_action:
+            self.unsave_requested.emit()
         elif action == slideshow_action:
             self.fullscreen_requested.emit()
         elif action == clear_action: