Session cache option, zip conversion fix, page boundary nav

- Add "Clear cache on exit" checkbox in Settings > Cache
- Fix ugoira zip conversion: don't crash if frames fail, verify gif
  exists before deleting zip
- Arrow key past last/first post loads next/prev page

booru_viewer/core/cache.py

@@ -68,12 +68,14 @@ def _convert_ugoira_to_gif(zip_path: Path) -> Path:
             except Exception:
                 continue
     if not frames:
-        raise ValueError("Zip contains no image frames")
+        # Can't convert — just return the zip path as-is
+        return zip_path
     frames[0].save(
         gif_path, save_all=True, append_images=frames[1:],
         duration=80, loop=0, disposal=2,
     )
-    zip_path.unlink()
+    if gif_path.exists():
+        zip_path.unlink()
     return gif_path
 
 

booru_viewer/gui/app.py

@@ -787,6 +787,10 @@ class BooruApp(QMainWindow):
             if 0 <= idx < len(self._posts):
                 self._grid._select(idx)
                 self._on_post_activated(idx)
+            elif idx >= len(self._posts) and direction == 1 and len(self._posts) > 0:
+                self._next_page()
+            elif idx < 0 and direction == -1 and self._current_page > 1:
+                self._prev_page()
 
     def _favorite_from_preview(self) -> None:
         idx = self._grid.selected_index
@@ -1335,6 +1339,9 @@ class BooruApp(QMainWindow):
                 thumbs[index].set_saved_locally(True)
 
     def closeEvent(self, event) -> None:
+        if self._db.get_setting_bool("clear_cache_on_exit"):
+            from ..core.cache import clear_cache
+            clear_cache(clear_images=True, clear_thumbnails=True)
         self._db.close()
         super().closeEvent(event)
 

booru_viewer/gui/settings.py

@@ -166,6 +166,10 @@ class SettingsDialog(QDialog):
         self._auto_evict.setChecked(self._db.get_setting_bool("auto_evict"))
         limits_layout.addRow("", self._auto_evict)
 
+        self._clear_on_exit = QCheckBox("Clear cache on exit (session-only cache)")
+        self._clear_on_exit.setChecked(self._db.get_setting_bool("clear_cache_on_exit"))
+        limits_layout.addRow("", self._clear_on_exit)
+
         layout.addWidget(limits_group)
 
         # Cache actions
@@ -614,6 +618,7 @@ class SettingsDialog(QDialog):
         self._db.set_setting("preload_thumbnails", "1" if self._preload.isChecked() else "0")
         self._db.set_setting("max_cache_mb", str(self._max_cache.value()))
         self._db.set_setting("auto_evict", "1" if self._auto_evict.isChecked() else "0")
+        self._db.set_setting("clear_cache_on_exit", "1" if self._clear_on_exit.isChecked() else "0")
         if self._file_dialog_combo is not None:
             self._db.set_setting("file_dialog_platform", self._file_dialog_combo.currentText())
         self.settings_changed.emit()