Add installed/not installed filter dropdown

Scans libraryfolders.vdf and all steamapps directories at load time to
build the installed appid set. Dropdown filters the roll pool between
All games, Installed, and Not installed. Re-scans on each library refresh.

steam_dice.py

@@ -1,5 +1,7 @@
 #!/usr/bin/env python3
+import glob
 import os
+import re
 import sys
 import random
 import subprocess
@@ -8,7 +10,7 @@ import requests
 # Run natively on Wayland if available, fall back to X11 otherwise
 if os.environ.get("WAYLAND_DISPLAY"):
     os.environ.setdefault("QT_QPA_PLATFORM", "wayland")
-from PyQt6.QtWidgets import QApplication, QMainWindow, QWidget, QVBoxLayout, QHBoxLayout, QPushButton, QLabel
+from PyQt6.QtWidgets import QApplication, QMainWindow, QWidget, QVBoxLayout, QHBoxLayout, QPushButton, QLabel, QComboBox
 from PyQt6.QtCore import Qt, QThread, QTimer, pyqtSignal
 from PyQt6.QtGui import QPixmap, QFont, QIcon
 
@@ -26,6 +28,26 @@ def _get_version():
         return VERSION
 
 
+def _scan_installed_appids():
+    """Return a set of appids currently installed across all Steam library folders."""
+    steam_root = os.path.expanduser("~/.local/share/Steam")
+    library_paths = [os.path.join(steam_root, "steamapps")]
+    vdf_path = os.path.join(steam_root, "steamapps", "libraryfolders.vdf")
+    try:
+        with open(vdf_path) as f:
+            for path in re.findall(r'"path"\s+"([^"]+)"', f.read()):
+                library_paths.append(os.path.join(path, "steamapps"))
+    except Exception:
+        pass
+    installed = set()
+    for lib in library_paths:
+        for acf in glob.glob(os.path.join(lib, "appmanifest_*.acf")):
+            m = re.search(r"appmanifest_(\d+)\.acf", acf)
+            if m:
+                installed.add(int(m.group(1)))
+    return installed
+
+
 STEAM_API_KEY = "A2B1B59F6F16FA3CD3107378AE737C3D"
 STEAM_ID = "76561198000382373"
 
@@ -62,6 +84,33 @@ DICE_STYLE = """
     QPushButton:disabled { color: #4a5a6a; }
 """
 
+COMBO_STYLE = """
+    QComboBox {
+        background-color: #2a3f5f;
+        color: #c6d4df;
+        border: 1px solid #3d5a7a;
+        border-radius: 4px;
+        padding: 2px 8px;
+        min-width: 115px;
+    }
+    QComboBox:hover { border-color: #5a8ab0; }
+    QComboBox:disabled { color: #4a5a6a; border-color: #2a3a50; }
+    QComboBox::drop-down { border: none; width: 20px; }
+    QComboBox::down-arrow {
+        border-left: 4px solid transparent;
+        border-right: 4px solid transparent;
+        border-top: 5px solid #c6d4df;
+        width: 0; height: 0;
+    }
+    QComboBox QAbstractItemView {
+        background-color: #2a3f5f;
+        color: #c6d4df;
+        selection-background-color: #3d6b9e;
+        border: 1px solid #3d5a7a;
+        outline: none;
+    }
+"""
+
 REFRESH_STYLE = """
     QPushButton {
         background: transparent;
@@ -115,7 +164,9 @@ class FetchImageThread(QThread):
 class SteamDice(QMainWindow):
     def __init__(self):
         super().__init__()
+        self.all_games = []
         self.games = []
+        self.installed_appids = set()
         self.image_thread = None
         self.cooldown_remaining = 0
         self.current_appid = None
@@ -132,9 +183,18 @@ class SteamDice(QMainWindow):
         layout.setContentsMargins(MARGIN, MARGIN, MARGIN, MARGIN)
         layout.setSpacing(SPACING)
 
-        # Top row: refresh button + cooldown label pinned to right
+        # Top row: filter dropdown (left) | stretch | refresh button (right)
         top_row = QHBoxLayout()
         top_row.setContentsMargins(0, 0, 0, 0)
+
+        self.filter_combo = QComboBox()
+        self.filter_combo.addItems(["All games", "Installed", "Not installed"])
+        self.filter_combo.setFixedHeight(28)
+        self.filter_combo.setStyleSheet(COMBO_STYLE)
+        self.filter_combo.setEnabled(False)
+        self.filter_combo.currentIndexChanged.connect(self._apply_filter)
+        top_row.addWidget(self.filter_combo, alignment=Qt.AlignmentFlag.AlignTop)
+
         top_row.addStretch()
 
         refresh_col = QVBoxLayout()
@@ -262,15 +322,31 @@ class SteamDice(QMainWindow):
         self.fetch_thread.start()
 
     def _on_library_loaded(self, games):
-        self.games = games
-        self.status_label.setText(f"{len(games)} games — roll the dice!")
-        self.dice_btn.setEnabled(True)
+        self.all_games = games
+        self.installed_appids = _scan_installed_appids()
+        self.filter_combo.setEnabled(True)
         self.refresh_btn.setEnabled(True)
+        self._apply_filter()
 
     def _on_library_error(self, msg):
         self.status_label.setText(f"Error loading library: {msg}")
         self.refresh_btn.setEnabled(True)
 
+    def _apply_filter(self):
+        idx = self.filter_combo.currentIndex()
+        if idx == 1:
+            self.games = [g for g in self.all_games if g["appid"] in self.installed_appids]
+        elif idx == 2:
+            self.games = [g for g in self.all_games if g["appid"] not in self.installed_appids]
+        else:
+            self.games = list(self.all_games)
+        count = len(self.games)
+        if count:
+            self.status_label.setText(f"{count} games — roll the dice!")
+        else:
+            self.status_label.setText("No games match this filter.")
+        self.dice_btn.setEnabled(bool(self.games))
+
     def _refresh(self):
         self.refresh_btn.setEnabled(False)
         self.dice_btn.setEnabled(False)