Initial commit

app/paths.py

@@ -0,0 +1,45 @@
+"""Canonical per-user data paths for the application.
+
+All persistent artifacts (SQLite DB, image cache, label PDFs, history JSON,
+package presets, log file) live under one directory so they're easy to find,
+back up, or nuke without touching the install.
+"""
+
+from __future__ import annotations
+
+import os
+from pathlib import Path
+
+_APP_SUBDIR = Path("CollisionStoneGuard") / "PartsLookup"
+
+
+def appdata_dir() -> Path:
+    """Return (and create) the per-user appdata directory.
+
+    Resolution order:
+      1. %LOCALAPPDATA%   (Windows standard)
+      2. ~/AppData/Local  (fallback — same folder, explicit)
+      3. ~               (last resort)
+    """
+    local = os.environ.get("LOCALAPPDATA", "")
+    base  = Path(local) if local else Path.home() / "AppData" / "Local"
+    d     = base / _APP_SUBDIR
+    d.mkdir(parents=True, exist_ok=True)
+    return d
+
+
+def default_sqlite_path() -> str:
+    """Default path for the parts/invoices SQLite database."""
+    return str(appdata_dir() / "parts.db")
+
+
+def default_image_cache_dir() -> str:
+    """Default directory for cached part images."""
+    p = appdata_dir() / "images"
+    p.mkdir(exist_ok=True)
+    return str(p)
+
+
+def log_file_path() -> Path:
+    """Path for the application log file."""
+    return appdata_dir() / "app.log"