Create app_environment.py

app_environment.py

@@ -0,0 +1,36 @@
+"""Hosting boundaries and session-owned temporary storage."""
+from pathlib import Path
+import os
+import re
+import shutil
+import uuid
+
+
+PROJECT_ROOT = Path(__file__).resolve().parent
+UPLOAD_ROOT = PROJECT_ROOT / '.uploads'
+PRIVATE_CACHE_ROOT = PROJECT_ROOT / '.model-cache' / 'sessions'
+
+
+def hosted_mode():
+    return os.environ.get('TOKEN_VISUALISER_HOSTED') == '1' or bool(os.environ.get('SPACE_ID'))
+
+
+def new_session_directory(root):
+    root = Path(root).resolve()
+    directory = root / uuid.uuid4().hex
+    directory.mkdir(parents=True, exist_ok=False)
+    return directory
+
+
+def remove_session_directory(directory, root):
+    """Delete only an opaque session folder strictly within its designated root."""
+    root = Path(root).resolve()
+    target = Path(directory).resolve()
+    if target.parent != root or not re.fullmatch(r'[0-9a-f]{32}', target.name):
+        raise ValueError('Refusing to remove a folder outside session storage.')
+    if target.exists():
+        shutil.rmtree(target)
+
+
+def hosted_download_limit():
+    return 4_000_000_000 if hosted_mode() else None