More annotation added to the program

backend/pdk_access.py

@@ -10,6 +10,8 @@ import shutil
 import uuid
 
 
+# Role names control which PDK tree the backend exposes for browsing, preview,
+# and GDS export requests.
 MANAGER_GROUP = "manager"
 DEVELOPER_GROUP = "developers"
 USER_GROUP = "user"
@@ -17,12 +19,16 @@ ALLOWED_GROUPS = {MANAGER_GROUP, DEVELOPER_GROUP, USER_GROUP}
 
 
 def normalize_user_group(user_group: str) -> str:
+    """Normalize a session user group into the supported PDK access scope."""
     group = (user_group or USER_GROUP).strip().lower()
     return group if group in ALLOWED_GROUPS else USER_GROUP
 
 
 def pdk_root_for_group(user_group: str, repo_root: str) -> str:
+    """Resolve the PDK library root that belongs to a user group."""
     group = normalize_user_group(user_group)
+    # Managers may access the private atlas PDK tree; all other roles stay on
+    # the public PDK tree used for normal project editing.
     if group == MANAGER_GROUP:
         return os.path.abspath(os.environ.get(
             "MXPIC_PDK_ATLAS_ROOT",
@@ -35,14 +41,17 @@ def pdk_root_for_group(user_group: str, repo_root: str) -> str:
 
 
 def pdk_root_for_session(session_obj, repo_root: str) -> str:
+    """Resolve the active PDK root from the current Flask session."""
     return pdk_root_for_group(session_obj.get("user_group"), repo_root)
 
 
 def prefer_full_gds_for_session(session_obj) -> bool:
+    """Decide whether resolved PDK assets should prefer full GDS files."""
     return normalize_user_group(session_obj.get("user_group")) == MANAGER_GROUP
 
 
 def create_export_path(export_root: str, project_name: str) -> tuple[str, str, str]:
+    """Create a unique export directory and filename for generated downloads."""
     export_id = uuid.uuid4().hex
     filename = f"{project_name}.gds"
     export_dir = os.path.abspath(os.path.join(export_root, export_id))
@@ -51,9 +60,12 @@ def create_export_path(export_root: str, project_name: str) -> tuple[str, str, s
 
 
 def cleanup_expired_exports(export_root: str, max_age_seconds: int = 86400) -> None:
+    """Remove old export folders so temporary download storage stays bounded."""
     if not os.path.isdir(export_root):
         return
     now = time.time()
+    # Each export is stored in its own UUID directory, so old folders can be
+    # removed independently without touching active project data.
     for name in os.listdir(export_root):
         path = os.path.join(export_root, name)
         if not os.path.isdir(path):