update refactoring and add new features

SYS/config.py

@@ -26,12 +26,16 @@ SCRIPT_DIR = Path(__file__).resolve().parent
 _SAVE_LOCK_DIRNAME = ".medios_save_lock"
 _SAVE_LOCK_TIMEOUT = 30.0  # seconds to wait for save lock
 _SAVE_LOCK_STALE_SECONDS = 3600  # consider lock stale after 1 hour
+_SAVE_LOCK_POLL_INTERVAL = 0.1  # seconds between lock acquisition attempts
+
+_WAL_CHECKPOINT_TIMEOUT = 5.0  # seconds for WAL checkpoint connection
 
 _CONFIG_CACHE: Dict[str, Any] = {}
 _LAST_SAVED_CONFIG: Dict[str, Any] = {}
 _CONFIG_SUMMARY_PENDING = False
 _CONFIG_SAVE_MAX_RETRIES = 5
 _CONFIG_SAVE_RETRY_DELAY = 0.15
+_CONFIG_SAVE_VERIFY_RETRIES = 3
 _CONFIG_MISSING = object()
 _PATH_ALIAS_TOKEN_RE = re.compile(r"^\$(?:\((?P<braced>[^)]+)\)|(?P<plain>[A-Za-z0-9_.-]+))$")
 
@@ -890,7 +894,7 @@ def _acquire_save_lock(timeout: float = _SAVE_LOCK_TIMEOUT):
                 logger.exception("Failed to inspect save lock directory %s: %s", lock_dir, exc)
             if time.time() - start > timeout:
                 raise ConfigSaveConflict("Save lock busy; could not acquire in time")
-            time.sleep(0.1)
+            time.sleep(_SAVE_LOCK_POLL_INTERVAL)
 
 
 def _release_save_lock(lock_dir: Path) -> None:
@@ -1030,10 +1034,10 @@ def save_config(config: Dict[str, Any]) -> int:
             # we don't contend with our main connection lock or active transactions.
             try:
                 try:
-                    with sqlite3.connect(str(db.db_path), timeout=5.0) as _con:
+                    with sqlite3.connect(str(db.db_path), timeout=_WAL_CHECKPOINT_TIMEOUT) as _con:
                         _con.execute("PRAGMA wal_checkpoint(TRUNCATE)")
                 except Exception:
-                    with sqlite3.connect(str(db.db_path), timeout=5.0) as _con:
+                    with sqlite3.connect(str(db.db_path), timeout=_WAL_CHECKPOINT_TIMEOUT) as _con:
                         _con.execute("PRAGMA wal_checkpoint")
             except Exception as exc:
                 log(f"Warning: WAL checkpoint failed: {exc}")
@@ -1084,7 +1088,7 @@ def save(config: Dict[str, Any]) -> int:
     return save_config(config)
 
 
-def save_config_and_verify(config: Dict[str, Any], retries: int = 3, delay: float = 0.15) -> int:
+def save_config_and_verify(config: Dict[str, Any], retries: int = _CONFIG_SAVE_VERIFY_RETRIES, delay: float = _CONFIG_SAVE_RETRY_DELAY) -> int:
     """Save configuration and verify crucial keys persisted to disk.
 
     This helper performs a best-effort verification loop that reloads the