merge: testing → main (reconcile 2-week divergence)

decnet/asn/paths.py

@@ -0,0 +1,18 @@
+"""Filesystem layout for ASN data — mirror of :mod:`decnet.geoip.paths`.
+
+``ASN_ROOT`` is where providers drop their raw files and cache indexes.
+Default ``/var/lib/decnet/asn``. Override with ``DECNET_ASN_ROOT`` for
+test harnesses.
+"""
+from __future__ import annotations
+
+import os
+from pathlib import Path
+
+ASN_ROOT = Path(os.environ.get("DECNET_ASN_ROOT", "/var/lib/decnet/asn"))
+
+
+def ensure_root() -> Path:
+    """Create ``ASN_ROOT`` if absent and return it. No-op if present."""
+    ASN_ROOT.mkdir(parents=True, exist_ok=True)
+    return ASN_ROOT