diff --git a/paskia/db/paths.py b/paskia/db/paths.py
new file mode 100644
index 0000000..09d9452
--- /dev/null
+++ b/paskia/db/paths.py
@@ -0,0 +1,47 @@
+from __future__ import annotations
+
+import os
+import shutil
+from pathlib import Path
+
+
+def db_root_path(*, rp_id: str = "localhost") -> Path:
+    """Return the configured persistence root directory."""
+    return Path(os.environ.get("PASKIA_DB", f"{rp_id}.paskiadb"))
+
+
+def db_file_path(*, rp_id: str = "localhost", create_root: bool = False) -> Path:
+    """Return the JSONL database file path under the persistence root."""
+    root = db_root_path(rp_id=rp_id)
+
+    if root.is_file():
+        _migrate_legacy_db_file(root)
+
+    if create_root:
+        root.mkdir(parents=True, exist_ok=True)
+
+    return root / "main.db"
+
+
+def users_root_path(*, rp_id: str = "localhost", create_root: bool = False) -> Path:
+    """Return the filesystem root for persisted user files."""
+    root = db_root_path(rp_id=rp_id)
+
+    if root.is_file():
+        _migrate_legacy_db_file(root)
+
+    if create_root:
+        root.mkdir(parents=True, exist_ok=True)
+
+    return root / "users"
+
+
+def _migrate_legacy_db_file(legacy_path: Path) -> None:
+    """Upgrade a legacy single-file database path into a directory root."""
+    temp_root = legacy_path.parent / f".{legacy_path.name}.migrating"
+    shutil.rmtree(temp_root, ignore_errors=True)
+    temp_root.unlink(missing_ok=True)
+
+    temp_root.mkdir(parents=True)
+    legacy_path.replace(temp_root / "main.db")
+    temp_root.rename(legacy_path)