feat(lib): implement A-4 M0~M1 BaseAgentAdapter pattern and resolve_home contract

.agents/skills/lib_py/paths.py

@@ -0,0 +1,14 @@
+# paths.py — unified HOME_DIR and filesystem path resolution contract (N0)
+
+import os
+
+def resolve_home(home_dir=None):
+    """
+    Unified HOME_DIR resolution contract across lib_py modules and adapters.
+    Tries: 1. explicit home_dir argument, 2. HOME_DIR env var, 3. HOME env var, 4. os.path.expanduser('~').
+    Raises ValueError if result is empty or filesystem root ('/'), preventing root-relative silent fail-close.
+    """
+    h = home_dir or os.environ.get("HOME_DIR") or os.environ.get("HOME") or os.path.expanduser("~")
+    if not h or h == "/":
+        raise ValueError("HOME_DIR unresolvable — refusing to build paths from the filesystem root")
+    return h