fix(skills): return no skills when the skills directory cannot be read (#2083)

discover_skills raised when dir pointed to a file or could not be listed,
which broke client setup. It now warns and returns an empty list, matching
how unreadable lockfiles and entries are handled.

Co-authored-by: Cursor Agent <cursoragent@cursor.com>
Co-authored-by: Hassieb Pakzad <hassiebp@users.noreply.github.com>

Author: hassiebp

langfuse/_client/skills.py

@@ -21,12 +21,23 @@ def discover_skills(*, dir: str) -> list[SkillReference]:
     Unlocked skills use their directory name without a version. Lock records
     do not verify local edits.
 
-    Missing directories return an empty list. Unreadable or malformed lockfiles
-    warn and fall back to directory names. Entries that cannot be inspected,
-    invalid lock entries, and duplicate names are skipped with a warning.
+    Missing directories return an empty list; unreadable ones warn and return
+    an empty list. Unreadable or malformed lockfiles warn and fall back to
+    directory names. Entries that cannot be inspected, invalid lock entries,
+    and duplicate names are skipped with a warning.
     """
     root = Path(os.path.abspath(dir))
-    if _stat_if_exists(root) is None:
+    try:
+        if _stat_if_exists(root) is None:
+            return []
+        with os.scandir(root) as entries:
+            candidates = sorted(entries, key=lambda entry: entry.name)
+    except OSError as error:
+        langfuse_logger.warning(
+            "Could not read skills directory %s. No skills discovered: %s",
+            root,
+            error,
+        )
         return []
 
     locked: dict[Path, SkillReference] = {}
@@ -39,8 +50,6 @@ def discover_skills(*, dir: str) -> list[SkillReference]:
             error,
         )
     available: dict[str, SkillReference] = {}
-    with os.scandir(root) as entries:
-        candidates = sorted(entries, key=lambda entry: entry.name)
     for candidate in candidates:
         if candidate.name.startswith("."):
             continue

tests/unit/test_skills.py

@@ -150,6 +150,21 @@ def test_discovery_skips_entries_with_filesystem_errors(
     assert "missing-target" not in caplog.text
 
 
+@pytest.mark.parametrize("kind", ["file", "symlink-loop"])
+def test_unreadable_skills_directory_returns_empty_list(
+    tmp_path, monkeypatch, kind, caplog
+):
+    monkeypatch.chdir(tmp_path)
+    root = tmp_path / "skills"
+    if kind == "file":
+        root.write_text("not a directory", encoding="utf-8")
+    else:
+        root.symlink_to(root)
+
+    assert discover_skills(dir=str(root)) == []
+    assert "Could not read skills directory" in caplog.text
+
+
 def test_serialization_preserves_extra_fields():
     skills = [{"name": "customer", "version": 2, "futureField": {"nested": True}}]
     assert json.loads(serialize_available_skills(skills)) == skills