skills: clarify download_skills docstring and ruff format

Address review nit — restructure the download_skills docstring into
explicit list/decide/fetch stages. Run ruff format to wrap an
over-length line in tests (fixes the test_ruff_format CI check).

Author: xsh310

src/ucode/skills_download.py

@@ -259,12 +259,19 @@ def _fetch_bundles(
 def download_skills(workspace: str, token: str, locations: list[str], path: str | None) -> None:
     """Download every skill in each ``<catalog>.<schema>`` location to disk.
 
-    Locations are processed sequentially. Within each, overwrite prompts run
-    first so declined skills are never fetched, then the survivors' bundles are
-    fetched concurrently (with a progress bar) and written. Processing one
-    location fully before the next lets a same-named skill from a later location
-    see the earlier one on disk and prompt. A failure on one skill warns and
-    skips it without aborting the batch.
+    Locations are processed one at a time, and each runs three stages:
+
+    1. **List** the schema's skill leaves.
+    2. **Decide** which to download via ``should_download_skill`` (skips invalid
+       names and prompts before overwriting a skill already on disk), so a
+       declined skill is never fetched.
+    3. **Fetch** the survivors' bundles concurrently (with a progress bar) and
+       **write** them.
+
+    Finishing one location before starting the next means a skill written for an
+    earlier location is already on disk when a same-named skill in a later
+    location reaches its decide stage, so the overwrite prompt still fires. A
+    failure on one skill warns and skips it without aborting the batch.
     """
     roots = skill_dir_roots(path)
     roots_display = " and ".join(str(root) for root in roots)

tests/test_skills_download.py

@@ -291,7 +291,9 @@ def test_writes_bundle_into_every_root(self, tmp_path):
     def test_path_traversal_is_rejected(self, tmp_path):
         roots = skill_dir_roots(str(tmp_path))
 
-        write_skill(roots, "triage", {"SKILL.md": b"ok", "../escape.md": b"nope", "/abs.md": b"nope"})
+        write_skill(
+            roots, "triage", {"SKILL.md": b"ok", "../escape.md": b"nope", "/abs.md": b"nope"}
+        )
 
         assert (roots[0] / "triage/SKILL.md").read_bytes() == b"ok"
         assert not (tmp_path / "escape.md").exists()