fix(skills): update set_available_skills docstring, add duplicate URL test

- Mention HTTPS URL support in set_available_skills docstring
- Add test for duplicate skill names from URL sources (Codecov gap)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: Davide Gallitelli

src/strands/vended_plugins/skills/agent_skills.py

@@ -177,8 +177,9 @@ def set_available_skills(self, skills: SkillSources) -> None:
         """Set the available skills, replacing any existing ones.
 
         Each element can be a ``Skill`` instance, a ``str`` or ``Path`` to a
-        skill directory (containing SKILL.md), or a ``str`` or ``Path`` to a
-        parent directory containing skill subdirectories.
+        skill directory (containing SKILL.md), a ``str`` or ``Path`` to a
+        parent directory containing skill subdirectories, or an ``https://``
+        URL pointing directly to raw SKILL.md content.
 
         Note: this does not persist state or deactivate skills on any agent.
         Active skill state is managed per-agent and will be reconciled on the

tests/strands/vended_plugins/skills/test_agent_skills.py

@@ -727,6 +727,28 @@ def test_resolve_url_failure_skips_gracefully(self, caplog):
         assert len(plugin.get_available_skills()) == 0
         assert "failed to load skill from URL" in caplog.text
 
+    def test_resolve_duplicate_url_skills_warns(self, caplog):
+        """Test that duplicate skill names from URLs log a warning."""
+        import logging
+        from unittest.mock import patch
+
+        with (
+            patch(
+                f"{self._SKILL_MODULE}.urllib.request.urlopen",
+                return_value=self._mock_urlopen(self._SAMPLE_CONTENT),
+            ),
+            caplog.at_level(logging.WARNING),
+        ):
+            plugin = AgentSkills(
+                skills=[
+                    "https://example.com/a/SKILL.md",
+                    "https://example.com/b/SKILL.md",
+                ]
+            )
+
+        assert len(plugin.get_available_skills()) == 1
+        assert "duplicate skill name" in caplog.text
+
 
 class TestImports:
     """Tests for module imports."""