fix: allow skill download in non-interactive environments via auth hook

Add _create_plus_client_hook to the skill registry, mirroring the
existing pattern in agent_utils for from_repository agents.

When set (by the Studio Runner or similar host), download_skill() uses
the hook-provided PlusAPI client instead of the default unauthenticated
one. In non-interactive mode, the SkillNotCachedError is only raised
when no hook is available — allowing deployed environments to
auto-download skills on first use.

Co-authored-by: João Moura <joaomdmoura@gmail.com>

lib/crewai/src/crewai/skills/registry.py

@@ -6,6 +6,7 @@ via the CrewAI+ API with a global cache at ~/.crewai/skills/.
 
 from __future__ import annotations
 
+from collections.abc import Callable
 import logging
 from pathlib import Path
 import sys
@@ -16,6 +17,12 @@ from crewai.skills.cache import SkillCacheManager
 
 _logger = logging.getLogger(__name__)
 
+# Hook for injecting an authenticated PlusAPI client in environments that lack
+# interactive auth (e.g. the Studio Runner subprocess).  When set, it must be a
+# callable that returns a ``PlusAPI`` instance.  See the analogous pattern in
+# ``crewai.utilities.agent_utils._create_plus_client_hook``.
+_create_plus_client_hook: Callable[[], Any] | None = None
+
 
 class SkillNotCachedError(Exception):
     """Raised when a registry skill is not cached and the environment is non-interactive."""
@@ -125,7 +132,11 @@ def resolve_registry_ref(
             )
 
     if _is_noninteractive():
-        raise SkillNotCachedError(ref)
+        if not callable(_create_plus_client_hook):
+            raise SkillNotCachedError(ref)
+        _logger.debug(
+            "Non-interactive but auth hook available; attempting download for %s", ref
+        )
 
     return download_skill(org, name, source=source)
 
@@ -170,9 +181,12 @@ def download_skill(
         )
 
     try:
-        from crewai_core.plus_api import PlusAPI
+        if callable(_create_plus_client_hook):
+            api = _create_plus_client_hook()
+        else:
+            from crewai_core.plus_api import PlusAPI
 
-        api = PlusAPI()
+            api = PlusAPI()
         response = api.get_skill(org, name)
         response.raise_for_status()
         data = response.json()

lib/crewai/tests/skills/test_registry.py

@@ -125,3 +125,75 @@ class TestResolveRegistryRef:
         err = SkillNotCachedError("@foo/bar")
         assert "@foo/bar" in str(err)
         assert err.ref == "@foo/bar"
+
+    def test_noninteractive_downloads_when_hook_set(self, tmp_path: Path) -> None:
+        """When _create_plus_client_hook is set, non-interactive mode attempts download."""
+        mock_cache = MagicMock()
+        mock_cache.get_cached_path.return_value = None
+
+        mock_download = MagicMock()
+        mock_download.return_value = MagicMock(name="downloaded-skill")
+
+        with (
+            patch("crewai.skills.registry._is_noninteractive", return_value=True),
+            patch.object(Path, "cwd", return_value=tmp_path),
+            patch("crewai.skills.registry.SkillCacheManager", return_value=mock_cache),
+            patch("crewai.skills.registry._create_plus_client_hook", new=MagicMock),
+            patch("crewai.skills.registry.download_skill", mock_download),
+        ):
+            from crewai.skills.registry import resolve_registry_ref
+
+            result = resolve_registry_ref("@acme/remote-skill")
+
+        mock_download.assert_called_once_with("acme", "remote-skill", source=None)
+        assert result == mock_download.return_value
+
+    def test_noninteractive_raises_without_hook(self, tmp_path: Path) -> None:
+        """Without _create_plus_client_hook, non-interactive mode still raises."""
+        mock_cache = MagicMock()
+        mock_cache.get_cached_path.return_value = None
+
+        with (
+            patch("crewai.skills.registry._is_noninteractive", return_value=True),
+            patch.object(Path, "cwd", return_value=tmp_path),
+            patch("crewai.skills.registry.SkillCacheManager", return_value=mock_cache),
+            patch("crewai.skills.registry._create_plus_client_hook", new=None),
+        ):
+            from crewai.skills.registry import resolve_registry_ref
+
+            with pytest.raises(SkillNotCachedError):
+                resolve_registry_ref("@acme/ghost-skill")
+
+
+class TestDownloadSkillUsesHook:
+    """Test that download_skill respects _create_plus_client_hook."""
+
+    def test_uses_hook_client(self, tmp_path: Path) -> None:
+        """download_skill uses the hook-provided client when available."""
+        mock_api = MagicMock()
+        mock_response = MagicMock()
+        mock_response.json.return_value = {
+            "latest_version": "1.0.0",
+            "file": "," + __import__("base64").b64encode(b"").decode(),
+        }
+        mock_response.raise_for_status = MagicMock()
+        mock_api.get_skill.return_value = mock_response
+
+        mock_cache = MagicMock()
+        skill_dir = tmp_path / "acme" / "hooked-skill"
+        skill_dir.mkdir(parents=True)
+        (skill_dir / "SKILL.md").write_text(
+            "---\nname: hooked-skill\ndescription: Hooked.\n---\n\nHooked instructions."
+        )
+        mock_cache.store.return_value = skill_dir
+
+        with (
+            patch("crewai.skills.registry._create_plus_client_hook", new=lambda: mock_api),
+            patch("crewai.skills.registry.SkillCacheManager", return_value=mock_cache),
+        ):
+            from crewai.skills.registry import download_skill
+
+            skill = download_skill("acme", "hooked-skill")
+
+        mock_api.get_skill.assert_called_once_with("acme", "hooked-skill")
+        assert skill.name == "hooked-skill"