fix(skills): isolate malformed persisted config entries

agent/skills/manager.py

@@ -166,6 +166,9 @@ class SkillManager:
         for name, entry in self.skills.items():
             skill = entry.skill
             prev = saved.get(name, {})
+            if not isinstance(prev, dict):
+                logger.warning(f"[SkillManager] Ignoring malformed config entry for {name}")
+                prev = {}
             category = prev.get("category", "skill")
 
             if name in saved:

tests/test_skill_config_entry_shapes.py

@@ -0,0 +1,21 @@
+import json
+import pytest
+from agent.skills.manager import SkillManager
+
+
+@pytest.mark.parametrize('damaged', [None, [], 3, 'invalid'])
+def test_bad_entry_does_not_lose_valid_skill_choices(tmp_path, damaged):
+    builtin = tmp_path / 'builtin'
+    builtin.mkdir()
+    custom = tmp_path / 'skills'
+    for name in ['damaged', 'healthy']:
+        directory = custom / name
+        directory.mkdir(parents=True)
+        (directory / 'SKILL.md').write_text(f'---\nname: {name}\ndescription: Test\n---\nBody\n')
+    config_path = custom / 'skills_config.json'
+    config_path.write_text(json.dumps({'damaged': damaged, 'healthy': {'enabled': False, 'display_name': 'Kept'}}))
+    manager = SkillManager(builtin_dir=str(builtin), custom_dir=str(custom))
+    assert manager.get_skill('damaged') is not None
+    assert not manager.is_skill_enabled('healthy')
+    assert manager.skills_config['healthy']['display_name'] == 'Kept'
+    assert isinstance(json.loads(config_path.read_text())['damaged'], dict)