diff --git a/agent/skill_commands.py b/agent/skill_commands.py
index fc11c5312..8f02aeb8d 100644
--- a/agent/skill_commands.py
+++ b/agent/skill_commands.py
@@ -26,8 +26,7 @@ def scan_skill_commands() -> Dict[str, Dict[str, Any]]:
         if not SKILLS_DIR.exists():
             return _skill_commands
         for skill_md in SKILLS_DIR.rglob("SKILL.md"):
-            path_str = str(skill_md)
-            if '/.git/' in path_str or '/.github/' in path_str or '/.hub/' in path_str:
+            if any(part in ('.git', '.github', '.hub') for part in skill_md.parts):
                 continue
             try:
                 content = skill_md.read_text(encoding='utf-8')
diff --git a/tests/tools/test_hidden_dir_filter.py b/tests/tools/test_hidden_dir_filter.py
new file mode 100644
index 000000000..d7c10846b
--- /dev/null
+++ b/tests/tools/test_hidden_dir_filter.py
@@ -0,0 +1,95 @@
+"""Tests for the hidden directory filter in skills listing.
+
+Regression test: the original filter used hardcoded forward-slash strings
+like '/.git/' which never match on Windows where Path uses backslashes.
+This caused quarantined skills (.hub/quarantine/) to appear as installed.
+
+Now uses Path.parts which is platform-independent.
+"""
+
+import os
+from pathlib import Path, PurePosixPath, PureWindowsPath
+
+
+def _old_filter_matches(path_str: str) -> bool:
+    """The BROKEN filter that used hardcoded forward slashes.
+
+    Returns True when the path SHOULD be filtered out.
+    """
+    return '/.git/' in path_str or '/.github/' in path_str or '/.hub/' in path_str
+
+
+def _new_filter_matches(path: Path) -> bool:
+    """The FIXED filter using Path.parts.
+
+    Returns True when the path SHOULD be filtered out.
+    """
+    return any(part in ('.git', '.github', '.hub') for part in path.parts)
+
+
+class TestOldFilterBrokenOnWindows:
+    """Demonstrate the bug: hardcoded '/' never matches Windows backslash paths."""
+
+    def test_old_filter_misses_hub_on_windows_path(self):
+        """Old filter fails to catch .hub in a Windows-style path string."""
+        win_path = r"C:\Users\me\.hermes\skills\.hub\quarantine\evil-skill\SKILL.md"
+        assert _old_filter_matches(win_path) is False  # Bug: should be True
+
+    def test_old_filter_misses_git_on_windows_path(self):
+        """Old filter fails to catch .git in a Windows-style path string."""
+        win_path = r"C:\Users\me\.hermes\skills\.git\config\SKILL.md"
+        assert _old_filter_matches(win_path) is False  # Bug: should be True
+
+    def test_old_filter_works_on_unix_path(self):
+        """Old filter works fine on Unix paths (the original platform)."""
+        unix_path = "/home/user/.hermes/skills/.hub/quarantine/evil-skill/SKILL.md"
+        assert _old_filter_matches(unix_path) is True
+
+
+class TestNewFilterCrossPlatform:
+    """The fixed filter works on both Windows and Unix paths."""
+
+    def test_hub_quarantine_filtered(self, tmp_path):
+        """A SKILL.md inside .hub/quarantine/ must be filtered out."""
+        p = tmp_path / ".hermes" / "skills" / ".hub" / "quarantine" / "evil" / "SKILL.md"
+        assert _new_filter_matches(p) is True
+
+    def test_git_dir_filtered(self, tmp_path):
+        """A SKILL.md inside .git/ must be filtered out."""
+        p = tmp_path / ".hermes" / "skills" / ".git" / "hooks" / "SKILL.md"
+        assert _new_filter_matches(p) is True
+
+    def test_github_dir_filtered(self, tmp_path):
+        """A SKILL.md inside .github/ must be filtered out."""
+        p = tmp_path / ".hermes" / "skills" / ".github" / "workflows" / "SKILL.md"
+        assert _new_filter_matches(p) is True
+
+    def test_normal_skill_not_filtered(self, tmp_path):
+        """A regular skill SKILL.md must NOT be filtered out."""
+        p = tmp_path / ".hermes" / "skills" / "my-cool-skill" / "SKILL.md"
+        assert _new_filter_matches(p) is False
+
+    def test_nested_skill_not_filtered(self, tmp_path):
+        """A deeply nested regular skill must NOT be filtered out."""
+        p = tmp_path / ".hermes" / "skills" / "org" / "deep-skill" / "SKILL.md"
+        assert _new_filter_matches(p) is False
+
+    def test_dot_prefix_not_false_positive(self, tmp_path):
+        """A skill dir starting with dot but not in the filter list passes."""
+        p = tmp_path / ".hermes" / "skills" / ".my-hidden-skill" / "SKILL.md"
+        assert _new_filter_matches(p) is False
+
+
+class TestWindowsPathParts:
+    """Verify Path.parts correctly splits on the native separator."""
+
+    def test_parts_contains_hidden_dir(self, tmp_path):
+        """Path.parts includes each directory component individually."""
+        p = tmp_path / "skills" / ".hub" / "quarantine" / "SKILL.md"
+        assert ".hub" in p.parts
+
+    def test_parts_does_not_contain_combined_string(self, tmp_path):
+        """Path.parts splits by separator, not by substring."""
+        p = tmp_path / "skills" / "my-hub-skill" / "SKILL.md"
+        # ".hub" should NOT match "my-hub-skill" as a part
+        assert ".hub" not in p.parts
diff --git a/tools/skills_tool.py b/tools/skills_tool.py
index 315549430..4972cacd7 100644
--- a/tools/skills_tool.py
+++ b/tools/skills_tool.py
@@ -196,8 +196,7 @@ def _find_all_skills() -> List[Dict[str, Any]]:
         return skills
     
     for skill_md in SKILLS_DIR.rglob("SKILL.md"):
-        path_str = str(skill_md)
-        if '/.git/' in path_str or '/.github/' in path_str or '/.hub/' in path_str:
+        if any(part in ('.git', '.github', '.hub') for part in skill_md.parts):
             continue
             
         skill_dir = skill_md.parent