Fix empty tool selection persistence

tests/hermes_cli/test_tools_config.py

@@ -0,0 +1,19 @@
+"""Tests for hermes_cli.tools_config platform tool persistence."""
+
+from hermes_cli.tools_config import _get_platform_tools
+
+
+def test_get_platform_tools_uses_default_when_platform_not_configured():
+    config = {}
+
+    enabled = _get_platform_tools(config, "cli")
+
+    assert enabled
+
+
+def test_get_platform_tools_preserves_explicit_empty_selection():
+    config = {"platform_toolsets": {"cli": []}}
+
+    enabled = _get_platform_tools(config, "cli")
+
+    assert enabled == set()