fix(tools): normalize numeric entries and clear stale no_mcp in _save_platform_tools

YAML parses bare numeric toolset names (e.g. 12306:) as int, causing
TypeError in sorted() since the read path normalizes to str but the
save path did not.

The no_mcp sentinel was preserved in existing entries even when the
user re-enabled MCP servers, causing MCP to stay silently disabled.

hermes_cli/tools_config.py

@@ -717,6 +717,7 @@ def _save_platform_tools(config: dict, platform: str, enabled_toolset_keys: Set[
     existing_toolsets = config.get("platform_toolsets", {}).get(platform, [])
     if not isinstance(existing_toolsets, list):
         existing_toolsets = []
+    existing_toolsets = [str(ts) for ts in existing_toolsets]
 
     # Preserve any entries that are NOT configurable toolsets and NOT platform
     # defaults (i.e. only MCP server names should be preserved)
@@ -724,6 +725,8 @@ def _save_platform_tools(config: dict, platform: str, enabled_toolset_keys: Set[
         entry for entry in existing_toolsets
         if entry not in configurable_keys and entry not in platform_default_keys
     }
+    if "no_mcp" not in enabled_toolset_keys:
+        preserved_entries.discard("no_mcp")
 
     # Merge preserved entries with new enabled toolsets
     config["platform_toolsets"][platform] = sorted(enabled_toolset_keys | preserved_entries)

tests/hermes_cli/test_tools_config.py

@@ -601,3 +601,53 @@ class TestImagegenModelPicker:
             _configure_imagegen_model("fal", config)
         assert isinstance(config["image_gen"], dict)
         assert config["image_gen"]["model"] == "fal-ai/flux-2/klein/9b"
+
+
+def test_save_platform_tools_normalizes_numeric_entries():
+    """YAML may parse bare numeric toolset names as int. They should be
+    normalized to str so they survive the save round-trip.
+    """
+    config = {
+        "platform_toolsets": {
+            "cli": ["web", "terminal", 12306, "custom-mcp"]
+        }
+    }
+
+    with patch("hermes_cli.tools_config.save_config"):
+        _save_platform_tools(config, "cli", {"web", "browser"})
+
+    saved = config["platform_toolsets"]["cli"]
+    assert "12306" in saved
+    assert 12306 not in saved
+
+
+def test_save_platform_tools_clears_stale_no_mcp():
+    """When the new selection doesn't include no_mcp, the sentinel should
+    be stripped from preserved entries so MCP servers are re-enabled.
+    """
+    config = {
+        "platform_toolsets": {
+            "cli": ["web", "terminal", "no_mcp"]
+        }
+    }
+
+    with patch("hermes_cli.tools_config.save_config"):
+        _save_platform_tools(config, "cli", {"web", "browser"})
+
+    saved = config["platform_toolsets"]["cli"]
+    assert "no_mcp" not in saved
+
+
+def test_save_platform_tools_preserves_explicit_no_mcp():
+    """When the new selection explicitly includes no_mcp, it should be kept."""
+    config = {
+        "platform_toolsets": {
+            "cli": ["web", "no_mcp"]
+        }
+    }
+
+    with patch("hermes_cli.tools_config.save_config"):
+        _save_platform_tools(config, "cli", {"web", "no_mcp"})
+
+    saved = config["platform_toolsets"]["cli"]
+    assert "no_mcp" in saved