test: reorganize test structure and add missing unit tests

Reorganize flat tests/ directory to mirror source code structure
(tools/, gateway/, hermes_cli/, integration/). Add 11 new test files
covering previously untested modules: registry, patch_parser,
fuzzy_match, todo_tool, approval, file_tools, gateway session/config/
delivery, and hermes_cli config/models. Total: 147 unit tests passing,
9 integration tests gated behind pytest marker.

tests/tools/test_file_tools.py

@@ -0,0 +1,99 @@
+"""Tests for the file tools module (schema and handler wiring).
+
+These tests verify the tool schemas and handler wiring without
+requiring a running terminal environment. The actual file operations
+(ShellFileOperations) depend on a terminal backend, so we mock
+_get_file_ops to test the handler logic in isolation.
+"""
+
+import json
+from unittest.mock import MagicMock, patch
+
+from tools.file_tools import (
+    FILE_TOOLS,
+    READ_FILE_SCHEMA,
+    WRITE_FILE_SCHEMA,
+    PATCH_SCHEMA,
+    SEARCH_FILES_SCHEMA,
+)
+
+
+class TestSchemas:
+    def test_read_file_schema(self):
+        assert READ_FILE_SCHEMA["name"] == "read_file"
+        props = READ_FILE_SCHEMA["parameters"]["properties"]
+        assert "path" in props
+        assert "offset" in props
+        assert "limit" in props
+
+    def test_write_file_schema(self):
+        assert WRITE_FILE_SCHEMA["name"] == "write_file"
+        assert "path" in WRITE_FILE_SCHEMA["parameters"]["properties"]
+        assert "content" in WRITE_FILE_SCHEMA["parameters"]["properties"]
+
+    def test_patch_schema(self):
+        assert PATCH_SCHEMA["name"] == "patch"
+        props = PATCH_SCHEMA["parameters"]["properties"]
+        assert "mode" in props
+        assert "old_string" in props
+        assert "new_string" in props
+
+    def test_search_files_schema(self):
+        assert SEARCH_FILES_SCHEMA["name"] == "search_files"
+        props = SEARCH_FILES_SCHEMA["parameters"]["properties"]
+        assert "pattern" in props
+        assert "target" in props
+
+
+class TestFileToolsList:
+    def test_file_tools_has_expected_entries(self):
+        names = {t["name"] for t in FILE_TOOLS}
+        assert names == {"read_file", "write_file", "patch", "search_files"}
+
+
+class TestReadFileHandler:
+    @patch("tools.file_tools._get_file_ops")
+    def test_read_file_returns_json(self, mock_get):
+        mock_ops = MagicMock()
+        result_obj = MagicMock()
+        result_obj.to_dict.return_value = {"content": "hello", "total_lines": 1}
+        mock_ops.read_file.return_value = result_obj
+        mock_get.return_value = mock_ops
+
+        from tools.file_tools import read_file_tool
+
+        result = json.loads(read_file_tool("/tmp/test.txt"))
+        assert result["content"] == "hello"
+        mock_ops.read_file.assert_called_once_with("/tmp/test.txt", 1, 500)
+
+
+class TestWriteFileHandler:
+    @patch("tools.file_tools._get_file_ops")
+    def test_write_file_returns_json(self, mock_get):
+        mock_ops = MagicMock()
+        result_obj = MagicMock()
+        result_obj.to_dict.return_value = {"status": "ok", "path": "/tmp/test.txt"}
+        mock_ops.write_file.return_value = result_obj
+        mock_get.return_value = mock_ops
+
+        from tools.file_tools import write_file_tool
+
+        result = json.loads(write_file_tool("/tmp/test.txt", "content"))
+        assert result["status"] == "ok"
+        mock_ops.write_file.assert_called_once_with("/tmp/test.txt", "content")
+
+
+class TestPatchHandler:
+    @patch("tools.file_tools._get_file_ops")
+    def test_replace_mode_missing_path_errors(self, mock_get):
+        from tools.file_tools import patch_tool
+
+        result = json.loads(patch_tool(mode="replace", path=None, old_string="a", new_string="b"))
+        assert "error" in result
+
+    @patch("tools.file_tools._get_file_ops")
+    def test_unknown_mode_errors(self, mock_get):
+        from tools.file_tools import patch_tool
+
+        result = json.loads(patch_tool(mode="unknown"))
+        assert "error" in result