feat: add suggestion to use delete when patch with empty content

- Change response key from 'reason' to 'hint' for deletion suggestions
- Add test case for empty content patch

Author: Yoshihiro Takahara

src/mcp_text_editor/text_editor.py

@@ -219,19 +219,10 @@ async def edit_file_contents(
         Args:
             file_path (str): Path to the file to edit
             expected_hash (str): Expected hash of the file before editing
-            patches (List[EditPatch]): List of patches to apply
-                - start (int): Starting line number (1-based, optional, default: 1)
-                - end (Optional[int]): Ending line number (inclusive)
-                - contents (str): New content to insert
-        Edit file contents with hash-based conflict detection and multiple patches (supporting new file creation).
-
-        Args:
-            file_path (str): Path to the file to edit (parent directories are created automatically)
-            expected_hash (str): Expected hash of the file before editing (empty string for new files)
             patches (List[Dict[str, Any]]): List of patches to apply, each containing:
                 - start (int): Starting line number (1-based)
                 - end (Optional[int]): Ending line number (inclusive)
-                - contents (str): New content to insert
+                - contents (str): New content to insert (if empty string, consider using delete_text_file_contents instead)
                 - range_hash (str): Expected hash of the content being replaced
 
         Returns:
@@ -269,9 +260,14 @@ async def edit_file_contents(
                 encoding = "utf-8"
             else:
                 # Read current file content and verify hash
-                current_content, _, _, current_hash, total_lines, _ = (
-                    await self.read_file_contents(file_path, encoding=encoding)
-                )
+                (
+                    current_content,
+                    _,
+                    _,
+                    current_hash,
+                    total_lines,
+                    _,
+                ) = await self.read_file_contents(file_path, encoding=encoding)
 
                 # Treat empty file as new file
                 if not current_content:
@@ -396,6 +392,15 @@ async def edit_file_contents(
                 else:
                     contents = patch["contents"]
 
+                # Check if this is a deletion (empty content)
+                if not contents.strip():
+                    return {
+                        "result": "ok",
+                        "file_hash": current_hash,  # Return current hash since no changes made
+                        "hint": "For content deletion, please consider using delete_text_file_contents instead of patch with empty content",
+                        "suggestion": "delete",
+                    }
+
                 new_content = contents if contents.endswith("\n") else contents + "\n"
                 new_lines = new_content.splitlines(keepends=True)
 
@@ -471,11 +476,16 @@ async def insert_text_file_contents(
             }
 
         try:
-            current_content, _, _, current_hash, total_lines, _ = (
-                await self.read_file_contents(
-                    file_path,
-                    encoding=encoding,
-                )
+            (
+                current_content,
+                _,
+                _,
+                current_hash,
+                total_lines,
+                _,
+            ) = await self.read_file_contents(
+                file_path,
+                encoding=encoding,
             )
 
             if current_hash != file_hash:
@@ -563,11 +573,16 @@ async def delete_text_file_contents(
         self._validate_file_path(request.file_path)
 
         try:
-            current_content, _, _, current_hash, total_lines, _ = (
-                await self.read_file_contents(
-                    request.file_path,
-                    encoding=request.encoding or "utf-8",
-                )
+            (
+                current_content,
+                _,
+                _,
+                current_hash,
+                total_lines,
+                _,
+            ) = await self.read_file_contents(
+                request.file_path,
+                encoding=request.encoding or "utf-8",
             )
 
             # Check for conflicts

tests/test_patch_text_file.py

@@ -53,6 +53,53 @@ async def test_patch_text_file_middle(tmp_path):
     assert updated_content == "line1\nnew line2\nnew line3\nline4\nline5\n"
 
 
+@pytest.mark.asyncio
+async def test_patch_text_file_empty_content(tmp_path):
+    """Test patching with empty content suggests using delete_text_file_contents."""
+    # Create a test file
+    file_path = os.path.join(tmp_path, "test.txt")
+    editor = TextEditor()
+
+    # Create initial content
+    content = "line1\nline2\nline3\nline4\nline5\n"
+    with open(file_path, "w", encoding="utf-8") as f:
+        f.write(content)
+
+    # Get file hash and range hash
+    file_info = await editor.read_multiple_ranges(
+        [{"file_path": str(file_path), "ranges": [{"start": 2, "end": 3}]}]
+    )
+
+    # Extract file and range hashes
+    file_content = file_info[str(file_path)]
+    file_hash = file_content["file_hash"]
+    range_hash = file_content["ranges"][0]["range_hash"]
+
+    # Patch the file with empty content
+    patch = {
+        "start": 2,
+        "end": 3,
+        "contents": "",
+        "range_hash": range_hash,
+    }
+    result = await editor.edit_file_contents(
+        str(file_path),
+        file_hash,
+        [patch],
+    )
+
+    # Verify that the operation suggests using delete_text_file_contents
+    assert result["result"] == "ok"
+    assert result["file_hash"] == file_hash
+    assert "delete_text_file_contents" in result["hint"]
+    assert result["suggestion"] == "delete"
+
+    # Verify file content remains unchanged
+    with open(file_path, "r", encoding="utf-8") as f:
+        updated_content = f.read()
+    assert updated_content == content
+
+
 @pytest.mark.asyncio
 async def test_patch_text_file_errors(tmp_path):
     """Test error handling when patching a file."""