Hotfix: fix create_text_file (had raised FileNotFound on new files), fix return type of the tool

src/serena/mcp.py

@@ -71,7 +71,7 @@ class SerenaMCPFactory:
         """
         s = deepcopy(schema)
 
-        def walk(node):
+        def walk(node):  # type: ignore
             if not isinstance(node, dict):
                 # lists get handled by parent calls
                 return node

src/serena/project.py

@@ -89,7 +89,8 @@ class Project:
 
     def _is_ignored_relative_path(self, relative_path: str | Path, ignore_non_source_files: bool = True) -> bool:
         """
-        Determine whether a path should be ignored based on file type and ignore patterns.
+        Determine whether an existing path should be ignored based on file type and ignore patterns.
+        Raises `FileNotFoundError` if the path does not exist.
 
         :param relative_path: Relative path to check
         :param ignore_non_source_files: whether files that are not source files (according to the file masks
@@ -156,10 +157,22 @@ class Project:
         path = path.resolve()
         return path.is_relative_to(_proj_root)
 
+    def relative_path_exists(self, relative_path: str) -> bool:
+        """
+        Checks if the given relative path exists in the project directory.
+
+        :param relative_path: the path to check, relative to the project root
+        :return: True if the path exists, False otherwise
+        """
+        abs_path = Path(self.project_root) / relative_path
+        return abs_path.exists()
+
     def validate_relative_path(self, relative_path: str) -> None:
         """
-        Validates that the given relative path is safe to read or edit,
+        Validates that the given relative path to an existing file/dir is safe to read or edit,
         meaning it's inside the project directory and is not ignored by git.
+
+        Passing a path to a non-existing file will lead to a `FileNotFoundError`.
         """
         if not self.is_path_in_project(relative_path):
             raise ValueError(f"{relative_path=} points to path outside of the repository root; cannot access for safety reasons")

src/serena/tools/file_tools.py

@@ -65,17 +65,23 @@ class CreateTextFileTool(Tool, ToolMarkerCanEdit):
         :param content: the (utf-8-encoded) content to write to the file
         :return: a message indicating success or failure
         """
-        self.project.validate_relative_path(relative_path)
-
-        abs_path = (Path(self.get_project_root()) / relative_path).resolve()
+        project_root = self.get_project_root()
+        abs_path = (Path(project_root) / relative_path).resolve()
         will_overwrite_existing = abs_path.exists()
 
+        if will_overwrite_existing:
+            self.project.validate_relative_path(relative_path)
+        else:
+            assert abs_path.is_relative_to(
+                self.get_project_root()
+            ), f"Cannot create file outside of the project directory, got {relative_path=}"
+
         abs_path.parent.mkdir(parents=True, exist_ok=True)
         abs_path.write_text(content, encoding="utf-8")
         answer = f"File created: {relative_path}."
         if will_overwrite_existing:
             answer += " Overwrote existing file."
-        return answer
+        return json.dumps(answer)
 
 
 class ListDirTool(Tool):