Method patch

core/filesystem.py:218–279

Patch file content (replace old_str with new_str). Enforces checkpoint for core file modifications. Args: path: Path to file old_str: String to find and replace new_str: Replacement string Returns: Diff of ch

(self, path: Union[str, Path], old_str: str, new_str: str)

            raise FilesystemAccessError(f"Failed to write {path}: {e}")
    
    def patch(self, path: Union[str, Path], old_str: str, new_str: str) -> str:
        """
        Patch file content (replace old_str with new_str).
        
        Enforces checkpoint for core file modifications.

        Args:
            path: Path to file
            old_str: String to find and replace
            new_str: Replacement string

        Returns:
            Diff of changes made

        Raises:
            FilesystemAccessError: If patch cannot be applied
        """
        try:
            path = self._validate_path(path)

            if not path.exists():
                raise FilesystemAccessError(f"File not found: {path}")

            # Check if modifying core files (requires checkpoint)
            is_core = _is_core_file(str(path))
            if is_core:
                self._require_checkpoint(path)

            # Read current content
            content = path.read_text(encoding='utf-8')

            # Find and replace
            if old_str not in content:
                raise FilesystemAccessError(
                    f"Could not find specified string in {path}"
                )

            new_content = content.replace(old_str, new_str, 1)

            # Generate diff
            diff = self._generate_diff(
                path.name,
                content.splitlines(keepends=True),
                new_content.splitlines(keepends=True)
            )
            self._last_diff = diff

            # Write new content
            path.write_text(new_content, encoding='utf-8')

            try:
                rel = path.relative_to(self.workspace)
            except ValueError:
                rel = path
            msg = f"Patched {rel}"
            success(msg)
            return diff