claude-code - 💡(How to fix) Fix Edit tool: show diff when 'String to replace not found' fails

TL;DR

Modify the Edit tool to display the closest near-match from the file with differences highlighted when the old_string is not found.

Guidance

• Identify the cause of the match failure by comparing the expected old_string with the actual content of the file, focusing on invisible whitespace differences.
• Implement a diff-like feature to highlight the differences between the expected and actual strings, such as trailing spaces, tabs vs spaces, or CRLF vs LF.
• Consider displaying a simple "did you mean line X?" message with the actual content to help the user locate the closest match.
• Review the formatting tools used in the project (Black, Prettier, EditorConfig) to ensure consistent whitespace normalization.

Example

def find_closest_match(old_string, file_content):
    # Split the file content into lines
    lines = file_content.splitlines()
    
    # Initialize the closest match and its distance
    closest_match = None
    min_distance = float('inf')
    
    # Iterate over the lines to find the closest match
    for i, line in enumerate(lines):
        # Calculate the Levenshtein distance between the old_string and the current line
        distance = levenshtein_distance(old_string, line)
        
        # Update the closest match if the distance is smaller
        if distance < min_distance:
            min_distance = distance
            closest_match = (i, line)
    
    return closest_match

def levenshtein_distance(s1, s2):
    # Calculate the Levenshtein distance between two strings
    # ...

Notes

This solution assumes that the Edit tool has access to the file content and can perform string comparisons. The implementation of the diff-like feature and the Levenshtein distance calculation may vary depending on the programming language and the specific requirements of the project.

Recommendation

Apply a workaround by modifying the Edit tool to display the closest near-match with differences highlighted, as this will provide a better user experience and help identify the cause of the match failure.