Previously, when git status reported an untracked directory (e.g., "?? apps/"),
the code would try to read the directory as a file, which failed and showed
"[Unable to read file content]".
Now, when encountering a directory:
- Strip trailing slash from path (git reports dirs as "dirname/")
- Check if path is a directory using stats.isDirectory()
- Recursively list all files inside using listAllFilesInDirectory
- Generate synthetic diffs for each file found
This ensures users see the actual file contents in the diff view instead
of an error placeholder.
