When dragging multiple files in the explorer, the onWillRenameFiles event is fired multiple times concurrently with a single file per-call - even though the API supports an array:

This means an extension will produce multiple edits for a single operation if there are multiple files moved - though it looks like VS Code merges them together:

However, this fails if two of the edits modified the same file with "(file) has changed in the meantime".

Here's a gif showing individual file moves correctly updating the file on the right. However if I moved them both at the same time, only one edit is applied and the other one fails.

The code for that repro is available here:

https://github.com/DanTup/vscode-repro-will-rename-files (extension.ts).