Synchronization issue due to inconsistent EOL sequences in Monaco model

[ggrossetie]

Checklist

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Describe the bug

There is a synchronization issue when the EOL (end-of-line) sequence is not explicitly defined in the Monaco model. On Windows, the default EOL is \r\n, whereas on Linux and macOS, it is \n.

This causes inconsistencies because y-monaco uses an offset provided by event.delta.retain, and that offset differs depending on the operating system.

y-monaco/src/y-monaco.js

Line 140 in 33d1583

index += op.retain

To Reproduce
Consider a text with two line breaks (i.e., three empty lines). A Linux user modifies the text on the third line at offset 2 (\n\n). This change is propagated to a Windows user, but it affects line 2 instead, because offset 2 corresponds to \r\n.

Expected behavior
At the very least, this behavior should be documented in the README. Ideally, the EOL sequence should be enforced when constructing the MonacoBinding:

model.setEOL(monaco.editor.EndOfLineSequence.LF)

[Begus001]

Thank you so much for this issue! This should absolutely be in the README, I spent hours debugging weird synchronization issues between Windows and Linux clients thinking it had to do with concurrency.