@Aklapper: Hi! I think it will be better to reassign this ticket to another developer. Thanks for the invitation!

This is an example:

How is that incorrect or problematic markup?

This can be reproduced if you collapse a section and then navigate out and back. The root cause seems to be javascript mutating the layout. One possible fix is to record the position offset to the current section, and restore after all layout mutating code are finished.

Syntax error should include details, for examples "Missing close brace", "Missing argument for \frac".

You cannot manually add tracking category but Mathoid will do it for you now.
You can try to insert invalid math in you user sandbox and see it appear here:
https://en.wikipedia.org/wiki/Category:Pages_with_math_errors

The main complaint is solved by T134872. Close.

The code responsible for this is at function
formatHeadings at core/includes/parser/Parser.php

This should be easy to do once we have a Promise API in mathjax-node.

Maybe I have some misunderstanding, but it seems that currently mathoid is not using MathJax-node, instead it uses mathoid-mathjax-node. The latter one's lasted version is published at 2016-08-18. See ticket T170760

The logger is provided by service-runner, so Mathoid cannot control how the log is be displayed on terminal.

I realized this feature can be implemented as a client side js gadget. Though paging will be broken.

Thanks for your advice, I am finding a good way to refactor every "Vector" into a new name, preferably automatically so that changes can be pulled easily.

I think both approach are good. More code is needed to replace chars, but it is manageable.

Yes I am aware of it.

1. Do we need to care about the compatibility with third party modifications of Vector? There are 450 skins of Wikipedia on this site link, If we make breaking changes to the Vector, they will all break.