I have two questions:

1. Is it possible to write working squiffy links from JS code without doing it manually?
   squiffy.ui.write('[Part2](part2)')
   doesn't work
   squiffy.ui.write('<a class="squiffy-link link-section" data-section=part2 role="link" tabindex="0">Part2</a>')
   works, but it's kinda ugly.
2. Is it possible to replace a label from JS code?
   As above, it is possible to do it manually, but I hope to find a more elegant way to do it.

I'm not quite sure what you are asking. Do you want to change links based on external events? That I can do (in squiffy) but not globally.

This is a crude way to do it, by passing flags down to the squiffy engine to light up section links. Not sure its what you were really looking for....

[[init]]:

    set("flag1",true); //this represents setting a flag based on game logic.
    
{if flag1:[[special door]]}

[[normal door]]

[[special door]]:
This is a special place.

[[normal door]]:
This is a normal place.