Apologies, I just found the solution:
https://wiki.contextgarden.net/Command/setinjector

El lun, 21 ago 2023 a las 23:43, Andres Conrado Montoya (<
andresconrado@gmail.com>) escribió:

> I'm trying to force a page break in a table of contents, using what is
> recommended at
> https://wiki.contextgarden.net/Table_of_Contents#Forced_Page_Break
>
> However, it does not work. Here's a MWE:
>
> \definelistextra[page][before=\page]
> \starttext
> \starttitle[title={Table of contents}]
> \placecontent[extras={2=page}]
> \stoptitle
> \startchapter[title={First chapter}]
> \input knuth
> \stopchapter
> \startchapter[title={Second chapter}]
> \input knuth
> \stopchapter
> \startchapter[title={Third chapter}]
> \input knuth
> \stopchapter
> \stoptext
>
> Is there a new way of obtaining a page break before a given part, chapter
> or section in the ToC?
>
> Thank you in advance.
>
> --
> Andrés Conrado Montoya
> Andi Kú
> andresconrado@gmail.com
> http://sesentaycuatro.com
> http://messier87.com
> http://chiquitico.org
> ----------------------------------------
> Los fines no justifican los medios, porque la medida verdadera de nuestro
> carácter está dada por los medios que estamos dispuestos a utilizar, no por
> los fines que proclamamos.
> ----------------------------------------
>
> “You develop an instant global consciousness, a people orientation, an
> intense dissatisfaction with the state of the world, and a compulsion to do
> something about it. From out there on the moon, international politics look
> so petty. You want to grab a politician by the scruff of the neck and drag
> him a quarter of a million miles out and say, ‘Look at that, you son of a
> bitch.’” — Apollo 14 astronaut Edgar Mitchell
>


-- 
Andrés Conrado Montoya
Andi Kú
andresconrado@gmail.com
http://sesentaycuatro.com
http://messier87.com
http://chiquitico.org
----------------------------------------
Los fines no justifican los medios, porque la medida verdadera de nuestro
carácter está dada por los medios que estamos dispuestos a utilizar, no por
los fines que proclamamos.
----------------------------------------

“You develop an instant global consciousness, a people orientation, an
intense dissatisfaction with the state of the world, and a compulsion to do
something about it. From out there on the moon, international politics look
so petty. You want to grab a politician by the scruff of the neck and drag
him a quarter of a million miles out and say, ‘Look at that, you son of a
bitch.’” — Apollo 14 astronaut Edgar Mitchell