Customise marks and nodes in text block in blocks fields

Happy new year and 4.0 release !
I know how to customize marks and blocks in writer fields but I can’t do it in the context of the blocks field.
I tried this way :

        type: blocks
            extends: blocks/text
              - bold
              - italic
              - underline
              - strike
              - sup
              - clear
              - link
              - bulletList
              - orderedList
          - heading
          - quote

but nothing is changed in marks and node in contextual tools popup.

Do I have to copy the entire text block (which appears to be the writer field) to create a custom block?

PS: To go further, on the subject of custom marks and nodes, do you know of a way to make footnotes with Kirby 4? Or any ideas on how ProseMirror is integrated into Kirby, based on their example: ProseMirror footnote example?

Here you extend the original block fieldset, but it is a fieldset, not a single field. So what you need to do is change the writer field inside a new custom block.

of course ! and on rereading the document it’s very clear, with the right links to the right pages. I don’t know how I managed to miss it.

to make the topic as useful as possible:

thx !