Keeping marks of first node after SelectAll or delete all

1
Scenario 1
  1. user starts with an empty paragraph
  2. types “hello world”
  3. update colour of the entire text to blue (I’m using a mark to set text colour)
  4. user selects all text using ctrl+A or cmd+A
  5. user starts typing “cat”

Goal: “cat” to retain the mark of “hello world”. In the scenario above, “cat” is blue

Scenario 2
  1. user starts with an empty paragraph
  2. types “a”
  3. update colour of the entire text to blue (I’m using a mark to set text colour)
  4. user deletes “a”
  5. user starts typing “b”

Goal: “b” retains color mark.

I tried writing a plugin and uses appendTransaction that will return tr.setStoredMark when the selection is currently an instance of AllSelection but it keeps getting ignored. After digging deeper, I find out that storedMarks will only be used if it’s a TextSelection

Source code from prosemirror-state 
  new FieldDesc("storedMarks", {
    init(config) { return config.storedMarks || null },
    apply(tr, _marks, _old, state) { return state.selection.$cursor ? tr.storedMarks : null }
  }),

I’m sure there are good reasons for it to behave that way. My question would be, how then would one go about achieving my goal as stated on scenario 1?

My current approach is hacky because it’s mutating the state directly instead of using transactions. This solves for both scenario 1 and 2.

function keepMarksAfterDeleteAll (): Plugin {
  return new Plugin({
    appendTransaction (transactions, prevState, curState) {
      if (prevState.selection instanceof AllSelection && transactions[0].docChanged) {
        curState.storedMarks = prevState.storedMarks || prevState.doc.resolve(1).marks()
      } else if (curState.selection instanceof AllSelection) {
        curState.storedMarks = curState.doc.resolve(1).marks()
      }
    }
  })
}

is there a cleaner approach to this?

2

Instead of modifying the storedMark, you can use tr.addStoredMark(you_mark) to achieve the ability to persist your color mark.

Side note, in the scenario 2 you don’t really need to implement anything, prose mirror can be made to remember your mark. I tried it on basic example by typing an italic a and then deleting it and then when I type b, it correctly applies italic mark.