The rules of punctuation of dialogue tags and interruptions without a dialogue tag are quite different. The two types of interruptions usually can be distinguished by the verb used - if it describes speech, it's a dialogue tag. If it doesn't, it's speech interrupted by action.
Which rules to use though, if one side of the dialogue is mute, and using various alternate means to communicate. I mean "tags"(?) like
- she wrote
- she signalled with her hands [sign language]
- appeared on the screen [while she typed it out of sight, but within earshot]
- she amended the text [added to what was already written].
- she touched letters on the keyboard in sequence. [unpowered computer]
- she scratched in the sand with her foot.
Should actions like these be considered dialogue tags?