On multimodal input, the UX you’re prototyping where you switch between dictating and typing while composing is interesting. I haven’t really seen that approach before.
The direction I took is a bit different. Instead of mixing modalities mid-composition, dictation becomes context-aware during post-processing. Selected/Copied text or surrounding field content can be inserted into the post-processing prompt so the spoken input is interpreted relative to what’s already on screen.