Comint sets ‘(rear-nonsticky t) on the entire detected prompt text, which prevents `cursor-intangible from functioning correctly when applied to the prompt. As Stefan put it:
I suspect the issue comes from the difference between `get-pos-property` and `get-char-property`: positions (like `point`) are not placed on a character but between two characters. But text properties only apply to characters. So the properties that are "on a position" are based on what properties would a character inherit if it where inserted at that position.
By default text properties are front-nonstick and rear-sticky, so basically a position gets its properties from the char right before it. But if you set (rear-nonsticky t), then you get no properties at all at that position.
This causes issues when "