Editing Openai/69186d20-2d14-8013-b9c6-c09000f173f6 (section)

==== Over time you get: ====
* Unstressed syllables reduced: vowels → /ə/ → dropped.
* Final -d, -t often weaken or vanish.
* Some person distinctions collapse; paradigms get analogically leveled.

So molaid > something like molann (with -ann from a different set) in many dialects; molae → a short 2sg form that eventually mostly dies in the standard; 1sg molaim stays pretty stable.

In parallel, a verbal noun + auxiliary construction for habitual turns into a new synthetic habitual in many dialects. That’s the ancestor of the modern -íonn/-ann pattern.