Samatha and vipassana in enlightened night of bodhisatta

In abhidhamma's commentary said "samatha people already saw some part of anicca and dukkha, except anatta" (so they try to get out off samsaravatta, too). But they didn't choose to develop vipassana. They didn't chosen to always clearly comprehend anicca and dukkha. They try to just pause unwholesome consciousness by samatha instead. Samatha people just divert attention from unwholesome consciousness's object to wholesome consciousness's object.

So bodhisatta, who already have jhana, just meditate the method that samatha people haven't chosen, develop clearly comprehend in anicca and dukkha to access insight anatta, the most part that just buddha can done.
Anapanassati in anapanassati sutta have 16 steps:

• 4 first steps of anapanassati are samatha.
• 12 last steps of anapanassati are vipassana.

In the enlightened night of bodhisatta, he meditate samatha and vipassana. Based jhana of pubbenivasanussati and cutupapata is samatha. Asavakkhaya is vipassana.

Each jhana step of bodhisatta have 4 first steps, and after get out of each jhana have 12 last steps.
These method are called yuggalanaddha and samathapubba.

Reference from vinaya mahavibhanga veranjakanda, mahavagga bodhikatha, patisambhidamagga, anapanassati sutta's commentary, ayatanavibhanga's commentary, and visuddhimagga.