What does background music actually need to do to not pull you out of deep work?

Building a faceless YouTube channel that makes AI-generated focus music for founders/builders/coders — split into three moods (morning execution, late-night coding, deep-focus silence) because I noticed most "focus music" channels treat concentration as one generic state instead of something that shifts across a working day.

Everything's produced with AI for the music and visuals, with the creative direction (mood system, visual pacing, pairing music to the type of work) done manually. Currently mid-way through building out Profile C — a beatless ambient line for deep problem-solving — and refining what actually gets people to sit through a 4-hour session vs bounce in the first 30 seconds.

Curious if anyone else here works long stretches with music running in the background, and if so, what that music actually needs to do for you to not get pulled out of the work.

Newest session: https://youtu.be/DxbFQWlVyh4