Keep your MacBook awake with the lid closed, on battery, with no external display. A native menu-bar app that uses pmset disablesleep, with an auto-off timer and a battery-floor cutoff so it can't drain your Mac. The open-source, MIT alternative to Amphetamine.

Make a Mac's stay-awake behavior power- and display-aware, overriding an unwanted caffeinate (stay awake = AC ∪ active display; otherwise force sleep).