Added
- XDR Brightness now knows about your battery. The boost drives the built-in panel's backlight
to its HDR maximum — the single largest power draw a laptop has — and until now nothing ever
turned it back off. Four opt-in rules, under the Labs toggle in Settings → Health & Recovery, each
independent: turn the boost off when the Mac switches to battery power, turn it off below a
battery percentage you choose (10/20/30/50%), turn it off while Low Power Mode is on, and turn it
off a set time after you engaged it (15 min / 30 min / 1 h / 2 h). The first three are conditions,
so a fifth setting — "Bring the boost back when power returns", on by default — puts the exact
brightness you had back once all of them clear, and stays out of the way if you changed the boost
yourself in the meantime. The timer is not: time spent is spent, and an elapsed allowance is never
given back. Each automatic switch-off says why in a notification ("Battery at 18%") if you have
display notifications on. The power watcher is only held while XDR Brightness is on and one of
the battery-family rules is enabled — no IOKit listeners for a user who asked for none — and a
desktop Mac, which reports no battery at all, is unaffected by every one of these rules. - A boost no longer outlives the panel it was applied to. Closing the lid (or otherwise taking
the built-in out of service) while boosted used to leave the fraction set and the slider up on a
display nobody was looking at. It's now cleared through the normal path, with no restore when the
panel comes back — the same session-only rule the feature has always stated, where a relaunch
starts at normal brightness.