Blog
Architecture notes and shipping decisions — written for engineers who skim.
Why your 25 minutes weren't 25 minutes?
Users kept switching tabs and the timer fell behind. We fixed it twice. First with web workers, then by stopping the countdown and measuring wall clock instead.
Did changing the music change the week?
We held the person fixed. Eighteen people who turned a focus sound on logged 4.2 hours in the week before that session and 5.6 in the week after. Most streaks held.