You already know the phone is the problem. Knowing does not stop the reflex to pick it up during hard thinking.
Environment design helps — phone in another room, blocker apps, timed sessions. But environment alone fails when you are tired and alone.
Public streaks add a second layer: your group sees whether you checked in. Missing a day resets the number everyone can see.
Focus is not about becoming a monk. It is about protecting one block daily until the habit survives bad days.
Put the phone in another room for one block. Report it to your group.