Accountability works. The problem is that accountability is usually another person, and other people get busy.
The standard app answer is a social feed: friends, streaks, nudges, and public reactions. That can work for a while, but it also makes practice into something performed for an audience. Meditation is one of the few habits that is often better kept private.
There is a second kind of accountability that does not need an audience: a system that will not let you record something you did not do. A referee, not a spectator.
A machine can hold one narrow boundary
A referee is a strange thing to want from software because software is normally designed to say yes as often as possible. An app that refuses to count part of a session is making an unusual choice: it is choosing the rule you set before sitting over the comfort you want in the middle of it.
The machine does not know whether your thoughts wandered. It does not know whether the session felt meaningful. Those are not reasonable things for software to judge. It can hold a much narrower boundary: whether you remained present and inside your calibrated posture range.
Refusal should feel dignified
The design consequence is that refusal must feel calm rather than punitive. A red banner reading SESSION FAILED would be humiliating. A timer that quietly pauses and quietly resumes when you straighten up behaves more like a referee than a critic.
This also leaves room for ordinary human movement. A posture break can be information rather than a moral event. The session remains yours; only the recorded verified time follows the rule.
Private accountability still needs transparency
An automated observer earns trust only when its limits are visible. The person sitting should know what signal is used, what leaves the phone, why time paused, and how to recover. Camera frames should not become content, diagnostics, or cloud data.
Good accountability is not the feeling that something is always watching. It is the confidence that one clear agreement will be kept, even when nobody else is in the room.