Brent Franson spent four years building a mental-health app that users liked, but that didn’t ultimately work as a business.

The product wasn’t an obvious flop. It had enough promise, he said, to make further rounds of changes seem worthwhile — the trap of something that seemed “pretty good,” though ultimately isn’t viable.

“Mediocrity is so dangerous,” Franson said.

In late 2024, seeing a need for a fresh start, he shut down the app, called Most Days, and discarded the codebase that his team had spent years building.

The San Francisco-based staff then shifted their attention to building a consumer-health product called Death Clock, which…