Dev Log: Fitness App 'Sidewalk to Summit' Uncovers Silent Plan-Length Bug in Testing

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Developer building a hiking fitness app called 'Sidewalk to Summit' discovered a long-standing bug in the plan engine that caused it to undercount the number of weeks a training plan would take. The flaw stemmed from two errors: the code assumed training always ramped at the fastest allowed rate, and it failed to count the first week entirely, both mistakes pushing estimates in the same direction. The bug was caught through property testing, which stress-tests code with hundreds of randomized inputs rather than hand-picked examples. Continuous integration was also set up, immediately flagging four pre-existing security vulnerabilities in third-party dependencies that require a major framework upgrade to fix. Progress has otherwise been slower than usual due to ongoing planning calls with collaborator Melanie Michaelchuk and the developer's recent travel to Amsterdam.

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