Some kind of planning / speccing out is becoming inevitable. No personal experience with openspec but I do rely on generating plans, and then a set of tasks from the plan. And keeping a close eye on what's going as the tasks are churned through (although I wonder if simply saying Yes to the diffs has been adding much value /shrug).

Matt Pocock talks about specs and Openspec after 23:00 minute mark and again after 33:00 minute mark here: https://www.youtube.com/watch?v=-QFHIoCo-Ko. He doesn't believe in simply translating specs-to-code. He emphasizes tracer bullets, TDD, setting up quick feedback loops.