Do you save the plans from plan mode alongside of the feature? I use specs to save the artifact but hadn't thought of using plan mode as the spec generator itself.

> been trained on enough long context tasks to have become pretty good at planning

This is absolutely not true

They can plan, but no guarantee it will produce what you want. Sometimes most of the work is aligning on what to build. And I'm not handing over technical planning to it yet.

I use this skill and it makes the specing process progressive. Human driven for the "what", 50/50 for higher level technical planning, only where it has questions in the low level details: https://github.com/scosman/vibe-crafting

I bother because Claude Code does wacky nonsense unless I use OpenSpec (or something similar) to explicitly research, scope, persist, then implement in a brand-new context. Even Opus will do ridiculous nonsense like throw its hands up when asked to start a Docker container, ignore explicit architectural instructions, write verbose make-work documentation riddled with inaccuracies, etc. Using OpenSpec keeps things as constrained as possible with the side effect of recording what your system does.

OpenCode and various open models do not exhibit this tendency nearly as much in my experience. My recent experiences with GPT-5.6 were also very positive in this regard. Alas for regulatory reasons this stack is a non-starter at $DAYJOB so I'm stuck working around Anthropic's capacity optimizing shenanigans.

specifying is not planning