I mostly use speckit, not openspec. I think basically these are the same tools. There are other reasons for using such tools, but one reason is to enforce discipline for me and the LLM. Otherwise, often it starts going round in circles. Helps me save tokens as well. Again, the discipline is the important bit (along with clearly produced artefacts). Can I do all of this just with the LLM? Yes and that's what I did but it was very messy.

I agree but your taste in making solutions, or that of your organisation may be very different from what an LLM does by default. I personally use specs to capture this taste; an example shared by most LLMs is that they like to document not only what they have built but also what they have not built. Especially after changing solutions or small migrations. Specifications can resolve most if not all of that behaviour.

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

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

This is absolutely not true

That's what I thought too. I used speckit quite a bit before and I've had mixed results at best. You are just moving ambiguity and code review from one place to another without really gaining anything.

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.

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.

specifying is not planning