It’s additional features that are related.

For example making a computer use agent… Made the plan, implementation was good, now I want to add a new tool for the agent, but I want to discuss best way to implement this tool first.

Clearing context means Claude forgets everything about what was just built.

Asking to discuss this new tool in plan mode makes Claude rewrite entire spec for some reason.

As workaround, I tell Claude “looks good, delete the plan” before doing anything. I liked the old way where once you exit plan mode the plan is done, and next plan mode is new plan with existing context.

I get where you're coming from. But you'll likely get better results by starting fresh and letting it read key files or only just a summary of the project goals/spec. And then implement the next feature building up on the previous one. It's unlikely you'll need all the underlying code of the foundation in context to implement something that builds up on it - especially if interfaces are clean. Models still get dumber the more context is loaded, and the usable window isn't all that big, so starting fresh gives best results usually. I try to avoid compaction in any way possible, and I rarely continue the session after compaction, for that reason.