alt Hacker News+1 for generating plans and then clearing context. I typically have a skill and an agent. I use the skill to generate an initial plan for an atomic unit of work, clear context and then use the agent to review said plan. Finally clear context and use the skill to implement the plan phase by phase, ensuring to review each phase for consistency with the next phase and the overall plan. I've had moderate success with this.
Another important thing to do is to instruct the agent to keep a <plan-name>-NOTES.md file where it tracks its progress and keeps implementation notes. The notes are usually short with Opus 4.5 but very helpful, especially when you need to reset mid-phase and restart it with a fresh context.
If you keep the notes around in repo, you can instruct future plan writers to review implementation notes from relevant plans to keep continuity.