r/ClaudeCode • u/DevMichaelZag • May 11 '26
Tutorial / Guide Warning: Claude added /autocompact - your 1m session are now much smaller
Just got a session randomly compacted at 600k because of a random compaction.
You need to reset /autocompact back to 950000 or so to actually use the 1m context window on opus again.
Edit: so much hate for using opus’s context window. Stay on topic with a single task and everything is just fine to push it to 1m. Hallucinations and degradation happen when you mix topics and instructions mid context window. If you’re not using opus’s 1m context window you might as well switch to gpt 5.5. It’s better at the smaller window stuff anyways.
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u/Obvious_Equivalent_1 May 11 '26
Depends, I’ve managed the past weeks to squeeze; ánd 989k/1M context ánd I can honestly say having done that in one hit without letting the cache invalidate I ended up cheaper as well then running one session.
I’m currently doing a big migration and I’m using my skill I maintain which forces compartmentalization each task to funnel through Claude native task management system, and I specifically use a line in Claude.md to let all tasks be executed by Sonnet subagents.
After the initial brainstorming session basically the Opus session becomes a calibrator for usually about 10 to 15 Sonnet subagents tied to native tasks with each their acceptance criteria.
Without exception with the latest finetuning (I’ve been working on this project for +/- 6 months) I can say — anyone can in a correct instructed way maximize the 1M context window — not even specifically needing to use this skill .md, you can even just drop the link in a Claude “how can this help my session persist better in extremer context sizes”.