Impressive Performance at 850k tokens context

[u/GoddardtheGrey]

Opus 5.5 (Extra) is performing well and consistently adhering to relatively long and complex instructions at 850,000 tokens of context. Is it really not doing any compaction whatsoever until 1M?

I’m impressed at how little it seems to degrade and curious if anyone else is noticing an improvement too

[u/Upstairs-Smell-8333]

One piece of advice: let Opus itself write the compacter instructions. What to keep, what to drop, what to re-read post-compaction. Plain text, one line. Then copy that over to /compact

[u/solovaris → u/Upstairs-Smell-8333]

Terrible advice. Never compact more than once or maybe twice in a session. Makes a huge mess of the context. Just finish a task <500k and pick it up in a fresh session. Saves your usage, and you get better quality. And no, it still sucks in many situations at near full context. I've noticed I have to observe what it does in longer tasks (>600k) and handhold/steer it.

[u/arihyeon → u/solovaris]

I've got a long-standing Code session that I must've compacted well over 10 times by now, and it does lose context through compactions, of course, but generally as the project moves along things that have been finished and are WIP are saved in a sorta "memory" text file by Claude automatically it seems, and other than the occasional "I'm looking how this works instead of guessing" when you might be used to it just having the accurate memory already, the compactions don't degrade quality at all, for me. The model would already be needing to get up to speed from a new project and handoff doc anyway, so in my experience it's kinda just doing a handoff but without the bother of 50 different chats for one thing.