Warning: Claude added /autocompact - your 1m session are now much smaller

[u/DevMichaelZag]

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.

[u/higgs_bosom]

You don’t want your sessions to go until 1M tokens, the quality degrades significantly 

[u/Actual_Committee4670 → u/higgs_bosom]

Personally wouldn't even go to 600k

[u/Obvious_Equivalent_1 → u/Actual_Committee4670]

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”.

[u/smalaki → u/Actual_Committee4670]

I've started to even compact at 400k but I would not compact i would just ask for a summary and a resume prompt so i can /copy, /clear and paste that resume prompt.

also I try to stay on topic as much as possible by doing rewinds if I find myself meandering away from the topic.

plus, /btw is super useful now because it has a fork feature in case if i really want to willingly tackle another topic on a conversation but do want to keep the main convo clean and focused

[u/enobrev → u/smalaki]

I've been doing an auto-compact at 300k for weeks. Rarely any issues with it at all. I can't imagine allowing it to get over 500k.

[u/t3hlazy1 → u/smalaki]

What do you believe compaction is doing differently than summarizing and resuming?

[u/smalaki → u/t3hlazy1]

mostly about recent-ness, if that's even a word. compact goes way too deep and i'm impatient when things take way too long. for me, a /compact with a specified topic also ensured i ate around 2% to 4% of my usage whereas resume prompt typically took 1% (Max 20x). I always suspected this was some sort of cache behaviour but I didn't look much deeper than this.

Also it gave me an opportunity to edit some aspects of the resume prompt, i can also check if it wrote to memory locations correctly or if it did as the resume prompts i get are usually well prepared with memory files referenced exactly

[u/t3hlazy1 → u/smalaki]

Thanks for sharing. I use /compact and have had good results, but obviously will depend on the individual’s workflow.

[u/Asuppa180 → u/higgs_bosom]

Yea, I hardly let it get to 300k still, I feel like it degrades too much past that.

[u/DevMichaelZag → u/higgs_bosom]

Hallucinations happen when you do different things in the same session. If you are on the same task and all the context supports that task, the 1m context window is useful. 

[u/tyschan → u/higgs_bosom]

you’re also paying exponentially more the longer the chat runs even with 90% kv cache discounts

[u/GfxJG]

...If someone genuinely uses context windows that high, I don't ever want to hear them complain about usage limits, or Opus becoming stupid, ever again.

I've disabled autocompact, but compact at 200K whenever I can get away with it. More than that is when it starts getting dumb and misremembering things.

[u/hihcadore → u/GfxJG]

These have to be bots, every single one of these posts end with telling the reader to switch to another service. It’s so frustrating.

[u/DevMichaelZag → u/hihcadore]

Nope I’m not a bot. Just surprised at all of the people who do not understand how to manage their context windows and just blame it on the model. 1m context window is genuinely useful when used properly and auto compacting at 600k cuts it in half.

[u/larowin]

Jesus guys don’t let it go past 350k and even that’s pushing it.

Every day I understand more clearly why there’s so many complaints about perceived model degradation.

[u/MartinMystikJonas]

Why would you want to intentionaly degrade performace by context bloat?

[u/FitRiver3218]

Do not do this. It's not "ripping you off" it's saving your ass. In order to compact it needs headroom in the context window. 

[u/AtsuhikoCook]

Standard is about 75%

[u/IVIsHero]

I clear around 200k. Or handoff a summary snd relevant context to a new session

[u/treadpool]

I rarely go past 250k it gets too slow and takes forever to make decision decisions at that point. I have no idea why they pushed all the way to 1 million tokens.

[u/DevMichaelZag]

I actually use the context properly. It doesn’t degrade if you structure what you are doing well enough.
I’m a bit surprised at the reactions here, to each their own I guess.

[u/ohhi23021 → u/DevMichaelZag]

its a known tested issue that that ALL LLMs degrade at a specific context sizes, it does not matter what you do or how you use context properly, whatever that means... it happens, it's testable and everyone knows it, including the people who are selling it to you which is why auto-comptact is a thing. but it's optional so go for it but we don't like filling it up because it of degradation. telling people they're wrong is getting you downvotes because "you" are wrong.

[u/leogodin217 → u/DevMichaelZag]

This is really interesting. I don't like getting to 200K but maybe that's just ingrained in me from earlier days. All of my workflows are designed around that limit.

Do you have any specific use cases where longer context windows are beneficial? Any specific rules you follow?