[martinald]

Well a few things.

Firstly, it's very useful to have your (or at least some) previous messages in. There's often a lot of nuance it can pick up. This is probably the main benefit - there's often tiny tidbits in your prompts that don't get written to plans.

Secondly, it can keep eg long running background bash commands "going" and know what they are. This is very useful when diagnosing problems with a lot of tedious log prepping/debugging (no real reason these couldn't be moved to a new session tho).

I think with better models they are much better at joining the dots after compactation. I'd agree with you a few months ago that compactation is nearly always useless but lately I've actually found it pretty good (I'm sure harness changes have helped as well).

Obviously if you have a total fresh task to do then start a new session. But I do find it helpful to use on a task that is just about finished but ran out of space, OR it's preferable to a new task if you've got some hellish bug to find and it requires a bunch of detective work.

[CjHuber]

I mean I agree the last couple of messages in a rolling window are good to include, but that is not really most of what happens in compaction, right?

> there's often tiny tidbits in your prompts that don't get written to plans.

Then the prompt of what should be written down is not good enough, I don't see any way how those tidbits would survive any compaction attempts if the llm won't even write them down when prompted.

>Secondly, it can keep eg long running background bash commands "going" and know what they are. This is very useful when diagnosing problems with a lot of tedious log prepping/debugging (no real reason these couldn't be moved to a new session tho).

I cannot really say anything about that, because I never had the issue of having to debug background commands that exhaust the context window when started in a fresh one.

I agree they are better now, probably because they have been trained on continuing after compaction, but still I wonder if I'm the only one who does not like compaction at all. Its just so much easier for an LLM to hallucinate stuff when it does have some lossy information instead of no information at all

[martinald]

AFIAK claude code includes _all_ messages you sent to the LLM in compactation (or it used to). So it should catch those bits of nuance. There is so much nuance in language that it picks up on that is lost when writing it to a plan.

Anyway, that's just my experience.