TopolearnQuality drops as the context fills; managing it is the single biggest lever on results and cost.
Everything in a session (your messages, every file Claude read, every command output, CLAUDE.md, tool descriptions) sits in the model's context window. It fills fast: one debugging session can use tens of thousands of tokens. As it fills, Claude starts losing track of early instructions and makes more mistakes.
Tools to manage it:
/contextshows what is using space, as a grid with suggestions./clearthrows the conversation away and starts empty. Use it between unrelated tasks. It is free and usually the best choice./compact [focus]replaces the history with a summary. Claude Code also does this automatically near the limit, first clearing old tool output. Detailed early instructions can be lost, so put lasting rules in CLAUDE.md, and steer the summary:/compact keep the list of modified files and test commands.- The rewind menu (Esc Esc) can summarize only part of the conversation, from or up to a chosen message.
/btw <question>asks a side question whose answer never enters the history.
A strong habit: if you have corrected Claude twice on the same thing, the context is full of failed attempts. /clear and restart with a better prompt that includes what you learned.
Sessions are saved locally, so long tasks can span days without one giant conversation:
claude -c(--continue) continues the latest session in this folder.claude -r(--resume) or/resumepicks from a list./rename oauth-migrationnames a session so it is easy to find;/branchforks the conversation to try another direction.
Later lessons add subagents, which do noisy research in their own separate context.
Example
> /context # what's filling the window?
> /compact keep: modified files, failing test names, the chosen design
> /btw what's the flag for verbose jest output? # not added to history
> /rename oauth-migration
> /clear # unrelated task next: start clean
$ claude --continue # pick up the latest session here
$ claude --resume # choose any earlier sessionRemember
- Context fills quickly and quality degrades as it does
- /clear between unrelated tasks; /compact with a focus when you must continue
- Name sessions with /rename and come back with --continue or --resume
Watch out for
- Running one "kitchen sink" session all day across unrelated tasks, so every request carries stale context.