Using Claude Code: Session Management & 1M Context

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Today we’re rolling out a new update to /usage to help you understand your usage with Claude Code, this was informed by a number of conversations with customers. What came up again and again in these calls is that there is a lot of variance in how you might manage your sessions, especially with our new update to 1 million context in Claude Code. Do you only use one session or two sessions that you keep open in a terminal? Do you start a new session with every prompt? When do you use compact, rewind or subagents? What causes a bad compact? There’s a surprising amount of detail here that can really shape your experience with Claude Code and almost all of it comes from managing your context window. A Quick Primer on Context, Compaction & Context Rot The context window is everything the model can "see" at once when generating its next response. It includes your system prompt, the conversation so far, every tool call and its output, and every file that's been read. Claude Code has a context window of one million tokens. Unfortunately using context has a slight cost, which is often called context rot. Context rot is the observation that model performance degrades as context grows because attention gets spread across more tokens, and older, irrelevant content starts to distract from the current task. Context windows are a hard cutoff, so when you’re nearing the end of the context window, you will need to summarize the task you’ve been working on into a smaller description and continue the work in a new context window, we call this compaction. You can also trigger compaction yourself. Every Turn Is a Branching Point Say you've just asked Claude to do something and it's finished, you’ve now got some information in your context (tool calls, tool outputs, your instructions) and you have a surprising number of options for what to do next: Continue — send another message in the same session /rewind (esc esc) — jump back to a previous message and try again from there /clear —