Claude Code v2.1.288 · 2 Oct 2026
Auto-compact window can now be set per model
autoCompactWindow can now hold a different value for each model, and /autocompact and /config show and save it for the current model
Use it now Tier: how much it should matter to you
4 Useful: my rating, 1 to 5
2 Signal: worth watching, 1 to 5
Compaction Area: what it touches
New Features Kind: in v2.1.288, 02 Oct 26
What probably matters to you Section of the release
What
The auto-compact window is how full the conversation gets before Claude Code automatically summarises it to free up room. It used to be one value for all models. It can now differ by model:
autoCompactWindow modelSettings auto The value can also be an object with byModel default auto falls back to the later sources: server-provided data, any experiment, then the model's own default.
/autocompact /config The message about the CLAUDE_CODE_AUTO_COMPACT_WINDOW
Why
A window you set while using one model no longer applies to every other model, so models with different context sizes can each compact at a point that suits them.
What the documentation says
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Names in this entry
slash /autocompact Set the auto-compact window: how full the context window gets before Claude Code compacts automatically. Pass a size such as 500k, or auto to return to the window tuned for your model. Claude Code saves the value to user settings and applies it to the current session. See Set the auto-compact window for accepted values and what overrides it. Without an argument, opens a dialog that shows the current window. Requires Claude Code v2.1.221 or later
slash /config Open the Settings interface to adjust theme, model, output style , and other preferences. Pass one or more key=value pairs to set a setting directly without opening the interface, for example /config thinking=false, /config theme=dark, or /config model=sonnet. The key=value form also works in non-interactive mode (-p) and from the Claude mobile app via Remote Control . The key=value form can't turn on a setting that needs your confirmation in the panel, such as autoContinueAtUsageLimit/config --help to list the keys it accepts. Alias: /settings
setting autoCompactWindow Set how full the context gets before Claude Code compacts
setting modelSettings Keep a saved effort level per model, or cap one model's effort
setting auto You can set the auto-compact window at launch with --autocompact, using auto or 100k to 1M.
setting byModel Thinking effort can now be set per model, with a default and an inherit option.
setting default Subagent nudging behaviour can be picked per model, but the whole feature stays behind a gate.
env CLAUDE_CODE_AUTO_COMPACT_WINDOW Set the auto-compact window in tokens, from 100000 to 1000000. Accepts a plain integer such as 500000 only: a value like 500k reads as 500 and clamps to the 100K minimum. The effective window is also capped at the model's context window. Takes precedence over the /autocompact command, the --autocompact flag, and the autoCompactWindow setting. The status line's used_percentage always measures against the model's full context window, so once this variable is set, that percentage no longer indicates when compaction will run
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