CLAUDE_CODE_DISABLE_1M_CONTEXT

Updated October 13, 2026 by Alex Sorokoletov

CLAUDE_CODE_DISABLE_1M_CONTEXT is a Claude Code environment variable: Disable extended 1M token context window. Present since v2.1.69 or earlier and still present in v2.1.294. It is listed in the official reference.

Status	Present in v2.1.294
Added	Present since v2.1.69 or earlier
Category	Context and compaction
Official docs	Listed

How to set it

For one session, export it in the shell that starts Claude Code:

export CLAUDE_CODE_DISABLE_1M_CONTEXT=<value>
claude

To apply it to every session, add it to the env object of a settings file:

// ~/.claude/settings.json
{
  "env": {
    "CLAUDE_CODE_DISABLE_1M_CONTEXT": "<value>"
  }
}

Release notes that mention it

Related variables

CLAUDE_CODE_AUTO_MODE_PRIOR_ASSISTANT_CONTEXT: Feeds prior assistant turns into the decision, so the classifier can see the reasoning behind an edit.
CLAUDE_CODE_AUTO_MODE_SIBLING_CONTEXT: Includes sibling files (or sessions) when classifying.
CLAUDE_CODE_DISABLE_PRECOMPACT_SKIP: Disable skipping pre-compaction checks.
CLAUDE_CODE_SAVE_HOOK_ADDITIONAL_CONTEXT: Extra context passed to save hooks.
CLAUDE_CONTEXT_COLLAPSE: Collapses context on the fly, with a dedicated model to do it.
DISABLE_AUTO_COMPACT: Disable automatic compaction only (manual /compact still works).
DISABLE_CLAUDE_CODE_SM_COMPACT: Disable session memory compaction.
DISABLE_COMPACT: Disable all compaction (manual + auto).

Frequently asked questions

What does CLAUDE_CODE_DISABLE_1M_CONTEXT do?

Disable extended 1M token context window

Which Claude Code version has CLAUDE_CODE_DISABLE_1M_CONTEXT?

Present since v2.1.69 or earlier and still present in v2.1.294.

How do I set CLAUDE_CODE_DISABLE_1M_CONTEXT?

Export it before starting Claude Code (export CLAUDE_CODE_DISABLE_1M_CONTEXT=value), or add it to the "env" object in ~/.claude/settings.json to apply it to every session.

All variables, searchable: Claude Code environment variables.