[DOCS] Fast mode docs still describe Opus 4.6 as the default after v2.1.142 switched the default to Opus 4.7

Documentation Type

Incorrect/outdated documentation

Documentation Location

https://code.claude.com/docs/en/fast-mode

Section/Topic

The overview bullets and the "Use fast mode on Opus 4.7" section

Current Documentation

The docs currently say:

* By default, /fast runs on Opus 4.6. To run fast mode on Opus 4.7 instead, set the CLAUDE_CODE_ENABLE_OPUS_4_7_FAST_MODE environment variable.

* If you're on a different model, Claude Code automatically switches to the fast mode model: Opus 4.6 by default, or Opus 4.7 when CLAUDE_CODE_ENABLE_OPUS_4_7_FAST_MODE is set.

On May 14, 2026, Opus 4.7 becomes the default fast mode model. Until then, opt in by setting CLAUDE_CODE_ENABLE_OPUS_4_7_FAST_MODE=1.

To opt in, set CLAUDE_CODE_ENABLE_OPUS_4_7_FAST_MODE=1 before launching Claude Code. With the variable set, /fast runs on Opus 4.7. Without it, /fast continues to run on Opus 4.6.

The environment variable reference also still says:

CLAUDE_CODE_ENABLE_OPUS_4_7_FAST_MODE: Set to 1 to run fast mode on Claude Opus 4.7 instead of Opus 4.6. With the variable set, /fast switches to Opus 4.7; without it, /fast continues to use Opus 4.6

What's Wrong or Missing?

This content is outdated after changelog v2.1.142, which says fast mode now uses Opus 4.7 by default and that CLAUDE_CODE_OPUS_4_6_FAST_MODE_OVERRIDE=1 pins fast mode to Opus 4.6.

The current docs still describe Opus 4.7 as an opt-in preview path and Opus 4.6 as the default. That leaves users with the opposite expectation from current behavior and makes the new override variable look unnecessary or confusing.

Suggested Improvement

Update the fast mode and environment variable docs to reflect the v2.1.142 behavior change:

Before:

By default, /fast runs on Opus 4.6.

After:

By default, /fast runs on Opus 4.7. To keep fast mode on Opus 4.6, set CLAUDE_CODE_OPUS_4_6_FAST_MODE_OVERRIDE=1.

Also remove or rewrite the dated note that says Opus 4.7 "becomes" the default on May 14, 2026, and update the CLAUDE_CODE_ENABLE_OPUS_4_7_FAST_MODE entry so it explains whether the variable is now legacy, redundant, or still needed in any specific rollout scenario.

Impact

Medium - Makes feature difficult to understand

Additional Context

Affected Pages:

| Page | Line(s) | Context |
|------|---------|---------|
| https://code.claude.com/docs/en/fast-mode | 24, 44, 60, 63, 83 | Fast mode page still says Opus 4.6 is the default and Opus 4.7 is opt-in, while also documenting the new Opus 4.6 override |
| https://code.claude.com/docs/en/env-vars | 103, 133 | Env var table still says CLAUDE_CODE_ENABLE_OPUS_4_7_FAST_MODE switches from an Opus 4.6 default, while the new override entry implies the default has changed |

Total scope: 2 pages affected

Version context: changelog v2.1.142 says: "Fast mode now uses Opus 4.7 by default (previously Opus 4.6). Set CLAUDE_CODE_OPUS_4_6_FAST_MODE_OVERRIDE=1 to pin fast mode to Opus 4.6".