[DOCS] Fast mode docs still recommend deprecated Opus 4.6 override variable

Documentation Type

Incorrect/outdated documentation

Documentation Location

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

Section/Topic

Toggle fast mode and the environment variable reference for CLAUDE_CODE_OPUS_4_6_FAST_MODE_OVERRIDE

Current Documentation

The fast mode page currently says:

Fast mode for Opus 4.6 is deprecated and will be removed approximately 30 days after the Opus 4.8 launch. After removal, fast mode on Opus 4.6 falls back to standard speed at standard pricing. Migrate to Opus 4.8 or Opus 4.7 to keep the speedup.

It later recommends the override variable for users who want Opus 4.6:

Opus 4.8 is the fast mode default in Claude Code v2.1.154 and later. On v2.1.142 through v2.1.153, fast mode defaults to Opus 4.7. To pin fast mode to Opus 4.6 instead, set CLAUDE_CODE_OPUS_4_6_FAST_MODE_OVERRIDE=1; this override will be removed when fast mode for Opus 4.6 is retired.

The environment variable reference also says:

CLAUDE_CODE_OPUS_4_6_FAST_MODE_OVERRIDE: Set to 1 to pin fast mode to Claude Opus 4.6 instead of the current fast mode default, which depends on your Claude Code version. With the variable set, /fast runs on Opus 4.6. Fast mode for Opus 4.6 is deprecated, and this variable will be removed when it is retired

What's Wrong or Missing?

Changelog v2.1.154 says CLAUDE_CODE_OPUS_4_6_FAST_MODE_OVERRIDE is deprecated and will be removed on 06/01, and tells users to switch to Opus 4.6 with /model claude-opus-4-6[1m] and then run /fast on instead.

The current docs still present the environment variable as the way to pin fast mode to Opus 4.6, without the 06/01 removal date or the replacement /model ... plus /fast on workflow.

The fast mode page also says fast mode on Opus 4.6 itself will be removed and fall back to standard speed. That appears to conflict with the v2.1.154 migration instruction, which says users can continue using fast mode on Opus 4.6 by selecting the model first and then enabling /fast.

Suggested Improvement

Update the fast mode and environment variable docs so they no longer recommend CLAUDE_CODE_OPUS_4_6_FAST_MODE_OVERRIDE as the current pinning path.

Suggested wording:

CLAUDE_CODE_OPUS_4_6_FAST_MODE_OVERRIDE is deprecated and will be removed on 06/01. To use fast mode on Opus 4.6 after the override is removed, switch models with /model claude-opus-4-6[1m], then run /fast on.

Also clarify whether Opus 4.6 fast mode itself remains available after 06/01, or whether only the environment variable is being removed.

Impact

Medium - Makes feature difficult to understand

Additional Context

Affected Pages:

| Page | Line(s) | Context |
|------|---------|---------|
| https://code.claude.com/docs/en/fast-mode | 18, 54 | Says Opus 4.6 fast mode is deprecated and recommends CLAUDE_CODE_OPUS_4_6_FAST_MODE_OVERRIDE=1 for Opus 4.6 pinning |
| https://code.claude.com/docs/en/env-vars | 212 | Documents CLAUDE_CODE_OPUS_4_6_FAST_MODE_OVERRIDE without the 06/01 removal date or replacement command sequence |
| https://code.claude.com/docs/en/model-config | 52 | Documents /model <alias|name> but does not cross-reference the Opus 4.6 fast mode migration path |

Total scope: 3 pages affected

Version context: v2.1.154 says CLAUDE_CODE_OPUS_4_6_FAST_MODE_OVERRIDE is deprecated, will be removed on 06/01, and should be replaced by /model claude-opus-4-6[1m] followed by /fast on.