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DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.

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Claude Code v2.1.129 5 May 2026

Opus 4.7 Fast Mode [In Development]

What

Claude Code has infrastructure to switch Fast Mode labeling and model selection from Opus 4.6 to Opus 4.7.

Status

Environment-gated

Details

The new gate is CLAUDE_CODE_ENABLE_OPUS_4_7_FAST_MODE.
When enabled, Fast Mode text can report Opus 4.7; otherwise it remains on Opus 4.6.
Because this is gated by an environment variable and existing docs elsewhere still mention Opus 4.6 Fast behavior, treat this as experimental rather than broadly available.

Evidence

Environment-gated model switch (search for "CLAUDE_CODE_ENABLE_OPUS_4_7_FAST_MODE" and "Opus 4.7")

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

See this entry in the whole of v2.1.129 →