Sweep 19 Sep 2026 · 02:36Z Build v2.1.278 500 read Stable v2.1.267 Latest v2.1.278 Next v2.1.278 Feeds RSS JSON llms.txt Unofficial
Claude Code v2.1.277 ·

Model catalog version bump and per-surface model reassignment

Bundled model catalog updated to version 629 with model reassignments across ccr, ccd, and other surfaces

TierUnder the hoodhow much it should matter to you
Useful2my rating, 1 to 5
Signal3worth watching, 1 to 5
AreaModelswhat it touches
KindInternal Changesin v2.1.277,
Under the hood

Bundled model catalog updated to version 629 with model reassignments across ccr, ccd, and other surfaces

What

The bundled model catalog that Claude Code ships with was updated from version 554 to version 629, with a new issue and expiry window. Several catalog surfaces, including ccr and ccd, had the model assigned to their existing slot swapped between claude-fable-5-1, claude-sonnet-5, and claude-opus-5.

Why

This changes which model a given surface falls back to when using the bundled catalog, continuing the same kind of reassignment seen in earlier catalog updates for ccr and ccd.

Read from
Names in the bundleclaude-fable-5-1claude-sonnet-5claude-opus-5
Since it was published

The entry above is what we published on the day. These lines were added later, as Anthropic's own pages caught up, and they sit beside the original rather than replacing it.

Confirmed since Anthropic's documentation has since written up claude-sonnet-5, on browser-use-tool. - claude-sonnet-5 agents-and-tools/tool-use/browser-use-tool see the edit
Confirmed since Anthropic's documentation has since written up claude-fable-5-1, on browser-use-tool. - claude-fable-5-1 agents-and-tools/tool-use/browser-use-tool see the edit
Confirmed since Anthropic's documentation has since written up claude-opus-5, on skills-guide. "model": "claude-opus-5", build-with-claude/skills-guide see the edit
How sure we are
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubtThe finding does not specify which surfaces ended up on which of the three models after this swap.
Anthropic's documentation agreesAnthropic's documentation has since written up claude-opus-5, on skills-guide.

See this entry in the whole of v2.1.277 →