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 family list touched at several offsets (opus/sonnet/mythos cycling)

Several entries in the internal model-family table were reassigned between opus, sonnet, and mythos

TierUnder the hoodhow much it should matter to you
Useful1my rating, 1 to 5
Signal2worth watching, 1 to 5
AreaModelswhat it touches
KindInternal Changesin v2.1.277,
Under the hood

Several entries in the internal model-family table were reassigned between opus, sonnet, and mythos

What

Multiple rows in the internal table that tracks each model's capability family had their value changed among "opus", "sonnet", and "mythos" across a number of separate edits.

Why

This affects how these models are internally categorized for capability purposes, though the finding doesn't specify which models moved or what depends on their family assignment.

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 doubtWhich specific models changed family, and what practical effect the reassignment has, is not stated.

See this entry in the whole of v2.1.277 →