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Sweep 28 Sep 2026 · 18:16Z Build v2.1.284 505 read Stable v2.1.277 Latest v2.1.284 Next v2.1.284 Feeds RSS JSON llms.txt llms-full.txt Unofficial

Claude Code v2.1.280 ·

Safety-classification model routing table gains a 'frontier_llm' entry

Safety-classification model routing gains a new 'frontier_llm' category mapped to claude-opus-5

Under the hood Internal Changes
JSON All of v2.1.280
Under the hoodTier: how much it should matter to you
2Useful: my rating, 1 to 5
3Signal: worth watching, 1 to 5
PermissionsArea: what it touches
Internal ChangesKind: in v2.1.280,
Internal ChangesSection of the release
What

A routing table used internally for specific risk-classification categories (previously covering bio and cyber) now includes a new frontier_llm entry, mapped to claude-opus-5. The bio category maps to claude-opus-5 and cyber to claude-opus-4-8. Related sibling tables still only cover bio and cyber.

Why

This adds a new classification category for routing certain safety checks, alongside the existing bio and cyber risk categories.

Read from
Names in the bundlefrontier_llm
What the documentation says
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.

Added since A small documentation edit on Or, for the model with the same capabilities and no access approval requirement: touched a line naming frontier_llm after this was published. A refusal that arrives before any output is billed when its category is `"bio"`, `"frontier_llm"`, or `"reasoning_extraction"`. A refusal before any output in any other category, or with a `null` category, is not billed ([How refusals are … models/fable-5/migration-guide see the edit
Confirmed since Anthropic's documentation has since written up frontier_llm, on refusals-and-fallback. | `"frontier_llm"` | The request could assist the development of competing AI models, which is restricted under [Anthropic's commercial terms](https://www.anthropic.com/legal/commercial-terms). Benign machine learning work can also trigger… build-with-claude/refusals-and-fallback see the edit
How sure we are
One source agreesOne thing we can check says the same as this entry.
Anthropic's documentation agreesAnthropic's documentation has since written up frontier_llm, on refusals-and-fallback.

See this entry in the whole of v2.1.280 →

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