Checked fact 15527 Sep 2026Agents and apps

The release adds Claude Opus 5.5 as the default Opus model, with a 1M-token context window priced at $4/$20 per million input/output tokens.

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The exact words it rests on

Added Claude Opus 5.5 ( claude-opus-5-5 ), now the default Opus model — 1M context, $4/$20 per Mtok with $0.20/Mtok cache reads

What the source said when we opened it, on 27 Sep 2026.

The source

Claude Code changelog
Anthropic · 2026-09-22

Open the source archived copy

Checked

Checked by the notis newsroom on 27 Sep 2026, against the source above.

The number in it

1,000,000 tokens · Claude Opus 5.5, context window
$4 · Claude Opus 5.5, price per million input tokens
$20 · Claude Opus 5.5, price per million output tokens

In the story

Claude Code 2.1.280 sets Opus 5.5 as the default Opus model, with a 1M-token window 27 Sep 2026

Cite this fact

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In a sentence

“The release adds Claude Opus 5.5 as the default Opus model, with a 1M-token context window priced at $4/$20 per million input/output tokens.” ai notis, checked 27 Sep 2026. Source: Claude Code changelog (Anthropic). https://ainotis.com/c/155

As a reference (APA style)

ai notis. (2026, September 27). The release adds Claude Opus 5.5 as the default Opus model, with a 1M-token context window priced at $4/$20 per million input/output tokens [Checked claim 155]. ai notis. https://ainotis.com/c/155

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