Sweep 22 Sep 2026 · 17:19Z Build v2.1.280 501 read Stable v2.1.267 Latest v2.1.280 Next v2.1.280 Feeds RSS JSON llms.txt Unofficial
One change · claude-code

How Claude Code uses prompt caching changed

prompt-caching

Nearest release: v2.1.280, published under an hour before upstream edited the page. Shown because the two are within 24 hours of each other. Nothing here says the release caused the edit.

Upstream edited this page at 22 Sep 2026 16:28 UTC, give or take a minute or two: the time comes from Anthropic’s own sitemap rather than from a commit. This site recorded the change at 22 Sep 2026 16:37 UTC.

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8484 
8585The [`opusplan` model setting](/docs/en/model-config#opusplan-model-setting) resolves to Opus during plan mode and Sonnet during execution, so each plan-mode toggle is a model switch and starts a fresh cache.
8686 
87[Automatic model fallback](/docs/en/model-config#automatic-model-fallback) on Fable models and Opus 5 is also a model switch. When a safety classifier flags a request in a category that has a fallback model, Claude Code re-runs the request on that model and the session continues there.
87[Automatic model fallback](/docs/en/model-config#automatic-model-fallback) on Fable models, Opus 5.5, and Opus 5 is also a model switch. When a safety classifier flags a request in a category that has a fallback model, Claude Code re-runs the request on that model and the session continues there.
8888 
8989When a skill or command's frontmatter names a [`model`](/docs/en/skills#frontmatter-reference) other than the session's current model, that turn is also a model switch: the next request reads the entire conversation history with no cache hits. The session model resumes on your next prompt. A `context: fork` skill sets the [forked subagent's model](/docs/en/skills#run-skills-in-a-subagent) instead.
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