Mid-session effort switches don't break Opus 5.5 prompt cache (Claude Code v2.1.280+)
lydiahallie · x · 2026-09-23
- Lydia Hallie notes that switching effort mid-session on Opus 5.5 doesn't invalidate your prompt cache, as long as you're on Claude Code v2.1.280+.
- Caveat: this doesn't apply on Bedrock/Vertex — same as Fable 5.1.
- A practical caching detail for developers managing costs in Claude Code.
Related event: Claude Code update keeps prompt cache intact when switching effort(3 posts)→
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