Switching Effort Mid-Session in Claude Code No Longer Breaks Prompt Cache

Developer Lydia Hallie confirmed that switching effort levels mid-session on Opus 5.5 no longer invalidates the prompt cache, provided Claude Code is updated to v2.1.280 or later.

2026-09-23 ~ 2026-09-23 · 4 related posts

• Mid-session effort switching on Opus 5.5 preserves prompt cache in Claude Code v2.1.280+ — lydiahallie · 2026-09-23
• Claude Code v2.1.280+ lets you switch Opus 5.5 effort mid-session without breaking prompt cache — kimmonismus · 2026-09-23
• Mid-session effort switches don't break Opus 5.5 prompt cache (Claude Code v2.1.280+) — lydiahallie · 2026-09-23
• Switching reasoning effort mid-session doesn't break Claude prompt cache on v2.1.280+ — MaziyarPanahi · 2026-09-23