Daily · · Claude Code · 🌶️🌶️Worth a lookMedium: worth a look Why: Fast mode on Opus 4.8 will error
Opus 4.8 fast mode in Claude Code ends Nov 30
Action needed: Claude Code deprecated fast mode for Opus 4.8 as of Oct 30, 2026, and removes it on Nov 30, 2026. After that, fast mode requests on Opus 4.8 return an error and don’t fall back to standard Opus 4.8.
What changed
Moving to Opus 5.5 keeps the speedup. That’s the migration path in Claude Code’s release notes, published late on Oct 30, 2026. Fast mode on Opus 4.8 keeps working until Nov 30, 2026.
After the removal, those requests fail with an error instead of switching to standard Opus 4.8, so anything still set to it gets errors rather than answers.
What to do
If you use fast mode with Opus 4.8, switch to Opus 5.5 before Nov 30, 2026.
Also in this release
CLAUDE_sets the effort level subagents run at when nothing else names one, instead of inheriting the session’s.CODE_ SUBAGENT_ EFFORT CLAUDE_turns theCODE_ DISABLE_ ULTRATHINK ultrathinkkeyword off.- Claude apps gateway admins can give a group one shared monthly budget, on top of each member’s own limit, with
pooled_budgeton the spend limits admin API. --restrictedsessions no longer upload files from outside the working directories when a Read allow rule covered them.