Claude Opus 5 becomes the default Opus model; Opus 4.7 loses fast mode

What changed

Version 2.1.219 adds claude-opus-5 as the default Opus model with 1M context; fast mode on Opus 5 costs $10 / $50 per million tokens. Opus 4.7 no longer supports fast mode, so /fast works only with Opus 5 and Opus 4.8. Subagents can now spawn nested subagents up to depth 3 by default (set CLAUDE_CODE_MAX_SUBAGENT_SPAWN_DEPTH=1 to turn nesting off), and a new sandbox.network.strictAllowlist setting blocks non-allowlisted hosts for sandboxed commands.

Who it affects

Opus users, anyone using fast mode on Opus 4.7, and teams running subagent-heavy workflows.

What to do

Move fast-mode work off Opus 4.7, and set the subagent depth back to 1 if nesting would blow your budget.

Source: https://github.com/anthropics/claude-code/blob/main/CHANGELOG.md