Claude Code 2.1.42
**One-time Opus 4.6 effort callout** — introduces a new system-level user communication for eligible users, improving model discoverability and driving adoption of the latest capability tier without ongoing permission friction.
1 new primitives 0 workflow recipes 4 fixes
New primitives
Opus 4.6 effort calloutsetting/capabilityDisplays one-time notification to eligible users about Opus 4.6 availability
Added one-time Opus 4.6 effort callout for eligible users
Agentic relevance
The Opus 4.6 callout is a lightweight adoption signal mechanism. For agents, this means model tier visibility is now automatic for eligible users rather than user-discovered. The hardening fixes improve agent startup latency and cache efficiency, reducing wall-clock time for multi-turn reasoning and large-context ingestion.
Hardening & fixes (4)
- Improved startup performance by deferring Zod schema construction
- Improved prompt cache hit rates by moving date out of system prompt
- Fixed /resume showing interrupt messages as session titles
- Fixed image dimension limit errors to suggest /compact
Raw changelog
## 2.1.42 - Improved startup performance by deferring Zod schema construction - Improved prompt cache hit rates by moving date out of system prompt - Added one-time Opus 4.6 effort callout for eligible users - Fixed /resume showing interrupt messages as session titles - Fixed image dimension limit errors to suggest /compact