Claude Code v2.1.251 adds model-switch hooks and prompt-cache observability
Anthropic
Claude Code v2.1.251 (Aug 28), following v2.1.248 earlier this week, ships PreModelSwitch/PostModelSwitch hook events, a spend-limit bar in /usage, and per-session prompt-cache stats (hit ratio, tokens re-cached) in /cost. Security fixes stop file tools from following symlinks swapped after the permission check and reject plugin-marketplace path traversal; the default model for seat-based Enterprise subscriptions moves to Opus 5, and /effort now saves effort per model. v2.1.250 (Aug 28) was bugfix-only.
Why it matters
hooks plus cache observability deepen Claude Code as an automatable dev platform
Importance: 3/5
minor version with real changes, security fixes included
Sources
official
claude-code releases (v2.1.251)