Claude Code 2.1.251 Adds Model Switch Hooks
ClaudeCodeLog · x · 2026-08-29
Claude Code CLI released version 2.1.251.
New Features:
- Added PreModelSwitch and PostModelSwitch hook events (block, confirm, or annotate a model switch); SessionStart resume hooks now receive session staleness and estimated re-cache cost.
- Added live streaming of a foreground subagent's tool calls and results to Remote Control clients (background subagents still show status only).
CLI Surface Changes:
- Removed env vars: SCREENSHOTDIR, USERPROFILE.
Metadata:
- Bundle file size decreased by 7,842.7 kB (-14.4%) compared to v2.1.250.
- Prompt files increased by 2 (+18.2%); Prompt tokens increased by 7,355 (+53.9%).
- Prompt token mix: tools占比 decreased from 69.3% to 59.8%; system占比 increased from 30.7% to 40.2%.
Related event: Claude Code Update: Faster CLI, Token Visualization, and Model Switch Hooks(3 posts)→
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