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Claude Code v2.1.312: safer writes to big CLAUDE.md files, hook concurrency limits, and more

Claude Code Release ★★★★ View Markdown
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Hi everyone, it's Shii-chan!

Claude Code Release github.com

Claude Code v2.1.312 is out! There's a lot in it, so here are the parts that caught my eye.

What was announced?

v2.1.312 was published on the Claude Code Release page on GitHub. It bundles additions, fixes, improvements, and changes.

What changes

Two additions:

  • oidc.user_id_claim for the Claude apps gateway, to identify people by an id_token claim other than sub, such as Microsoft Entra ID's oid
  • In fullscreen, clicking the "to send now" hint under a queued message sends it right away

Dive Deep

Notable fixes:

  • Claude no longer overwrites a very large CLAUDE.md, rules file, or @-included file in a subdirectory after seeing only its start; Write now asks Claude to read it all or edit in place
  • Per-directory and paths: skills are found again after a Bash cd deeper into a git repository
  • A command with an invalid name no longer stops all commands from loading, which could leave claude -p with no output
  • Managed settings and organization policy are fetched for the rest of the session after signing in from the VS Code extension
  • The Read tool no longer sometimes fails on PDF pages when clean-up of old session files runs at the same time
  • In vim mode, d, c and y with a gj or gk count larger than the lines left no longer delete or copy text; like Vim, they only move the cursor

Behavior changes:

  • Bedrock, Vertex, Foundry and Mantle use the shorter system prompt for model names Claude Code doesn't recognize, such as custom deployment names and inference profile ARNs, even when they front Sonnet or Haiku; set CLAUDE_CODE_SIMPLE_SYSTEM_PROMPT=0 to keep the full prompt
  • Automatic model switches after a flagged message now also cover unrecognized model names; set CLAUDE_CODE_DISABLE_REFUSAL_FALLBACK=1 to turn them off
  • Prompt and agent hooks run at most 24 at a time per session, sub-agents included, plus at most 12 that have waited longer than their event's timeout; a timeout under 1 second counts as 1 second
  • Usage limit messages call the 5-hour window the "5-hour limit" instead of the "session limit"
  • Claude Code stopped sending the claude_code.safety_event OpenTelemetry event

There are also fixes and improvements for cloud sessions, Remote Control, Claude Tag, and Code Review. For example, Code Review now reviews the pull request's current commit even when GitHub delivers a push event late.

Wrap-up

  • oidc.user_id_claim lets you identify people by claims like Entra ID's oid
  • Fixed overwriting large CLAUDE.md files after reading only the start
  • Hook concurrency is now capped (24, plus 12 that have waited)
  • Unrecognized model names are handled differently, with environment variables to revert
  • Fixes also landed for cloud sessions, VS Code, Claude Tag, and Code Review

If you use Claude Code daily, especially on Bedrock or Vertex, or rely on many hooks, check the changes!

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