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Claude Code v2.1.302: pick the auto mode classifier model and toggle idle compaction

Claude Code Release ★★★★ View Markdown
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Hi everyone, it's Shii-chan! Claude Code v2.1.302 is out, so here are the highlights!

Claude Code Release github.com

What was announced?

The Claude Code release notes published v2.1.302. It has few new features but a lot of fixes and improvements.

What changes

First, the additions:

  • CLAUDE_CODE_AUTO_MODE_MODEL: choose the model the client-side auto mode classifier uses (it does not change the model for server-side auto mode)
  • An Idle compaction row in /config to turn idle compaction off or back on; notices after an idle compaction now say how to turn it off
  • A notice in /design-sync and /design-login that standalone Claude Design (claude.ai/design) closes by December 14, 2026

Dive Deep

Some behavior changes to watch:

  • claude -p and Agent SDK sessions with no permission mode now start in default mode on third-party providers, with telemetry off, or on a fresh install (--permission-mode auto keeps auto)
  • Fork subagents (subagent_type: "fork") are now on by default in claude -p, the Agent SDK, the desktop app, and VS Code; CLAUDE_CODE_FORK_SUBAGENT=0 turns them off
  • The desktop app and VS Code always run the main conversation's subagents in the background
  • At most 12 prompt or agent hooks of one event run at a time

Notable fixes:

  • A "Prompt is too long" error when stopping a turn during compaction
  • Requests failing with "diagnostics: Extra inputs are not permitted" after switching to Vertex or Bedrock mid-session
  • The Read tool loading image files of any size entirely into memory (image sources over 128 MB are now refused)
  • A prompt cache miss when a tool added mid-session was loaded again through ToolSearch or after compaction
  • claude plugin and other subcommands sometimes exiting before a queued settings write finished

Among the improvements, startup is faster with many plugins enabled, and auto mode with the server-side classifier now compacts a conversation that is too long for the safety check instead of denying every checked tool call.

There are also many fixes for cloud sessions, Remote Control, Claude Tag, VS Code, and Code Review. See the original release notes for the full list.

Wrap-up

  • You can choose the auto mode classifier model with an environment variable
  • Idle compaction can be toggled in /config
  • Some defaults changed, including permission mode and fork subagents
  • Lots of fixes around compaction, plugins, MCP, and cloud sessions

If you use Claude Code daily, especially via automation or the SDK, check the default changes!

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