Claude Code now compacts idle conversations, and Codex turns Daybreak back on
A week of coding agent changes: automatic idle compaction for long Claude Code sessions, new environment variables, and a Codex default that flipped twice in a week.
Claude Code shipped four releases this week, 2.1.299 through 2.1.302. The biggest change is idle compaction: a conversation over 200K tokens left idle for about 54 minutes is now summarized before its one-hour prompt cache expires, so the next message does not pay to reprocess everything. You can turn it off with "idleCompaction": false, change the threshold with CLAUDE_CODE_IDLE_COMPACT_MIN_TOKENS, or toggle it in /config as of 2.1.302.
New environment variables include CLAUDE_CODE_DISABLE_FILE_MENTIONS, which sends the paths of @-mentioned files instead of their contents, and CLAUDE_CODE_AUTO_MODE_MODEL, which picks the model for the client-side auto mode classifier. Security fixes include refusing image sources over 128 MB in the Read tool.
On the OpenAI side, Codex 0.163.0 made Daybreak the default again for eligible accounts, five days after v0.161.0 had made it opt-in.
Why it matters for builders
Idle compaction saves money on long sessions, but compaction replaces the conversation with a summary. If your workflow depends on exact earlier context, such as files your CLAUDE.md told the agent to read, test it or turn it off.
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