Earlier-subagents list now defaults on, and a new CLAUDE_CODE_CRYPTIC_HORIZON variable appears

What

The list of subagents that ran earlier in a session (a subagent is a helper Claude starts to do part of a task) used to be off unless switched on. Its switches have changed:

• The check for the list still reads CLAUDE_CODE_SUBAGENT_HISTORY first, but the fallback for the server switch tengu_rustling_crescent moved from false to true. When the server sends no value, the list is now on. The environment variable still overrides it.
• A new environment variable, CLAUDE_CODE_CRYPTIC_HORIZON, is read by one function that used to read CLAUDE_CODE_SUBAGENT_HISTORY. When it is unset, that function falls back to a different server switch, with a default of false. CLAUDE_CODE_SUBAGENT_HISTORY is now read by a separate function.

Nothing has been read about tengu_rustling_crescent. What CLAUDE_CODE_CRYPTIC_HORIZON controls is not known.

Why

You may start seeing the earlier-subagents list without having set anything. Setting CLAUDE_CODE_SUBAGENT_HISTORY still lets you choose. The feature appears to be split into two switches, and the purpose of the new one is unclear.