An environment variable is a named value set outside Claude Code, for example in your shell. Claude Code keeps a protected set of these names that it checks separately, alongside ones such as CLAUDE_CODE_SYNC_PLUGINS. Two names are added to that set:
CLAUDE_CODE_TETHER_LIVECLAUDE_CODE_MCP_APPS_HOST
CLAUDE_CODE_MCP_APPS_HOST is also added to a second list, and is only treated as set when its value is exactly true.
CLAUDE_CODE_TETHER_LIVE used to fall back to the tengu_curious_tower gate when it was not set, and that fallback defaulted to off in the earlier code. That fallback pattern is replaced here. For that gate, the flag server has returned on for this site's account and for an anonymous account, first seen on 2026-09-17.
The protected set exists to stop certain variables from being set where Claude Code does not accept them. The likely effect is that an env block in a settings file, the section that sets environment variables for Claude Code, cannot set these two.
tengu_curious_tower Off by default, switched on for this accountThe shipped code defaults this off, and the flag server returned on for the one account this site reads on this version. That is the reading that makes the entry above worth a second look, and it still says nothing about your account.
This account: on · anonymous baseline: on · compiled default in v2.1.281: off
These values were read against a different version of Claude Code, so treat them as the nearest reading available instead of one taken on this release.
Read once, for one account on one subscription tier, against v2.1.281. It isn't a statement about your account. What a flag value here can and cannot tell you
The finding does not confirm that being in the protected set stops settings `env` blocks from setting these variables.
New in this build: CLAUDE_CODE_MCP_APPS_HOST