Unclear Which environment variable names fall into the ignored set is not stated.
What
Your settings file can set environment variables (named values programs read at startup) through its env section. Claude Code now drops certain of these keys entirely and logs a warning once for each one.
The warning says the key names a use case, and that only the environment Claude Code is started with can set it. To use such a variable, set it in your shell or launcher before starting Claude Code, not in settings.
Why
If you set one of these variables in settings.json, it stops having any effect. The warning is the only sign of this, so check your logs if a setting seems to have stopped working.
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Which environment variable names fall into the ignored set is not stated.