Use a PreToolUse SDK hook to prepend `unset ANTHROPIC_API_KEY
CLAUDE_CODE_OAUTH_TOKEN` to every Bash command Kit runs, preventing
secret leakage via env/printenv/echo/$PROC. Secrets are now passed
via stdin JSON instead of mounted env files, closing all known
exfiltration vectors.
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>