The env field in .claude/settings.json injects environment variables into every Claude session.
This is how you give Claude access to API keys, feature flags, or environment-specific config without hardcoding them in scripts. Set "ANTHROPIC_API_KEY", "NODE_ENV", or any variable your tools expect.
I want to flag the scope difference here: project-level env values in .claude/settings.json are shared with your team when committed. For secrets, use your personal ~/.claude/settings.json instead so they don't end up in git.