[gen740]

Summary

• Add .env field to ArgParameter and ArgImpl to specify an environment variable name
• After CLI token dispatch, apply_env_fallback() checks getenv() for each unprovided option that has .env set
• Normal action pipeline (conversion + validation) runs on the env value, so type checking still applies
• CLI values always take precedence over env
• Env values satisfy required option checks

struct Args {
  cli::StringOption<"output"> output{{.env = "MYAPP_OUTPUT"}};
  cli::IntOption<"jobs">     jobs{{.presence = cli::required, .env = "MYAPP_JOBS"}};
};

🤖 Generated with Claude Code