mise-agent-env

mise-agent-env detects whether a command is running under an AI coding agent. It is environment-only: detection does not inspect processes or the filesystem and does not spawn subprocesses.

if mise_agent_env::is_agent() {
    // Prefer complete, machine-readable output.
}

if let Some(detection) = mise_agent_env::detect() {
    eprintln!("agent: {} (via {})", detection.agent, detection.signal);
}

Tests and embedded callers can provide their own lookup without changing the process environment:

use std::ffi::OsString;

let detected = mise_agent_env::detect_with_env(|name| {
    (name == "CODEX_THREAD_ID").then(|| OsString::from("thread-1"))
});
assert_eq!(detected.unwrap().agent, mise_agent_env::Agent::Codex);

The provider signals are informed by the language-neutral vercel/detect-agent definitions and the agents' own implementations. Detection is intentionally conservative: an editor or hosted development environment alone is not classified as an agent.