Proposal: Standard environment variable for agent runtime detection

[ianlet]

Problem

Scripts and CLIs can detect CI environments via the CI=true convention, enabling non-interactive behavior and CI-appropriate output. It seems there's no equivalent for AI coding agents.

When agents execute commands, scripts have no way to know they're running in an agent context. This matters because:

• Error output — Agents benefit from structured errors (JSON with actionable suggestions) rather than human-friendly prose
• Verbosity — Agents can process more context; humans need scannable output
• Interactivity — Like CI, agents can't respond to prompts, but the existing CI=true doesn't capture the full picture

Use cases

# Script adapts output format
if [[ -n "${AGENT:-}" ]]; then
  echo '{"error": "config_missing", "suggestion": "run ./setup.sh", "docs": "https://..."}'
  exit 1
else
  echo "Error: Config file not found. Run ./setup.sh to initialize."
  exit 1
fi

# Test runner provides richer failure context for agents
if [[ -n "${AGENT:-}" ]]; then
  pytest --tb=long --verbose "$@"
else
  pytest "$@"
fi

Proposal

Agents set an environment variable when executing commands:

Variable	Value	Meaning
AGENT	1	Running under an AI coding agent

Precedent

• CI=true — Set by GitHub Actions, GitLab CI, CircleCI, Travis, Jenkins, etc.
• NO_COLOR=1 — Disables color output across CLIs
• TERM=dumb — Signals limited terminal capabilities

The CI convention emerged organically as tools independently adopted it. A coordinated standard would accelerate adoption for agents.

Open questions

1. Variable name — AGENT, AI_AGENT, AGENTIC, LLM_AGENT?
2. Scope — Should this cover all automation (like CI) or specifically AI agents?
3. Relationship to CI — Should agents also set CI=true, or is this orthogonal?

Prior art

• InfoQ: Patterns for AI Agent Driven CLIs — Recommends --no-interactive flags and structured output, but no env var convention
• OpenAI Codex uses CODEX_SANDBOX=1 internally for sandbox detection
• No cross-agent standard exists today

---

Hopefully this is the right place to propose such standard, let me know if I should post this somewhere else.