Add `isAgent` flag

[pi0]

Describe the feature

(from discussion with @danielroe)

We can export a flag to indicate if CLI is running within an AI agent for increasing verbosity or span more info.

We might also have something like agentProvider additionally.

Some references for env detection (chatgpt assisted might need double check)

• Generic: AI_AGENT (*)
• Cursor: CURSOR_AGENT / CURSOR_TRACE_ID (*) (cli)
• Gemeni: GEMINI_CLI (*)
• Codex: CODEX_SANDBOX (*)
• ClaudeCode: CLAUDECODE / CLAUDE_CODE (*)
• Replit: REPL_ID (*)
• Mastra CLI: MASTRA_TELEMETRY_DISABLED
• Open Code: OPENCODE_CONFIG_DIR / OPENCODE_DISABLE_LSP_DOWNLOAD /...
• Goose CLI: GOOSE_PROVIDER/GOOSE_MODEL/...
• Offline‑AI CLI: AI_NPM_LOG_LEVEL/AI_NPM_REGISTRY
• Devin: /opt/.devin file (*)

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Copilot agent in VSCode seems needing parent crawling: (vscode-copilot-terminal-detection)

* : learned from @vercel/detect-agent ❤️

[pi0]

/cc @ekroon i see vscode-copilot-terminal-detection is archived. Do you know a better way to detect it?

[ekroon]

I created that to deal with copilot not understanding complicated prompts and not waiting. As the copilot plugin lept changing, it was hard to keep it working. I now just use a simple prompt all the time.

I am not aware of other ways to detect this in vscode.

[nathanchase]

Claude Code has an environment variable available: CLAUDECODE=1 that you can hook into to know that you're running from within Claude Code.

You can see it by opening Claude Code and then typing ! to run bash mode and then run env from within Claude Code and see CLAUDECODE=1 within the env vars list.

[sapphi-red]

In Vite, we have discussed the idea of having a standard env var for detecting AI agents, so that we don’t have to maintain our own list (related: vitejs/vite#20916).
@hi-ogawa and I found that @vercel/detect-agent already supports the AI_AGENT env var, and we were wondering if there are any other general environment variables proposed for this purpose (there's also a list of env vars here).
If not, it might be nice to encourage tools to start setting the AI_AGENT env var.

[pi0]

Thanks for references @sapphi-red. Standarzing on AI_AGENT makes sense.

[pi0]

http://npmjs.com/@vercel/detect-agent seems already doing ~ same thing (only hope it was ESM (/cc @tknickman @onsclom)

(closed and reopened, wondering a smaller env-only based flag could be still viable)