The Claude Code statusline is a per-turn telemetry side channel

nickboy@users.noreply.github.com (Nick Liu) — Sun, 10 May 2026 00:00:00 +0000

Claude Code calls a custom statusline command every turn with a JSON payload on stdin. The payload includes the current context-window fill percentage, model, cost, and cwd. Nothing in the contract says you can only read it, and you can fork it to anything you want while the command stays a statusline.

🧪 Tested with Claude Code 2.1.x · macOS

(Quick framing for anyone new to Claude Code: it’s Anthropic’s terminal CLI for Claude, and the statusline is the configurable line of text it prints under your prompt every turn, like a shell prompt for the agent. You point at any script in settings.local.json, Claude pipes a JSON object to it on stdin, and whatever the script writes to stdout becomes the visible line.)

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The Claude Code statusline is a per-turn telemetry side channel