Claude Code status line: display context percentage from stdin JSON

When to use

• You need model and context information and can review the script.[1]

When not to use

• You need the bar to prove task success, settled billing or exact remaining quota.[1]

Input and display are separate interfaces

The docs describe a statusLine command receiving stdin JSON and rendering stdout, configured with type: command and command. This exercise reads only model.display_name and context_window.used_percentage, without credentials or network access. Missing values display unknown, avoiding an unverified zero usage claim.[1]

Original script and local calculation

Save the script below as an .mjs file in your own directory. Synthetic display_name: demo-model and used_percentage: 25 should produce demo-model | context 25%; missing fields produce unknown. The script does not execute input text. Still inspect the configured command and every dependency before real use.[1]

import fs from "node:fs";
const data = JSON.parse(fs.readFileSync(0, "utf8"));
const name = data.model?.display_name ?? "unknown";
const used = data.context_window?.used_percentage;
const pct = typeof used === "number" ? `${used}%` : "unknown";
console.log(`${name} | context ${pct}`);

[1]

Inspect commands and dependencies before configuration

Confirm Node.js is available and the script path is correct before setting statusLine.command. The docs also offer /statusline to generate a script and modify settings, which involves file edits and model usage. This page uses a reviewable manual sample and explains placement only; it did not run generation or write settings.[1]

Verify display and stop conditions

Offline calculation checked complete input, missing input and script syntax. After real enablement, inspect the rendered bar and errors separately. Disable the command for diagnosis when parsing, paths or values are wrong. A session context percentage does not directly establish subscription quota or settled cost. No Claude Code status line or model call was run here.[1]