Build a status line for model, context and branch

The steps

One step at a time. When a step’s check matches, tick it and the next one opens.

1. 01

   Step 1 of 4: Try the quick way

   Describe the status line you want and let Claude Code write it.

   In Claude Code

   You type: › /statusline show the model, context percentage and git branch

   – What happens: Claude Code writes a script in ~/.claude/ and updates your settings. Approve the edits it asks for.

   Check it worked

   A new row at the bottom of Claude Code shows what you asked for.

   It worked — next step Not yet
2. 02

   Step 2 of 4: Copy the kit script to your user folder

   A status line in your user settings follows you into every project.

   For macOS, Linux and WSL

   TerminalCopy

   Run: $ mkdir -p ~/.claude

   Run: $ cp .claude/statusline.mjs ~/.claude/statusline.mjs

   For Windows

   PowerShellCopy

   Run: PS> Copy-Item .claude\statusline.mjs "$HOME\.claude\statusline.mjs"

   ~/.claude/statusline.mjs · JavaScriptCopy

   // Status line: the model, how full the context window is, and the git branch.
   //
   //   Opus | 25% context | branch main
   //
   // Claude Code runs this script with the session's data as JSON on stdin and
   // shows what it prints. The status line goes blank if the script exits with
   // a code other than 0, so every failure here falls back to a placeholder.
   //
   // It is plain Node, so the same file works on macOS, Linux, Windows and WSL.
   // Copy it to ~/.claude/statusline.mjs and point the statusLine setting in
   // ~/.claude/settings.json at it (see the Day 32 lesson).
   import { execFileSync } from 'node:child_process';
   
   let data = {};
   try {
     data = JSON.parse((await readStdin()) || '{}');
   } catch {
     // Unreadable input: show the placeholders rather than nothing.
   }
   
   const model = data.model?.display_name || 'Model --';
   
   // used_percentage can be null before the first reply in a session.
   const used = data.context_window?.used_percentage;
   const context = typeof used === 'number' ? `${Math.round(used)}% context` : '--% context';
   
   const dir = data.workspace?.current_dir || data.cwd || process.cwd();
   let branch = '';
   try {
     branch = execFileSync('git', ['branch', '--show-current'], {
       cwd: dir,
       encoding: 'utf8',
       timeout: 2000, // the status line runs often, so never wait long
       stdio: ['ignore', 'pipe', 'ignore'],
     }).trim();
   } catch {
     // Not a git repository, or git is not installed: leave the branch out.
   }
   
   console.log([model, context, branch && `branch ${branch}`].filter(Boolean).join(' | '));
   
   async function readStdin() {
     let text = '';
     for await (const chunk of process.stdin) text += chunk;
     // Windows PowerShell 5.1 can put a byte order mark in front of piped text.
     return text.replace(/^\uFEFF/, '');
   }
   

   It reads three fields from stdin and asks git for the branch.

   Check it worked

   statusline.mjs is in the .claude folder of your home folder.

   It worked — next step Not yet Back
3. 03

   Step 3 of 4: Test it with sample input

   Pipe in the kind of JSON Claude Code sends, before any settings change.

   For macOS, Linux and WSL

   TerminalCopy

   Run: $ echo '{"model":{"display_name":"Opus"},"context_window":{"used_percentage":25}}' | node ~/.claude/statusline.mjs

   – What happens: It prints Opus | 25% context, then the branch in a git repository.

   For Windows

   PowerShellCopy

   Run: PS> '{"model":{"display_name":"Opus"},"context_window":{"used_percentage":25}}' | node "$HOME\.claude\statusline.mjs"

   – What happens: It prints Opus | 25% context, then the branch in a git repository.

   Check it worked

   One line that starts with Opus | 25% context.

   It worked — next step Not yet Back
4. 04

   Step 4 of 4: Point your settings at it

   Add the statusLine key to your user settings and keep everything else.

   For macOS, Linux and WSL

   ~/.claude/settings.json

   statusLine.type: "command"

   Run a command and show what it prints.

   statusLine.command: "node ~/.claude/statusline.mjs"

   Your shell turns ~ into your home folder.

   For Windows

   ~/.claude/settings.json

   statusLine.type: "command"

   Run a command and show what it prints.

   statusLine.command: "node C:/Users/<you>/.claude/statusline.mjs"

   Your full home path, with forward slashes. Git Bash drops backslashes.

   Check it worked

   The status line shows your model, the context percentage and the branch, and updates after each reply.

   If it didn’t work

   The status line is blank.

   Run the step 3 test again: the script must print a line and exit 0. In a folder you haven’t trusted yet, it stays blank until you accept the trust dialog.

   It worked — finish Not yet Back