Build a Developer Status Bar Script for Claude Code

Role You are a systems programmer creating a single-file Python script for Claude Code's status line. The script must be extremely performant (<100ms execution), use only standard library, and output exactly one line with ANSI colour codes.

Context you provide

• Model display name {{the name of the AI model, e.g., 'Opus', 'Sonnet', 'Haiku'}} (optional, default 'Claude')
• Workspace directory {{the project directory path}} (optional, will read from environment or CWD)

Instructions

1. If no workspace directory is provided, use the current working directory. If missing, ask.
2. Write a Python script saved to ~/.claude/statusline.py that reads JSON from stdin with fields: model, workspace, output_style, cost.
3. The script must:

• Parse the JSON and handle missing fields gracefully (omit that section, do not crash).
• Display model name (orange), project directory basename (blue), git branch (green), git status (clean ● dim gray, modified ~N yellow, added +N yellow, uncommitted !N red), and API ratio (dim gray).
• Use ANSI 256-colour codes for high contrast. Visible text width ≤80 characters (exclude ANSI codes).
• Read git info efficiently: branch from .git/HEAD directly, file counts from git status --porcelain with a cache in /tmp/claude_statusline_cache.json (TTL 5 seconds or on .git/index mtime change).
• Use only sys, json, os, pathlib, subprocess, time.
• On any error, return empty string.

1. Meet all constraints: <100 lines, type hints, docstrings, one function per concern.
2. Output the final script with integration instructions (save, chmod, add to settings.json).

Output format

# Full script code

Guardrails

• Do not include external dependencies; only standard library.
• Ensure the script does not produce side effects beyond writing cache file.
• Verify that ANSI codes do not count toward the 80-character visible width limit.

Example Input: {"model":{"display_name":"Opus"},"workspace":{"current_dir":"/home/user/project"},"cost":{"total_cost_usd":0.12,"total_duration_ms":1500,"total_api_duration_ms":1200}} Output (with ANSI): Opus project ● A:80%