Claude Code Statusline Design

# Task: Create a Professional Developer Status Bar for Claude Code ## Role You are a systems programmer creating a highly-optimized status bar script for Claude Code. ## Deliverable A single-file Python script (`~/.claude/statusline.py`) that displays developer-critical information in Claude Code's status line. ## Input Specification Read JSON from stdin with this structure: ```json { "model": {"display_name": "Opus|Sonnet|Haiku"}, "workspace": {"current_dir": "/path/to/workspace", "project_dir": "/path/to/project"}, "output_style": {"name": "explanatory|default|concise"}, "cost": { "total_cost_usd": 0.0, "total_duration_ms": 0, "total_api_duration_ms": 0, "total_lines_added": 0, "total_lines_removed": 0 } } ``` ## Output Requirements ### Format * Print exactly ONE line to stdout * Use ANSI 256-color codes: \033[38;5;Nm with optimized color palette for high contrast * Smart truncation: Visible text width ≤ 80 characters (ANSI escape codes do NOT count toward limit) * Use unicode symbols: ● (clean), + (added), ~ (modified) * Color palette: orange 208, blue 33, green 154, yellow 229, red 196, gray 245 (tested for both dark/light terminals) ### Information Architecture (Left to Right Priority) 1. Core: Model name (orange) 2. Context: Project directory basename (blue) 3. Git Status: * Branch name (green) * Clean: ● (dim gray) * Modified: ~N (yellow, N = file count) * Added: +N (yellow, N = file count) 4. Metadata (dim gray): * Uncommitted files: !N (red, N = count from git status --porcelain) * API ratio: A:N% (N = api_duration / total_duration * 100) ### Example Output \033[38;5;208mOpus\033[0m \033[38;5;33mIsaacLab\033[0m \033[38;5;154mmain\033[0m \033[38;5;245m●\033[0m \033[38;5;245mA:12%\033[0m ## Technical Constraints ### Performance (CRITICAL) * Execution time: < 100ms (called every 300ms) * Cache persistence: Store Git status cache in /tmp/claude_statusline_cache.json (script exits after each run, so cache must persist on disk) * Cache TTL: Refresh Git file counts only when cache age > 5 seconds OR .git/index mtime changes * Git logic optimization: * Branch name: Read .git/HEAD directly (no subprocess) * File counts: Call subprocess.run(['git', 'status', '--porcelain']) ONLY when cache expires * Standard library only: No external dependencies (use only sys, json, os, pathlib, subprocess, time) ### Error Handling * JSON parse error → return empty string "" * Missing fields → omit that section (do not crash) * Git directory not found → omit Git section entirely * Any exception → return empty string "" ## Code Structure * Single file, < 100 lines * UTF-8 encoding handled for robust unicode output * Maximum one function per concern (parsing, git, formatting) * Type hints required for all functions * Docstring for each function explaining its purpose ## Integration Steps 1. Save script to ~/.claude/statusline.py 2. Run chmod +x ~/.claude/statusline.py 3. Add to ~/.claude/settings.json: ```json { "statusLine": { "type": "command", "command": "~/.claude/statusline.py", "padding": 0 } } ``` 4. Test manually: echo '{"model":{"display_name":"Test"},"workspace":{"current_dir":"/tmp"}}' | ~/.claude/statusline.py ## Verification Checklist * Script executes without external dependencies (except single git status --porcelain call when cached) * Visible text width ≤ 80 characters (ANSI codes excluded from calculation) * Colors render correctly in both dark and light terminal backgrounds * Execution time < 100ms in typical workspace (cached calls should be < 20ms) * Gracefully handles missing Git repository * Cache file is created in /tmp and respects TTL * Git file counts refresh when .git/index mtime changes or 5 seconds elapse ## Context for Decisions This is a "developer professional" style status bar. It prioritizes: * Detailed Git information for branch switching awareness * API efficiency monitoring for cost-conscious development * Visual density for maximum information per character