ADS-Bit/CLAUDE.md

CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Project Overview

ADS-Bit is a retro SNES-style side-view flight tracker that displays ADS-B aircraft data with custom pixel art sprites.

Running the Server

# Start the server (port configured in config.json, default 2001)
python3 server.py

# Or use the startup script
./start.sh

Access at http://localhost:{web_port} (configured in config.json)

Deployment / fielding notes

• Config path is overridable via the ADSBIT_CONFIG env var (defaults to config.json beside server.py). Docker uses /app/data/config.json on a mounted volume.
• /health (no auth) returns status/version/receiver/flight counts — used by the Docker HEALTHCHECK and any external monitoring.
• VERSION constant in server.py is the single source of truth; surfaced at startup, via GET /api/config, and in the admin header. Bump it for releases.
• Auto-scan (scan_for_receivers) skips subnets larger than MIN_SCAN_PREFIX (/20) so a docker /16 doesn't stall startup; the manual scan endpoint enforces the same limit.
• docker-entrypoint.sh seeds config.json from config.json.example on first run, so a fresh docker compose up needs no manual steps. SIGTERM/SIGINT shut down cleanly (no traceback).

Architecture

Components

• server.py - Python WebSocket server using aiohttp

  • Reads configuration from config.json
  • Auto-scans for ADS-B receivers or connects to configured IPs
  • Parses SBS/BaseStation format messages from receivers (port 30003)
  • Polls dump1090 JSON API (/dump1090/data/aircraft.json) every 5s for ADS-B emitter categories
  • Broadcasts flight data (including emitter category) to WebSocket clients every 1 second
  • Cleans up flights not seen in 60 seconds
  • Serves static files, admin panel, setup wizard, and APIs
  • Authentication via bcrypt password hashing and session cookies

• config.json - Configuration file for receiver and location settings

  • See CONFIG.md for full documentation

• ads-bit.js - JavaScript rendering engine (Canvas-based)

  • Handles WebSocket connection and flight data updates
  • Renders 10 FPS retro-style canvas animation
  • Layer order (bottom to top): sky gradient → clouds → sun → moon → directional background → grid → aircraft → labels
  • Directional backgrounds include horizon, so low sun/moon is realistically occluded
  • Aircraft sprites flip horizontally when heading west (track 90°-270°)
  • View direction rotates between N/E/S/W (arrow keys or A/D), changing the background

• index.html - Main HTML interface with embedded styles

• admin/ - Admin panel (login + tabbed settings UI)

  • Theme management: rename display names, upload per-direction background PNGs, create new themes
  • Display names stored in config.json theme_names map (folder name -> display name)
  • Receivers tab: live per-receiver health (via GET /api/admin/receiver-status and POST /api/admin/test-receivers), a select → SAVE & APPLY → auto-test flow, selectable scan results, and a per-interface scan selector
  • Version (from server.py VERSION) is surfaced via public GET /api/config and shown in the admin header
  • pixel-editor.js - In-app Canvas2D pixel editor (Sprites tab "EDIT" button)
    • Edits sprites at native 500x333; tools: pencil, eraser, color picker, fill bucket, pan, line, rectangle, ellipse (outline/filled), rectangular select
    • Select & move: marquee + floating layer, drag/arrow-nudge, Ctrl+C/X/V clipboard, Delete, Enter/Esc commit
    • Zoom/pan, undo/redo (snapshot-per-stroke), grid overlay, brush size & opacity, retro + custom (localStorage) + recent palettes, adjustable reference-image overlay
    • Exports a 500x333 PNG via srcCanvas.toBlob and POSTs to the existing /api/admin/sprites/{type} upload endpoint (no new server route)
    • Keyboard: B/E/I/F/L/R/O/M tools, Space=pan, +/-/0 zoom, Ctrl+Z/Y undo/redo, Ctrl+C/X/V, arrows nudge, G grid, Esc close
  • Asset cache-busting: admin.html references admin.css/admin.js/pixel-editor.js with a ?v=YYYYMMDD[x] query — bump it whenever those files change so browsers reload them

• setup/ - First-run setup wizard (multi-step configuration)

Sprite Assets

All PNG sprites face right (eastward) and are flipped in-canvas for westbound aircraft:

• 9 aircraft types: smallProp, regionalJet, narrowBody, wideBody, heavy, helicopter, balloon, glider, uav
• Directional backgrounds: north.png, south.png, east.png, west.png (1536x1024, shown based on view direction)
• Celestial: sun.png, moon_6_phases.png (2x3 sprite sheet)
• Weather: happycloud.png (clear), raincloud.png (rain/snow)

Aircraft Type Detection Logic

Two-tier system: real ADS-B emitter categories when available, heuristic fallback otherwise.

Tier 1: ADS-B Emitter Category (from dump1090 JSON API)

The server polls http://{receiver_ip}/dump1090/data/aircraft.json every 5 seconds. The SBS/BaseStation protocol (port 30003) does not include emitter category, but the dump1090/readsb JSON API exposes the raw ADS-B transponder category field. When available, this is authoritative and always preferred over heuristics.

Mapping from DO-260B emitter categories to sprite types:

ADS-B Category	Description	Sprite
A1	Light (< 15,500 lbs)	smallProp
A2	Small (15,500 - 75,000 lbs)	regionalJet
A3	Large (75,000 - 300,000 lbs)	narrowBody
A4	High vortex large (B757)	narrowBody
A5	Heavy (> 300,000 lbs)	wideBody or heavy (by altitude/speed)
A6	High performance (> 5g, > 400 kts)	narrowBody
A7	Rotorcraft	helicopter
B1	Glider / sailplane	glider
B2	Lighter-than-air	balloon
B4	Skydiver drop plane	smallProp
B6	UAV	uav

Once an emitter category is received for an aircraft, it is locked in and heuristic re-evaluation is skipped.

Tier 2: Heuristic Fallback (when no emitter category available)

Priority order when ADS-B category is not available (some transponders don't broadcast it):

1. Helicopter callsigns: known operator prefixes (LFE, MED, CHP, PHI, ERA, BHS) or keywords (LIFE, MERCY, COPTER, etc.)
2. Heavy/Wide body callsigns: major airline ICAO prefixes (CPA, UAE, ETH, QTR, SIA, AAL, DAL, UAL, FDX, UPS, etc.) + altitude/speed thresholds
3. Altitude/speed extremes: altitude > 42000 ft or speed > 550 kts = heavy; > 40000 ft or > 500 kts = wideBody
4. N-number (US GA registration): pattern N + digit + 2-4 alphanumerics = smallProp (or narrowBody if above 25000 ft)
5. Regional airline callsigns: SKW, RPA, ASH, PDT, CHQ, ENY, JIA, CPZ
6. Speed/altitude heuristics: speed < 60 + alt < 5000 = helicopter; alt < 18000 + speed < 300 = smallProp or regionalJet
7. Altitude-only: < 10000 ft = smallProp, < 25000 ft = regionalJet, higher = narrowBody
8. Default: narrowBody (re-evaluated when better data arrives)

Important: speed=0 or altitude=0 means data not yet received, not actual zero. The system re-categorizes when better data arrives (speed > 0 and callsign present).

View Direction Controls

The viewer can rotate between cardinal directions (N/E/S/W), showing aircraft in a 90° field of view:

• Keyboard: Left/Right arrow keys or A/D keys
• UI: Arrow buttons on the interface
• Each direction displays a unique background image (north.png, east.png, south.png, west.png)
• Sun and moon positions are calculated based on actual azimuth and only appear when in the current field of view

External APIs

• Open-Meteo: Weather and sunrise/sunset data (updates every 10 minutes)
• ADS-B Receivers: SBS/BaseStation protocol on port 30003 (flight data)
• dump1090 JSON API: http://{receiver}/dump1090/data/aircraft.json on port 80 (emitter categories, polled every 5s)

Dependencies

Python packages required:

• aiohttp (web server and WebSocket)
• netifaces (network interface scanning)
• bcrypt (password hashing)

No package.json - frontend is vanilla JavaScript with no build step.

Key Code Patterns

• Canvas version parameter on assets (?v=36) for cache busting
• Aircraft direction: const isFacingLeft = flight.track > 90 && flight.track < 270
• Moon phases use sprite sheet cropping with 2x3 grid (3 columns, 2 rows)
• Flight data stored in global flights dict keyed by ICAO hex code

Debugging

# Check for running server instances
ps aux | grep server.py

# Kill all instances
pkill -9 -f server.py

# Test receiver connectivity (replace with your receiver IP)
nc -zv <receiver_ip> 30003