Opal is an advanced Terminal User Interface (TUI) and Elm Architecture framework built in Crystal.

Core capabilities:

• The Elm Architecture (TEA): Declarative, predictable state management with Model-Update-View loops, subscriptions, and async command pipelines (Opal::Tea::Program).
• Tactile VCR Cassette Recording (Opal::VCR): Programmatic double-buffered screen recording and playback in standard Asciinema v2 (.cast) format with tape-deck controls (record, pause, step, seek).
• Real-Time Terminal Text Shaders: Multi-pass compositing shader engine rendering Matrix Rain, CRT scanlines, Glitch, Plasma waves, and Fire FX directly in ANSI terminal cells.
• Interactive 3D Color Picker: 3D RGB Cube, Sphere, and 2D Wheel color pickers featuring surface raycasting and pitch/yaw rotation.
• Headless Testing: Comprehensive MockDriver and Asciicast headless driver for zero-flicker automated CLI testing.