ChessPrism/cline_docs/techContext.md

Technical Context

Development Environment

• macOS Application
• Swift & SwiftUI
• Xcode 14+
• Target: macOS 12.3+

Core Technologies

1. Vision Framework

   • VNDetectRectanglesRequest for board detection
   • VNCoreMLRequest for piece classification
   • VNImageRequestHandler for image processing

2. Core ML Model

   • Name: ChessPieceClassifier.mlmodel
   • Input: RGB/RGBA images
   • Output: Classification label
   • Categories (exact names):

     white_pawn, white_knight, white_bishop, white_rook, white_queen, white_king,
     black_pawn, black_knight, black_bishop, black_rook, black_queen, black_king
     

3. ScreenCaptureKit

   • Window capture at 30 FPS
   • Configurable cursor visibility
   • Chess.com window detection

Image Processing

1. Preprocessing Pipeline

   • Contrast enhancement (1.3x)
   • Edge sharpening
   • Noise reduction
   • Color normalization

2. Square Extraction

   • Aspect ratio validation
   • Size normalization
   • Center crop

Model Integration

1. Loading

   let config = MLModelConfiguration()
   config.computeUnits = .all
   let model = try MLModel(contentsOf: modelURL)
   let vnModel = try VNCoreMLModel(for: model)
   

2. Classification

   let request = VNCoreMLRequest(model: vnModel)
   request.imageCropAndScaleOption = .centerCrop
   

3. Result Handling

   • Confidence threshold: 0.75
   • Empty square fallback
   • Direct category mapping

Dependencies

• Foundation
• Vision
• CoreML
• CoreImage
• ScreenCaptureKit
• SwiftUI

Error Handling

• Invalid dimensions
• Model loading failures
• Recognition errors
• Low confidence results

File Organization

ChessPrism/
├── Models/
│   ├── SquareClassification.swift  # Model output mapping
│   └── ChessPosition.swift         # Board state
├── Recognition/
│   ├── PieceRecognizer.swift      # ML integration
│   ├── FenGenerator.swift         # Position encoding
│   └── MoveDetector.swift         # Move analysis
└── Core/
    ├── BoardDetector.swift        # Square extraction
    └── ScreenCapture.swift        # Window capture