Engine

The engine is the core C++ application that plays chess. It implements the Universal Chess Interface (UCI) protocol, runs the search algorithm, and evaluates positions using a natively-compiled Factorized Mixture-of-Experts neural network — or a classical heuristic fallback when no weights are loaded.

The engine is split into three logical subsystems, each documented in detail below:

• Search — The search algorithm and move ordering
• Evaluation — Neural network evaluation and heuristic fallback
• Infrastructure — Transposition table, time control, UCI, tablebases, and opening book

Directory Layout

engine/
├── CMakeLists.txt          # Build configuration
├── src/
│   ├── main.cpp            # Entry point
│   ├── Types.h             # Shared type definitions
│   ├── feature_api.cpp     # Feature bridge for native inference
│   ├── search/
│   │   ├── Negamax.h/cpp   # Core search algorithm
│   │   ├── MovePicker.h/cpp # Move generation and ordering
│   │   ├── MCTS.h/cpp      # Monte Carlo Tree Search (experimental)
│   │   ├── TT.h/cpp        # Transposition table
│   │   ├── TimeManager.h   # Time allocation
│   │   ├── SearchHeuristics.h # Killer, history, counter-move tables
│   │   ├── ISearch.h       # Search interface
│   │   └── TablebaseFallback.h/cpp
│   ├── eval/
│   │   ├── Evaluator.h/cpp       # Evaluator dispatcher
│   │   ├── IEvaluator.h          # Evaluator interface
│   │   ├── EvalContextMoECache.h/cpp # Native MoE inference
│   │   ├── SimpleEvalContext.h/cpp   # Classical piece-square tables
│   │   ├── MoERouting.h          # Expert routing logic
│   │   └── WDLConverter.hpp      # Centipawn ↔ WDL conversion
│   ├── uci/
│   │   ├── UCI.h/cpp       # UCI command loop
│   │   └── UciOptions.h/cpp # Dynamic option parsing
│   ├── book/
│   │   ├── polyglot_book.h/cpp  # Polyglot book reader
│   │   └── polyglot_keys.cpp    # Zobrist key tables
│   └── tablebases/
│       ├── Tablebase.h/cpp      # Syzygy probing API
│       └── tbprobe/             # Fathom probing library