Integration & Perft validation

[Hardcode3]

🎯 Goal

Validate the entire pipeline.

🧠 Key Idea

Perft never lies.

🛠️ Tasks

• Integrate generate_legal_moves:

void generate_legal_moves(MoveList& moves, const Board& board, Color us) {
    Square king_sq = board.king_square(us);

    Color them = opposite(us);

    // 1. Who is checking the king?
    Bitboard checkers = attackers_to(king_sq, board, them);

    // 2. Where are we allowed to play to resolve check?
    Bitboard check_mask = compute_check_mask(king_sq, checkers, board);

    // 3. Which of our pieces are pinned?
    Bitboard pinned;
    Bitboard pin_ray[64] = {0};
    compute_pins(king_sq, board, us, pinned, pin_ray);

    // 4. Squares attacked by the enemy (needed for king safety)
    Bitboard enemy_attacks = compute_enemy_attacks(board, them);

    // 5. King moves (always generated)
    generate_legal_king_moves(
        moves,
        board,
        us,
        king_sq,
        enemy_attacks,
        check_mask
    );

    // 6. Double check → only king moves are legal
    if (popcount(checkers) > 1)
        return;

    // 7. Other pieces
    generate_legal_knight_moves(moves, board, us, check_mask, pinned, pin_ray);
    generate_legal_bishop_moves(moves, board, us, check_mask, pinned, pin_ray);
    generate_legal_rook_moves(moves, board, us, check_mask, pinned, pin_ray);
    generate_legal_queen_moves(moves, board, us, check_mask, pinned, pin_ray);
    generate_legal_pawn_moves(moves, board, us, check_mask, pinned, pin_ray);

    // 8. Castling (depends on check + enemy attacks)
    generate_legal_castling_moves(
        moves,
        board,
        us,
        checkers,
        enemy_attacks
    );
}

• Run perft (depth 1 -> 5)
• Compare against known references

✅ Acceptance Criteria

• Exact perft numbers
• No illegal moves generated