Lynx 1.3.3

Patch release focused on UCI tournament compatibility, protocol diagnostics, and illegal-move prevention.

Added

• Added UCI go perft N support for counting legal leaf nodes from the current position.
• Added advertised UCI Ponder option.
• Added process-level UCI regression tests that launch the engine binary and verify protocol behavior.

Changed

• Invalid position commands now report a clear critical UCI error and exit instead of continuing from the previous board state.
• Unknown UCI commands and unknown options now print explicit diagnostics.
• Empty go now starts an unbounded search until a limit or control command stops it.
• UCI coordinate move parsing now accepts uppercase square text such as E2E4.
• setoption now waits for an active search to finish before applying engine configuration.

Fixed

• Fixed compatibility with tournament managers that emit non-standard fullmove number 0 in FEN by normalizing it to fullmove 1.
• Fixed root draw positions, including fifty-move claim and dead-material positions, so Lynx still returns a legal move when legal moves exist.
• bestmove 0000 is now reserved for positions with no legal moves.