how it works / how x,y is enforced
Drop an image on the board, drag it, resize by the corners — every pixel you claim mints as a compressed NFT on Solana named “PX x,y #COLOR” (coordinate + color committed into the merkle leaf). A program PDA holding a 1M-bit occupancy bitmap is the tree’s only mint authority, so claiming a taken pixel reverts on-chain. You sign exactly one payment transaction; the server mints your pixels to your wallet and they land verified in the collection.