The emoji set.

Column then row, two digits each. The pair round-trips, the whole grid expands row-major, and the pixel offset is (-x·cell_size, -y·cell_size) — the same arithmetic the frontend uses to place the cell.

iex> Codemojex.EmojiSet.xy("0305")
{3, 5}
iex> Codemojex.EmojiSet.code(3, 5)
"0305"
iex> set = Codemojex.EmojiSet.new("demo", 6, 6, cell_size: 144)
iex> Codemojex.EmojiSet.bg_position(set, "0305")
{-432, -720}
iex> length(Codemojex.EmojiSet.all_cells(6, 6))
36

The EMS set carries the sprite grid (cols, rows, cell_size, sprite_url) and the exposed codes — the full keyboard. The sheet is addressed by a plain sprite_url asset path, not a branded id. Two sets are seeded, each measured from the real PNG at cell size 72.

# grids measured from the PNGs under docs/codemojex/emoji-sets/
EmojiSet.new("emoji-set-01", 10, 15, cell_size: 72,
             sprite_url: "/emoji-sets/01-emoji-set.png")   # 720×1080 → 150 cells
EmojiSet.new("emoji-set-02", 10, 21, cell_size: 72,
             sprite_url: "/emoji-sets/02-emoji-set.png")   # 720×1512 → 210 cells

A classic game snapshots the full keyboard. A golden game can shrink it: when the room sets cell_count: N, snapshot_cells/2 draws a fresh randomized N-cell subset, and the six-code secret is drawn only from that snapshot.

The player-facing snapshot/1 carries only the keyboard — codes, sprite_url, cell_size, cols, rows, count — and nothing the secret could be derived from.