Quality and difficulty

Quality is a bundle of signals rather than a single notion of “good”. The engine measures scramble movement, entropy, readability, rarity, phrase structure, emotional fit, harmony, and conflict penalties. Editorial difficulty calibrates those signals into easy, normal, and hard lanes.

Validation is the final safety boundary: letters must match, separators must be compatible, and the generated envelope must satisfy the rule contract. A high score does not excuse an invalid puzzle.

For content-side measures such as familiarity, tone, and entry difficulty, see Themes and Editorial difficulty.