Why Smarter Models Make Worse Keyboards

That instant word suggestion appearing as you type isn't a neural model — it's a lookup table, and it's faster than any transformer you could run in its place. Modern AI keyboards are actually three-tier systems: a deterministic n-gram layer for speed, a small on-device neural model for context, and a cloud LLM for complex intent. The engineering that matters isn't in any individual model — it's in the router that decides which tier fires. Reaching for a smarter model in the wrong layer doesn't improve the keyboard; it breaks it. The keyboards that feel most intelligent aren't running the most powerful models. They're running the right one at the right moment.