This is the promise the whole project was built to keep: a real autocomplete engine. Loading the list builds a trie whose every node already carries its cached top completions, so each keystroke - go, then goo, then goog - is an instant cache read that narrows the ranked suggestions exactly as a search box does. go offers the heaviest completions of go; goo drops to the words under goo; goog resolves to the single google. No rescan, no re-sort - just walk the prefix and read.

Then the engine learns. Five selections of golang lift it from 6 to 11, past go at 10, so the very next Suggest("go", 3) leads with golang - the rankings changed because a person used it. Recording gospel, a term never loaded, adds it on the fly at weight 1, taking the count to 7 and appearing at the tail of a full Suggest("go", 8) that falls back to a scan for the larger request. From an empty trie you have built the honest core of a production typeahead - a prefix tree, ranked top-K completions cached for O(prefix + K) reads, learning from selections, case-folding, phrases, and a single-typo fallback - the same design that sits inside Elasticsearch’s completion suggester and the search box you use every day, minus the compression and sharding they layer on top. That is a real autocomplete engine, and it is yours.