Wirewiki hits p99 0 ms autocomplete on 240M domains via Tranco trie and keyDown prefetch

The implementation prefetches suggestions for the current character plus every possible next character on keyDown, then renders on keyUp. Measured typing intervals across 100 domains yield a p99 budget of 121 ms, allowing the API round-trip to complete before the next key release. The server returns precomputed top-8 results per prefix from a trie that stores only the head of the distribution, falling back to CZDS for less popular names when needed.

Tranco provides the ranked head while CZDS supplies the gTLD tail; ccTLD coverage remains incomplete. The system therefore prioritizes traffic-weighted domains and guarantees rank order in responses. This approach avoids full-text search and keeps trie memory footprint small enough for single-node deployment, a pattern also used in production DNS resolvers and certificate transparency indexers.

The original coverage understates scaling limits once the trie exceeds RAM or when CZDS update latency exceeds daily refreshes. Adding certificate transparency logs would close the ccTLD gap but requires incremental trie rebuilds. Operational impact is immediate for any domain-inspection tool: perceived latency drops below one display frame for 99 % of keystrokes.

Next integration step is daily CZDS delta ingestion with background trie rebuilds; query p99 must stay under 30 ms after the dataset reaches one billion entries.