The four groups
Node event-loop phases
TIMERS · PENDING · POLL · CHECK
Four of the six phases in
libuv's loop.Node timer functions
SETTIMEOUT · SETINTERVAL · SETIMMEDIATE · NEXTTICK
Web Worker API methods/events
POSTMESSAGE · ONMESSAGE · TERMINATE · IMPORTSCRIPTS
Words that precede POOL
THREAD · CONNECTION · CAR · GENE
Why this puzzle works
Almost a single-domain Node puzzle until the purple group steals THREAD (which would happily live in a real 'concurrency primitives' bucket). CHECK is the trap in yellow — it sounds like a verb but it's a real libuv phase name. The Node-loop trivia is solidly Senior-Engineer-Interview material.
How to read a Connectle without solving it
A code-themed grouping puzzle rewards counting as much as recognition. Start by listing every plausible group, then notice which tiles appear in two lists. Whichever group has exactly four unambiguous members is your anchor — solve it first and the rest of the board collapses by elimination. The hardest tier (purple) is almost always wordplay: tiles that share a prefix or suffix, not a concept. If a tile feels orphaned, ask whether the same word could follow or precede a common engineering word like root, stack, cache, or queue.