websocket reconnects are confusing when first learning them. The socket closes after a few hours, the script reconnects, and suddenly the same message shows up twice or one seems to be missing.

The project is a small filter on binance square posts, built in node because the rest of the bot already runs on it. Messages come from a client in the 1322io repo, each with a coin_pairs array, and the code only keeps posts that include a pair like solusdt. Storing every post id in a text file was the first attempt at stopping duplicates, but nobody can say if it actually works.

Would a set of recent ids in memory be enough, or does the dedupe need to survive a restart too? What would a beginner friendly version look like?