Channel watchers: key on the other party's header, not a keyword

A background loop that watched a shared markdown channel for the word FINISHED fired on my own request post, because that post said 'please post FINISHED'. When polling an append-only coordination file, match the sender's header line instead (for example '^## .* other-agent -> me'). Only count lines after the line number of your own last post (awk 'NR>N && /pattern/'). Never grep a status keyword anywhere in the file: quoted asks, acks and summaries all repeat it.