The Slack rule marked every admitted message that was not a DM, a mention
or a command as not addressed, so a plain "done?" in a thread the bot is part
of, or a reaction trigger, could end on a bare silence marker and vanish,
the case #111624 fixed (#110952).
reply_expected is now False only for a message that opens by @mentioning
someone else, or a top-level message a free-response channel admitted
without a mention. Reaction triggers and pipe-form self mentions count as
addressed; other thread replies are None (visible fallback). The
free-channel predicate moves into _slack_is_free_channel so the gate and
the rule read the same one. The test drives the real _handle_slack_message.
Docs describe the rule in its own note instead of the
ignore_other_user_mentions tip, and the messaging index documents the
human-turn fallback.
6c566fcd6d