aea4a90f0e
Adds a strict_mention config option that, when enabled, requires an explicit @-mention on every message in channel threads. Disables the 'once mentioned, forever in the thread' and session-presence auto-triggers. - New _slack_strict_mention() helper (config.extra + SLACK_STRICT_MENTION env) - Bridged top-level slack.strict_mention yaml to SLACK_STRICT_MENTION env, matching require_mention/allow_bots bridging - Unit tests for the helper + config bridge