With no SLACK_* secrets at all the app readiness check is NOT_CONFIGURED and the health indicator reports UNKNOWN (HTTP 200) with configured=false, so an optional, unset Slack integration can't fail a readiness probe (it took kof22's probe down). Not-yet-checked is UNKNOWN too. Partial or invalid configuration stays DOWN. Tests for all three. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>