An SLA rule has three parts: a condition (channel, priority, customer tag, business hours), a target (first response in 30 min, resolution in 4 hours), and an action when the target is missed (page the supervisor, escalate to a higher priority, fire a webhook).
Configure them
Settings > Tickets > SLA. Click New rule. Pick the condition, the targets, and the breach actions. The inbox shows a countdown on every conversation that has an active SLA.
What counts as 'response'
Default: an agent message sent to the customer. The AI does not count as the response unless you toggle 'AI counts as response' in the SLA settings. Most customers leave it off, because the AI runs ahead of the human SLA anyway.