feat: Monitor grath zoom

server/internal/models/monitor.go

@@ -71,6 +71,21 @@ type Incident struct {
 	Cause      string     `bson:"cause,omitempty" json:"cause,omitempty"`
 }
 
+// MonitorSample is one check result, kept only long enough to draw the
+// sub-hour views of the history chart. Rollup remains the durable record: a
+// sample expires by TTL, a rollup does not.
+//
+// It carries no message. The failure text is on the incident, and a document
+// per check is the one place in this schema where a few bytes multiply by the
+// check rate.
+type MonitorSample struct {
+	InstanceID string    `bson:"instance_id" json:"instance_id"`
+	MonitorID  string    `bson:"monitor_id" json:"monitor_id"`
+	At         time.Time `bson:"at" json:"at"`
+	Up         bool      `bson:"up" json:"up"`
+	LatencyMs  int       `bson:"latency_ms" json:"latency_ms"`
+}
+
 type Rollup struct {
 	InstanceID  string    `bson:"instance_id" json:"instance_id"`
 	MonitorID   string    `bson:"monitor_id" json:"monitor_id"`