hub: offsite pool-box checker logs the pool trend on each refresh (operator visibility)

hub/internal/monitor/offsite_box.go

@@ -153,8 +153,12 @@ func (c *OffsiteBoxChecker) Check() {
 	c.haveSnap = true
 
 	if snap.Degraded {
+		c.logger.Printf("[INFO] Offsite pool-box refreshed: DEGRADED (capacity unavailable) — box %d", c.boxID)
 		return // no band transitions on degraded data
 	}
+	// Periodic operator visibility of the pool trend (one line per 15-min refresh; keys, no secrets).
+	c.logger.Printf("[INFO] Offsite pool-box refreshed: %.1f%% full (%s of %s), Σ shared quota %d GB, oversub %.2fx",
+		snap.FillPercent, fmtSize(snap.UsedBytes), fmtSize(snap.CapacityBytes), snap.SumQuotaGB, snap.Ratio)
 
 	// FILL band (escalation-only; recovery re-arms because bandOK has rank 0).
 	if bandRank(snap.FillBand) > bandRank(c.fillBand) {