Restore review-flagged comment content cut too aggressively in comment reduction

src/core/wire/sample_usage.cpp

@@ -65,6 +65,9 @@ UsagePublishPlan planUsagePublish(const std::optional<std::string>& existing,
     plan.wire = encodeUsageRecord(cleanMine);
 
     if (!existing || existing->empty()) {
+        // NOTE (>16 MB gap): readReasamplerExtState returning nullopt for a value
+        // larger than 16 MB is indistinguishable from "absent" here, so that narrow
+        // case also takes this fresh-write branch rather than remint.
         return plan;  // fresh key — write mine
     }