From 13f9726534d84d48607c2c34bbd1ee51d5b564b5 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Mon, 9 Feb 2026 04:30:59 -0600
Subject: [PATCH] Add comment explaining available() <= 0 check

---
 esphome/components/rd03d/rd03d.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/esphome/components/rd03d/rd03d.cpp b/esphome/components/rd03d/rd03d.cpp
index 1b3212e2c09..5e644e537ef 100644
--- a/esphome/components/rd03d/rd03d.cpp
+++ b/esphome/components/rd03d/rd03d.cpp
@@ -81,6 +81,8 @@ void RD03DComponent::dump_config() {
 }
 
 void RD03DComponent::loop() {
+  // All current UART available() implementations return >= 0,
+  // use <= 0 to future-proof against any that may return negative on error.
   int avail = this->available();
   if (avail <= 0)
     return;