From bde67d83f22596b96d595a8f6f57517faeb337b7 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Mon, 12 Oct 2026 01:33:19 -1000
Subject: [PATCH] [noise] Exclude the handshake write step from the loop
 blocking guard (#20573)

---
 esphome/components/noise/noise_handshake.cpp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/esphome/components/noise/noise_handshake.cpp b/esphome/components/noise/noise_handshake.cpp
index e0b7ca7c372..181dd63bb21 100644
--- a/esphome/components/noise/noise_handshake.cpp
+++ b/esphome/components/noise/noise_handshake.cpp
@@ -1,5 +1,6 @@
 #include "noise_handshake.h"
 #ifdef USE_NOISE
+#include "esphome/core/application.h"
 #include "esphome/core/hal.h"
 #include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
@@ -111,6 +112,8 @@ int NoiseResponderHandshake::read_message(uint8_t *data, size_t len) {
 
 int NoiseResponderHandshake::write_message(uint8_t *out, size_t capacity, size_t &out_len) {
   out_len = 0;
+  // The key agreement cannot be split across loop passes
+  UnavoidableBlockingScope scope;
   CpuFrequencyBoost boost;
   NoiseBuffer mbuf;
   noise_buffer_init(mbuf);