From fe8e7c134cdb180fd762b34aa51358151310f01c Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Fri, 27 Mar 2026 15:53:47 -1000
Subject: [PATCH] Add debug assert for uint16_t overflow in
 callback_manager_grow

---
 esphome/core/helpers.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/esphome/core/helpers.cpp b/esphome/core/helpers.cpp
index 8c97a03b121..5940f6ec985 100644
--- a/esphome/core/helpers.cpp
+++ b/esphome/core/helpers.cpp
@@ -24,6 +24,7 @@ static const char *const TAG = "helpers";
 
 __attribute__((noinline, cold)) void *callback_manager_grow(void *data, uint16_t size, uint16_t &capacity,
                                                             size_t elem_size) {
+  ESPHOME_DEBUG_ASSERT(size < UINT16_MAX);
   uint16_t new_cap = size + 1;
   auto *new_data = ::operator new(new_cap *elem_size);
   if (data) {