From 53345724f2f5f1fd8f6c31080e8c296555190da2 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Wed, 11 Feb 2026 18:38:25 -0600
Subject: [PATCH] Use fixed stack buffer for query strings bounded by
 CONFIG_HTTPD_MAX_URI_LEN

Query strings cannot exceed the max URI length, so SmallBufferWithHeapFallback
is unnecessary. Use a plain stack array instead for zero heap allocation.
---
 esphome/components/web_server_idf/utils.cpp          | 11 ++++-------
 esphome/components/web_server_idf/web_server_idf.cpp |  6 +++---
 2 files changed, 7 insertions(+), 10 deletions(-)

diff --git a/esphome/components/web_server_idf/utils.cpp b/esphome/components/web_server_idf/utils.cpp
index 5bdd219944f..d9c43bd6c7a 100644
--- a/esphome/components/web_server_idf/utils.cpp
+++ b/esphome/components/web_server_idf/utils.cpp
@@ -1,5 +1,4 @@
 #ifdef USE_ESP32
-#include <memory>
 #include <cstring>
 #include <cctype>
 #include "esphome/core/helpers.h"
@@ -56,15 +55,13 @@ optional<std::string> query_key_value(const char *query_url, size_t query_len, c
     return {};
   }
 
-  // Use stack buffer for typical query strings, heap fallback for large ones
-  SmallBufferWithHeapFallback<256, char> val(query_len);
-
-  if (httpd_query_key_value(query_url, key, val.get(), query_len) != ESP_OK) {
+  char val[CONFIG_HTTPD_MAX_URI_LEN + 1];
+  if (httpd_query_key_value(query_url, key, val, query_len) != ESP_OK) {
     return {};
   }
 
-  url_decode(val.get());
-  return {val.get()};
+  url_decode(val);
+  return {val};
 }
 
 bool query_has_key(const char *query_url, size_t query_len, const char *key) {
diff --git a/esphome/components/web_server_idf/web_server_idf.cpp b/esphome/components/web_server_idf/web_server_idf.cpp
index 9ce4b3673d5..8e1623f0998 100644
--- a/esphome/components/web_server_idf/web_server_idf.cpp
+++ b/esphome/components/web_server_idf/web_server_idf.cpp
@@ -422,11 +422,11 @@ static auto search_query_sources(httpd_req_t *req, const std::string &post_query
   if (len == 0) {
     return {};
   }
-  SmallBufferWithHeapFallback<256, char> buf(len + 1);
-  if (httpd_req_get_url_query_str(req, buf.get(), len + 1) != ESP_OK) {
+  char buf[AsyncWebServerRequest::URL_BUF_SIZE];
+  if (httpd_req_get_url_query_str(req, buf, len + 1) != ESP_OK) {
     return {};
   }
-  return func(buf.get(), len, name);
+  return func(buf, len, name);
 }
 
 optional<std::string> AsyncWebServerRequest::find_query_value_(const char *name) const {