From b125cd6979dd2393802db92db03354852829eb1e Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Sat, 19 Jul 2025 13:43:47 -1000
Subject: [PATCH] save some more

---
 esphome/components/api/api_frame_helper.cpp | 10 +++++++---
 esphome/components/api/api_frame_helper.h   |  9 +++++----
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/esphome/components/api/api_frame_helper.cpp b/esphome/components/api/api_frame_helper.cpp
index a6070185af..2e7956cb74 100644
--- a/esphome/components/api/api_frame_helper.cpp
+++ b/esphome/components/api/api_frame_helper.cpp
@@ -80,8 +80,11 @@ APIError APIFrameHelper::loop() {
 void APIFrameHelper::buffer_data_from_iov_(const struct iovec *iov, int iovcnt, uint16_t total_write_len,
                                            uint16_t offset) {
   SendBuffer buffer;
-  buffer.data.reserve(total_write_len - offset);
+  buffer.size = total_write_len - offset;
+  buffer.data = std::make_unique<uint8_t[]>(buffer.size);
+
   uint16_t to_skip = offset;
+  uint16_t write_pos = 0;
 
   for (int i = 0; i < iovcnt; i++) {
     if (to_skip >= iov[i].iov_len) {
@@ -89,9 +92,10 @@ void APIFrameHelper::buffer_data_from_iov_(const struct iovec *iov, int iovcnt,
       to_skip -= static_cast<uint16_t>(iov[i].iov_len);
     } else {
       // Include this segment (partially or fully)
-      const uint8_t *data = reinterpret_cast<uint8_t *>(iov[i].iov_base) + to_skip;
+      const uint8_t *src = reinterpret_cast<uint8_t *>(iov[i].iov_base) + to_skip;
       uint16_t len = static_cast<uint16_t>(iov[i].iov_len) - to_skip;
-      buffer.data.insert(buffer.data.end(), data, data + len);
+      std::memcpy(buffer.data.get() + write_pos, src, len);
+      write_pos += len;
       to_skip = 0;
     }
   }
diff --git a/esphome/components/api/api_frame_helper.h b/esphome/components/api/api_frame_helper.h
index 2debfb6131..b5b25700a8 100644
--- a/esphome/components/api/api_frame_helper.h
+++ b/esphome/components/api/api_frame_helper.h
@@ -116,12 +116,13 @@ class APIFrameHelper {
 
   // Buffer containing data to be sent
   struct SendBuffer {
-    std::vector<uint8_t> data;
-    uint16_t offset{0};  // Current offset within the buffer (uint16_t to reduce memory usage)
+    std::unique_ptr<uint8_t[]> data;
+    uint16_t size{0};    // Total size of the buffer
+    uint16_t offset{0};  // Current offset within the buffer
 
     // Using uint16_t reduces memory usage since ESPHome API messages are limited to UINT16_MAX (65535) bytes
-    uint16_t remaining() const { return static_cast<uint16_t>(data.size()) - offset; }
-    const uint8_t *current_data() const { return data.data() + offset; }
+    uint16_t remaining() const { return size - offset; }
+    const uint8_t *current_data() const { return data.get() + offset; }
   };
 
   // Common implementation for writing raw data to socket