From c432ab146fad2cab46b21c698d29d00cdb58a83b Mon Sep 17 00:00:00 2001
From: kbx81 <kbx81x@gmail.com>
Date: Thu, 3 Sep 2026 01:16:55 -0500
Subject: [PATCH] [serial_proxy] Compile out mode state in builds without a tap

PROTOCOL is refused when no tap exists, so mode_ could never leave RAW
there; gate the member and reset_mode_() behind USE_SERIAL_PROXY_TAP
(no-op inline otherwise), saving the member and the four reset calls in
every tapless build.
---
 esphome/components/serial_proxy/serial_proxy.cpp |  4 ++--
 esphome/components/serial_proxy/serial_proxy.h   | 11 +++++++++--
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/esphome/components/serial_proxy/serial_proxy.cpp b/esphome/components/serial_proxy/serial_proxy.cpp
index 416deddc92..129745c1c9 100644
--- a/esphome/components/serial_proxy/serial_proxy.cpp
+++ b/esphome/components/serial_proxy/serial_proxy.cpp
@@ -43,6 +43,7 @@ void SerialProxy::setup() {
   this->disable_loop();
 }
 
+#ifdef USE_SERIAL_PROXY_TAP
 void SerialProxy::reset_mode_() {
   // The mode belongs to a session, not to the port. Carrying a departed client's choice
   // over to the next one would inject protocol bytes into a stream that never asked for
@@ -55,6 +56,7 @@ void SerialProxy::reset_mode_() {
   ESP_LOGD(TAG, "Session ended, returning serial proxy [%" PRIu32 "] to RAW mode", this->instance_index_);
   this->mode_ = api::enums::SERIAL_PROXY_MODE_RAW;
 }
+#endif
 
 void SerialProxy::loop() {
 #ifdef USE_API
@@ -261,10 +263,8 @@ SerialProxyResult SerialProxy::set_mode_from_client(api::APIConnection *api_conn
 #ifdef USE_SERIAL_PROXY_TAP
   const bool leaving_protocol_mode =
       this->mode_ != api::enums::SERIAL_PROXY_MODE_RAW && mode == api::enums::SERIAL_PROXY_MODE_RAW;
-#endif
   this->mode_ = mode;
 
-#ifdef USE_SERIAL_PROXY_TAP
   // Only for an explicit client request, not for reset_mode_() at the end of a session:
   // an ordinary disconnect says nothing about the device, whereas a client deliberately
   // asking for raw bytes usually precedes changing what the device is.
diff --git a/esphome/components/serial_proxy/serial_proxy.h b/esphome/components/serial_proxy/serial_proxy.h
index e7b28c0221..e3f4264cfa 100644
--- a/esphome/components/serial_proxy/serial_proxy.h
+++ b/esphome/components/serial_proxy/serial_proxy.h
@@ -204,9 +204,14 @@ class SerialProxy final : public uart::UARTDevice, public Component {
   bool is_subscriber_(api::APIConnection *api_connection) const { return this->api_connection_ == api_connection; }
 #endif
 
-  /// Return the port to RAW when a subscriber goes away, so the mode never outlives it.
-  /// Not tap-gated: the mode is a client-visible property whether or not a tap acts on it.
+#ifdef USE_SERIAL_PROXY_TAP
+  /// Return the port to RAW when a subscriber goes away, so the mode never outlives it
   void reset_mode_();
+#else
+  /// Without a tap, PROTOCOL is refused, so the mode is fixed at RAW and there is
+  /// nothing to reset
+  void reset_mode_() {}
+#endif
 
 #ifdef USE_SERIAL_PROXY_TAP
   /// True when the tap should be shown the traffic passing through this port
@@ -230,8 +235,10 @@ class SerialProxy final : public uart::UARTDevice, public Component {
   /// Port type
   api::enums::SerialProxyPortType port_type_{};
 
+#ifdef USE_SERIAL_PROXY_TAP
   /// How the bytes passing through are treated; zero is SERIAL_PROXY_MODE_RAW
   api::enums::SerialProxyMode mode_{};
+#endif
 
   /// Optional GPIO pins for modem control
   GPIOPin *rts_pin_{nullptr};