From 2113858f8955ab4464d3bb271477f9ae595aa9b6 Mon Sep 17 00:00:00 2001
From: Keith Burzinski <kbx81x@gmail.com>
Date: Sun, 21 Dec 2025 02:45:24 -0600
Subject: [PATCH 1/9] [sprinkler] Squash a few bugs + minor optimization
 (#12436)

---
 esphome/components/sprinkler/automation.h  |   6 +-
 esphome/components/sprinkler/sprinkler.cpp | 113 +++++++++++++--------
 esphome/components/sprinkler/sprinkler.h   |  16 +--
 3 files changed, 83 insertions(+), 52 deletions(-)

diff --git a/esphome/components/sprinkler/automation.h b/esphome/components/sprinkler/automation.h
index d6c877ae90..b3f030805d 100644
--- a/esphome/components/sprinkler/automation.h
+++ b/esphome/components/sprinkler/automation.h
@@ -4,8 +4,7 @@
 #include "esphome/core/component.h"
 #include "esphome/components/sprinkler/sprinkler.h"
 
-namespace esphome {
-namespace sprinkler {
+namespace esphome::sprinkler {
 
 template<typename... Ts> class SetDividerAction : public Action<Ts...> {
  public:
@@ -181,5 +180,4 @@ template<typename... Ts> class ResumeOrStartAction : public Action<Ts...> {
   Sprinkler *sprinkler_;
 };
 
-}  // namespace sprinkler
-}  // namespace esphome
+}  // namespace esphome::sprinkler
diff --git a/esphome/components/sprinkler/sprinkler.cpp b/esphome/components/sprinkler/sprinkler.cpp
index 8edb240a41..69452f2e9e 100644
--- a/esphome/components/sprinkler/sprinkler.cpp
+++ b/esphome/components/sprinkler/sprinkler.cpp
@@ -7,8 +7,7 @@
 #include <cinttypes>
 #include <utility>
 
-namespace esphome {
-namespace sprinkler {
+namespace esphome::sprinkler {
 
 static const char *const TAG = "sprinkler";
 
@@ -411,7 +410,8 @@ void Sprinkler::loop() {
   for (auto &vo : this->valve_op_) {
     vo.loop();
   }
-  if (this->prev_req_.has_request() && this->prev_req_.valve_operator()->state() == IDLE) {
+  if (this->prev_req_.has_request() && this->prev_req_.has_valve_operator() &&
+      this->prev_req_.valve_operator()->state() == IDLE) {
     this->prev_req_.reset();
   }
 }
@@ -808,11 +808,11 @@ bool Sprinkler::standby() {
 
 void Sprinkler::start_from_queue() {
   if (this->standby()) {
-    ESP_LOGD(TAG, "start_from_queue called but standby is enabled; no action taken");
+    this->log_standby_warning_(LOG_STR("start_from_queue"));
     return;
   }
   if (this->multiplier() == 0) {
-    ESP_LOGD(TAG, "start_from_queue called but multiplier is set to zero; no action taken");
+    this->log_multiplier_zero_warning_(LOG_STR("start_from_queue"));
     return;
   }
   if (this->queued_valves_.empty()) {
@@ -832,11 +832,11 @@ void Sprinkler::start_from_queue() {
 
 void Sprinkler::start_full_cycle() {
   if (this->standby()) {
-    ESP_LOGD(TAG, "start_full_cycle called but standby is enabled; no action taken");
+    this->log_standby_warning_(LOG_STR("start_full_cycle"));
     return;
   }
   if (this->multiplier() == 0) {
-    ESP_LOGD(TAG, "start_full_cycle called but multiplier is set to zero; no action taken");
+    this->log_multiplier_zero_warning_(LOG_STR("start_full_cycle"));
     return;
   }
   if (this->auto_advance() && this->active_valve().has_value()) {
@@ -855,11 +855,11 @@ void Sprinkler::start_full_cycle() {
 
 void Sprinkler::start_single_valve(const optional<size_t> valve_number, optional<uint32_t> run_duration) {
   if (this->standby()) {
-    ESP_LOGD(TAG, "start_single_valve called but standby is enabled; no action taken");
+    this->log_standby_warning_(LOG_STR("start_single_valve"));
     return;
   }
   if (this->multiplier() == 0) {
-    ESP_LOGD(TAG, "start_single_valve called but multiplier is set to zero; no action taken");
+    this->log_multiplier_zero_warning_(LOG_STR("start_single_valve"));
     return;
   }
   if (!valve_number.has_value() || (valve_number == this->active_valve())) {
@@ -891,6 +891,11 @@ void Sprinkler::clear_queued_valves() {
 }
 
 void Sprinkler::next_valve() {
+  if (this->standby()) {
+    this->log_standby_warning_(LOG_STR("next_valve"));
+    return;
+  }
+
   if (this->state_ == IDLE) {
     this->reset_cycle_states_();  // just in case auto-advance is switched on later
   }
@@ -914,6 +919,11 @@ void Sprinkler::next_valve() {
 }
 
 void Sprinkler::previous_valve() {
+  if (this->standby()) {
+    this->log_standby_warning_(LOG_STR("previous_valve"));
+    return;
+  }
+
   if (this->state_ == IDLE) {
     this->reset_cycle_states_();  // just in case auto-advance is switched on later
   }
@@ -964,7 +974,7 @@ void Sprinkler::pause() {
 
 void Sprinkler::resume() {
   if (this->standby()) {
-    ESP_LOGD(TAG, "resume called but standby is enabled; no action taken");
+    this->log_standby_warning_(LOG_STR("resume"));
     return;
   }
 
@@ -1009,7 +1019,7 @@ optional<SprinklerValveRunRequestOrigin> Sprinkler::active_valve_request_is_from
 }
 
 optional<size_t> Sprinkler::active_valve() {
-  if (!this->valve_overlap_ && this->prev_req_.has_request() &&
+  if (!this->valve_overlap_ && this->prev_req_.has_request() && this->prev_req_.has_valve_operator() &&
       (this->prev_req_.valve_operator()->state() == STARTING || this->prev_req_.valve_operator()->state() == ACTIVE)) {
     return this->prev_req_.valve_as_opt();
   }
@@ -1029,9 +1039,7 @@ optional<size_t> Sprinkler::manual_valve() { return this->manual_valve_; }
 
 size_t Sprinkler::number_of_valves() { return this->valve_.size(); }
 
-bool Sprinkler::is_a_valid_valve(const size_t valve_number) {
-  return ((valve_number >= 0) && (valve_number < this->number_of_valves()));
-}
+bool Sprinkler::is_a_valid_valve(const size_t valve_number) { return (valve_number < this->number_of_valves()); }
 
 bool Sprinkler::pump_in_use(SprinklerSwitch *pump_switch) {
   if (pump_switch == nullptr) {
@@ -1062,8 +1070,12 @@ bool Sprinkler::pump_in_use(SprinklerSwitch *pump_switch) {
       this->active_req_.has_request() && (this->state_ != STOPPING)) {
     // ...the controller is configured to keep the pump on during a valve open delay, so just return
     //  whether or not the next valve shares the same pump
-    return (pump_switch->off_switch() == this->valve_pump_switch(this->active_req_.valve())->off_switch()) &&
-           (pump_switch->on_switch() == this->valve_pump_switch(this->active_req_.valve())->on_switch());
+    auto *valve_pump = this->valve_pump_switch(this->active_req_.valve());
+    if (valve_pump == nullptr) {
+      return false;  // valve has no pump, so this pump isn't in use by it
+    }
+    return (pump_switch->off_switch() == valve_pump->off_switch()) &&
+           (pump_switch->on_switch() == valve_pump->on_switch());
   }
   return false;
 }
@@ -1426,8 +1438,8 @@ void Sprinkler::start_valve_(SprinklerValveRunRequest *req) {
     if (vo.state() == IDLE) {
       auto run_duration = req->run_duration() ? req->run_duration() : this->valve_run_duration_adjusted(req->valve());
       ESP_LOGD(TAG, "%s is starting valve %zu for %" PRIu32 " seconds, cycle %" PRIu32 " of %" PRIu32,
-               this->req_as_str_(req->request_is_from()).c_str(), req->valve(), run_duration, this->repeat_count_ + 1,
-               this->repeat().value_or(0) + 1);
+               LOG_STR_ARG(this->req_as_str_(req->request_is_from())), req->valve(), run_duration,
+               this->repeat_count_ + 1, this->repeat().value_or(0) + 1);
       req->set_valve_operator(&vo);
       vo.set_controller(this);
       vo.set_valve(&this->valve_[req->valve()]);
@@ -1488,7 +1500,7 @@ void Sprinkler::fsm_kick_() {
 }
 
 void Sprinkler::fsm_transition_() {
-  ESP_LOGVV(TAG, "fsm_transition_ called; state is %s", this->state_as_str_(this->state_).c_str());
+  ESP_LOGVV(TAG, "fsm_transition_ called; state is %s", LOG_STR_ARG(this->state_as_str_(this->state_)));
   switch (this->state_) {
     case IDLE:  // the system was off -> start it up
       // advances to ACTIVE
@@ -1502,8 +1514,11 @@ void Sprinkler::fsm_transition_() {
 
     case STARTING: {
       // follows valve open delay interval
-      this->set_timer_duration_(sprinkler::TIMER_SM,
-                                this->active_req_.run_duration() - this->switching_delay_.value_or(0));
+      uint32_t timer_duration = this->active_req_.run_duration();
+      if (timer_duration > this->switching_delay_.value_or(0)) {
+        timer_duration -= this->switching_delay_.value_or(0);
+      }
+      this->set_timer_duration_(sprinkler::TIMER_SM, timer_duration);
       this->start_timer_(sprinkler::TIMER_SM);
       this->start_valve_(&this->active_req_);
       this->state_ = ACTIVE;
@@ -1531,7 +1546,7 @@ void Sprinkler::fsm_transition_() {
     this->set_timer_duration_(sprinkler::TIMER_SM, this->manual_selection_delay_.value_or(1));
     this->start_timer_(sprinkler::TIMER_SM);
   }
-  ESP_LOGVV(TAG, "fsm_transition_ complete; new state is %s", this->state_as_str_(this->state_).c_str());
+  ESP_LOGVV(TAG, "fsm_transition_ complete; new state is %s", LOG_STR_ARG(this->state_as_str_(this->state_)));
 }
 
 void Sprinkler::fsm_transition_from_shutdown_() {
@@ -1543,8 +1558,11 @@ void Sprinkler::fsm_transition_from_shutdown_() {
     this->active_req_.set_run_duration(this->next_req_.run_duration());
     this->next_req_.reset();
 
-    this->set_timer_duration_(sprinkler::TIMER_SM,
-                              this->active_req_.run_duration() - this->switching_delay_.value_or(0));
+    uint32_t timer_duration = this->active_req_.run_duration();
+    if (timer_duration > this->switching_delay_.value_or(0)) {
+      timer_duration -= this->switching_delay_.value_or(0);
+    }
+    this->set_timer_duration_(sprinkler::TIMER_SM, timer_duration);
     this->start_timer_(sprinkler::TIMER_SM);
     this->start_valve_(&this->active_req_);
     this->state_ = ACTIVE;
@@ -1571,8 +1589,9 @@ void Sprinkler::fsm_transition_from_valve_run_() {
   this->load_next_valve_run_request_(this->active_req_.valve());
 
   if (this->next_req_.has_request()) {  // there is another valve to run...
-    bool same_pump =
-        this->valve_pump_switch(this->active_req_.valve()) == this->valve_pump_switch(this->next_req_.valve());
+    auto *active_pump = this->valve_pump_switch(this->active_req_.valve());
+    auto *next_pump = this->valve_pump_switch(this->next_req_.valve());
+    bool same_pump = (active_pump != nullptr) && (next_pump != nullptr) && (active_pump == next_pump);
 
     this->active_req_.set_valve(this->next_req_.valve());
     this->active_req_.set_request_from(this->next_req_.request_is_from());
@@ -1581,8 +1600,11 @@ void Sprinkler::fsm_transition_from_valve_run_() {
 
     // this->state_ = ACTIVE;  // state isn't changing
     if (this->valve_overlap_ || !this->switching_delay_.has_value()) {
-      this->set_timer_duration_(sprinkler::TIMER_SM,
-                                this->active_req_.run_duration() - this->switching_delay_.value_or(0));
+      uint32_t timer_duration = this->active_req_.run_duration();
+      if (timer_duration > this->switching_delay_.value_or(0)) {
+        timer_duration -= this->switching_delay_.value_or(0);
+      }
+      this->set_timer_duration_(sprinkler::TIMER_SM, timer_duration);
       this->start_timer_(sprinkler::TIMER_SM);
       this->start_valve_(&this->active_req_);
     } else {
@@ -1605,41 +1627,49 @@ void Sprinkler::fsm_transition_to_shutdown_() {
   this->start_timer_(sprinkler::TIMER_SM);
 }
 
-std::string Sprinkler::req_as_str_(SprinklerValveRunRequestOrigin origin) {
+void Sprinkler::log_standby_warning_(const LogString *method_name) {
+  ESP_LOGW(TAG, "%s called but standby is enabled; no action taken", LOG_STR_ARG(method_name));
+}
+
+void Sprinkler::log_multiplier_zero_warning_(const LogString *method_name) {
+  ESP_LOGW(TAG, "%s called but multiplier is set to zero; no action taken", LOG_STR_ARG(method_name));
+}
+
+const LogString *Sprinkler::req_as_str_(SprinklerValveRunRequestOrigin origin) {
   switch (origin) {
     case USER:
-      return "USER";
+      return LOG_STR("USER");
 
     case CYCLE:
-      return "CYCLE";
+      return LOG_STR("CYCLE");
 
     case QUEUE:
-      return "QUEUE";
+      return LOG_STR("QUEUE");
 
     default:
-      return "UNKNOWN";
+      return LOG_STR("UNKNOWN");
   }
 }
 
-std::string Sprinkler::state_as_str_(SprinklerState state) {
+const LogString *Sprinkler::state_as_str_(SprinklerState state) {
   switch (state) {
     case IDLE:
-      return "IDLE";
+      return LOG_STR("IDLE");
 
     case STARTING:
-      return "STARTING";
+      return LOG_STR("STARTING");
 
     case ACTIVE:
-      return "ACTIVE";
+      return LOG_STR("ACTIVE");
 
     case STOPPING:
-      return "STOPPING";
+      return LOG_STR("STOPPING");
 
     case BYPASS:
-      return "BYPASS";
+      return LOG_STR("BYPASS");
 
     default:
-      return "UNKNOWN";
+      return LOG_STR("UNKNOWN");
   }
 }
 
@@ -1737,5 +1767,4 @@ void Sprinkler::dump_config() {
   }
 }
 
-}  // namespace sprinkler
-}  // namespace esphome
+}  // namespace esphome::sprinkler
diff --git a/esphome/components/sprinkler/sprinkler.h b/esphome/components/sprinkler/sprinkler.h
index c4a8b8aeb8..7aa33c2df9 100644
--- a/esphome/components/sprinkler/sprinkler.h
+++ b/esphome/components/sprinkler/sprinkler.h
@@ -8,8 +8,7 @@
 
 #include <vector>
 
-namespace esphome {
-namespace sprinkler {
+namespace esphome::sprinkler {
 
 const std::string MIN_STR = "min";
 
@@ -490,11 +489,17 @@ class Sprinkler : public Component {
   /// starts up the system from IDLE state
   void fsm_transition_to_shutdown_();
 
+  /// log error message when a method is called but standby is enabled
+  void log_standby_warning_(const LogString *method_name);
+
+  /// log error message when a method is called but multiplier is zero
+  void log_multiplier_zero_warning_(const LogString *method_name);
+
   /// return the specified SprinklerValveRunRequestOrigin as a string
-  std::string req_as_str_(SprinklerValveRunRequestOrigin origin);
+  const LogString *req_as_str_(SprinklerValveRunRequestOrigin origin);
 
   /// return the specified SprinklerState state as a string
-  std::string state_as_str_(SprinklerState state);
+  const LogString *state_as_str_(SprinklerState state);
 
   /// Start/cancel/get status of valve timers
   void start_timer_(SprinklerTimerIndex timer_index);
@@ -607,5 +612,4 @@ class Sprinkler : public Component {
   std::unique_ptr<Automation<>> sprinkler_standby_turn_on_automation_;
 };
 
-}  // namespace sprinkler
-}  // namespace esphome
+}  // namespace esphome::sprinkler

From 60756db06d9ce8bd58a499a58df5b1406b1f60b6 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Sat, 20 Dec 2025 22:47:37 -1000
Subject: [PATCH 2/9] [syslog] Use C++17 nested namespace syntax (#12594)

---
 esphome/components/syslog/esphome_syslog.cpp | 6 ++----
 esphome/components/syslog/esphome_syslog.h   | 6 ++----
 2 files changed, 4 insertions(+), 8 deletions(-)

diff --git a/esphome/components/syslog/esphome_syslog.cpp b/esphome/components/syslog/esphome_syslog.cpp
index 851fb30c22..d48fb4f15c 100644
--- a/esphome/components/syslog/esphome_syslog.cpp
+++ b/esphome/components/syslog/esphome_syslog.cpp
@@ -4,8 +4,7 @@
 #include "esphome/core/application.h"
 #include "esphome/core/time.h"
 
-namespace esphome {
-namespace syslog {
+namespace esphome::syslog {
 
 // Map log levels to syslog severity using an array, indexed by ESPHome log level (1-7)
 constexpr int LOG_LEVEL_TO_SYSLOG_SEVERITY[] = {
@@ -54,5 +53,4 @@ void Syslog::log_(const int level, const char *tag, const char *message, size_t
   this->parent_->send_packet((const uint8_t *) data.data(), data.size());
 }
 
-}  // namespace syslog
-}  // namespace esphome
+}  // namespace esphome::syslog
diff --git a/esphome/components/syslog/esphome_syslog.h b/esphome/components/syslog/esphome_syslog.h
index 1010993265..bde6ab5ed4 100644
--- a/esphome/components/syslog/esphome_syslog.h
+++ b/esphome/components/syslog/esphome_syslog.h
@@ -7,8 +7,7 @@
 #include "esphome/components/time/real_time_clock.h"
 
 #ifdef USE_NETWORK
-namespace esphome {
-namespace syslog {
+namespace esphome::syslog {
 class Syslog : public Component, public Parented<udp::UDPComponent>, public logger::LogListener {
  public:
   Syslog(int level, time::RealTimeClock *time) : log_level_(level), time_(time) {}
@@ -24,6 +23,5 @@ class Syslog : public Component, public Parented<udp::UDPComponent>, public logg
   bool strip_{true};
   int facility_{16};
 };
-}  // namespace syslog
-}  // namespace esphome
+}  // namespace esphome::syslog
 #endif

From 5a36cea5eccead440a6984227ae84d2ac4c34173 Mon Sep 17 00:00:00 2001
From: polyfloyd <polyfloyd@users.noreply.github.com>
Date: Sun, 21 Dec 2025 15:26:03 +0100
Subject: [PATCH 3/9] Add nix files to gitignore (#12604)

---
 .gitignore | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/.gitignore b/.gitignore
index 390d1ab45b..da568d9b83 100644
--- a/.gitignore
+++ b/.gitignore
@@ -91,6 +91,10 @@ venv-*/
 # mypy
 .mypy_cache/
 
+# nix
+/default.nix
+/shell.nix
+
 .pioenvs
 .piolibdeps
 .pio

From a799ac64882db9f7817e55386ea9c782adaa30b1 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Sun, 21 Dec 2025 07:10:27 -1000
Subject: [PATCH 4/9] [syslog] Eliminate heap allocations in log path (#12589)

---
 esphome/components/syslog/esphome_syslog.cpp |  46 ++-
 tests/integration/fixtures/syslog.yaml       |  43 +++
 tests/integration/test_syslog.py             | 284 +++++++++++++++++++
 3 files changed, 362 insertions(+), 11 deletions(-)
 create mode 100644 tests/integration/fixtures/syslog.yaml
 create mode 100644 tests/integration/test_syslog.py

diff --git a/esphome/components/syslog/esphome_syslog.cpp b/esphome/components/syslog/esphome_syslog.cpp
index d48fb4f15c..83ad6b2720 100644
--- a/esphome/components/syslog/esphome_syslog.cpp
+++ b/esphome/components/syslog/esphome_syslog.cpp
@@ -33,15 +33,7 @@ void Syslog::log_(const int level, const char *tag, const char *message, size_t
     severity = LOG_LEVEL_TO_SYSLOG_SEVERITY[level];
   }
   int pri = this->facility_ * 8 + severity;
-  auto now = this->time_->now();
-  std::string timestamp;
-  if (now.is_valid()) {
-    timestamp = now.strftime("%b %e %H:%M:%S");
-  } else {
-    // RFC 5424: A syslog application MUST use the NILVALUE as TIMESTAMP if the syslog application is incapable of
-    //           obtaining system time.
-    timestamp = "-";
-  }
+
   size_t len = message_len;
   // remove color formatting
   if (this->strip_ && message[0] == 0x1B && len > 11) {
@@ -49,8 +41,40 @@ void Syslog::log_(const int level, const char *tag, const char *message, size_t
     len -= 11;
   }
 
-  auto data = str_sprintf("<%d>%s %s %s: %.*s", pri, timestamp.c_str(), App.get_name().c_str(), tag, len, message);
-  this->parent_->send_packet((const uint8_t *) data.data(), data.size());
+  // Build syslog packet on stack (508 bytes chosen as practical limit for syslog over UDP)
+  char packet[508];
+  size_t offset = 0;
+  size_t remaining = sizeof(packet);
+
+  // Write PRI - abort if this fails as packet would be malformed
+  int ret = snprintf(packet, remaining, "<%d>", pri);
+  if (ret <= 0 || static_cast<size_t>(ret) >= remaining) {
+    return;
+  }
+  offset = ret;
+  remaining -= ret;
+
+  // Write timestamp directly into packet (RFC 5424: use "-" if time not valid or strftime fails)
+  auto now = this->time_->now();
+  size_t ts_written = now.is_valid() ? now.strftime(packet + offset, remaining, "%b %e %H:%M:%S") : 0;
+  if (ts_written > 0) {
+    offset += ts_written;
+    remaining -= ts_written;
+  } else if (remaining > 0) {
+    packet[offset++] = '-';
+    remaining--;
+  }
+
+  // Write hostname, tag, and message
+  ret = snprintf(packet + offset, remaining, " %s %s: %.*s", App.get_name().c_str(), tag, (int) len, message);
+  if (ret > 0) {
+    // snprintf returns chars that would be written; clamp to actual buffer space
+    offset += std::min(static_cast<size_t>(ret), remaining > 0 ? remaining - 1 : 0);
+  }
+
+  if (offset > 0) {
+    this->parent_->send_packet(reinterpret_cast<const uint8_t *>(packet), offset);
+  }
 }
 
 }  // namespace esphome::syslog
diff --git a/tests/integration/fixtures/syslog.yaml b/tests/integration/fixtures/syslog.yaml
new file mode 100644
index 0000000000..df376087e3
--- /dev/null
+++ b/tests/integration/fixtures/syslog.yaml
@@ -0,0 +1,43 @@
+esphome:
+  name: syslog-test
+
+host:
+
+api:
+  services:
+    - service: log_long_message
+      then:
+        - lambda: |-
+            // Log a message that exceeds 508 bytes to test truncation
+            ESP_LOGI("trunctest", "START|%s|END",
+              "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
+              "BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB"
+              "CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC"
+              "DDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDD"
+              "EEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE"
+              "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF");
+    - service: log_short_message
+      then:
+        - lambda: |-
+            // Log a short message that should arrive complete (not truncated)
+            ESP_LOGI("shorttest", "BEGIN|SHORT_MESSAGE_CONTENT|FINISH");
+
+logger:
+  level: DEBUG
+
+time:
+  - platform: host
+    id: host_time
+
+udp:
+  - id: syslog_udp
+    addresses:
+      - "127.0.0.1"
+
+syslog:
+  udp_id: syslog_udp
+  time_id: host_time
+  port: SYSLOG_PORT_PLACEHOLDER
+  level: DEBUG
+  strip: true
+  facility: 16
diff --git a/tests/integration/test_syslog.py b/tests/integration/test_syslog.py
new file mode 100644
index 0000000000..b31a19392c
--- /dev/null
+++ b/tests/integration/test_syslog.py
@@ -0,0 +1,284 @@
+"""Integration test for syslog component."""
+
+from __future__ import annotations
+
+import asyncio
+from collections.abc import AsyncGenerator
+import contextlib
+from contextlib import asynccontextmanager
+from dataclasses import dataclass, field
+import re
+import socket
+from typing import TypedDict
+
+import pytest
+
+from .types import APIClientConnectedFactory, RunCompiledFunction
+
+
+class ParsedSyslogMessage(TypedDict):
+    """Parsed syslog message components."""
+
+    pri: int
+    facility: int
+    severity: int
+    timestamp: str
+    hostname: str
+    tag: str
+    message: str
+
+
+# RFC 3164 syslog message pattern:
+# <PRI>TIMESTAMP HOSTNAME TAG: MESSAGE
+# Example: <134>Dec 20 14:30:45 syslog-test app: [D][app:029]: Running...
+SYSLOG_PATTERN = re.compile(
+    r"<(\d+)>"  # PRI (priority = facility * 8 + severity)
+    r"(\S+ +\d+ \d+:\d+:\d+|-)"  # TIMESTAMP (BSD-style "%b %e %H:%M:%S", e.g. "Dec 20 14:30:45", or NILVALUE "-")
+    r" (\S+)"  # HOSTNAME
+    r" (\S+):"  # TAG
+    r" (.*)"  # MESSAGE
+)
+
+
+@dataclass
+class SyslogReceiver:
+    """Collects syslog messages received over UDP."""
+
+    messages: list[str] = field(default_factory=list)
+    message_received: asyncio.Event = field(default_factory=asyncio.Event)
+    _waiters: list[tuple[re.Pattern, asyncio.Event]] = field(default_factory=list)
+
+    def on_message(self, msg: str) -> None:
+        """Called when a message is received."""
+        self.messages.append(msg)
+        self.message_received.set()
+        # Check pattern waiters
+        for pattern, event in self._waiters:
+            if pattern.search(msg):
+                event.set()
+
+    async def wait_for_messages(self, timeout: float = 10.0) -> None:
+        """Wait for at least one message to be received."""
+        await asyncio.wait_for(self.message_received.wait(), timeout=timeout)
+
+    async def wait_for_pattern(self, pattern: str, timeout: float = 5.0) -> str:
+        """Wait for a message matching the pattern."""
+        compiled = re.compile(pattern)
+        event = asyncio.Event()
+        self._waiters.append((compiled, event))
+        try:
+            # Check existing messages first
+            for msg in self.messages:
+                if compiled.search(msg):
+                    return msg
+            # Wait for new message
+            await asyncio.wait_for(event.wait(), timeout=timeout)
+            # Find and return the matching message
+            for msg in reversed(self.messages):
+                if compiled.search(msg):
+                    return msg
+            raise RuntimeError("Event set but no matching message found")
+        finally:
+            self._waiters.remove((compiled, event))
+
+
+@asynccontextmanager
+async def syslog_udp_listener() -> AsyncGenerator[tuple[int, SyslogReceiver]]:
+    """Async context manager that listens for syslog UDP messages.
+
+    Yields:
+        Tuple of (port, SyslogReceiver) where port is the UDP port to send to
+        and SyslogReceiver contains the received messages.
+    """
+    # Create and bind UDP socket
+    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+    sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+    sock.bind(("127.0.0.1", 0))
+    sock.setblocking(False)
+    port = sock.getsockname()[1]
+
+    receiver = SyslogReceiver()
+
+    async def receive_messages() -> None:
+        """Background task to receive syslog messages."""
+        loop = asyncio.get_running_loop()
+        while True:
+            try:
+                data = await loop.sock_recv(sock, 4096)
+                if data:
+                    msg = data.decode("utf-8", errors="replace")
+                    receiver.on_message(msg)
+            except BlockingIOError:
+                await asyncio.sleep(0.01)
+            except Exception:
+                break
+
+    task = asyncio.create_task(receive_messages())
+    try:
+        yield port, receiver
+    finally:
+        task.cancel()
+        with contextlib.suppress(asyncio.CancelledError):
+            await task
+        sock.close()
+
+
+def parse_syslog_message(msg: str) -> ParsedSyslogMessage | None:
+    """Parse a syslog message and return its components."""
+    match = SYSLOG_PATTERN.match(msg)
+    if not match:
+        return None
+    pri, timestamp, hostname, tag, message = match.groups()
+    pri_val = int(pri)
+    # PRI = facility * 8 + severity
+    facility = pri_val // 8
+    severity = pri_val % 8
+    return ParsedSyslogMessage(
+        pri=pri_val,
+        facility=facility,
+        severity=severity,
+        timestamp=timestamp,
+        hostname=hostname,
+        tag=tag,
+        message=message,
+    )
+
+
+@pytest.mark.asyncio
+async def test_syslog(
+    yaml_config: str,
+    run_compiled: RunCompiledFunction,
+    api_client_connected: APIClientConnectedFactory,
+) -> None:
+    """Test syslog component sends properly formatted messages."""
+    async with syslog_udp_listener() as (udp_port, receiver):
+        # Replace the placeholder port in the config
+        config = yaml_config.replace("SYSLOG_PORT_PLACEHOLDER", str(udp_port))
+
+        async with run_compiled(config), api_client_connected() as client:
+            # Verify device is running
+            device_info = await client.device_info()
+            assert device_info is not None
+            assert device_info.name == "syslog-test"
+
+            # Wait for syslog messages (ESPHome logs during startup)
+            try:
+                await receiver.wait_for_messages(timeout=10.0)
+            except TimeoutError:
+                pytest.fail("No syslog messages received within timeout")
+
+            # Give it a moment to collect more messages
+            await asyncio.sleep(0.5)
+
+            # Verify we received messages
+            assert len(receiver.messages) > 0, "No syslog messages received"
+
+            # Parse and validate all messages
+            parsed_messages: list[ParsedSyslogMessage] = []
+            for msg in receiver.messages:
+                parsed = parse_syslog_message(msg)
+                if parsed:
+                    parsed_messages.append(parsed)
+
+            assert len(parsed_messages) > 0, (
+                f"No valid syslog messages found. Received: {receiver.messages[:5]}"
+            )
+
+            # Validate message format for all parsed messages
+            for parsed in parsed_messages:
+                # Validate PRI is in valid range (0-191)
+                assert 0 <= parsed["pri"] <= 191, f"Invalid PRI: {parsed['pri']}"
+
+                # Validate facility matches config (16 = local0)
+                assert parsed["facility"] == 16, (
+                    f"Expected facility 16, got {parsed['facility']}"
+                )
+
+                # Validate severity is in valid range (0-7)
+                assert 0 <= parsed["severity"] <= 7, (
+                    f"Invalid severity: {parsed['severity']}"
+                )
+
+                # Validate hostname matches device name
+                assert parsed["hostname"] == "syslog-test", (
+                    f"Unexpected hostname: {parsed['hostname']}"
+                )
+
+                # Validate timestamp format (BSD or NILVALUE)
+                if parsed["timestamp"] != "-":
+                    assert re.match(
+                        r"[A-Z][a-z]{2} +\d+ \d{2}:\d{2}:\d{2}",
+                        parsed["timestamp"],
+                    ), f"Invalid timestamp format: {parsed['timestamp']}"
+
+            # Verify we see different severity levels in the logs
+            severities_seen = {p["severity"] for p in parsed_messages}
+            # ESPHome startup logs should include at least INFO (5) or DEBUG (7)
+            assert len(severities_seen) >= 1, "Expected to see at least one severity"
+
+            # Verify messages don't contain ANSI color codes (strip=true)
+            for parsed in parsed_messages:
+                assert "\x1b[" not in parsed["message"], (
+                    f"Color codes not stripped: {parsed['message'][:50]}"
+                )
+
+            # Verify message content is not empty for most messages
+            non_empty_messages = [p for p in parsed_messages if p["message"].strip()]
+            assert len(non_empty_messages) > 0, "All messages are empty"
+
+            # Verify tag format (should be component name like "app", "wifi", etc.)
+            for parsed in parsed_messages:
+                assert len(parsed["tag"]) > 0, "Empty tag"
+                # Tag should not contain spaces or colons
+                assert " " not in parsed["tag"], f"Tag contains space: {parsed['tag']}"
+
+            # Test message truncation - call service that logs a very long message
+            _, services = await client.list_entities_services()
+            log_service = next(
+                (s for s in services if s.name == "log_long_message"), None
+            )
+            assert log_service is not None, "log_long_message service not found"
+
+            # Call the service to trigger a long log message
+            await client.execute_service(log_service, {})
+
+            # Wait specifically for the truncation test message
+            try:
+                trunc_msg = await receiver.wait_for_pattern(r"trunctest.*START\|")
+            except TimeoutError:
+                pytest.fail(
+                    f"Truncation test message not received. Got: {receiver.messages}"
+                )
+
+            # Verify message is truncated to max 508 bytes
+            assert len(trunc_msg) <= 508, f"Message exceeds 508 bytes: {len(trunc_msg)}"
+
+            # Verify the message starts correctly but is truncated (no "|END")
+            assert "START|" in trunc_msg, "Message should contain START marker"
+            assert "|END" not in trunc_msg, (
+                "Message should be truncated before END marker"
+            )
+
+            # Test short message - should arrive complete (not truncated)
+            short_service = next(
+                (s for s in services if s.name == "log_short_message"), None
+            )
+            assert short_service is not None, "log_short_message service not found"
+
+            await client.execute_service(short_service, {})
+
+            try:
+                short_msg = await receiver.wait_for_pattern(r"shorttest.*BEGIN\|")
+            except TimeoutError:
+                pytest.fail(
+                    f"Short test message not received. Got: {receiver.messages[-10:]}"
+                )
+
+            # Verify short message arrived complete with both markers
+            assert "BEGIN|" in short_msg, "Short message missing BEGIN marker"
+            assert "|FINISH" in short_msg, (
+                f"Short message truncated unexpectedly: {short_msg}"
+            )
+            assert "SHORT_MESSAGE_CONTENT" in short_msg, (
+                f"Short message content missing: {short_msg}"
+            )

From c70eab931e003be5704ebdc6261f62c7357537c7 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Sun, 21 Dec 2025 07:31:54 -1000
Subject: [PATCH 5/9] [api] Add zero-copy support for Home Assistant state
 response messages (#12585)

---
 esphome/components/api/api.proto            |  6 ++---
 esphome/components/api/api_connection.cpp   | 28 +++++++++++++++------
 esphome/components/api/api_pb2.cpp          | 21 +++++++++++-----
 esphome/components/api/api_pb2.h            | 11 +++++---
 esphome/components/api/api_pb2_dump.cpp     | 12 ++++++---
 tests/integration/test_api_homeassistant.py |  6 +++++
 6 files changed, 61 insertions(+), 23 deletions(-)

diff --git a/esphome/components/api/api.proto b/esphome/components/api/api.proto
index 5d44d7e549..bf39f0b14b 100644
--- a/esphome/components/api/api.proto
+++ b/esphome/components/api/api.proto
@@ -824,9 +824,9 @@ message HomeAssistantStateResponse {
   option (no_delay) = true;
   option (ifdef) = "USE_API_HOMEASSISTANT_STATES";
 
-  string entity_id = 1;
-  string state = 2;
-  string attribute = 3;
+  string entity_id = 1 [(pointer_to_buffer) = true];
+  string state = 2 [(pointer_to_buffer) = true];
+  string attribute = 3 [(pointer_to_buffer) = true];
 }
 
 // ==================== IMPORT TIME ====================
diff --git a/esphome/components/api/api_connection.cpp b/esphome/components/api/api_connection.cpp
index 0f551d1bc3..1bcb90b0b0 100644
--- a/esphome/components/api/api_connection.cpp
+++ b/esphome/components/api/api_connection.cpp
@@ -1582,15 +1582,29 @@ bool APIConnection::send_device_info_response(const DeviceInfoRequest &msg) {
 
 #ifdef USE_API_HOMEASSISTANT_STATES
 void APIConnection::on_home_assistant_state_response(const HomeAssistantStateResponse &msg) {
-  for (auto &it : this->parent_->get_state_subs()) {
-    // Compare entity_id and attribute with message fields
-    bool entity_match = (strcmp(it.entity_id, msg.entity_id.c_str()) == 0);
-    bool attribute_match = (it.attribute != nullptr && strcmp(it.attribute, msg.attribute.c_str()) == 0) ||
-                           (it.attribute == nullptr && msg.attribute.empty());
+  // Skip if entity_id is empty (invalid message)
+  if (msg.entity_id_len == 0) {
+    return;
+  }
 
-    if (entity_match && attribute_match) {
-      it.callback(msg.state);
+  for (auto &it : this->parent_->get_state_subs()) {
+    // Compare entity_id: check length matches and content matches
+    size_t entity_id_len = strlen(it.entity_id);
+    if (entity_id_len != msg.entity_id_len || memcmp(it.entity_id, msg.entity_id, msg.entity_id_len) != 0) {
+      continue;
     }
+
+    // Compare attribute: either both have matching attribute, or both have none
+    size_t sub_attr_len = it.attribute != nullptr ? strlen(it.attribute) : 0;
+    if (sub_attr_len != msg.attribute_len ||
+        (sub_attr_len > 0 && memcmp(it.attribute, msg.attribute, sub_attr_len) != 0)) {
+      continue;
+    }
+
+    // Create temporary string for callback (callback takes const std::string &)
+    // Handle empty state (nullptr with len=0)
+    std::string state(msg.state_len > 0 ? reinterpret_cast<const char *>(msg.state) : "", msg.state_len);
+    it.callback(state);
   }
 }
 #endif
diff --git a/esphome/components/api/api_pb2.cpp b/esphome/components/api/api_pb2.cpp
index 8b84f9651f..6a2d902f8f 100644
--- a/esphome/components/api/api_pb2.cpp
+++ b/esphome/components/api/api_pb2.cpp
@@ -966,15 +966,24 @@ void SubscribeHomeAssistantStateResponse::calculate_size(ProtoSize &size) const
 }
 bool HomeAssistantStateResponse::decode_length(uint32_t field_id, ProtoLengthDelimited value) {
   switch (field_id) {
-    case 1:
-      this->entity_id = value.as_string();
+    case 1: {
+      // Use raw data directly to avoid allocation
+      this->entity_id = value.data();
+      this->entity_id_len = value.size();
       break;
-    case 2:
-      this->state = value.as_string();
+    }
+    case 2: {
+      // Use raw data directly to avoid allocation
+      this->state = value.data();
+      this->state_len = value.size();
       break;
-    case 3:
-      this->attribute = value.as_string();
+    }
+    case 3: {
+      // Use raw data directly to avoid allocation
+      this->attribute = value.data();
+      this->attribute_len = value.size();
       break;
+    }
     default:
       return false;
   }
diff --git a/esphome/components/api/api_pb2.h b/esphome/components/api/api_pb2.h
index 668c0af461..22deb19be8 100644
--- a/esphome/components/api/api_pb2.h
+++ b/esphome/components/api/api_pb2.h
@@ -1203,13 +1203,16 @@ class SubscribeHomeAssistantStateResponse final : public ProtoMessage {
 class HomeAssistantStateResponse final : public ProtoDecodableMessage {
  public:
   static constexpr uint8_t MESSAGE_TYPE = 40;
-  static constexpr uint8_t ESTIMATED_SIZE = 27;
+  static constexpr uint8_t ESTIMATED_SIZE = 57;
 #ifdef HAS_PROTO_MESSAGE_DUMP
   const char *message_name() const override { return "home_assistant_state_response"; }
 #endif
-  std::string entity_id{};
-  std::string state{};
-  std::string attribute{};
+  const uint8_t *entity_id{nullptr};
+  uint16_t entity_id_len{0};
+  const uint8_t *state{nullptr};
+  uint16_t state_len{0};
+  const uint8_t *attribute{nullptr};
+  uint16_t attribute_len{0};
 #ifdef HAS_PROTO_MESSAGE_DUMP
   void dump_to(std::string &out) const override;
 #endif
diff --git a/esphome/components/api/api_pb2_dump.cpp b/esphome/components/api/api_pb2_dump.cpp
index 38c3b473e6..7815eb73e4 100644
--- a/esphome/components/api/api_pb2_dump.cpp
+++ b/esphome/components/api/api_pb2_dump.cpp
@@ -1184,9 +1184,15 @@ void SubscribeHomeAssistantStateResponse::dump_to(std::string &out) const {
 }
 void HomeAssistantStateResponse::dump_to(std::string &out) const {
   MessageDumpHelper helper(out, "HomeAssistantStateResponse");
-  dump_field(out, "entity_id", this->entity_id);
-  dump_field(out, "state", this->state);
-  dump_field(out, "attribute", this->attribute);
+  out.append("  entity_id: ");
+  out.append(format_hex_pretty(this->entity_id, this->entity_id_len));
+  out.append("\n");
+  out.append("  state: ");
+  out.append(format_hex_pretty(this->state, this->state_len));
+  out.append("\n");
+  out.append("  attribute: ");
+  out.append(format_hex_pretty(this->attribute, this->attribute_len));
+  out.append("\n");
 }
 #endif
 void GetTimeRequest::dump_to(std::string &out) const { out.append("GetTimeRequest {}"); }
diff --git a/tests/integration/test_api_homeassistant.py b/tests/integration/test_api_homeassistant.py
index 1343691f5f..3fe0dfe045 100644
--- a/tests/integration/test_api_homeassistant.py
+++ b/tests/integration/test_api_homeassistant.py
@@ -179,6 +179,12 @@ async def test_api_homeassistant(
         client.send_home_assistant_state("binary_sensor.external_motion", "", "ON")
         client.send_home_assistant_state("weather.home", "condition", "sunny")
 
+        # Test edge cases for zero-copy implementation safety
+        # Empty entity_id should be silently ignored (no crash)
+        client.send_home_assistant_state("", "", "should_be_ignored")
+        # Empty state with valid entity should work (use different entity to not interfere with test)
+        client.send_home_assistant_state("sensor.edge_case_empty_state", "", "")
+
         # List entities and services
         _, services = await client.list_entities_services()
 

From bf617c327902fbc739e4a551c31450891af9464c Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Sun, 21 Dec 2025 07:32:05 -1000
Subject: [PATCH 6/9] [web_server] Replace str_sprintf with stack buffers
 (#12592)

---
 esphome/components/web_server/web_server.cpp  | 27 ++++++++++++++++---
 .../web_server_idf/web_server_idf.cpp         |  5 ++--
 2 files changed, 26 insertions(+), 6 deletions(-)

diff --git a/esphome/components/web_server/web_server.cpp b/esphome/components/web_server/web_server.cpp
index 0c22c2f08d..6870a1dc87 100644
--- a/esphome/components/web_server/web_server.cpp
+++ b/esphome/components/web_server/web_server.cpp
@@ -1042,7 +1042,13 @@ std::string WebServer::date_json(datetime::DateEntity *obj, JsonDetail start_con
   json::JsonBuilder builder;
   JsonObject root = builder.root();
 
-  std::string value = str_sprintf("%d-%02d-%02d", obj->year, obj->month, obj->day);
+  // Format: YYYY-MM-DD (max 10 chars + null)
+  char value[12];
+#ifdef USE_ESP8266
+  snprintf_P(value, sizeof(value), PSTR("%d-%02d-%02d"), obj->year, obj->month, obj->day);
+#else
+  snprintf(value, sizeof(value), "%d-%02d-%02d", obj->year, obj->month, obj->day);
+#endif
   set_json_icon_state_value(root, obj, "date", value, value, start_config);
   if (start_config == DETAIL_ALL) {
     this->add_sorting_info_(root, obj);
@@ -1098,7 +1104,13 @@ std::string WebServer::time_json(datetime::TimeEntity *obj, JsonDetail start_con
   json::JsonBuilder builder;
   JsonObject root = builder.root();
 
-  std::string value = str_sprintf("%02d:%02d:%02d", obj->hour, obj->minute, obj->second);
+  // Format: HH:MM:SS (8 chars + null)
+  char value[12];
+#ifdef USE_ESP8266
+  snprintf_P(value, sizeof(value), PSTR("%02d:%02d:%02d"), obj->hour, obj->minute, obj->second);
+#else
+  snprintf(value, sizeof(value), "%02d:%02d:%02d", obj->hour, obj->minute, obj->second);
+#endif
   set_json_icon_state_value(root, obj, "time", value, value, start_config);
   if (start_config == DETAIL_ALL) {
     this->add_sorting_info_(root, obj);
@@ -1154,8 +1166,15 @@ std::string WebServer::datetime_json(datetime::DateTimeEntity *obj, JsonDetail s
   json::JsonBuilder builder;
   JsonObject root = builder.root();
 
-  std::string value =
-      str_sprintf("%d-%02d-%02d %02d:%02d:%02d", obj->year, obj->month, obj->day, obj->hour, obj->minute, obj->second);
+  // Format: YYYY-MM-DD HH:MM:SS (max 19 chars + null)
+  char value[24];
+#ifdef USE_ESP8266
+  snprintf_P(value, sizeof(value), PSTR("%d-%02d-%02d %02d:%02d:%02d"), obj->year, obj->month, obj->day, obj->hour,
+             obj->minute, obj->second);
+#else
+  snprintf(value, sizeof(value), "%d-%02d-%02d %02d:%02d:%02d", obj->year, obj->month, obj->day, obj->hour, obj->minute,
+           obj->second);
+#endif
   set_json_icon_state_value(root, obj, "datetime", value, value, start_config);
   if (start_config == DETAIL_ALL) {
     this->add_sorting_info_(root, obj);
diff --git a/esphome/components/web_server_idf/web_server_idf.cpp b/esphome/components/web_server_idf/web_server_idf.cpp
index 8c3ad288c0..3d76b86a14 100644
--- a/esphome/components/web_server_idf/web_server_idf.cpp
+++ b/esphome/components/web_server_idf/web_server_idf.cpp
@@ -343,8 +343,9 @@ bool AsyncWebServerRequest::authenticate(const char *username, const char *passw
 
 void AsyncWebServerRequest::requestAuthentication(const char *realm) const {
   httpd_resp_set_hdr(*this, "Connection", "keep-alive");
-  auto auth_val = str_sprintf("Basic realm=\"%s\"", realm ? realm : "Login Required");
-  httpd_resp_set_hdr(*this, "WWW-Authenticate", auth_val.c_str());
+  // Note: realm is never configured in ESPHome, always nullptr -> "Login Required"
+  (void) realm;  // Unused - always use default
+  httpd_resp_set_hdr(*this, "WWW-Authenticate", "Basic realm=\"Login Required\"");
   httpd_resp_send_err(*this, HTTPD_401_UNAUTHORIZED, nullptr);
 }
 #endif

From d89eaf5bf6312d101537a4a9842abede020c96b5 Mon Sep 17 00:00:00 2001
From: Anna Oake <anna@oa.ke>
Date: Sun, 21 Dec 2025 19:04:17 +0100
Subject: [PATCH 7/9] [cc1101] Fix option defaults and move them to YAML
 (#12608)

---
 esphome/components/cc1101/__init__.py | 95 +++++++++++++++++----------
 esphome/components/cc1101/cc1101.cpp  | 17 -----
 2 files changed, 59 insertions(+), 53 deletions(-)

diff --git a/esphome/components/cc1101/__init__.py b/esphome/components/cc1101/__init__.py
index e314da7079..c205ff2f69 100644
--- a/esphome/components/cc1101/__init__.py
+++ b/esphome/components/cc1101/__init__.py
@@ -160,41 +160,63 @@ HYST_LEVEL = {
     "High": HystLevel.HYST_LEVEL_HIGH,
 }
 
-# Config key -> Validator mapping
+# Optional settings to generate setter calls for
 CONFIG_MAP = {
-    CONF_OUTPUT_POWER: cv.float_range(min=-30.0, max=11.0),
-    CONF_RX_ATTENUATION: cv.enum(RX_ATTENUATION, upper=False),
-    CONF_DC_BLOCKING_FILTER: cv.boolean,
-    CONF_FREQUENCY: cv.All(cv.frequency, cv.float_range(min=300.0e6, max=928.0e6)),
-    CONF_IF_FREQUENCY: cv.All(cv.frequency, cv.float_range(min=25000, max=788000)),
-    CONF_FILTER_BANDWIDTH: cv.All(cv.frequency, cv.float_range(min=58000, max=812000)),
-    CONF_CHANNEL: cv.uint8_t,
-    CONF_CHANNEL_SPACING: cv.All(cv.frequency, cv.float_range(min=25000, max=405000)),
-    CONF_FSK_DEVIATION: cv.All(cv.frequency, cv.float_range(min=1500, max=381000)),
-    CONF_MSK_DEVIATION: cv.int_range(min=1, max=8),
-    CONF_SYMBOL_RATE: cv.float_range(min=600, max=500000),
-    CONF_SYNC_MODE: cv.enum(SYNC_MODE, upper=False),
-    CONF_CARRIER_SENSE_ABOVE_THRESHOLD: cv.boolean,
-    CONF_MODULATION_TYPE: cv.enum(MODULATION, upper=False),
-    CONF_MANCHESTER: cv.boolean,
-    CONF_NUM_PREAMBLE: cv.int_range(min=0, max=7),
-    CONF_SYNC1: cv.hex_uint8_t,
-    CONF_SYNC0: cv.hex_uint8_t,
-    CONF_MAGN_TARGET: cv.enum(MAGN_TARGET, upper=False),
-    CONF_MAX_LNA_GAIN: cv.enum(MAX_LNA_GAIN, upper=False),
-    CONF_MAX_DVGA_GAIN: cv.enum(MAX_DVGA_GAIN, upper=False),
-    CONF_CARRIER_SENSE_ABS_THR: cv.int_range(min=-8, max=7),
-    CONF_CARRIER_SENSE_REL_THR: cv.enum(CARRIER_SENSE_REL_THR, upper=False),
-    CONF_LNA_PRIORITY: cv.boolean,
-    CONF_FILTER_LENGTH_FSK_MSK: cv.enum(FILTER_LENGTH_FSK_MSK, upper=False),
-    CONF_FILTER_LENGTH_ASK_OOK: cv.enum(FILTER_LENGTH_ASK_OOK, upper=False),
-    CONF_FREEZE: cv.enum(FREEZE, upper=False),
-    CONF_WAIT_TIME: cv.enum(WAIT_TIME, upper=False),
-    CONF_HYST_LEVEL: cv.enum(HYST_LEVEL, upper=False),
-    CONF_PACKET_MODE: cv.boolean,
-    CONF_PACKET_LENGTH: cv.uint8_t,
-    CONF_CRC_ENABLE: cv.boolean,
-    CONF_WHITENING: cv.boolean,
+    cv.Optional(CONF_OUTPUT_POWER, default=10): cv.float_range(min=-30.0, max=11.0),
+    cv.Optional(CONF_RX_ATTENUATION, default="0dB"): cv.enum(
+        RX_ATTENUATION, upper=False
+    ),
+    cv.Optional(CONF_DC_BLOCKING_FILTER, default=True): cv.boolean,
+    cv.Optional(CONF_FREQUENCY, default="433.92MHz"): cv.All(
+        cv.frequency, cv.float_range(min=300.0e6, max=928.0e6)
+    ),
+    cv.Optional(CONF_IF_FREQUENCY, default="153kHz"): cv.All(
+        cv.frequency, cv.float_range(min=25000, max=788000)
+    ),
+    cv.Optional(CONF_FILTER_BANDWIDTH, default="203kHz"): cv.All(
+        cv.frequency, cv.float_range(min=58000, max=812000)
+    ),
+    cv.Optional(CONF_CHANNEL, default=0): cv.uint8_t,
+    cv.Optional(CONF_CHANNEL_SPACING, default="200kHz"): cv.All(
+        cv.frequency, cv.float_range(min=25000, max=405000)
+    ),
+    cv.Optional(CONF_FSK_DEVIATION): cv.All(
+        cv.frequency, cv.float_range(min=1500, max=381000)
+    ),
+    cv.Optional(CONF_MSK_DEVIATION): cv.int_range(min=1, max=8),
+    cv.Optional(CONF_SYMBOL_RATE, default=5000): cv.float_range(min=600, max=500000),
+    cv.Optional(CONF_SYNC_MODE, default="16/16"): cv.enum(SYNC_MODE, upper=False),
+    cv.Optional(CONF_CARRIER_SENSE_ABOVE_THRESHOLD, default=False): cv.boolean,
+    cv.Optional(CONF_MODULATION_TYPE, default="ASK/OOK"): cv.enum(
+        MODULATION, upper=False
+    ),
+    cv.Optional(CONF_MANCHESTER, default=False): cv.boolean,
+    cv.Optional(CONF_NUM_PREAMBLE, default=2): cv.int_range(min=0, max=7),
+    cv.Optional(CONF_SYNC1, default=0xD3): cv.hex_uint8_t,
+    cv.Optional(CONF_SYNC0, default=0x91): cv.hex_uint8_t,
+    cv.Optional(CONF_MAGN_TARGET, default="42dB"): cv.enum(MAGN_TARGET, upper=False),
+    cv.Optional(CONF_MAX_LNA_GAIN, default="Default"): cv.enum(
+        MAX_LNA_GAIN, upper=False
+    ),
+    cv.Optional(CONF_MAX_DVGA_GAIN, default="-3"): cv.enum(MAX_DVGA_GAIN, upper=False),
+    cv.Optional(CONF_CARRIER_SENSE_ABS_THR): cv.int_range(min=-8, max=7),
+    cv.Optional(CONF_CARRIER_SENSE_REL_THR): cv.enum(
+        CARRIER_SENSE_REL_THR, upper=False
+    ),
+    cv.Optional(CONF_LNA_PRIORITY, default=False): cv.boolean,
+    cv.Optional(CONF_FILTER_LENGTH_FSK_MSK): cv.enum(
+        FILTER_LENGTH_FSK_MSK, upper=False
+    ),
+    cv.Optional(CONF_FILTER_LENGTH_ASK_OOK): cv.enum(
+        FILTER_LENGTH_ASK_OOK, upper=False
+    ),
+    cv.Optional(CONF_FREEZE): cv.enum(FREEZE, upper=False),
+    cv.Optional(CONF_WAIT_TIME, default="32"): cv.enum(WAIT_TIME, upper=False),
+    cv.Optional(CONF_HYST_LEVEL): cv.enum(HYST_LEVEL, upper=False),
+    cv.Optional(CONF_PACKET_MODE, default=False): cv.boolean,
+    cv.Optional(CONF_PACKET_LENGTH): cv.uint8_t,
+    cv.Optional(CONF_CRC_ENABLE, default=False): cv.boolean,
+    cv.Optional(CONF_WHITENING, default=False): cv.boolean,
 }
 
 
@@ -217,7 +239,7 @@ CONFIG_SCHEMA = cv.All(
             cv.Optional(CONF_ON_PACKET): automation.validate_automation(single=True),
         }
     )
-    .extend({cv.Optional(key): validator for key, validator in CONFIG_MAP.items()})
+    .extend(CONFIG_MAP)
     .extend(cv.COMPONENT_SCHEMA)
     .extend(spi.spi_device_schema(cs_pin_required=True)),
     _validate_packet_mode,
@@ -229,7 +251,8 @@ async def to_code(config):
     await cg.register_component(var, config)
     await spi.register_spi_device(var, config)
 
-    for key in CONFIG_MAP:
+    for opt in CONFIG_MAP:
+        key = opt.schema
         if key in config:
             cg.add(getattr(var, f"set_{key}")(config[key]))
 
diff --git a/esphome/components/cc1101/cc1101.cpp b/esphome/components/cc1101/cc1101.cpp
index 1fe402d6c6..f98afd94a1 100644
--- a/esphome/components/cc1101/cc1101.cpp
+++ b/esphome/components/cc1101/cc1101.cpp
@@ -98,25 +98,8 @@ CC1101Component::CC1101Component() {
   this->state_.LENGTH_CONFIG = 2;
   this->state_.FS_AUTOCAL = 1;
 
-  // Default Settings
-  this->set_frequency(433920000);
-  this->set_if_frequency(153000);
-  this->set_filter_bandwidth(203000);
-  this->set_channel(0);
-  this->set_channel_spacing(200000);
-  this->set_symbol_rate(5000);
-  this->set_sync_mode(SyncMode::SYNC_MODE_NONE);
-  this->set_carrier_sense_above_threshold(true);
-  this->set_modulation_type(Modulation::MODULATION_ASK_OOK);
-  this->set_magn_target(MagnTarget::MAGN_TARGET_42DB);
-  this->set_max_lna_gain(MaxLnaGain::MAX_LNA_GAIN_DEFAULT);
-  this->set_max_dvga_gain(MaxDvgaGain::MAX_DVGA_GAIN_MINUS_3);
-  this->set_lna_priority(false);
-  this->set_wait_time(WaitTime::WAIT_TIME_32_SAMPLES);
-
   // CRITICAL: Initialize PA Table to avoid transmitting 0 power (Silence)
   memset(this->pa_table_, 0, sizeof(this->pa_table_));
-  this->set_output_power(10.0f);
 }
 
 void CC1101Component::setup() {

From 637e032528d9c35496b429fd5ef9d64aded0c5f6 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Sun, 21 Dec 2025 09:04:43 -1000
Subject: [PATCH 8/9] [esp32_camera] Throttle frame logging to reduce overhead
 and improve throughput (#12586)

---
 .../components/esp32_camera/esp32_camera.cpp   | 18 +++++++++++++++++-
 esphome/components/esp32_camera/esp32_camera.h |  4 ++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/esphome/components/esp32_camera/esp32_camera.cpp b/esphome/components/esp32_camera/esp32_camera.cpp
index 5080a6f32d..a3677330ca 100644
--- a/esphome/components/esp32_camera/esp32_camera.cpp
+++ b/esphome/components/esp32_camera/esp32_camera.cpp
@@ -11,6 +11,9 @@ namespace esphome {
 namespace esp32_camera {
 
 static const char *const TAG = "esp32_camera";
+#if ESPHOME_LOG_LEVEL < ESPHOME_LOG_LEVEL_VERBOSE
+static constexpr uint32_t FRAME_LOG_INTERVAL_MS = 60000;
+#endif
 
 /* ---------------- public API (derivated) ---------------- */
 void ESP32Camera::setup() {
@@ -204,7 +207,20 @@ void ESP32Camera::loop() {
   }
   this->current_image_ = std::make_shared<ESP32CameraImage>(fb, this->single_requesters_ | this->stream_requesters_);
 
-  ESP_LOGD(TAG, "Got Image: len=%u", fb->len);
+#if ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_VERBOSE
+  ESP_LOGV(TAG, "Got Image: len=%u", fb->len);
+#else
+  // Initialize log time on first frame to ensure accurate interval measurement
+  if (this->frame_count_ == 0) {
+    this->last_log_time_ = now;
+  }
+  this->frame_count_++;
+  if (now - this->last_log_time_ >= FRAME_LOG_INTERVAL_MS) {
+    ESP_LOGD(TAG, "Received %u images in last %us", this->frame_count_, FRAME_LOG_INTERVAL_MS / 1000);
+    this->last_log_time_ = now;
+    this->frame_count_ = 0;
+  }
+#endif
   for (auto *listener : this->listeners_) {
     listener->on_camera_image(this->current_image_);
   }
diff --git a/esphome/components/esp32_camera/esp32_camera.h b/esphome/components/esp32_camera/esp32_camera.h
index 54a7d6064a..a49fca6511 100644
--- a/esphome/components/esp32_camera/esp32_camera.h
+++ b/esphome/components/esp32_camera/esp32_camera.h
@@ -213,6 +213,10 @@ class ESP32Camera : public camera::Camera {
 
   uint32_t last_idle_request_{0};
   uint32_t last_update_{0};
+#if ESPHOME_LOG_LEVEL < ESPHOME_LOG_LEVEL_VERBOSE
+  uint32_t last_log_time_{0};
+  uint16_t frame_count_{0};
+#endif
 #ifdef USE_I2C
   i2c::InternalI2CBus *i2c_bus_{nullptr};
 #endif  // USE_I2C

From 39926909af216486cc42edd6e3b1de53a8a98e13 Mon Sep 17 00:00:00 2001
From: Douwe <61123717+dhoeben@users.noreply.github.com>
Date: Sun, 21 Dec 2025 22:36:34 +0100
Subject: [PATCH 9/9] [water_heater] (1/4)  Implement API/Core/component for
 new water_heater component (#12498)

Co-authored-by: pre-commit-ci-lite[bot] <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>
Co-authored-by: J. Nick Koston <nick+github@koston.org>
Co-authored-by: J. Nick Koston <nick@home-assistant.io>
Co-authored-by: J. Nick Koston <nick@koston.org>
---
 CODEOWNERS                                    |   1 +
 esphome/components/api/api.proto              |  79 +++++
 esphome/components/api/api_connection.cpp     |  54 ++++
 esphome/components/api/api_connection.h       |  11 +
 esphome/components/api/api_pb2.cpp            | 108 +++++++
 esphome/components/api/api_pb2.h              |  83 ++++++
 esphome/components/api/api_pb2_dump.cpp       |  90 ++++++
 esphome/components/api/api_pb2_includes.h     |   4 +
 esphome/components/api/api_pb2_service.cpp    |  11 +
 esphome/components/api/api_pb2_service.h      |   4 +
 esphome/components/api/api_server.cpp         |   4 +
 esphome/components/api/api_server.h           |   3 +
 esphome/components/api/list_entities.cpp      |   3 +
 esphome/components/api/list_entities.h        |   3 +
 esphome/components/api/subscribe_state.cpp    |   3 +
 esphome/components/api/subscribe_state.h      |   3 +
 esphome/components/water_heater/__init__.py   | 111 +++++++
 .../components/water_heater/water_heater.cpp  | 281 ++++++++++++++++++
 .../components/water_heater/water_heater.h    | 259 ++++++++++++++++
 .../components/web_server/list_entities.cpp   |   7 +
 esphome/components/web_server/list_entities.h |   3 +
 esphome/const.py                              |   2 +
 esphome/core/application.h                    |  15 +
 esphome/core/component_iterator.cpp           |   6 +
 esphome/core/component_iterator.h             |   6 +
 esphome/core/controller.h                     |   6 +
 esphome/core/controller_registry.cpp          |   4 +
 esphome/core/controller_registry.h            |  10 +
 esphome/core/defines.h                        |   3 +
 29 files changed, 1177 insertions(+)
 create mode 100644 esphome/components/water_heater/__init__.py
 create mode 100644 esphome/components/water_heater/water_heater.cpp
 create mode 100644 esphome/components/water_heater/water_heater.h

diff --git a/CODEOWNERS b/CODEOWNERS
index 21be3e36d1..941c2e2849 100644
--- a/CODEOWNERS
+++ b/CODEOWNERS
@@ -537,6 +537,7 @@ esphome/components/version/* @esphome/core
 esphome/components/voice_assistant/* @jesserockz @kahrendt
 esphome/components/wake_on_lan/* @clydebarrow @willwill2will54
 esphome/components/watchdog/* @oarcher
+esphome/components/water_heater/* @dhoeben
 esphome/components/waveshare_epaper/* @clydebarrow
 esphome/components/web_server/ota/* @esphome/core
 esphome/components/web_server_base/* @esphome/core
diff --git a/esphome/components/api/api.proto b/esphome/components/api/api.proto
index bf39f0b14b..c351bc8c9c 100644
--- a/esphome/components/api/api.proto
+++ b/esphome/components/api/api.proto
@@ -1101,6 +1101,85 @@ message ClimateCommandRequest {
   uint32 device_id = 24 [(field_ifdef) = "USE_DEVICES"];
 }
 
+// ==================== WATER_HEATER ====================
+enum WaterHeaterMode {
+  WATER_HEATER_MODE_OFF = 0;
+  WATER_HEATER_MODE_ECO = 1;
+  WATER_HEATER_MODE_ELECTRIC = 2;
+  WATER_HEATER_MODE_PERFORMANCE = 3;
+  WATER_HEATER_MODE_HIGH_DEMAND = 4;
+  WATER_HEATER_MODE_HEAT_PUMP = 5;
+  WATER_HEATER_MODE_GAS = 6;
+}
+
+message ListEntitiesWaterHeaterResponse {
+  option (id) = 132;
+  option (base_class) = "InfoResponseProtoMessage";
+  option (source) = SOURCE_SERVER;
+  option (ifdef) = "USE_WATER_HEATER";
+
+  string object_id = 1;
+  fixed32 key = 2;
+  string name = 3;
+  string icon = 4 [(field_ifdef) = "USE_ENTITY_ICON"];
+  bool disabled_by_default = 5;
+  EntityCategory entity_category = 6;
+  uint32 device_id = 7 [(field_ifdef) = "USE_DEVICES"];
+  float min_temperature = 8;
+  float max_temperature = 9;
+  float target_temperature_step = 10;
+  repeated WaterHeaterMode supported_modes = 11 [(container_pointer_no_template) = "water_heater::WaterHeaterModeMask"];
+  // Bitmask of WaterHeaterFeature flags
+  uint32 supported_features = 12;
+}
+
+message WaterHeaterStateResponse {
+  option (id) = 133;
+  option (base_class) = "StateResponseProtoMessage";
+  option (source) = SOURCE_SERVER;
+  option (ifdef) = "USE_WATER_HEATER";
+  option (no_delay) = true;
+
+  fixed32 key = 1;
+  float current_temperature = 2;
+  float target_temperature = 3;
+  WaterHeaterMode mode = 4;
+  uint32 device_id = 5 [(field_ifdef) = "USE_DEVICES"];
+  // Bitmask of current state flags (bit 0 = away, bit 1 = on)
+  uint32 state = 6;
+  float target_temperature_low = 7;
+  float target_temperature_high = 8;
+}
+
+// Bitmask for WaterHeaterCommandRequest.has_fields
+enum WaterHeaterCommandHasField {
+  WATER_HEATER_COMMAND_HAS_NONE = 0;
+  WATER_HEATER_COMMAND_HAS_MODE = 1;
+  WATER_HEATER_COMMAND_HAS_TARGET_TEMPERATURE = 2;
+  WATER_HEATER_COMMAND_HAS_STATE = 4;
+  WATER_HEATER_COMMAND_HAS_TARGET_TEMPERATURE_LOW = 8;
+  WATER_HEATER_COMMAND_HAS_TARGET_TEMPERATURE_HIGH = 16;
+}
+
+message WaterHeaterCommandRequest {
+  option (id) = 134;
+  option (source) = SOURCE_CLIENT;
+  option (ifdef) = "USE_WATER_HEATER";
+  option (no_delay) = true;
+  option (base_class) = "CommandProtoMessage";
+
+  fixed32 key = 1;
+  // Bitmask of which fields are set (see WaterHeaterCommandHasField)
+  uint32 has_fields = 2;
+  WaterHeaterMode mode = 3;
+  float target_temperature = 4;
+  uint32 device_id = 5 [(field_ifdef) = "USE_DEVICES"];
+  // State flags bitmask (bit 0 = away, bit 1 = on)
+  uint32 state = 6;
+  float target_temperature_low = 7;
+  float target_temperature_high = 8;
+}
+
 // ==================== NUMBER ====================
 enum NumberMode {
   NUMBER_MODE_AUTO = 0;
diff --git a/esphome/components/api/api_connection.cpp b/esphome/components/api/api_connection.cpp
index 1bcb90b0b0..28970a321c 100644
--- a/esphome/components/api/api_connection.cpp
+++ b/esphome/components/api/api_connection.cpp
@@ -42,6 +42,9 @@
 #ifdef USE_ZWAVE_PROXY
 #include "esphome/components/zwave_proxy/zwave_proxy.h"
 #endif
+#ifdef USE_WATER_HEATER
+#include "esphome/components/water_heater/water_heater.h"
+#endif
 
 namespace esphome::api {
 
@@ -1306,6 +1309,57 @@ void APIConnection::alarm_control_panel_command(const AlarmControlPanelCommandRe
 }
 #endif
 
+#ifdef USE_WATER_HEATER
+bool APIConnection::send_water_heater_state(water_heater::WaterHeater *water_heater) {
+  return this->send_message_smart_(water_heater, &APIConnection::try_send_water_heater_state,
+                                   WaterHeaterStateResponse::MESSAGE_TYPE, WaterHeaterStateResponse::ESTIMATED_SIZE);
+}
+uint16_t APIConnection::try_send_water_heater_state(EntityBase *entity, APIConnection *conn, uint32_t remaining_size,
+                                                    bool is_single) {
+  auto *wh = static_cast<water_heater::WaterHeater *>(entity);
+  WaterHeaterStateResponse resp;
+  resp.mode = static_cast<enums::WaterHeaterMode>(wh->get_mode());
+  resp.current_temperature = wh->get_current_temperature();
+  resp.target_temperature = wh->get_target_temperature();
+  resp.target_temperature_low = wh->get_target_temperature_low();
+  resp.target_temperature_high = wh->get_target_temperature_high();
+  resp.state = wh->get_state();
+  resp.key = wh->get_object_id_hash();
+
+  return encode_message_to_buffer(resp, WaterHeaterStateResponse::MESSAGE_TYPE, conn, remaining_size, is_single);
+}
+uint16_t APIConnection::try_send_water_heater_info(EntityBase *entity, APIConnection *conn, uint32_t remaining_size,
+                                                   bool is_single) {
+  auto *wh = static_cast<water_heater::WaterHeater *>(entity);
+  ListEntitiesWaterHeaterResponse msg;
+  auto traits = wh->get_traits();
+  msg.min_temperature = traits.get_min_temperature();
+  msg.max_temperature = traits.get_max_temperature();
+  msg.target_temperature_step = traits.get_target_temperature_step();
+  msg.supported_modes = &traits.get_supported_modes();
+  msg.supported_features = traits.get_feature_flags();
+  return fill_and_encode_entity_info(wh, msg, ListEntitiesWaterHeaterResponse::MESSAGE_TYPE, conn, remaining_size,
+                                     is_single);
+}
+
+void APIConnection::on_water_heater_command_request(const WaterHeaterCommandRequest &msg) {
+  ENTITY_COMMAND_MAKE_CALL(water_heater::WaterHeater, water_heater, water_heater)
+  if (msg.has_fields & enums::WATER_HEATER_COMMAND_HAS_MODE)
+    call.set_mode(static_cast<water_heater::WaterHeaterMode>(msg.mode));
+  if (msg.has_fields & enums::WATER_HEATER_COMMAND_HAS_TARGET_TEMPERATURE)
+    call.set_target_temperature(msg.target_temperature);
+  if (msg.has_fields & enums::WATER_HEATER_COMMAND_HAS_TARGET_TEMPERATURE_LOW)
+    call.set_target_temperature_low(msg.target_temperature_low);
+  if (msg.has_fields & enums::WATER_HEATER_COMMAND_HAS_TARGET_TEMPERATURE_HIGH)
+    call.set_target_temperature_high(msg.target_temperature_high);
+  if (msg.has_fields & enums::WATER_HEATER_COMMAND_HAS_STATE) {
+    call.set_away((msg.state & water_heater::WATER_HEATER_STATE_AWAY) != 0);
+    call.set_on((msg.state & water_heater::WATER_HEATER_STATE_ON) != 0);
+  }
+  call.perform();
+}
+#endif
+
 #ifdef USE_EVENT
 void APIConnection::send_event(event::Event *event, const char *event_type) {
   this->send_message_smart_(event, MessageCreator(event_type), EventResponse::MESSAGE_TYPE,
diff --git a/esphome/components/api/api_connection.h b/esphome/components/api/api_connection.h
index b50be5d0d4..7351b5082f 100644
--- a/esphome/components/api/api_connection.h
+++ b/esphome/components/api/api_connection.h
@@ -176,6 +176,11 @@ class APIConnection final : public APIServerConnection {
   void alarm_control_panel_command(const AlarmControlPanelCommandRequest &msg) override;
 #endif
 
+#ifdef USE_WATER_HEATER
+  bool send_water_heater_state(water_heater::WaterHeater *water_heater);
+  void on_water_heater_command_request(const WaterHeaterCommandRequest &msg) override;
+#endif
+
 #ifdef USE_EVENT
   void send_event(event::Event *event, const char *event_type);
 #endif
@@ -456,6 +461,12 @@ class APIConnection final : public APIServerConnection {
   static uint16_t try_send_alarm_control_panel_info(EntityBase *entity, APIConnection *conn, uint32_t remaining_size,
                                                     bool is_single);
 #endif
+#ifdef USE_WATER_HEATER
+  static uint16_t try_send_water_heater_state(EntityBase *entity, APIConnection *conn, uint32_t remaining_size,
+                                              bool is_single);
+  static uint16_t try_send_water_heater_info(EntityBase *entity, APIConnection *conn, uint32_t remaining_size,
+                                             bool is_single);
+#endif
 #ifdef USE_EVENT
   static uint16_t try_send_event_response(event::Event *event, const char *event_type, APIConnection *conn,
                                           uint32_t remaining_size, bool is_single);
diff --git a/esphome/components/api/api_pb2.cpp b/esphome/components/api/api_pb2.cpp
index 6a2d902f8f..3376b022c5 100644
--- a/esphome/components/api/api_pb2.cpp
+++ b/esphome/components/api/api_pb2.cpp
@@ -1447,6 +1447,114 @@ bool ClimateCommandRequest::decode_32bit(uint32_t field_id, Proto32Bit value) {
   return true;
 }
 #endif
+#ifdef USE_WATER_HEATER
+void ListEntitiesWaterHeaterResponse::encode(ProtoWriteBuffer buffer) const {
+  buffer.encode_string(1, this->object_id_ref_);
+  buffer.encode_fixed32(2, this->key);
+  buffer.encode_string(3, this->name_ref_);
+#ifdef USE_ENTITY_ICON
+  buffer.encode_string(4, this->icon_ref_);
+#endif
+  buffer.encode_bool(5, this->disabled_by_default);
+  buffer.encode_uint32(6, static_cast<uint32_t>(this->entity_category));
+#ifdef USE_DEVICES
+  buffer.encode_uint32(7, this->device_id);
+#endif
+  buffer.encode_float(8, this->min_temperature);
+  buffer.encode_float(9, this->max_temperature);
+  buffer.encode_float(10, this->target_temperature_step);
+  for (const auto &it : *this->supported_modes) {
+    buffer.encode_uint32(11, static_cast<uint32_t>(it), true);
+  }
+  buffer.encode_uint32(12, this->supported_features);
+}
+void ListEntitiesWaterHeaterResponse::calculate_size(ProtoSize &size) const {
+  size.add_length(1, this->object_id_ref_.size());
+  size.add_fixed32(1, this->key);
+  size.add_length(1, this->name_ref_.size());
+#ifdef USE_ENTITY_ICON
+  size.add_length(1, this->icon_ref_.size());
+#endif
+  size.add_bool(1, this->disabled_by_default);
+  size.add_uint32(1, static_cast<uint32_t>(this->entity_category));
+#ifdef USE_DEVICES
+  size.add_uint32(1, this->device_id);
+#endif
+  size.add_float(1, this->min_temperature);
+  size.add_float(1, this->max_temperature);
+  size.add_float(1, this->target_temperature_step);
+  if (!this->supported_modes->empty()) {
+    for (const auto &it : *this->supported_modes) {
+      size.add_uint32_force(1, static_cast<uint32_t>(it));
+    }
+  }
+  size.add_uint32(1, this->supported_features);
+}
+void WaterHeaterStateResponse::encode(ProtoWriteBuffer buffer) const {
+  buffer.encode_fixed32(1, this->key);
+  buffer.encode_float(2, this->current_temperature);
+  buffer.encode_float(3, this->target_temperature);
+  buffer.encode_uint32(4, static_cast<uint32_t>(this->mode));
+#ifdef USE_DEVICES
+  buffer.encode_uint32(5, this->device_id);
+#endif
+  buffer.encode_uint32(6, this->state);
+  buffer.encode_float(7, this->target_temperature_low);
+  buffer.encode_float(8, this->target_temperature_high);
+}
+void WaterHeaterStateResponse::calculate_size(ProtoSize &size) const {
+  size.add_fixed32(1, this->key);
+  size.add_float(1, this->current_temperature);
+  size.add_float(1, this->target_temperature);
+  size.add_uint32(1, static_cast<uint32_t>(this->mode));
+#ifdef USE_DEVICES
+  size.add_uint32(1, this->device_id);
+#endif
+  size.add_uint32(1, this->state);
+  size.add_float(1, this->target_temperature_low);
+  size.add_float(1, this->target_temperature_high);
+}
+bool WaterHeaterCommandRequest::decode_varint(uint32_t field_id, ProtoVarInt value) {
+  switch (field_id) {
+    case 2:
+      this->has_fields = value.as_uint32();
+      break;
+    case 3:
+      this->mode = static_cast<enums::WaterHeaterMode>(value.as_uint32());
+      break;
+#ifdef USE_DEVICES
+    case 5:
+      this->device_id = value.as_uint32();
+      break;
+#endif
+    case 6:
+      this->state = value.as_uint32();
+      break;
+    default:
+      return false;
+  }
+  return true;
+}
+bool WaterHeaterCommandRequest::decode_32bit(uint32_t field_id, Proto32Bit value) {
+  switch (field_id) {
+    case 1:
+      this->key = value.as_fixed32();
+      break;
+    case 4:
+      this->target_temperature = value.as_float();
+      break;
+    case 7:
+      this->target_temperature_low = value.as_float();
+      break;
+    case 8:
+      this->target_temperature_high = value.as_float();
+      break;
+    default:
+      return false;
+  }
+  return true;
+}
+#endif
 #ifdef USE_NUMBER
 void ListEntitiesNumberResponse::encode(ProtoWriteBuffer buffer) const {
   buffer.encode_string(1, this->object_id_ref_);
diff --git a/esphome/components/api/api_pb2.h b/esphome/components/api/api_pb2.h
index 22deb19be8..2111c2a895 100644
--- a/esphome/components/api/api_pb2.h
+++ b/esphome/components/api/api_pb2.h
@@ -129,6 +129,25 @@ enum ClimatePreset : uint32_t {
   CLIMATE_PRESET_ACTIVITY = 7,
 };
 #endif
+#ifdef USE_WATER_HEATER
+enum WaterHeaterMode : uint32_t {
+  WATER_HEATER_MODE_OFF = 0,
+  WATER_HEATER_MODE_ECO = 1,
+  WATER_HEATER_MODE_ELECTRIC = 2,
+  WATER_HEATER_MODE_PERFORMANCE = 3,
+  WATER_HEATER_MODE_HIGH_DEMAND = 4,
+  WATER_HEATER_MODE_HEAT_PUMP = 5,
+  WATER_HEATER_MODE_GAS = 6,
+};
+#endif
+enum WaterHeaterCommandHasField : uint32_t {
+  WATER_HEATER_COMMAND_HAS_NONE = 0,
+  WATER_HEATER_COMMAND_HAS_MODE = 1,
+  WATER_HEATER_COMMAND_HAS_TARGET_TEMPERATURE = 2,
+  WATER_HEATER_COMMAND_HAS_STATE = 4,
+  WATER_HEATER_COMMAND_HAS_TARGET_TEMPERATURE_LOW = 8,
+  WATER_HEATER_COMMAND_HAS_TARGET_TEMPERATURE_HIGH = 16,
+};
 #ifdef USE_NUMBER
 enum NumberMode : uint32_t {
   NUMBER_MODE_AUTO = 0,
@@ -1516,6 +1535,70 @@ class ClimateCommandRequest final : public CommandProtoMessage {
   bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
 };
 #endif
+#ifdef USE_WATER_HEATER
+class ListEntitiesWaterHeaterResponse final : public InfoResponseProtoMessage {
+ public:
+  static constexpr uint8_t MESSAGE_TYPE = 132;
+  static constexpr uint8_t ESTIMATED_SIZE = 63;
+#ifdef HAS_PROTO_MESSAGE_DUMP
+  const char *message_name() const override { return "list_entities_water_heater_response"; }
+#endif
+  float min_temperature{0.0f};
+  float max_temperature{0.0f};
+  float target_temperature_step{0.0f};
+  const water_heater::WaterHeaterModeMask *supported_modes{};
+  uint32_t supported_features{0};
+  void encode(ProtoWriteBuffer buffer) const override;
+  void calculate_size(ProtoSize &size) const override;
+#ifdef HAS_PROTO_MESSAGE_DUMP
+  void dump_to(std::string &out) const override;
+#endif
+
+ protected:
+};
+class WaterHeaterStateResponse final : public StateResponseProtoMessage {
+ public:
+  static constexpr uint8_t MESSAGE_TYPE = 133;
+  static constexpr uint8_t ESTIMATED_SIZE = 35;
+#ifdef HAS_PROTO_MESSAGE_DUMP
+  const char *message_name() const override { return "water_heater_state_response"; }
+#endif
+  float current_temperature{0.0f};
+  float target_temperature{0.0f};
+  enums::WaterHeaterMode mode{};
+  uint32_t state{0};
+  float target_temperature_low{0.0f};
+  float target_temperature_high{0.0f};
+  void encode(ProtoWriteBuffer buffer) const override;
+  void calculate_size(ProtoSize &size) const override;
+#ifdef HAS_PROTO_MESSAGE_DUMP
+  void dump_to(std::string &out) const override;
+#endif
+
+ protected:
+};
+class WaterHeaterCommandRequest final : public CommandProtoMessage {
+ public:
+  static constexpr uint8_t MESSAGE_TYPE = 134;
+  static constexpr uint8_t ESTIMATED_SIZE = 34;
+#ifdef HAS_PROTO_MESSAGE_DUMP
+  const char *message_name() const override { return "water_heater_command_request"; }
+#endif
+  uint32_t has_fields{0};
+  enums::WaterHeaterMode mode{};
+  float target_temperature{0.0f};
+  uint32_t state{0};
+  float target_temperature_low{0.0f};
+  float target_temperature_high{0.0f};
+#ifdef HAS_PROTO_MESSAGE_DUMP
+  void dump_to(std::string &out) const override;
+#endif
+
+ protected:
+  bool decode_32bit(uint32_t field_id, Proto32Bit value) override;
+  bool decode_varint(uint32_t field_id, ProtoVarInt value) override;
+};
+#endif
 #ifdef USE_NUMBER
 class ListEntitiesNumberResponse final : public InfoResponseProtoMessage {
  public:
diff --git a/esphome/components/api/api_pb2_dump.cpp b/esphome/components/api/api_pb2_dump.cpp
index 7815eb73e4..9faf39e29e 100644
--- a/esphome/components/api/api_pb2_dump.cpp
+++ b/esphome/components/api/api_pb2_dump.cpp
@@ -348,6 +348,47 @@ template<> const char *proto_enum_to_string<enums::ClimatePreset>(enums::Climate
   }
 }
 #endif
+#ifdef USE_WATER_HEATER
+template<> const char *proto_enum_to_string<enums::WaterHeaterMode>(enums::WaterHeaterMode value) {
+  switch (value) {
+    case enums::WATER_HEATER_MODE_OFF:
+      return "WATER_HEATER_MODE_OFF";
+    case enums::WATER_HEATER_MODE_ECO:
+      return "WATER_HEATER_MODE_ECO";
+    case enums::WATER_HEATER_MODE_ELECTRIC:
+      return "WATER_HEATER_MODE_ELECTRIC";
+    case enums::WATER_HEATER_MODE_PERFORMANCE:
+      return "WATER_HEATER_MODE_PERFORMANCE";
+    case enums::WATER_HEATER_MODE_HIGH_DEMAND:
+      return "WATER_HEATER_MODE_HIGH_DEMAND";
+    case enums::WATER_HEATER_MODE_HEAT_PUMP:
+      return "WATER_HEATER_MODE_HEAT_PUMP";
+    case enums::WATER_HEATER_MODE_GAS:
+      return "WATER_HEATER_MODE_GAS";
+    default:
+      return "UNKNOWN";
+  }
+}
+#endif
+template<>
+const char *proto_enum_to_string<enums::WaterHeaterCommandHasField>(enums::WaterHeaterCommandHasField value) {
+  switch (value) {
+    case enums::WATER_HEATER_COMMAND_HAS_NONE:
+      return "WATER_HEATER_COMMAND_HAS_NONE";
+    case enums::WATER_HEATER_COMMAND_HAS_MODE:
+      return "WATER_HEATER_COMMAND_HAS_MODE";
+    case enums::WATER_HEATER_COMMAND_HAS_TARGET_TEMPERATURE:
+      return "WATER_HEATER_COMMAND_HAS_TARGET_TEMPERATURE";
+    case enums::WATER_HEATER_COMMAND_HAS_STATE:
+      return "WATER_HEATER_COMMAND_HAS_STATE";
+    case enums::WATER_HEATER_COMMAND_HAS_TARGET_TEMPERATURE_LOW:
+      return "WATER_HEATER_COMMAND_HAS_TARGET_TEMPERATURE_LOW";
+    case enums::WATER_HEATER_COMMAND_HAS_TARGET_TEMPERATURE_HIGH:
+      return "WATER_HEATER_COMMAND_HAS_TARGET_TEMPERATURE_HIGH";
+    default:
+      return "UNKNOWN";
+  }
+}
 #ifdef USE_NUMBER
 template<> const char *proto_enum_to_string<enums::NumberMode>(enums::NumberMode value) {
   switch (value) {
@@ -1398,6 +1439,55 @@ void ClimateCommandRequest::dump_to(std::string &out) const {
 #endif
 }
 #endif
+#ifdef USE_WATER_HEATER
+void ListEntitiesWaterHeaterResponse::dump_to(std::string &out) const {
+  MessageDumpHelper helper(out, "ListEntitiesWaterHeaterResponse");
+  dump_field(out, "object_id", this->object_id_ref_);
+  dump_field(out, "key", this->key);
+  dump_field(out, "name", this->name_ref_);
+#ifdef USE_ENTITY_ICON
+  dump_field(out, "icon", this->icon_ref_);
+#endif
+  dump_field(out, "disabled_by_default", this->disabled_by_default);
+  dump_field(out, "entity_category", static_cast<enums::EntityCategory>(this->entity_category));
+#ifdef USE_DEVICES
+  dump_field(out, "device_id", this->device_id);
+#endif
+  dump_field(out, "min_temperature", this->min_temperature);
+  dump_field(out, "max_temperature", this->max_temperature);
+  dump_field(out, "target_temperature_step", this->target_temperature_step);
+  for (const auto &it : *this->supported_modes) {
+    dump_field(out, "supported_modes", static_cast<enums::WaterHeaterMode>(it), 4);
+  }
+  dump_field(out, "supported_features", this->supported_features);
+}
+void WaterHeaterStateResponse::dump_to(std::string &out) const {
+  MessageDumpHelper helper(out, "WaterHeaterStateResponse");
+  dump_field(out, "key", this->key);
+  dump_field(out, "current_temperature", this->current_temperature);
+  dump_field(out, "target_temperature", this->target_temperature);
+  dump_field(out, "mode", static_cast<enums::WaterHeaterMode>(this->mode));
+#ifdef USE_DEVICES
+  dump_field(out, "device_id", this->device_id);
+#endif
+  dump_field(out, "state", this->state);
+  dump_field(out, "target_temperature_low", this->target_temperature_low);
+  dump_field(out, "target_temperature_high", this->target_temperature_high);
+}
+void WaterHeaterCommandRequest::dump_to(std::string &out) const {
+  MessageDumpHelper helper(out, "WaterHeaterCommandRequest");
+  dump_field(out, "key", this->key);
+  dump_field(out, "has_fields", this->has_fields);
+  dump_field(out, "mode", static_cast<enums::WaterHeaterMode>(this->mode));
+  dump_field(out, "target_temperature", this->target_temperature);
+#ifdef USE_DEVICES
+  dump_field(out, "device_id", this->device_id);
+#endif
+  dump_field(out, "state", this->state);
+  dump_field(out, "target_temperature_low", this->target_temperature_low);
+  dump_field(out, "target_temperature_high", this->target_temperature_high);
+}
+#endif
 #ifdef USE_NUMBER
 void ListEntitiesNumberResponse::dump_to(std::string &out) const {
   MessageDumpHelper helper(out, "ListEntitiesNumberResponse");
diff --git a/esphome/components/api/api_pb2_includes.h b/esphome/components/api/api_pb2_includes.h
index 55d95304b1..f45e091c6f 100644
--- a/esphome/components/api/api_pb2_includes.h
+++ b/esphome/components/api/api_pb2_includes.h
@@ -10,6 +10,10 @@
 #include "esphome/components/climate/climate_traits.h"
 #endif
 
+#ifdef USE_WATER_HEATER
+#include "esphome/components/water_heater/water_heater.h"
+#endif
+
 #ifdef USE_LIGHT
 #include "esphome/components/light/light_traits.h"
 #endif
diff --git a/esphome/components/api/api_pb2_service.cpp b/esphome/components/api/api_pb2_service.cpp
index 45f6ecd30e..984cb0bb6e 100644
--- a/esphome/components/api/api_pb2_service.cpp
+++ b/esphome/components/api/api_pb2_service.cpp
@@ -621,6 +621,17 @@ void APIServerConnectionBase::read_message(uint32_t msg_size, uint32_t msg_type,
       this->on_homeassistant_action_response(msg);
       break;
     }
+#endif
+#ifdef USE_WATER_HEATER
+    case WaterHeaterCommandRequest::MESSAGE_TYPE: {
+      WaterHeaterCommandRequest msg;
+      msg.decode(msg_data, msg_size);
+#ifdef HAS_PROTO_MESSAGE_DUMP
+      ESP_LOGVV(TAG, "on_water_heater_command_request: %s", msg.dump().c_str());
+#endif
+      this->on_water_heater_command_request(msg);
+      break;
+    }
 #endif
     default:
       break;
diff --git a/esphome/components/api/api_pb2_service.h b/esphome/components/api/api_pb2_service.h
index 6d94046a23..261d9fbd27 100644
--- a/esphome/components/api/api_pb2_service.h
+++ b/esphome/components/api/api_pb2_service.h
@@ -91,6 +91,10 @@ class APIServerConnectionBase : public ProtoService {
   virtual void on_climate_command_request(const ClimateCommandRequest &value){};
 #endif
 
+#ifdef USE_WATER_HEATER
+  virtual void on_water_heater_command_request(const WaterHeaterCommandRequest &value){};
+#endif
+
 #ifdef USE_NUMBER
   virtual void on_number_command_request(const NumberCommandRequest &value){};
 #endif
diff --git a/esphome/components/api/api_server.cpp b/esphome/components/api/api_server.cpp
index b1a5ee5d57..7a03d8f8ad 100644
--- a/esphome/components/api/api_server.cpp
+++ b/esphome/components/api/api_server.cpp
@@ -335,6 +335,10 @@ API_DISPATCH_UPDATE(valve::Valve, valve)
 API_DISPATCH_UPDATE(media_player::MediaPlayer, media_player)
 #endif
 
+#ifdef USE_WATER_HEATER
+API_DISPATCH_UPDATE(water_heater::WaterHeater, water_heater)
+#endif
+
 #ifdef USE_EVENT
 // Event is a special case - unlike other entities with simple state fields,
 // events store their state in a member accessed via obj->get_last_event_type()
diff --git a/esphome/components/api/api_server.h b/esphome/components/api/api_server.h
index ad7d8bf63d..96c56fd08a 100644
--- a/esphome/components/api/api_server.h
+++ b/esphome/components/api/api_server.h
@@ -133,6 +133,9 @@ class APIServer : public Component,
 #ifdef USE_MEDIA_PLAYER
   void on_media_player_update(media_player::MediaPlayer *obj) override;
 #endif
+#ifdef USE_WATER_HEATER
+  void on_water_heater_update(water_heater::WaterHeater *obj) override;
+#endif
 #ifdef USE_API_HOMEASSISTANT_SERVICES
   void send_homeassistant_action(const HomeassistantActionRequest &call);
 
diff --git a/esphome/components/api/list_entities.cpp b/esphome/components/api/list_entities.cpp
index b4d1454153..2470899c93 100644
--- a/esphome/components/api/list_entities.cpp
+++ b/esphome/components/api/list_entities.cpp
@@ -73,6 +73,9 @@ LIST_ENTITIES_HANDLER(media_player, media_player::MediaPlayer, ListEntitiesMedia
 LIST_ENTITIES_HANDLER(alarm_control_panel, alarm_control_panel::AlarmControlPanel,
                       ListEntitiesAlarmControlPanelResponse)
 #endif
+#ifdef USE_WATER_HEATER
+LIST_ENTITIES_HANDLER(water_heater, water_heater::WaterHeater, ListEntitiesWaterHeaterResponse)
+#endif
 #ifdef USE_EVENT
 LIST_ENTITIES_HANDLER(event, event::Event, ListEntitiesEventResponse)
 #endif
diff --git a/esphome/components/api/list_entities.h b/esphome/components/api/list_entities.h
index 4c90dbbad8..04e6525eb0 100644
--- a/esphome/components/api/list_entities.h
+++ b/esphome/components/api/list_entities.h
@@ -82,6 +82,9 @@ class ListEntitiesIterator : public ComponentIterator {
 #ifdef USE_ALARM_CONTROL_PANEL
   bool on_alarm_control_panel(alarm_control_panel::AlarmControlPanel *entity) override;
 #endif
+#ifdef USE_WATER_HEATER
+  bool on_water_heater(water_heater::WaterHeater *entity) override;
+#endif
 #ifdef USE_EVENT
   bool on_event(event::Event *entity) override;
 #endif
diff --git a/esphome/components/api/subscribe_state.cpp b/esphome/components/api/subscribe_state.cpp
index 3a563f2221..4bbc17018e 100644
--- a/esphome/components/api/subscribe_state.cpp
+++ b/esphome/components/api/subscribe_state.cpp
@@ -60,6 +60,9 @@ INITIAL_STATE_HANDLER(media_player, media_player::MediaPlayer)
 #ifdef USE_ALARM_CONTROL_PANEL
 INITIAL_STATE_HANDLER(alarm_control_panel, alarm_control_panel::AlarmControlPanel)
 #endif
+#ifdef USE_WATER_HEATER
+INITIAL_STATE_HANDLER(water_heater, water_heater::WaterHeater)
+#endif
 #ifdef USE_UPDATE
 INITIAL_STATE_HANDLER(update, update::UpdateEntity)
 #endif
diff --git a/esphome/components/api/subscribe_state.h b/esphome/components/api/subscribe_state.h
index 2c22c322ec..9230000ace 100644
--- a/esphome/components/api/subscribe_state.h
+++ b/esphome/components/api/subscribe_state.h
@@ -76,6 +76,9 @@ class InitialStateIterator : public ComponentIterator {
 #ifdef USE_ALARM_CONTROL_PANEL
   bool on_alarm_control_panel(alarm_control_panel::AlarmControlPanel *entity) override;
 #endif
+#ifdef USE_WATER_HEATER
+  bool on_water_heater(water_heater::WaterHeater *entity) override;
+#endif
 #ifdef USE_EVENT
   bool on_event(event::Event *event) override { return true; };
 #endif
diff --git a/esphome/components/water_heater/__init__.py b/esphome/components/water_heater/__init__.py
new file mode 100644
index 0000000000..5420e7c435
--- /dev/null
+++ b/esphome/components/water_heater/__init__.py
@@ -0,0 +1,111 @@
+import esphome.codegen as cg
+import esphome.config_validation as cv
+from esphome.const import (
+    CONF_ENTITY_CATEGORY,
+    CONF_ICON,
+    CONF_ID,
+    CONF_MAX_TEMPERATURE,
+    CONF_MIN_TEMPERATURE,
+    CONF_VISUAL,
+)
+from esphome.core import CORE, CoroPriority, coroutine_with_priority
+from esphome.core.entity_helpers import entity_duplicate_validator, setup_entity
+from esphome.cpp_generator import MockObjClass
+from esphome.types import ConfigType
+
+CODEOWNERS = ["@dhoeben"]
+
+IS_PLATFORM_COMPONENT = True
+
+water_heater_ns = cg.esphome_ns.namespace("water_heater")
+WaterHeater = water_heater_ns.class_("WaterHeater", cg.EntityBase, cg.Component)
+WaterHeaterCall = water_heater_ns.class_("WaterHeaterCall")
+WaterHeaterTraits = water_heater_ns.class_("WaterHeaterTraits")
+
+CONF_TARGET_TEMPERATURE_STEP = "target_temperature_step"
+
+WaterHeaterMode = water_heater_ns.enum("WaterHeaterMode")
+WATER_HEATER_MODES = {
+    "OFF": WaterHeaterMode.WATER_HEATER_MODE_OFF,
+    "ECO": WaterHeaterMode.WATER_HEATER_MODE_ECO,
+    "ELECTRIC": WaterHeaterMode.WATER_HEATER_MODE_ELECTRIC,
+    "PERFORMANCE": WaterHeaterMode.WATER_HEATER_MODE_PERFORMANCE,
+    "HIGH_DEMAND": WaterHeaterMode.WATER_HEATER_MODE_HIGH_DEMAND,
+    "HEAT_PUMP": WaterHeaterMode.WATER_HEATER_MODE_HEAT_PUMP,
+    "GAS": WaterHeaterMode.WATER_HEATER_MODE_GAS,
+}
+validate_water_heater_mode = cv.enum(WATER_HEATER_MODES, upper=True)
+
+_WATER_HEATER_SCHEMA = cv.ENTITY_BASE_SCHEMA.extend(
+    {
+        cv.Optional(CONF_VISUAL, default={}): cv.Schema(
+            {
+                cv.Optional(CONF_MIN_TEMPERATURE): cv.temperature,
+                cv.Optional(CONF_MAX_TEMPERATURE): cv.temperature,
+                cv.Optional(CONF_TARGET_TEMPERATURE_STEP): cv.float_,
+            }
+        ),
+    }
+).extend(cv.COMPONENT_SCHEMA)
+
+_WATER_HEATER_SCHEMA.add_extra(entity_duplicate_validator("water_heater"))
+
+
+def water_heater_schema(
+    class_: MockObjClass,
+    *,
+    icon: str = cv.UNDEFINED,
+    entity_category: str = cv.UNDEFINED,
+) -> cv.Schema:
+    schema = {cv.GenerateID(): cv.declare_id(class_)}
+
+    for key, default, validator in [
+        (CONF_ICON, icon, cv.icon),
+        (CONF_ENTITY_CATEGORY, entity_category, cv.entity_category),
+    ]:
+        if default is not cv.UNDEFINED:
+            schema[cv.Optional(key, default=default)] = validator
+
+    return _WATER_HEATER_SCHEMA.extend(schema)
+
+
+async def setup_water_heater_core_(var: cg.Pvariable, config: ConfigType) -> None:
+    """Set up the core water heater properties in C++."""
+    await setup_entity(var, config, "water_heater")
+
+    visual = config[CONF_VISUAL]
+    if (min_temp := visual.get(CONF_MIN_TEMPERATURE)) is not None:
+        cg.add_define("USE_WATER_HEATER_VISUAL_OVERRIDES")
+        cg.add(var.set_visual_min_temperature_override(min_temp))
+    if (max_temp := visual.get(CONF_MAX_TEMPERATURE)) is not None:
+        cg.add_define("USE_WATER_HEATER_VISUAL_OVERRIDES")
+        cg.add(var.set_visual_max_temperature_override(max_temp))
+    if (temp_step := visual.get(CONF_TARGET_TEMPERATURE_STEP)) is not None:
+        cg.add_define("USE_WATER_HEATER_VISUAL_OVERRIDES")
+        cg.add(var.set_visual_target_temperature_step_override(temp_step))
+
+
+async def register_water_heater(var: cg.Pvariable, config: ConfigType) -> cg.Pvariable:
+    if not CORE.has_id(config[CONF_ID]):
+        var = cg.Pvariable(config[CONF_ID], var)
+
+    cg.add_define("USE_WATER_HEATER")
+
+    await cg.register_component(var, config)
+
+    cg.add(cg.App.register_water_heater(var))
+
+    CORE.register_platform_component("water_heater", var)
+    await setup_water_heater_core_(var, config)
+    return var
+
+
+async def new_water_heater(config: ConfigType, *args) -> cg.Pvariable:
+    var = cg.new_Pvariable(config[CONF_ID], *args)
+    await register_water_heater(var, config)
+    return var
+
+
+@coroutine_with_priority(CoroPriority.CORE)
+async def to_code(config: ConfigType) -> None:
+    cg.add_global(water_heater_ns.using)
diff --git a/esphome/components/water_heater/water_heater.cpp b/esphome/components/water_heater/water_heater.cpp
new file mode 100644
index 0000000000..441872ec00
--- /dev/null
+++ b/esphome/components/water_heater/water_heater.cpp
@@ -0,0 +1,281 @@
+#include "water_heater.h"
+#include "esphome/core/log.h"
+#include "esphome/core/application.h"
+#include "esphome/core/controller_registry.h"
+
+#include <cmath>
+
+namespace esphome::water_heater {
+
+static const char *const TAG = "water_heater";
+
+void log_water_heater(const char *tag, const char *prefix, const char *type, WaterHeater *obj) {
+  if (obj != nullptr) {
+    ESP_LOGCONFIG(tag, "%s%s '%s'", prefix, type, obj->get_name().c_str());
+  }
+}
+
+WaterHeaterCall::WaterHeaterCall(WaterHeater *parent) : parent_(parent) {}
+
+WaterHeaterCall &WaterHeaterCall::set_mode(WaterHeaterMode mode) {
+  this->mode_ = mode;
+  return *this;
+}
+
+WaterHeaterCall &WaterHeaterCall::set_mode(const std::string &mode) {
+  if (str_equals_case_insensitive(mode, "OFF")) {
+    this->set_mode(WATER_HEATER_MODE_OFF);
+  } else if (str_equals_case_insensitive(mode, "ECO")) {
+    this->set_mode(WATER_HEATER_MODE_ECO);
+  } else if (str_equals_case_insensitive(mode, "ELECTRIC")) {
+    this->set_mode(WATER_HEATER_MODE_ELECTRIC);
+  } else if (str_equals_case_insensitive(mode, "PERFORMANCE")) {
+    this->set_mode(WATER_HEATER_MODE_PERFORMANCE);
+  } else if (str_equals_case_insensitive(mode, "HIGH_DEMAND")) {
+    this->set_mode(WATER_HEATER_MODE_HIGH_DEMAND);
+  } else if (str_equals_case_insensitive(mode, "HEAT_PUMP")) {
+    this->set_mode(WATER_HEATER_MODE_HEAT_PUMP);
+  } else if (str_equals_case_insensitive(mode, "GAS")) {
+    this->set_mode(WATER_HEATER_MODE_GAS);
+  } else {
+    ESP_LOGW(TAG, "'%s' - Unrecognized mode %s", this->parent_->get_name().c_str(), mode.c_str());
+  }
+  return *this;
+}
+
+WaterHeaterCall &WaterHeaterCall::set_target_temperature(float temperature) {
+  this->target_temperature_ = temperature;
+  return *this;
+}
+
+WaterHeaterCall &WaterHeaterCall::set_target_temperature_low(float temperature) {
+  this->target_temperature_low_ = temperature;
+  return *this;
+}
+
+WaterHeaterCall &WaterHeaterCall::set_target_temperature_high(float temperature) {
+  this->target_temperature_high_ = temperature;
+  return *this;
+}
+
+WaterHeaterCall &WaterHeaterCall::set_away(bool away) {
+  if (away) {
+    this->state_ |= WATER_HEATER_STATE_AWAY;
+  } else {
+    this->state_ &= ~WATER_HEATER_STATE_AWAY;
+  }
+  return *this;
+}
+
+WaterHeaterCall &WaterHeaterCall::set_on(bool on) {
+  if (on) {
+    this->state_ |= WATER_HEATER_STATE_ON;
+  } else {
+    this->state_ &= ~WATER_HEATER_STATE_ON;
+  }
+  return *this;
+}
+
+void WaterHeaterCall::perform() {
+  ESP_LOGD(TAG, "'%s' - Setting", this->parent_->get_name().c_str());
+  this->validate_();
+  if (this->mode_.has_value()) {
+    ESP_LOGD(TAG, "  Mode: %s", LOG_STR_ARG(water_heater_mode_to_string(*this->mode_)));
+  }
+  if (!std::isnan(this->target_temperature_)) {
+    ESP_LOGD(TAG, "  Target Temperature: %.2f", this->target_temperature_);
+  }
+  if (!std::isnan(this->target_temperature_low_)) {
+    ESP_LOGD(TAG, "  Target Temperature Low: %.2f", this->target_temperature_low_);
+  }
+  if (!std::isnan(this->target_temperature_high_)) {
+    ESP_LOGD(TAG, "  Target Temperature High: %.2f", this->target_temperature_high_);
+  }
+  if (this->state_ & WATER_HEATER_STATE_AWAY) {
+    ESP_LOGD(TAG, "  Away: YES");
+  }
+  if (this->state_ & WATER_HEATER_STATE_ON) {
+    ESP_LOGD(TAG, "  On: YES");
+  }
+  this->parent_->control(*this);
+}
+
+void WaterHeaterCall::validate_() {
+  auto traits = this->parent_->get_traits();
+  if (this->mode_.has_value()) {
+    if (!traits.supports_mode(*this->mode_)) {
+      ESP_LOGW(TAG, "'%s' - Mode %d not supported", this->parent_->get_name().c_str(), *this->mode_);
+      this->mode_.reset();
+    }
+  }
+  if (!std::isnan(this->target_temperature_)) {
+    if (traits.get_supports_two_point_target_temperature()) {
+      ESP_LOGW(TAG, "'%s' - Cannot set target temperature for device with two-point target temperature",
+               this->parent_->get_name().c_str());
+      this->target_temperature_ = NAN;
+    } else if (this->target_temperature_ < traits.get_min_temperature() ||
+               this->target_temperature_ > traits.get_max_temperature()) {
+      ESP_LOGW(TAG, "'%s' - Target temperature %.1f is out of range [%.1f - %.1f]", this->parent_->get_name().c_str(),
+               this->target_temperature_, traits.get_min_temperature(), traits.get_max_temperature());
+      this->target_temperature_ =
+          std::max(traits.get_min_temperature(), std::min(this->target_temperature_, traits.get_max_temperature()));
+    }
+  }
+  if (!std::isnan(this->target_temperature_low_) || !std::isnan(this->target_temperature_high_)) {
+    if (!traits.get_supports_two_point_target_temperature()) {
+      ESP_LOGW(TAG, "'%s' - Cannot set low/high target temperature", this->parent_->get_name().c_str());
+      this->target_temperature_low_ = NAN;
+      this->target_temperature_high_ = NAN;
+    }
+  }
+  if (!std::isnan(this->target_temperature_low_) && !std::isnan(this->target_temperature_high_)) {
+    if (this->target_temperature_low_ > this->target_temperature_high_) {
+      ESP_LOGW(TAG, "'%s' - Target temperature low %.2f must be less than high %.2f", this->parent_->get_name().c_str(),
+               this->target_temperature_low_, this->target_temperature_high_);
+      this->target_temperature_low_ = NAN;
+      this->target_temperature_high_ = NAN;
+    }
+  }
+  if ((this->state_ & WATER_HEATER_STATE_AWAY) && !traits.get_supports_away_mode()) {
+    ESP_LOGW(TAG, "'%s' - Away mode not supported", this->parent_->get_name().c_str());
+    this->state_ &= ~WATER_HEATER_STATE_AWAY;
+  }
+  // If ON/OFF not supported, device is always on - clear the flag silently
+  if (!traits.has_feature_flags(WATER_HEATER_SUPPORTS_ON_OFF)) {
+    this->state_ &= ~WATER_HEATER_STATE_ON;
+  }
+}
+
+void WaterHeater::setup() {
+  this->pref_ = global_preferences->make_preference<SavedWaterHeaterState>(this->get_preference_hash());
+}
+
+void WaterHeater::publish_state() {
+  auto traits = this->get_traits();
+  ESP_LOGD(TAG, "'%s' - Sending state:", this->name_.c_str());
+  ESP_LOGD(TAG, "  Mode: %s", LOG_STR_ARG(water_heater_mode_to_string(this->mode_)));
+  if (!std::isnan(this->current_temperature_)) {
+    ESP_LOGD(TAG, "  Current Temperature: %.2f°C", this->current_temperature_);
+  }
+  if (traits.get_supports_two_point_target_temperature()) {
+    ESP_LOGD(TAG, "  Target Temperature: Low: %.2f°C High: %.2f°C", this->target_temperature_low_,
+             this->target_temperature_high_);
+  } else if (!std::isnan(this->target_temperature_)) {
+    ESP_LOGD(TAG, "  Target Temperature: %.2f°C", this->target_temperature_);
+  }
+  if (this->state_ & WATER_HEATER_STATE_AWAY) {
+    ESP_LOGD(TAG, "  Away: YES");
+  }
+  if (traits.has_feature_flags(WATER_HEATER_SUPPORTS_ON_OFF)) {
+    ESP_LOGD(TAG, "  On: %s", (this->state_ & WATER_HEATER_STATE_ON) ? "YES" : "NO");
+  }
+
+#if defined(USE_WATER_HEATER) && defined(USE_CONTROLLER_REGISTRY)
+  ControllerRegistry::notify_water_heater_update(this);
+#endif
+
+  SavedWaterHeaterState saved{};
+  saved.mode = this->mode_;
+  if (traits.get_supports_two_point_target_temperature()) {
+    saved.target_temperature_low = this->target_temperature_low_;
+    saved.target_temperature_high = this->target_temperature_high_;
+  } else {
+    saved.target_temperature = this->target_temperature_;
+  }
+  saved.state = this->state_;
+  this->pref_.save(&saved);
+}
+
+optional<WaterHeaterCall> WaterHeater::restore_state() {
+  SavedWaterHeaterState recovered{};
+  if (!this->pref_.load(&recovered))
+    return {};
+
+  auto traits = this->get_traits();
+  auto call = this->make_call();
+  call.set_mode(recovered.mode);
+  if (traits.get_supports_two_point_target_temperature()) {
+    call.set_target_temperature_low(recovered.target_temperature_low);
+    call.set_target_temperature_high(recovered.target_temperature_high);
+  } else {
+    call.set_target_temperature(recovered.target_temperature);
+  }
+  call.set_away((recovered.state & WATER_HEATER_STATE_AWAY) != 0);
+  call.set_on((recovered.state & WATER_HEATER_STATE_ON) != 0);
+  return call;
+}
+
+WaterHeaterTraits WaterHeater::get_traits() {
+  auto traits = this->traits();
+#ifdef USE_WATER_HEATER_VISUAL_OVERRIDES
+  if (!std::isnan(this->visual_min_temperature_override_)) {
+    traits.set_min_temperature(this->visual_min_temperature_override_);
+  }
+  if (!std::isnan(this->visual_max_temperature_override_)) {
+    traits.set_max_temperature(this->visual_max_temperature_override_);
+  }
+  if (!std::isnan(this->visual_target_temperature_step_override_)) {
+    traits.set_target_temperature_step(this->visual_target_temperature_step_override_);
+  }
+#endif
+  return traits;
+}
+
+#ifdef USE_WATER_HEATER_VISUAL_OVERRIDES
+void WaterHeater::set_visual_min_temperature_override(float min_temperature_override) {
+  this->visual_min_temperature_override_ = min_temperature_override;
+}
+void WaterHeater::set_visual_max_temperature_override(float max_temperature_override) {
+  this->visual_max_temperature_override_ = max_temperature_override;
+}
+void WaterHeater::set_visual_target_temperature_step_override(float visual_target_temperature_step_override) {
+  this->visual_target_temperature_step_override_ = visual_target_temperature_step_override;
+}
+#endif
+
+const LogString *water_heater_mode_to_string(WaterHeaterMode mode) {
+  switch (mode) {
+    case WATER_HEATER_MODE_OFF:
+      return LOG_STR("OFF");
+    case WATER_HEATER_MODE_ECO:
+      return LOG_STR("ECO");
+    case WATER_HEATER_MODE_ELECTRIC:
+      return LOG_STR("ELECTRIC");
+    case WATER_HEATER_MODE_PERFORMANCE:
+      return LOG_STR("PERFORMANCE");
+    case WATER_HEATER_MODE_HIGH_DEMAND:
+      return LOG_STR("HIGH_DEMAND");
+    case WATER_HEATER_MODE_HEAT_PUMP:
+      return LOG_STR("HEAT_PUMP");
+    case WATER_HEATER_MODE_GAS:
+      return LOG_STR("GAS");
+    default:
+      return LOG_STR("UNKNOWN");
+  }
+}
+
+void WaterHeater::dump_traits_(const char *tag) {
+  auto traits = this->get_traits();
+  ESP_LOGCONFIG(tag,
+                "  Min Temperature: %.1f°C\n"
+                "  Max Temperature: %.1f°C\n"
+                "  Temperature Step: %.1f",
+                traits.get_min_temperature(), traits.get_max_temperature(), traits.get_target_temperature_step());
+  if (traits.get_supports_two_point_target_temperature()) {
+    ESP_LOGCONFIG(tag, "  Supports Two-Point Target Temperature: YES");
+  }
+  if (traits.get_supports_away_mode()) {
+    ESP_LOGCONFIG(tag, "  Supports Away Mode: YES");
+  }
+  if (traits.has_feature_flags(WATER_HEATER_SUPPORTS_ON_OFF)) {
+    ESP_LOGCONFIG(tag, "  Supports On/Off: YES");
+  }
+  if (!traits.get_supported_modes().empty()) {
+    ESP_LOGCONFIG(tag, "  Supported Modes:");
+    for (WaterHeaterMode m : traits.get_supported_modes()) {
+      ESP_LOGCONFIG(tag, "    - %s", LOG_STR_ARG(water_heater_mode_to_string(m)));
+    }
+  }
+}
+
+}  // namespace esphome::water_heater
diff --git a/esphome/components/water_heater/water_heater.h b/esphome/components/water_heater/water_heater.h
new file mode 100644
index 0000000000..e223dd59b2
--- /dev/null
+++ b/esphome/components/water_heater/water_heater.h
@@ -0,0 +1,259 @@
+#pragma once
+
+#include "esphome/core/component.h"
+#include "esphome/core/entity_base.h"
+#include "esphome/core/finite_set_mask.h"
+#include "esphome/core/helpers.h"
+#include "esphome/core/log.h"
+#include "esphome/core/preferences.h"
+
+namespace esphome::water_heater {
+
+class WaterHeater;
+struct WaterHeaterCallInternal;
+
+void log_water_heater(const char *tag, const char *prefix, const char *type, WaterHeater *obj);
+#define LOG_WATER_HEATER(prefix, type, obj) log_water_heater(TAG, prefix, LOG_STR_LITERAL(type), obj)
+
+enum WaterHeaterMode : uint32_t {
+  WATER_HEATER_MODE_OFF = 0,
+  WATER_HEATER_MODE_ECO = 1,
+  WATER_HEATER_MODE_ELECTRIC = 2,
+  WATER_HEATER_MODE_PERFORMANCE = 3,
+  WATER_HEATER_MODE_HIGH_DEMAND = 4,
+  WATER_HEATER_MODE_HEAT_PUMP = 5,
+  WATER_HEATER_MODE_GAS = 6,
+};
+
+// Type alias for water heater mode bitmask
+// Replaces std::set<WaterHeaterMode> to eliminate red-black tree overhead
+using WaterHeaterModeMask =
+    FiniteSetMask<WaterHeaterMode, DefaultBitPolicy<WaterHeaterMode, WATER_HEATER_MODE_GAS + 1>>;
+
+/// Feature flags for water heater capabilities (matches Home Assistant WaterHeaterEntityFeature)
+enum WaterHeaterFeature : uint32_t {
+  /// The water heater supports reporting the current temperature.
+  WATER_HEATER_SUPPORTS_CURRENT_TEMPERATURE = 1 << 0,
+  /// The water heater supports a target temperature.
+  WATER_HEATER_SUPPORTS_TARGET_TEMPERATURE = 1 << 1,
+  /// The water heater supports operation mode selection.
+  WATER_HEATER_SUPPORTS_OPERATION_MODE = 1 << 2,
+  /// The water heater supports an away/vacation mode.
+  WATER_HEATER_SUPPORTS_AWAY_MODE = 1 << 3,
+  /// The water heater can be turned on/off.
+  WATER_HEATER_SUPPORTS_ON_OFF = 1 << 4,
+  /// The water heater supports two-point target temperature (low/high range).
+  WATER_HEATER_SUPPORTS_TWO_POINT_TARGET_TEMPERATURE = 1 << 5,
+};
+
+/// State flags for water heater current state (bitmask)
+enum WaterHeaterStateFlag : uint32_t {
+  /// Away/vacation mode is currently active
+  WATER_HEATER_STATE_AWAY = 1 << 0,
+  /// Water heater is on (not in standby)
+  WATER_HEATER_STATE_ON = 1 << 1,
+};
+
+struct SavedWaterHeaterState {
+  WaterHeaterMode mode;
+  union {
+    float target_temperature;
+    struct {
+      float target_temperature_low;
+      float target_temperature_high;
+    };
+  } __attribute__((packed));
+  uint32_t state;
+} __attribute__((packed));
+
+class WaterHeaterCall {
+  friend struct WaterHeaterCallInternal;
+
+ public:
+  WaterHeaterCall() : parent_(nullptr) {}
+
+  WaterHeaterCall(WaterHeater *parent);
+
+  WaterHeaterCall &set_mode(WaterHeaterMode mode);
+  WaterHeaterCall &set_mode(const std::string &mode);
+  WaterHeaterCall &set_target_temperature(float temperature);
+  WaterHeaterCall &set_target_temperature_low(float temperature);
+  WaterHeaterCall &set_target_temperature_high(float temperature);
+  WaterHeaterCall &set_away(bool away);
+  WaterHeaterCall &set_on(bool on);
+
+  void perform();
+
+  const optional<WaterHeaterMode> &get_mode() const { return this->mode_; }
+  float get_target_temperature() const { return this->target_temperature_; }
+  float get_target_temperature_low() const { return this->target_temperature_low_; }
+  float get_target_temperature_high() const { return this->target_temperature_high_; }
+  /// Get state flags value
+  uint32_t get_state() const { return this->state_; }
+
+ protected:
+  void validate_();
+  WaterHeater *parent_;
+  optional<WaterHeaterMode> mode_;
+  float target_temperature_{NAN};
+  float target_temperature_low_{NAN};
+  float target_temperature_high_{NAN};
+  uint32_t state_{0};
+};
+
+struct WaterHeaterCallInternal : public WaterHeaterCall {
+  WaterHeaterCallInternal(WaterHeater *parent) : WaterHeaterCall(parent) {}
+
+  WaterHeaterCallInternal &set_from_restore(const WaterHeaterCall &restore) {
+    this->mode_ = restore.mode_;
+    this->target_temperature_ = restore.target_temperature_;
+    this->target_temperature_low_ = restore.target_temperature_low_;
+    this->target_temperature_high_ = restore.target_temperature_high_;
+    this->state_ = restore.state_;
+    return *this;
+  }
+};
+
+class WaterHeaterTraits {
+ public:
+  /// Get/set feature flags (see WaterHeaterFeature enum)
+  void add_feature_flags(uint32_t flags) { this->feature_flags_ |= flags; }
+  void clear_feature_flags(uint32_t flags) { this->feature_flags_ &= ~flags; }
+  bool has_feature_flags(uint32_t flags) const { return (this->feature_flags_ & flags) == flags; }
+  uint32_t get_feature_flags() const { return this->feature_flags_; }
+
+  bool get_supports_current_temperature() const {
+    return this->has_feature_flags(WATER_HEATER_SUPPORTS_CURRENT_TEMPERATURE);
+  }
+  void set_supports_current_temperature(bool supports) {
+    if (supports) {
+      this->add_feature_flags(WATER_HEATER_SUPPORTS_CURRENT_TEMPERATURE);
+    } else {
+      this->clear_feature_flags(WATER_HEATER_SUPPORTS_CURRENT_TEMPERATURE);
+    }
+  }
+
+  bool get_supports_away_mode() const { return this->has_feature_flags(WATER_HEATER_SUPPORTS_AWAY_MODE); }
+  void set_supports_away_mode(bool supports) {
+    if (supports) {
+      this->add_feature_flags(WATER_HEATER_SUPPORTS_AWAY_MODE);
+    } else {
+      this->clear_feature_flags(WATER_HEATER_SUPPORTS_AWAY_MODE);
+    }
+  }
+
+  bool get_supports_two_point_target_temperature() const {
+    return this->has_feature_flags(WATER_HEATER_SUPPORTS_TWO_POINT_TARGET_TEMPERATURE);
+  }
+  void set_supports_two_point_target_temperature(bool supports) {
+    if (supports) {
+      this->add_feature_flags(WATER_HEATER_SUPPORTS_TWO_POINT_TARGET_TEMPERATURE);
+    } else {
+      this->clear_feature_flags(WATER_HEATER_SUPPORTS_TWO_POINT_TARGET_TEMPERATURE);
+    }
+  }
+
+  void set_min_temperature(float min_temperature) { this->min_temperature_ = min_temperature; }
+  float get_min_temperature() const { return this->min_temperature_; }
+
+  void set_max_temperature(float max_temperature) { this->max_temperature_ = max_temperature; }
+  float get_max_temperature() const { return this->max_temperature_; }
+
+  void set_target_temperature_step(float target_temperature_step) {
+    this->target_temperature_step_ = target_temperature_step;
+  }
+  float get_target_temperature_step() const { return this->target_temperature_step_; }
+
+  void set_supported_modes(WaterHeaterModeMask modes) { this->supported_modes_ = modes; }
+  const WaterHeaterModeMask &get_supported_modes() const { return this->supported_modes_; }
+  bool supports_mode(WaterHeaterMode mode) const { return this->supported_modes_.count(mode); }
+
+ protected:
+  // Ordered to minimize padding: 4-byte members first
+  uint32_t feature_flags_{0};
+  float min_temperature_{0.0f};
+  float max_temperature_{0.0f};
+  float target_temperature_step_{0.0f};
+  WaterHeaterModeMask supported_modes_;
+};
+
+class WaterHeater : public EntityBase, public Component {
+ public:
+  WaterHeaterMode get_mode() const { return this->mode_; }
+  float get_current_temperature() const { return this->current_temperature_; }
+  float get_target_temperature() const { return this->target_temperature_; }
+  float get_target_temperature_low() const { return this->target_temperature_low_; }
+  float get_target_temperature_high() const { return this->target_temperature_high_; }
+  /// Get the current state flags bitmask
+  uint32_t get_state() const { return this->state_; }
+  /// Check if away mode is currently active
+  bool is_away() const { return (this->state_ & WATER_HEATER_STATE_AWAY) != 0; }
+  /// Check if the water heater is on
+  bool is_on() const { return (this->state_ & WATER_HEATER_STATE_ON) != 0; }
+
+  void set_current_temperature(float current_temperature) { this->current_temperature_ = current_temperature; }
+
+  virtual void publish_state();
+  virtual WaterHeaterTraits get_traits();
+  virtual WaterHeaterCallInternal make_call() = 0;
+
+#ifdef USE_WATER_HEATER_VISUAL_OVERRIDES
+  void set_visual_min_temperature_override(float min_temperature_override);
+  void set_visual_max_temperature_override(float max_temperature_override);
+  void set_visual_target_temperature_step_override(float visual_target_temperature_step_override);
+#endif
+  virtual void control(const WaterHeaterCall &call) = 0;
+
+  void setup() override;
+
+  optional<WaterHeaterCall> restore_state();
+
+ protected:
+  virtual WaterHeaterTraits traits() = 0;
+
+  /// Log the traits of this water heater for dump_config().
+  void dump_traits_(const char *tag);
+
+  /// Set the mode of the water heater. Should only be called from control().
+  void set_mode_(WaterHeaterMode mode) { this->mode_ = mode; }
+  /// Set the target temperature of the water heater. Should only be called from control().
+  void set_target_temperature_(float target_temperature) { this->target_temperature_ = target_temperature; }
+  /// Set the low target temperature (for two-point control). Should only be called from control().
+  void set_target_temperature_low_(float target_temperature_low) {
+    this->target_temperature_low_ = target_temperature_low;
+  }
+  /// Set the high target temperature (for two-point control). Should only be called from control().
+  void set_target_temperature_high_(float target_temperature_high) {
+    this->target_temperature_high_ = target_temperature_high;
+  }
+  /// Set the state flags. Should only be called from control().
+  void set_state_(uint32_t state) { this->state_ = state; }
+  /// Set or clear a state flag. Should only be called from control().
+  void set_state_flag_(uint32_t flag, bool value) {
+    if (value) {
+      this->state_ |= flag;
+    } else {
+      this->state_ &= ~flag;
+    }
+  }
+
+  WaterHeaterMode mode_{WATER_HEATER_MODE_OFF};
+  float current_temperature_{NAN};
+  float target_temperature_{NAN};
+  float target_temperature_low_{NAN};
+  float target_temperature_high_{NAN};
+  uint32_t state_{0};  // Bitmask of WaterHeaterStateFlag
+
+#ifdef USE_WATER_HEATER_VISUAL_OVERRIDES
+  float visual_min_temperature_override_{NAN};
+  float visual_max_temperature_override_{NAN};
+  float visual_target_temperature_step_override_{NAN};
+#endif
+
+  ESPPreferenceObject pref_;
+};
+
+/// Convert the given WaterHeaterMode to a human-readable string for logging.
+const LogString *water_heater_mode_to_string(WaterHeaterMode mode);
+
+}  // namespace esphome::water_heater
diff --git a/esphome/components/web_server/list_entities.cpp b/esphome/components/web_server/list_entities.cpp
index 6b27545549..16b1d1e797 100644
--- a/esphome/components/web_server/list_entities.cpp
+++ b/esphome/components/web_server/list_entities.cpp
@@ -135,6 +135,13 @@ bool ListEntitiesIterator::on_alarm_control_panel(alarm_control_panel::AlarmCont
 }
 #endif
 
+#ifdef USE_WATER_HEATER
+bool ListEntitiesIterator::on_water_heater(water_heater::WaterHeater *obj) {
+  // Water heater web_server support not yet implemented - this stub acknowledges the entity
+  return true;
+}
+#endif
+
 #ifdef USE_EVENT
 bool ListEntitiesIterator::on_event(event::Event *obj) {
   // Null event type, since we are just iterating over entities
diff --git a/esphome/components/web_server/list_entities.h b/esphome/components/web_server/list_entities.h
index 43e1cc2544..5d9049b082 100644
--- a/esphome/components/web_server/list_entities.h
+++ b/esphome/components/web_server/list_entities.h
@@ -79,6 +79,9 @@ class ListEntitiesIterator : public ComponentIterator {
 #ifdef USE_ALARM_CONTROL_PANEL
   bool on_alarm_control_panel(alarm_control_panel::AlarmControlPanel *obj) override;
 #endif
+#ifdef USE_WATER_HEATER
+  bool on_water_heater(water_heater::WaterHeater *obj) override;
+#endif
 #ifdef USE_EVENT
   bool on_event(event::Event *obj) override;
 #endif
diff --git a/esphome/const.py b/esphome/const.py
index f43204fd9f..1d46e81f9d 100644
--- a/esphome/const.py
+++ b/esphome/const.py
@@ -1086,6 +1086,7 @@ CONF_WARM_WHITE = "warm_white"
 CONF_WARM_WHITE_COLOR_TEMPERATURE = "warm_white_color_temperature"
 CONF_WATCHDOG_THRESHOLD = "watchdog_threshold"
 CONF_WATCHDOG_TIMEOUT = "watchdog_timeout"
+CONF_WATER_HEATER = "water_heater"
 CONF_WEB_SERVER = "web_server"
 CONF_WEB_SERVER_ID = "web_server_id"
 CONF_WEIGHT = "weight"
@@ -1179,6 +1180,7 @@ ICON_TIMELAPSE = "mdi:timelapse"
 ICON_TIMER = "mdi:timer-outline"
 ICON_VIBRATE = "mdi:vibrate"
 ICON_WATER = "mdi:water"
+ICON_WATER_HEATER = "mdi:water-boiler"
 ICON_WATER_PERCENT = "mdi:water-percent"
 ICON_WEATHER_SUNSET = "mdi:weather-sunset"
 ICON_WEATHER_SUNSET_DOWN = "mdi:weather-sunset-down"
diff --git a/esphome/core/application.h b/esphome/core/application.h
index f462553a81..d2146a6c16 100644
--- a/esphome/core/application.h
+++ b/esphome/core/application.h
@@ -87,6 +87,9 @@
 #ifdef USE_ALARM_CONTROL_PANEL
 #include "esphome/components/alarm_control_panel/alarm_control_panel.h"
 #endif
+#ifdef USE_WATER_HEATER
+#include "esphome/components/water_heater/water_heater.h"
+#endif
 #ifdef USE_EVENT
 #include "esphome/components/event/event.h"
 #endif
@@ -217,6 +220,10 @@ class Application {
   }
 #endif
 
+#ifdef USE_WATER_HEATER
+  void register_water_heater(water_heater::WaterHeater *water_heater) { this->water_heaters_.push_back(water_heater); }
+#endif
+
 #ifdef USE_EVENT
   void register_event(event::Event *event) { this->events_.push_back(event); }
 #endif
@@ -437,6 +444,11 @@ class Application {
   GET_ENTITY_METHOD(alarm_control_panel::AlarmControlPanel, alarm_control_panel, alarm_control_panels)
 #endif
 
+#ifdef USE_WATER_HEATER
+  auto &get_water_heaters() const { return this->water_heaters_; }
+  GET_ENTITY_METHOD(water_heater::WaterHeater, water_heater, water_heaters)
+#endif
+
 #ifdef USE_EVENT
   auto &get_events() const { return this->events_; }
   GET_ENTITY_METHOD(event::Event, event, events)
@@ -634,6 +646,9 @@ class Application {
   StaticVector<alarm_control_panel::AlarmControlPanel *, ESPHOME_ENTITY_ALARM_CONTROL_PANEL_COUNT>
       alarm_control_panels_{};
 #endif
+#ifdef USE_WATER_HEATER
+  StaticVector<water_heater::WaterHeater *, ESPHOME_ENTITY_WATER_HEATER_COUNT> water_heaters_{};
+#endif
 #ifdef USE_UPDATE
   StaticVector<update::UpdateEntity *, ESPHOME_ENTITY_UPDATE_COUNT> updates_{};
 #endif
diff --git a/esphome/core/component_iterator.cpp b/esphome/core/component_iterator.cpp
index 8c6a7b95b5..4015d8ec60 100644
--- a/esphome/core/component_iterator.cpp
+++ b/esphome/core/component_iterator.cpp
@@ -163,6 +163,12 @@ void ComponentIterator::advance() {
       break;
 #endif
 
+#ifdef USE_WATER_HEATER
+    case IteratorState::WATER_HEATER:
+      this->process_platform_item_(App.get_water_heaters(), &ComponentIterator::on_water_heater);
+      break;
+#endif
+
 #ifdef USE_EVENT
     case IteratorState::EVENT:
       this->process_platform_item_(App.get_events(), &ComponentIterator::on_event);
diff --git a/esphome/core/component_iterator.h b/esphome/core/component_iterator.h
index 1b1bd80ac5..37d1960601 100644
--- a/esphome/core/component_iterator.h
+++ b/esphome/core/component_iterator.h
@@ -84,6 +84,9 @@ class ComponentIterator {
 #ifdef USE_ALARM_CONTROL_PANEL
   virtual bool on_alarm_control_panel(alarm_control_panel::AlarmControlPanel *a_alarm_control_panel) = 0;
 #endif
+#ifdef USE_WATER_HEATER
+  virtual bool on_water_heater(water_heater::WaterHeater *water_heater) = 0;
+#endif
 #ifdef USE_EVENT
   virtual bool on_event(event::Event *event) = 0;
 #endif
@@ -161,6 +164,9 @@ class ComponentIterator {
 #ifdef USE_ALARM_CONTROL_PANEL
     ALARM_CONTROL_PANEL,
 #endif
+#ifdef USE_WATER_HEATER
+    WATER_HEATER,
+#endif
 #ifdef USE_EVENT
     EVENT,
 #endif
diff --git a/esphome/core/controller.h b/esphome/core/controller.h
index 697017217d..632b46c893 100644
--- a/esphome/core/controller.h
+++ b/esphome/core/controller.h
@@ -58,6 +58,9 @@
 #ifdef USE_ALARM_CONTROL_PANEL
 #include "esphome/components/alarm_control_panel/alarm_control_panel.h"
 #endif
+#ifdef USE_WATER_HEATER
+#include "esphome/components/water_heater/water_heater.h"
+#endif
 #ifdef USE_EVENT
 #include "esphome/components/event/event.h"
 #endif
@@ -123,6 +126,9 @@ class Controller {
 #ifdef USE_ALARM_CONTROL_PANEL
   virtual void on_alarm_control_panel_update(alarm_control_panel::AlarmControlPanel *obj){};
 #endif
+#ifdef USE_WATER_HEATER
+  virtual void on_water_heater_update(water_heater::WaterHeater *obj){};
+#endif
 #ifdef USE_EVENT
   virtual void on_event(event::Event *obj){};
 #endif
diff --git a/esphome/core/controller_registry.cpp b/esphome/core/controller_registry.cpp
index 0a84bb0d0d..13b505e8e9 100644
--- a/esphome/core/controller_registry.cpp
+++ b/esphome/core/controller_registry.cpp
@@ -98,6 +98,10 @@ CONTROLLER_REGISTRY_NOTIFY(media_player::MediaPlayer, media_player)
 CONTROLLER_REGISTRY_NOTIFY(alarm_control_panel::AlarmControlPanel, alarm_control_panel)
 #endif
 
+#ifdef USE_WATER_HEATER
+CONTROLLER_REGISTRY_NOTIFY(water_heater::WaterHeater, water_heater)
+#endif
+
 #ifdef USE_EVENT
 CONTROLLER_REGISTRY_NOTIFY_NO_UPDATE_SUFFIX(event::Event, event)
 #endif
diff --git a/esphome/core/controller_registry.h b/esphome/core/controller_registry.h
index 640a276a0a..d6452d8827 100644
--- a/esphome/core/controller_registry.h
+++ b/esphome/core/controller_registry.h
@@ -119,6 +119,12 @@ class AlarmControlPanel;
 }
 #endif
 
+#ifdef USE_WATER_HEATER
+namespace water_heater {
+class WaterHeater;
+}
+#endif
+
 #ifdef USE_EVENT
 namespace event {
 class Event;
@@ -228,6 +234,10 @@ class ControllerRegistry {
   static void notify_alarm_control_panel_update(alarm_control_panel::AlarmControlPanel *obj);
 #endif
 
+#ifdef USE_WATER_HEATER
+  static void notify_water_heater_update(water_heater::WaterHeater *obj);
+#endif
+
 #ifdef USE_EVENT
   static void notify_event(event::Event *obj);
 #endif
diff --git a/esphome/core/defines.h b/esphome/core/defines.h
index 0c12b29eb7..11c5062140 100644
--- a/esphome/core/defines.h
+++ b/esphome/core/defines.h
@@ -113,6 +113,8 @@
 #define USE_UART_WAKE_LOOP_ON_RX
 #define USE_UPDATE
 #define USE_VALVE
+#define USE_WATER_HEATER
+#define USE_WATER_HEATER_VISUAL_OVERRIDES
 #define USE_ZWAVE_PROXY
 
 // Feature flags which do not work for zephyr
@@ -337,3 +339,4 @@
 #define ESPHOME_ENTITY_TIME_COUNT 1
 #define ESPHOME_ENTITY_UPDATE_COUNT 1
 #define ESPHOME_ENTITY_VALVE_COUNT 1
+#define ESPHOME_ENTITY_WATER_HEATER_COUNT 1