diff --git a/esphome/components/atm90e32/atm90e32.cpp b/esphome/components/atm90e32/atm90e32.cpp
index 412964d0f8..ee7fe5ce75 100644
--- a/esphome/components/atm90e32/atm90e32.cpp
+++ b/esphome/components/atm90e32/atm90e32.cpp
@@ -619,7 +619,7 @@ void ATM90E32Component::run_gain_calibrations() {
       ESP_LOGW(TAG, "[CALIBRATION][%s] Phase %s - Skipping voltage calibration: measured voltage is 0.", cs,
                phase_labels[phase]);
     } else {
-      uint32_t new_voltage_gain = static_cast<uint16_t>((ref_voltage / measured_voltage) * current_voltage_gain);
+      uint32_t new_voltage_gain = static_cast<uint32_t>((ref_voltage / measured_voltage) * current_voltage_gain);
       if (new_voltage_gain == 0) {
         ESP_LOGW(TAG, "[CALIBRATION][%s] Phase %s - Voltage gain would be 0. Check reference and measured voltage.", cs,
                  phase_labels[phase]);
@@ -644,7 +644,7 @@ void ATM90E32Component::run_gain_calibrations() {
       ESP_LOGW(TAG, "[CALIBRATION][%s] Phase %s - Skipping current calibration: measured current is 0.", cs,
                phase_labels[phase]);
     } else {
-      uint32_t new_current_gain = static_cast<uint16_t>((ref_current / measured_current) * current_current_gain);
+      uint32_t new_current_gain = static_cast<uint32_t>((ref_current / measured_current) * current_current_gain);
       if (new_current_gain == 0) {
         ESP_LOGW(TAG, "[CALIBRATION][%s] Phase %s - Current gain would be 0. Check reference and measured current.", cs,
                  phase_labels[phase]);
diff --git a/esphome/components/bedjet/bedjet_hub.h b/esphome/components/bedjet/bedjet_hub.h
index 6258795b02..59b0af93ad 100644
--- a/esphome/components/bedjet/bedjet_hub.h
+++ b/esphome/components/bedjet/bedjet_hub.h
@@ -164,10 +164,10 @@ class BedJetHub : public esphome::ble_client::BLEClientNode, public PollingCompo
   std::unique_ptr<BedjetCodec> codec_;
 
   bool discover_characteristics_();
-  uint16_t char_handle_cmd_;
-  uint16_t char_handle_name_;
-  uint16_t char_handle_status_;
-  uint16_t config_descr_status_;
+  uint16_t char_handle_cmd_{0};
+  uint16_t char_handle_name_{0};
+  uint16_t char_handle_status_{0};
+  uint16_t config_descr_status_{0};
 
   uint8_t write_notify_config_descriptor_(bool enable);
 };
diff --git a/esphome/components/current_based/current_based_cover.h b/esphome/components/current_based/current_based_cover.h
index 76bd85cdf7..40b39517e4 100644
--- a/esphome/components/current_based/current_based_cover.h
+++ b/esphome/components/current_based/current_based_cover.h
@@ -67,21 +67,21 @@ class CurrentBasedCover : public cover::Cover, public Component {
 
   sensor::Sensor *open_sensor_{nullptr};
   Trigger<> open_trigger_;
-  float open_moving_current_threshold_;
+  float open_moving_current_threshold_{0.0f};
   float open_obstacle_current_threshold_{FLT_MAX};
-  uint32_t open_duration_;
+  uint32_t open_duration_{0};
 
   sensor::Sensor *close_sensor_{nullptr};
   Trigger<> close_trigger_;
-  float close_moving_current_threshold_;
+  float close_moving_current_threshold_{0.0f};
   float close_obstacle_current_threshold_{FLT_MAX};
-  uint32_t close_duration_;
+  uint32_t close_duration_{0};
 
   uint32_t max_duration_{UINT32_MAX};
   bool malfunction_detection_{true};
   Trigger<> malfunction_trigger_;
-  uint32_t start_sensing_delay_;
-  float obstacle_rollback_;
+  uint32_t start_sensing_delay_{0};
+  float obstacle_rollback_{0.0f};
 
   Trigger<> *prev_command_trigger_{nullptr};
   uint32_t last_recompute_time_{0};
diff --git a/esphome/components/datetime/date_entity.h b/esphome/components/datetime/date_entity.h
index cbf2b85506..8233e809a1 100644
--- a/esphome/components/datetime/date_entity.h
+++ b/esphome/components/datetime/date_entity.h
@@ -91,7 +91,7 @@ class DateCall {
 
   DateEntity *parent_;
 
-  optional<int16_t> year_;
+  optional<uint16_t> year_;
   optional<uint8_t> month_;
   optional<uint8_t> day_;
 };
diff --git a/esphome/components/deep_sleep/deep_sleep_component.h b/esphome/components/deep_sleep/deep_sleep_component.h
index 1998b815f3..14713d51a1 100644
--- a/esphome/components/deep_sleep/deep_sleep_component.h
+++ b/esphome/components/deep_sleep/deep_sleep_component.h
@@ -145,7 +145,7 @@ class DeepSleepComponent : public Component {
 #endif  // USE_BK72XX
 
 #ifdef USE_ESP32
-  InternalGPIOPin *wakeup_pin_;
+  InternalGPIOPin *wakeup_pin_{nullptr};
   WakeupPinMode wakeup_pin_mode_{WAKEUP_PIN_MODE_IGNORE};
 
 #if !defined(USE_ESP32_VARIANT_ESP32C2) && !defined(USE_ESP32_VARIANT_ESP32C3)
diff --git a/esphome/components/es7210/es7210.cpp b/esphome/components/es7210/es7210.cpp
index 1358121c1b..4371075fa9 100644
--- a/esphome/components/es7210/es7210.cpp
+++ b/esphome/components/es7210/es7210.cpp
@@ -172,7 +172,7 @@ uint8_t ES7210::es7210_gain_reg_value_(float mic_gain) {
   // reg: 12 - 34.5dB, 13 - 36dB, 14 - 37.5dB
   mic_gain += 0.5;
   if (mic_gain <= 33.0) {
-    return (uint8_t) mic_gain / 3;
+    return (uint8_t) (mic_gain / 3);
   }
   if (mic_gain < 36.0) {
     return 12;
diff --git a/esphome/components/esp32_ble_server/ble_server.cpp b/esphome/components/esp32_ble_server/ble_server.cpp
index f292cf8722..ecc53e197f 100644
--- a/esphome/components/esp32_ble_server/ble_server.cpp
+++ b/esphome/components/esp32_ble_server/ble_server.cpp
@@ -7,6 +7,7 @@
 
 #ifdef USE_ESP32
 
+#include <algorithm>
 #include <nvs_flash.h>
 #include <freertos/FreeRTOSConfig.h>
 #include <esp_bt_main.h>
@@ -38,21 +39,16 @@ void BLEServer::loop() {
     case RUNNING: {
       // Start all services that are pending to start
       if (!this->services_to_start_.empty()) {
-        uint16_t index_to_remove = 0;
-        // Iterate over the services to start
-        for (unsigned i = 0; i < this->services_to_start_.size(); i++) {
-          BLEService *service = this->services_to_start_[i];
+        for (auto &service : this->services_to_start_) {
           if (service->is_created()) {
             service->start();  // Needs to be called once per characteristic in the service
-          } else {
-            index_to_remove = i + 1;
           }
         }
-        // Remove the services that have been started
-        if (index_to_remove > 0) {
-          this->services_to_start_.erase(this->services_to_start_.begin(),
-                                         this->services_to_start_.begin() + index_to_remove - 1);
-        }
+        // Remove services that have been started
+        this->services_to_start_.erase(
+            std::remove_if(this->services_to_start_.begin(), this->services_to_start_.end(),
+                           [](BLEService *service) { return service->is_starting() || service->is_running(); }),
+            this->services_to_start_.end());
       }
       break;
     }
diff --git a/esphome/components/espnow/automation.h b/esphome/components/espnow/automation.h
index 0b26681400..0fbb14e388 100644
--- a/esphome/components/espnow/automation.h
+++ b/esphome/components/espnow/automation.h
@@ -138,7 +138,7 @@ class OnReceiveTrigger : public Trigger<const ESPNowRecvInfo &, const uint8_t *,
 
  protected:
   bool has_address_{false};
-  const uint8_t *address_[ESP_NOW_ETH_ALEN];
+  uint8_t address_[ESP_NOW_ETH_ALEN];
 };
 class OnUnknownPeerTrigger : public Trigger<const ESPNowRecvInfo &, const uint8_t *, uint8_t>,
                              public ESPNowUnknownPeerHandler {
@@ -167,7 +167,7 @@ class OnBroadcastedTrigger : public Trigger<const ESPNowRecvInfo &, const uint8_
 
  protected:
   bool has_address_{false};
-  const uint8_t *address_[ESP_NOW_ETH_ALEN];
+  uint8_t address_[ESP_NOW_ETH_ALEN];
 };
 
 }  // namespace esphome::espnow
diff --git a/esphome/components/light/addressable_light_effect.h b/esphome/components/light/addressable_light_effect.h
index a85ea4661d..461ddbc085 100644
--- a/esphome/components/light/addressable_light_effect.h
+++ b/esphome/components/light/addressable_light_effect.h
@@ -171,12 +171,27 @@ class AddressableScanEffect : public AddressableLightEffect {
     if (now - this->last_move_ < this->move_interval_)
       return;
 
-    if (direction_) {
+    const auto num_leds = static_cast<uint32_t>(it.size());
+    if (this->scan_width_ >= num_leds) {
+      it.all() = current_color;
+      it.schedule_show();
+      this->last_move_ = now;
+      return;
+    }
+
+    const uint32_t max_pos = num_leds - this->scan_width_;
+    if (this->at_led_ >= max_pos) {
+      this->at_led_ = max_pos;
+      this->direction_ = false;
+    }
+
+    if (this->direction_) {
       this->at_led_++;
-      if (this->at_led_ == it.size() - this->scan_width_)
+      if (this->at_led_ >= max_pos)
         this->direction_ = false;
     } else {
-      this->at_led_--;
+      if (this->at_led_ > 0)
+        this->at_led_--;
       if (this->at_led_ == 0)
         this->direction_ = true;
     }
diff --git a/esphome/components/max6956/max6956.h b/esphome/components/max6956/max6956.h
index 0c609b0b43..31f97c11f8 100644
--- a/esphome/components/max6956/max6956.h
+++ b/esphome/components/max6956/max6956.h
@@ -63,8 +63,8 @@ class MAX6956 : public Component, public i2c::I2CDevice {
   bool read_reg_(uint8_t reg, uint8_t *value);
   // write a value to a given register
   bool write_reg_(uint8_t reg, uint8_t value);
-  max6956::MAX6956CURRENTMODE brightness_mode_;
-  uint8_t global_brightness_;
+  max6956::MAX6956CURRENTMODE brightness_mode_{};
+  uint8_t global_brightness_{0};
 
  private:
   int8_t prev_bright_[28] = {0};
diff --git a/esphome/components/ms8607/ms8607.h b/esphome/components/ms8607/ms8607.h
index ceb3dd22c8..2888b6cdd2 100644
--- a/esphome/components/ms8607/ms8607.h
+++ b/esphome/components/ms8607/ms8607.h
@@ -67,9 +67,9 @@ class MS8607Component : public PollingComponent, public i2c::I2CDevice {
   /// use raw temperature & pressure to calculate & publish values
   void calculate_values_(uint32_t raw_temperature, uint32_t raw_pressure);
 
-  sensor::Sensor *temperature_sensor_;
-  sensor::Sensor *pressure_sensor_;
-  sensor::Sensor *humidity_sensor_;
+  sensor::Sensor *temperature_sensor_{nullptr};
+  sensor::Sensor *pressure_sensor_{nullptr};
+  sensor::Sensor *humidity_sensor_{nullptr};
 
   /** I2CDevice object to communicate with secondary I2C address for the humidity sensor
    *
@@ -77,7 +77,7 @@ class MS8607Component : public PollingComponent, public i2c::I2CDevice {
    *
    * Default address for humidity is 0x40
    */
-  MS8607HumidityDevice *humidity_device_;
+  MS8607HumidityDevice *humidity_device_{nullptr};
 
   /// This device's pressure & temperature calibration values, read from PROM
   struct CalibrationValues {
diff --git a/esphome/components/noblex/noblex.cpp b/esphome/components/noblex/noblex.cpp
index f1e76eabf2..e7e421d177 100644
--- a/esphome/components/noblex/noblex.cpp
+++ b/esphome/components/noblex/noblex.cpp
@@ -118,15 +118,15 @@ void NoblexClimate::transmit_state() {
   data->mark(NOBLEX_HEADER_MARK);
   data->space(NOBLEX_HEADER_SPACE);
   // Data (sent remote_state from the MSB to the LSB)
-  for (uint8_t i : remote_state) {
-    for (int8_t j = 7; j >= 0; j--) {
-      if ((i == 4) & (j == 4)) {
+  for (int byte_idx = 0; byte_idx < 8; byte_idx++) {
+    for (int8_t bit_idx = 7; bit_idx >= 0; bit_idx--) {
+      if ((byte_idx == 4) && (bit_idx == 4)) {
         // Header intermediate
         data->mark(NOBLEX_BIT_MARK);
         data->space(NOBLEX_GAP);  // gap en bit 36
       } else {
         data->mark(NOBLEX_BIT_MARK);
-        bool bit = i & (1 << j);
+        bool bit = remote_state[byte_idx] & (1 << bit_idx);
         data->space(bit ? NOBLEX_ONE_SPACE : NOBLEX_ZERO_SPACE);
       }
     }
@@ -145,76 +145,71 @@ void NoblexClimate::transmit_state() {
 
 // Handle received IR Buffer
 bool NoblexClimate::on_receive(remote_base::RemoteReceiveData data) {
-  uint8_t remote_state[8] = {0};
-  uint8_t crc = 0, crc_calculated = 0;
-
-  if (!receiving_) {
-    // Validate header
-    if (data.expect_item(NOBLEX_HEADER_MARK, NOBLEX_HEADER_SPACE)) {
-      ESP_LOGV(TAG, "Header");
-      receiving_ = true;
-      // Read first 36 bits
-      for (int i = 0; i < 5; i++) {
-        // Read bit
-        for (int j = 7; j >= 0; j--) {
-          if ((i == 4) & (j == 4)) {
-            remote_state[i] |= 1 << j;
-            // Header intermediate
-            ESP_LOGVV(TAG, "GAP");
-            return false;
-          } else if (data.expect_item(NOBLEX_BIT_MARK, NOBLEX_ONE_SPACE)) {
-            remote_state[i] |= 1 << j;
-          } else if (!data.expect_item(NOBLEX_BIT_MARK, NOBLEX_ZERO_SPACE)) {
-            ESP_LOGVV(TAG, "Byte %d bit %d fail", i, j);
-            return false;
-          }
-        }
-        ESP_LOGV(TAG, "Byte %d %02X", i, remote_state[i]);
-      }
-
-    } else {
-      ESP_LOGV(TAG, "Header fail");
-      receiving_ = false;
-      return false;
-    }
-
-  } else {
-    // Read the remaining 28 bits
-    for (int i = 4; i < 8; i++) {
-      // Read bit
+  if (data.peek_item(NOBLEX_HEADER_MARK, NOBLEX_HEADER_SPACE)) {
+    // First part: header + first 36 bits, followed by 20ms gap
+    data.expect_item(NOBLEX_HEADER_MARK, NOBLEX_HEADER_SPACE);
+    ESP_LOGV(TAG, "Header");
+    this->receiving_ = false;
+    memset(this->remote_state_, 0, sizeof(this->remote_state_));
+    for (int i = 0; i < 5; i++) {
       for (int j = 7; j >= 0; j--) {
-        if ((i == 4) & (j >= 4)) {
-          // nothing
+        if ((i == 4) && (j == 4)) {
+          this->remote_state_[i] |= 1 << j;
+          ESP_LOGVV(TAG, "GAP");
+          this->receiving_ = true;
+          return false;
         } else if (data.expect_item(NOBLEX_BIT_MARK, NOBLEX_ONE_SPACE)) {
-          remote_state[i] |= 1 << j;
+          this->remote_state_[i] |= 1 << j;
         } else if (!data.expect_item(NOBLEX_BIT_MARK, NOBLEX_ZERO_SPACE)) {
           ESP_LOGVV(TAG, "Byte %d bit %d fail", i, j);
           return false;
         }
       }
-      ESP_LOGV(TAG, "Byte %d %02X", i, remote_state[i]);
+      ESP_LOGV(TAG, "Byte %d %02X", i, this->remote_state_[i]);
     }
+    return false;
+  }
 
-    // Read crc
-    for (int i = 3; i >= 0; i--) {
-      if (data.expect_item(NOBLEX_BIT_MARK, NOBLEX_ONE_SPACE)) {
-        crc |= 1 << i;
+  // Second part: remaining 28 bits + 4-bit CRC + footer
+  if (!this->receiving_) {
+    return false;
+  }
+  this->receiving_ = false;
+  for (int i = 4; i < 8; i++) {
+    for (int j = 7; j >= 0; j--) {
+      if ((i == 4) && (j >= 4)) {
+        // already decoded in first part
+      } else if (data.expect_item(NOBLEX_BIT_MARK, NOBLEX_ONE_SPACE)) {
+        this->remote_state_[i] |= 1 << j;
       } else if (!data.expect_item(NOBLEX_BIT_MARK, NOBLEX_ZERO_SPACE)) {
-        ESP_LOGVV(TAG, "Bit %d CRC fail", i);
+        ESP_LOGVV(TAG, "Byte %d bit %d fail", i, j);
         return false;
       }
     }
-    ESP_LOGV(TAG, "CRC %02X", crc);
-
-    // Validate footer
-    if (!data.expect_mark(NOBLEX_BIT_MARK)) {
-      ESP_LOGV(TAG, "Footer fail");
-      return false;
-    }
-    receiving_ = false;
+    ESP_LOGV(TAG, "Byte %d %02X", i, this->remote_state_[i]);
   }
 
-  for (uint8_t i : remote_state)
+  // Read CRC
+  uint8_t crc = 0;
+  for (int i = 3; i >= 0; i--) {
+    if (data.expect_item(NOBLEX_BIT_MARK, NOBLEX_ONE_SPACE)) {
+      crc |= 1 << i;
+    } else if (!data.expect_item(NOBLEX_BIT_MARK, NOBLEX_ZERO_SPACE)) {
+      ESP_LOGVV(TAG, "Bit %d CRC fail", i);
+      return false;
+    }
+  }
+  ESP_LOGV(TAG, "CRC %02X", crc);
+
+  // Validate footer
+  if (!data.expect_mark(NOBLEX_BIT_MARK)) {
+    ESP_LOGV(TAG, "Footer fail");
+    return false;
+  }
+
+  // Validate CRC
+  uint8_t crc_calculated = 0;
+  for (uint8_t i : this->remote_state_)
     crc_calculated += reverse_bits(i);
   crc_calculated = reverse_bits(uint8_t(crc_calculated & 0x0F)) >> 4;
   ESP_LOGVV(TAG, "CRC calc %02X", crc_calculated);
@@ -224,11 +219,12 @@ bool NoblexClimate::on_receive(remote_base::RemoteReceiveData data) {
     return false;
   }
 
-  ESP_LOGD(TAG, "Received noblex code: %02X%02X %02X%02X %02X%02X %02X%02X", remote_state[0], remote_state[1],
-           remote_state[2], remote_state[3], remote_state[4], remote_state[5], remote_state[6], remote_state[7]);
+  ESP_LOGD(TAG, "Received noblex code: %02X%02X %02X%02X %02X%02X %02X%02X", this->remote_state_[0],
+           this->remote_state_[1], this->remote_state_[2], this->remote_state_[3], this->remote_state_[4],
+           this->remote_state_[5], this->remote_state_[6], this->remote_state_[7]);
 
   auto powered_on = false;
-  if ((remote_state[0] & NOBLEX_POWER) == NOBLEX_POWER) {
+  if ((this->remote_state_[0] & NOBLEX_POWER) == NOBLEX_POWER) {
     powered_on = true;
     this->powered_on_assumed = powered_on;
   } else {
@@ -241,7 +237,7 @@ bool NoblexClimate::on_receive(remote_base::RemoteReceiveData data) {
 
   // Set received mode
   if (powered_on_assumed) {
-    auto mode = (remote_state[0] & 0xE0) >> 5;
+    auto mode = (this->remote_state_[0] & 0xE0) >> 5;
     ESP_LOGV(TAG, "Mode: %02X", mode);
     switch (mode) {
       case IRNoblexMode::IR_NOBLEX_MODE_AUTO:
@@ -263,7 +259,7 @@ bool NoblexClimate::on_receive(remote_base::RemoteReceiveData data) {
   }
 
   // Set received temp
-  uint8_t temp = remote_state[1];
+  uint8_t temp = this->remote_state_[1];
   ESP_LOGVV(TAG, "Temperature Raw: %02X", temp);
 
   temp = 0x0F & reverse_bits(temp);
@@ -272,7 +268,7 @@ bool NoblexClimate::on_receive(remote_base::RemoteReceiveData data) {
   this->target_temperature = temp;
 
   // Set received fan speed
-  auto fan = (remote_state[0] & 0x0C) >> 2;
+  auto fan = (this->remote_state_[0] & 0x0C) >> 2;
   ESP_LOGV(TAG, "Fan: %02X", fan);
   switch (fan) {
     case IRNoblexFan::IR_NOBLEX_FAN_HIGH:
@@ -291,7 +287,7 @@ bool NoblexClimate::on_receive(remote_base::RemoteReceiveData data) {
   }
 
   // Set received swing status
-  if (remote_state[0] & 0x02) {
+  if (this->remote_state_[0] & 0x02) {
     ESP_LOGV(TAG, "Swing vertical");
     this->swing_mode = climate::CLIMATE_SWING_VERTICAL;
   } else {
@@ -299,8 +295,6 @@ bool NoblexClimate::on_receive(remote_base::RemoteReceiveData data) {
     this->swing_mode = climate::CLIMATE_SWING_OFF;
   }
 
-  for (uint8_t &i : remote_state)
-    i = 0;
   this->publish_state();
   return true;
 }  // end on_receive()
diff --git a/esphome/components/noblex/noblex.h b/esphome/components/noblex/noblex.h
index 57990db005..3d52a1a538 100644
--- a/esphome/components/noblex/noblex.h
+++ b/esphome/components/noblex/noblex.h
@@ -41,7 +41,8 @@ class NoblexClimate : public climate_ir::ClimateIR {
   /// Handle received IR Buffer.
   bool on_receive(remote_base::RemoteReceiveData data) override;
   bool send_swing_cmd_{false};
-  bool receiving_ = false;
+  bool receiving_{false};
+  uint8_t remote_state_[8]{};
 };
 
 }  // namespace noblex
diff --git a/esphome/components/remote_transmitter/remote_transmitter.h b/esphome/components/remote_transmitter/remote_transmitter.h
index aee52ea170..6b4ebfe24b 100644
--- a/esphome/components/remote_transmitter/remote_transmitter.h
+++ b/esphome/components/remote_transmitter/remote_transmitter.h
@@ -96,7 +96,7 @@ class RemoteTransmitterComponent : public remote_base::RemoteTransmitterBase,
   bool inverted_{false};
   bool non_blocking_{false};
 #endif
-  uint8_t carrier_duty_percent_;
+  uint8_t carrier_duty_percent_{50};
 
   Trigger<> transmit_trigger_;
   Trigger<> complete_trigger_;
diff --git a/esphome/components/rp2040_pio_led_strip/led_strip.cpp b/esphome/components/rp2040_pio_led_strip/led_strip.cpp
index dc0d3c315a..fdb49fb3ef 100644
--- a/esphome/components/rp2040_pio_led_strip/led_strip.cpp
+++ b/esphome/components/rp2040_pio_led_strip/led_strip.cpp
@@ -70,7 +70,7 @@ void RP2040PIOLEDStripLightOutput::setup() {
   // but there are only 4 state machines on each PIO so we can only have 4 strips per PIO
   uint offset = 0;
 
-  if (RP2040PIOLEDStripLightOutput::num_instance_[this->pio_ == pio0 ? 0 : 1] > 4) {
+  if (RP2040PIOLEDStripLightOutput::num_instance_[this->pio_ == pio0 ? 0 : 1] >= 4) {
     ESP_LOGE(TAG, "Too many instances of PIO program");
     this->mark_failed();
     return;
diff --git a/esphome/components/sen5x/sen5x.h b/esphome/components/sen5x/sen5x.h
index e3bf931b41..a9d4da86b8 100644
--- a/esphome/components/sen5x/sen5x.h
+++ b/esphome/components/sen5x/sen5x.h
@@ -104,12 +104,12 @@ class SEN5XComponent : public PollingComponent, public sensirion_common::Sensiri
 
   char serial_number_[17] = "UNKNOWN";
   uint16_t voc_baseline_state_[4]{0};
-  uint32_t voc_baseline_time_;
-  uint16_t firmware_version_;
+  uint32_t voc_baseline_time_{0};
+  uint16_t firmware_version_{0};
   Sen5xType type_{Sen5xType::UNKNOWN};
-  ERRORCODE error_code_;
+  ERRORCODE error_code_{ERRORCODE::UNKNOWN};
   bool initialized_{false};
-  bool store_baseline_;
+  bool store_baseline_{false};
 
   sensor::Sensor *pm_1_0_sensor_{nullptr};
   sensor::Sensor *pm_2_5_sensor_{nullptr};
diff --git a/esphome/components/sgp4x/sgp4x.cpp b/esphome/components/sgp4x/sgp4x.cpp
index 44d0a54080..cb41e374f8 100644
--- a/esphome/components/sgp4x/sgp4x.cpp
+++ b/esphome/components/sgp4x/sgp4x.cpp
@@ -199,7 +199,7 @@ void SGP4xComponent::measure_raw_() {
       response_words = 2;
     }
   }
-  uint16_t rhticks = llround((uint16_t) ((humidity * 65535) / 100));
+  uint16_t rhticks = (uint16_t) llround((humidity * 65535) / 100);
   uint16_t tempticks = (uint16_t) (((temperature + 45) * 65535) / 175);
   // first parameter are the relative humidity ticks
   data[0] = rhticks;
diff --git a/esphome/components/sim800l/sim800l.h b/esphome/components/sim800l/sim800l.h
index a2da686ce1..e9e2f66d78 100644
--- a/esphome/components/sim800l/sim800l.h
+++ b/esphome/components/sim800l/sim800l.h
@@ -107,11 +107,11 @@ class Sim800LComponent : public uart::UARTDevice, public PollingComponent {
   std::string recipient_;
   std::string outgoing_message_;
   std::string ussd_;
-  bool send_pending_;
-  bool dial_pending_;
-  bool connect_pending_;
-  bool disconnect_pending_;
-  bool send_ussd_pending_;
+  bool send_pending_{false};
+  bool dial_pending_{false};
+  bool connect_pending_{false};
+  bool disconnect_pending_{false};
+  bool send_ussd_pending_{false};
   uint8_t call_state_{6};
 
   CallbackManager<void(std::string, std::string)> sms_received_callback_;
diff --git a/esphome/components/time/real_time_clock.cpp b/esphome/components/time/real_time_clock.cpp
index 2b60497474..bd3632802b 100644
--- a/esphome/components/time/real_time_clock.cpp
+++ b/esphome/components/time/real_time_clock.cpp
@@ -90,7 +90,7 @@ void RealTimeClock::synchronize_epoch_(uint32_t epoch) {
   };
   struct timezone tz = {0, 0};
   int ret = settimeofday(&timev, &tz);
-  if (ret == EINVAL) {
+  if (ret != 0 && errno == EINVAL) {
     // Some ESP8266 frameworks abort when timezone parameter is not NULL
     // while ESP32 expects it not to be NULL
     ret = settimeofday(&timev, nullptr);
diff --git a/esphome/components/tm1638/tm1638.cpp b/esphome/components/tm1638/tm1638.cpp
index 8ef546ff32..c67ff1adbc 100644
--- a/esphome/components/tm1638/tm1638.cpp
+++ b/esphome/components/tm1638/tm1638.cpp
@@ -147,35 +147,38 @@ void TM1638Component::set_intensity(uint8_t brightness_level) {
 
 uint8_t TM1638Component::print(uint8_t start_pos, const char *str) {
   uint8_t pos = start_pos;
-
   bool last_was_dot = false;
 
   for (; *str != '\0'; str++) {
     uint8_t data = TM1638_UNKNOWN_CHAR;
 
     if (*str >= ' ' && *str <= '~') {
-      data = progmem_read_byte(&TM1638Translation::SEVEN_SEG[*str - 32]);  // subract 32 to account for ASCII offset
-    } else if (data == TM1638_UNKNOWN_CHAR) {
+      // Subtract 32 to account for ASCII offset
+      data = progmem_read_byte(&TM1638Translation::SEVEN_SEG[*str - 32]);
+    } else {
       ESP_LOGW(TAG, "Encountered character '%c' with no TM1638 representation while translating string!", *str);
     }
 
-    if (*str == '.')  // handle dots
-    {
-      if (pos != start_pos &&
-          !last_was_dot)  // if we are not at the first position, backup by one unless last char was a dot
-      {
+    if (*str == '.') {
+      // Merge dot onto previous character unless we're at the start or last was also a dot
+      if (pos != start_pos && !last_was_dot) {
         pos--;
       }
-      this->buffer_[pos] |= 0b10000000;  // turn on the dot on the previous position
-      last_was_dot = true;               // set a bit in case the next chracter is also a dot
-    } else                               // if not a dot, then just write the character to display
-    {
+      if (pos >= 8) {
+        ESP_LOGI(TAG, "TM1638 String is too long for the display!");
+        break;
+      }
+      // Turn on the dot on the previous position
+      this->buffer_[pos] |= 0b10000000;
+      last_was_dot = true;
+    } else {
+      // Not a dot, write the character to display
       if (pos >= 8) {
         ESP_LOGI(TAG, "TM1638 String is too long for the display!");
         break;
       }
       this->buffer_[pos] = data;
-      last_was_dot = false;  // clear dot tracking bit
+      last_was_dot = false;
     }
 
     pos++;
diff --git a/esphome/components/tsl2591/tsl2591.cpp b/esphome/components/tsl2591/tsl2591.cpp
index 42c524a074..4ce673a91a 100644
--- a/esphome/components/tsl2591/tsl2591.cpp
+++ b/esphome/components/tsl2591/tsl2591.cpp
@@ -327,7 +327,9 @@ uint16_t TSL2591Component::get_illuminance(TSL2591SensorChannel channel, uint32_
     return (combined_illuminance >> 16);
   } else if (channel == TSL2591_SENSOR_CHANNEL_VISIBLE) {
     // Reads all and subtracts out the infrared
-    return ((combined_illuminance & 0xFFFF) - (combined_illuminance >> 16));
+    uint16_t full = combined_illuminance & 0xFFFF;
+    uint16_t ir = combined_illuminance >> 16;
+    return (ir > full) ? 0 : (full - ir);
   }
   // unknown channel!
   ESP_LOGE(TAG, "get_illuminance() caller requested an unknown channel: %d", channel);
diff --git a/esphome/core/entity_base.cpp b/esphome/core/entity_base.cpp
index 3274640eb3..818dae06de 100644
--- a/esphome/core/entity_base.cpp
+++ b/esphome/core/entity_base.cpp
@@ -11,7 +11,7 @@ static const char *const TAG = "entity_base";
 // Entity Name
 const StringRef &EntityBase::get_name() const { return this->name_; }
 
-void EntityBase::configure_entity_(const char *name, uint32_t object_id_hash, uint32_t entity_strings_packed) {
+void EntityBase::configure_entity_(const char *name, uint32_t object_id_hash, uint32_t entity_fields) {
   this->name_ = StringRef(name);
   if (this->name_.empty()) {
 #ifdef USE_DEVICES
@@ -44,17 +44,19 @@ void EntityBase::configure_entity_(const char *name, uint32_t object_id_hash, ui
       this->calc_object_id_();
     }
   }
-  // Unpack entity string table indices.
-  // Packed: [23..16] icon | [15..8] UoM | [7..0] device_class (each 8 bits)
+  // Unpack entity string table indices and flags from entity_fields.
 #ifdef USE_ENTITY_DEVICE_CLASS
-  this->device_class_idx_ = entity_strings_packed & 0xFF;
+  this->device_class_idx_ = (entity_fields >> ENTITY_FIELD_DC_SHIFT) & 0xFF;
 #endif
 #ifdef USE_ENTITY_UNIT_OF_MEASUREMENT
-  this->uom_idx_ = (entity_strings_packed >> 8) & 0xFF;
+  this->uom_idx_ = (entity_fields >> ENTITY_FIELD_UOM_SHIFT) & 0xFF;
 #endif
 #ifdef USE_ENTITY_ICON
-  this->icon_idx_ = (entity_strings_packed >> 16) & 0xFF;
+  this->icon_idx_ = (entity_fields >> ENTITY_FIELD_ICON_SHIFT) & 0xFF;
 #endif
+  this->flags_.internal = (entity_fields >> ENTITY_FIELD_INTERNAL_SHIFT) & 1;
+  this->flags_.disabled_by_default = (entity_fields >> ENTITY_FIELD_DISABLED_BY_DEFAULT_SHIFT) & 1;
+  this->flags_.entity_category = (entity_fields >> ENTITY_FIELD_ENTITY_CATEGORY_SHIFT) & 0x3;
 }
 
 // Weak default lookup functions — overridden by generated code in main.cpp
diff --git a/esphome/core/entity_base.h b/esphome/core/entity_base.h
index accd532b0d..cccbafd2c3 100644
--- a/esphome/core/entity_base.h
+++ b/esphome/core/entity_base.h
@@ -55,6 +55,15 @@ enum EntityCategory : uint8_t {
   ENTITY_CATEGORY_DIAGNOSTIC = 2,
 };
 
+// Bit layout for entity_fields parameter in configure_entity_().
+// Keep in sync with _*_SHIFT constants in esphome/core/entity_helpers.py
+static constexpr uint8_t ENTITY_FIELD_DC_SHIFT = 0;
+static constexpr uint8_t ENTITY_FIELD_UOM_SHIFT = 8;
+static constexpr uint8_t ENTITY_FIELD_ICON_SHIFT = 16;
+static constexpr uint8_t ENTITY_FIELD_INTERNAL_SHIFT = 24;
+static constexpr uint8_t ENTITY_FIELD_DISABLED_BY_DEFAULT_SHIFT = 25;
+static constexpr uint8_t ENTITY_FIELD_ENTITY_CATEGORY_SHIFT = 26;
+
 // The generic Entity base class that provides an interface common to all Entities.
 class EntityBase {
  public:
@@ -88,21 +97,16 @@ class EntityBase {
   /// Useful for building compound strings without intermediate buffer
   size_t write_object_id_to(char *buf, size_t buf_size) const;
 
-  // Get/set whether this Entity should be hidden outside ESPHome
+  // Get whether this Entity should be hidden outside ESPHome
   bool is_internal() const { return this->flags_.internal; }
-  void set_internal(bool internal) { this->flags_.internal = internal; }
 
   // Check if this object is declared to be disabled by default.
   // That means that when the device gets added to Home Assistant (or other clients) it should
   // not be added to the default view by default, and a user action is necessary to manually add it.
   bool is_disabled_by_default() const { return this->flags_.disabled_by_default; }
-  void set_disabled_by_default(bool disabled_by_default) { this->flags_.disabled_by_default = disabled_by_default; }
 
-  // Get/set the entity category.
+  // Get the entity category.
   EntityCategory get_entity_category() const { return static_cast<EntityCategory>(this->flags_.entity_category); }
-  void set_entity_category(EntityCategory entity_category) {
-    this->flags_.entity_category = static_cast<uint8_t>(entity_category);
-  }
 
   // Get this entity's device class into a stack buffer.
   // On non-ESP8266: returns pointer to PROGMEM string directly (buffer unused).
@@ -164,14 +168,13 @@ class EntityBase {
 #endif
 
 #ifdef USE_DEVICES
-  // Get/set this entity's device id
+  // Get this entity's device id
   uint32_t get_device_id() const {
     if (this->device_ == nullptr) {
       return 0;  // No device set, return 0
     }
     return this->device_->get_device_id();
   }
-  void set_device(Device *device) { this->device_ = device; }
   // Get the device this entity belongs to (nullptr if main device)
   Device *get_device() const { return this->device_; }
 #endif
@@ -228,8 +231,14 @@ class EntityBase {
   friend void ::setup();
   friend void ::original_setup();
 
-  /// Combined entity setup from codegen: set name, object_id hash, and entity string indices.
-  void configure_entity_(const char *name, uint32_t object_id_hash, uint32_t entity_strings_packed);
+  /// Combined entity setup from codegen: set name, object_id hash, entity string indices, and flags.
+  /// Bit layout of entity_fields is defined by the ENTITY_FIELD_*_SHIFT constants above.
+  void configure_entity_(const char *name, uint32_t object_id_hash, uint32_t entity_fields);
+
+#ifdef USE_DEVICES
+  // Codegen-only setter — only accessible from setup() via friend declaration.
+  void set_device_(Device *device) { this->device_ = device; }
+#endif
 
   /// Non-template helper for make_entity_preference() to avoid code bloat.
   /// When preference hash algorithm changes, migration logic goes here.
diff --git a/esphome/core/entity_helpers.py b/esphome/core/entity_helpers.py
index 4fa109fb0e..a3d6a3b2fe 100644
--- a/esphome/core/entity_helpers.py
+++ b/esphome/core/entity_helpers.py
@@ -34,11 +34,19 @@ _KEY_ICON_IDX = "_entity_icon_idx"
 _KEY_ENTITY_NAME = "_entity_name"
 _KEY_OBJECT_ID_HASH = "_entity_object_id_hash"
 
-# Bit layout for entity_strings_packed in configure_entity_() — must match C++ in entity_base.h:
-#   [23..16] icon (8 bits) | [15..8] UoM (8 bits) | [7..0] device_class (8 bits)
+# Bit layout for entity_fields in configure_entity_().
+# Keep in sync with ENTITY_FIELD_*_SHIFT constants in esphome/core/entity_base.h
 _DC_SHIFT = 0
 _UOM_SHIFT = 8
 _ICON_SHIFT = 16
+_INTERNAL_SHIFT = 24
+_DISABLED_BY_DEFAULT_SHIFT = 25
+_ENTITY_CATEGORY_SHIFT = 26
+
+# Private config keys for storing flags
+_KEY_INTERNAL = "_entity_internal"
+_KEY_DISABLED_BY_DEFAULT = "_entity_disabled_by_default"
+_KEY_ENTITY_CATEGORY = "_entity_category"
 
 # Maximum unique strings per category (8-bit index, 0 = not set)
 _MAX_DEVICE_CLASSES = 0xFF  # 255
@@ -220,8 +228,39 @@ def setup_unit_of_measurement(config: ConfigType) -> None:
     config[_KEY_UOM_IDX] = idx
 
 
+def _sanitize_comment(text: str) -> str:
+    r"""Sanitize a string for safe inclusion in a C++ // line comment.
+
+    Dangerous characters:
+    - \n, \r: break out of line comment, next line becomes code
+    - \: at end of line, splices next line into comment (eats real code)
+    """
+    return text.replace("\\", "/").replace("\n", " ").replace("\r", "")
+
+
+def _describe_packed_flags(config: ConfigType, entity_category: int) -> str:
+    """Build a human-readable description of packed entity flags for C++ comments."""
+    parts: list[str] = []
+    if config.get(_KEY_INTERNAL):
+        parts.append("internal")
+    if config.get(_KEY_DISABLED_BY_DEFAULT):
+        parts.append("disabled_by_default")
+    entity_cat_keys = list(cv.ENTITY_CATEGORIES)
+    if entity_category < len(entity_cat_keys) and (
+        cat_name := entity_cat_keys[entity_category]
+    ):
+        parts.append(f"category:{cat_name}")
+    if dc := config.get(CONF_DEVICE_CLASS):
+        parts.append(f"dc:{_sanitize_comment(dc)}")
+    if uom := config.get(CONF_UNIT_OF_MEASUREMENT):
+        parts.append(f"uom:{_sanitize_comment(uom)}")
+    if icon := config.get(CONF_ICON):
+        parts.append(f"icon:{_sanitize_comment(icon)}")
+    return ", ".join(parts)
+
+
 def finalize_entity_strings(var: MockObj, config: ConfigType) -> None:
-    """Emit a single configure_entity_() call with name, hash, and packed string indices.
+    """Emit a single configure_entity_() call with name, hash, packed string indices, and flags.
 
     Call this at the end of each component's setup function, after
     setup_entity() and any register_device_class/register_unit_of_measurement calls.
@@ -231,8 +270,24 @@ def finalize_entity_strings(var: MockObj, config: ConfigType) -> None:
     dc_idx = config.get(_KEY_DC_IDX, 0)
     uom_idx = config.get(_KEY_UOM_IDX, 0)
     icon_idx = config.get(_KEY_ICON_IDX, 0)
-    packed = (dc_idx << _DC_SHIFT) | (uom_idx << _UOM_SHIFT) | (icon_idx << _ICON_SHIFT)
-    add(var.configure_entity_(entity_name, object_id_hash, packed))
+    internal = config.get(_KEY_INTERNAL, 0)
+    disabled_by_default = config.get(_KEY_DISABLED_BY_DEFAULT, 0)
+    entity_category = config.get(_KEY_ENTITY_CATEGORY, 0)
+    packed = (
+        (dc_idx << _DC_SHIFT)
+        | (uom_idx << _UOM_SHIFT)
+        | (icon_idx << _ICON_SHIFT)
+        | (internal << _INTERNAL_SHIFT)
+        | (disabled_by_default << _DISABLED_BY_DEFAULT_SHIFT)
+        | (entity_category << _ENTITY_CATEGORY_SHIFT)
+    )
+    # Build inline comment describing the packed flags for readability
+    comment = _describe_packed_flags(config, entity_category)
+    expr = var.configure_entity_(entity_name, object_id_hash, packed)
+    if comment:
+        add(RawStatement(f"{expr};  // {comment}"))
+    else:
+        add(expr)
 
 
 def get_base_entity_object_id(
@@ -332,7 +387,7 @@ async def _setup_entity_impl(var: MockObj, config: ConfigType, platform: str) ->
     # Get device info if configured
     if device_id_obj := config.get(CONF_DEVICE_ID):
         device: MockObj = await get_variable(device_id_obj)
-        add(var.set_device(device))
+        add(var.set_device_(device))
 
     # Pre-compute entity name and object_id hash for configure_entity_()
     # which is emitted later by finalize_entity_strings().
@@ -343,18 +398,25 @@ async def _setup_entity_impl(var: MockObj, config: ConfigType, platform: str) ->
     object_id_hash = fnv1_hash_object_id(entity_name) if entity_name else 0
     config[_KEY_ENTITY_NAME] = entity_name
     config[_KEY_OBJECT_ID_HASH] = object_id_hash
-    # Only set disabled_by_default if True (default is False)
-    if config[CONF_DISABLED_BY_DEFAULT]:
-        add(var.set_disabled_by_default(True))
+    # Store flags for packing into configure_entity_()
+    config[_KEY_DISABLED_BY_DEFAULT] = int(config[CONF_DISABLED_BY_DEFAULT])
     if CONF_INTERNAL in config:
-        add(var.set_internal(config[CONF_INTERNAL]))
+        config[_KEY_INTERNAL] = int(config[CONF_INTERNAL])
     icon_idx = 0
     if CONF_ICON in config:
         # Add USE_ENTITY_ICON define when icons are used
         cg.add_define("USE_ENTITY_ICON")
         icon_idx = register_icon(config[CONF_ICON])
     if CONF_ENTITY_CATEGORY in config:
-        add(var.set_entity_category(config[CONF_ENTITY_CATEGORY]))
+        # Derive integer value from key position in cv.ENTITY_CATEGORIES
+        # (must match C++ EntityCategory enum in entity_base.h)
+        entity_cat_str = str(config[CONF_ENTITY_CATEGORY])
+        entity_cat_keys = list(cv.ENTITY_CATEGORIES)
+        config[_KEY_ENTITY_CATEGORY] = (
+            entity_cat_keys.index(entity_cat_str)
+            if entity_cat_str in entity_cat_keys
+            else 0
+        )
     # Store icon index for finalize_entity_strings
     config[_KEY_ICON_IDX] = icon_idx
 
diff --git a/tests/component_tests/binary_sensor/test_binary_sensor.py b/tests/component_tests/binary_sensor/test_binary_sensor.py
index fbc2f37d9a..2667e90dda 100644
--- a/tests/component_tests/binary_sensor/test_binary_sensor.py
+++ b/tests/component_tests/binary_sensor/test_binary_sensor.py
@@ -45,8 +45,9 @@ def test_binary_sensor_config_value_internal_set(generate_main):
     )
 
     # Then
-    assert "bs_1->set_internal(true);" in main_cpp
-    assert "bs_2->set_internal(false);" in main_cpp
+    # internal flag is now packed into configure_entity_() third argument (bit 24)
+    assert "bs_1->configure_entity_(" in main_cpp
+    assert "bs_2->configure_entity_(" in main_cpp
 
 
 def test_binary_sensor_config_value_use_raw_set(generate_main):
diff --git a/tests/component_tests/button/test_button.py b/tests/component_tests/button/test_button.py
index 9f94d61c8c..cd767dd65b 100644
--- a/tests/component_tests/button/test_button.py
+++ b/tests/component_tests/button/test_button.py
@@ -40,5 +40,7 @@ def test_button_config_value_internal_set(generate_main):
     main_cpp = generate_main("tests/component_tests/button/test_button.yaml")
 
     # Then
-    assert "wol_1->set_internal(true);" in main_cpp
-    assert "wol_2->set_internal(false);" in main_cpp
+    # internal flag is packed into configure_entity_() third argument (bit 24)
+    # wol_1 has internal: true → bit 24 set → packed value 16777216
+    assert "wol_1->configure_entity_(" in main_cpp
+    assert "wol_2->configure_entity_(" in main_cpp
diff --git a/tests/component_tests/sensor/test_sensor.py b/tests/component_tests/sensor/test_sensor.py
index 1fd9322c07..d9ab3a022c 100644
--- a/tests/component_tests/sensor/test_sensor.py
+++ b/tests/component_tests/sensor/test_sensor.py
@@ -1,5 +1,15 @@
 """Tests for the sensor component."""
 
+import re
+
+
+def _extract_packed_value(main_cpp, var_name):
+    """Extract the third (packed) argument from a configure_entity_ call."""
+    pattern = rf"{re.escape(var_name)}->configure_entity_\([^,]+,\s*\w+,\s*(\d+)\)"
+    match = re.search(pattern, main_cpp)
+    assert match, f"configure_entity_ call not found for {var_name}"
+    return int(match.group(1))
+
 
 def test_sensor_device_class_set(generate_main):
     """
@@ -10,5 +20,6 @@ def test_sensor_device_class_set(generate_main):
     # When
     main_cpp = generate_main("tests/component_tests/sensor/test_sensor.yaml")
 
-    # Then
-    assert "s_1->configure_entity_(" in main_cpp
+    # Then: device_class: voltage means packed value must be non-zero
+    packed = _extract_packed_value(main_cpp, "s_1")
+    assert packed != 0
diff --git a/tests/component_tests/text/test_text.py b/tests/component_tests/text/test_text.py
index 3ceaa9b8f8..bad7ad3a33 100644
--- a/tests/component_tests/text/test_text.py
+++ b/tests/component_tests/text/test_text.py
@@ -38,8 +38,9 @@ def test_text_config_value_internal_set(generate_main):
     main_cpp = generate_main("tests/component_tests/text/test_text.yaml")
 
     # Then
-    assert "it_2->set_internal(false);" in main_cpp
-    assert "it_3->set_internal(true);" in main_cpp
+    # internal flag is now packed into configure_entity_() third argument (bit 24)
+    assert "it_2->configure_entity_(" in main_cpp
+    assert "it_3->configure_entity_(" in main_cpp
 
 
 def test_text_config_value_mode_set(generate_main):
diff --git a/tests/component_tests/text_sensor/test_text_sensor.py b/tests/component_tests/text_sensor/test_text_sensor.py
index cdbb9d2b66..21a273b947 100644
--- a/tests/component_tests/text_sensor/test_text_sensor.py
+++ b/tests/component_tests/text_sensor/test_text_sensor.py
@@ -1,5 +1,15 @@
 """Tests for the text sensor component."""
 
+import re
+
+
+def _extract_packed_value(main_cpp, var_name):
+    """Extract the third (packed) argument from a configure_entity_ call."""
+    pattern = rf"{re.escape(var_name)}->configure_entity_\([^,]+,\s*\w+,\s*(\d+)\)"
+    match = re.search(pattern, main_cpp)
+    assert match, f"configure_entity_ call not found for {var_name}"
+    return int(match.group(1))
+
 
 def test_text_sensor_is_setup(generate_main):
     """
@@ -40,8 +50,9 @@ def test_text_sensor_config_value_internal_set(generate_main):
     main_cpp = generate_main("tests/component_tests/text_sensor/test_text_sensor.yaml")
 
     # Then
-    assert "ts_2->set_internal(true);" in main_cpp
-    assert "ts_3->set_internal(false);" in main_cpp
+    # internal flag is now packed into configure_entity_() third argument (bit 24)
+    assert "ts_2->configure_entity_(" in main_cpp
+    assert "ts_3->configure_entity_(" in main_cpp
 
 
 def test_text_sensor_device_class_set(generate_main):
@@ -53,6 +64,9 @@ def test_text_sensor_device_class_set(generate_main):
     # When
     main_cpp = generate_main("tests/component_tests/text_sensor/test_text_sensor.yaml")
 
-    # Then
-    assert "ts_2->configure_entity_(" in main_cpp
-    assert "ts_3->configure_entity_(" in main_cpp
+    # Then: ts_2 has device_class: timestamp, ts_3 has device_class: date
+    # so their packed values must be non-zero
+    packed_ts_2 = _extract_packed_value(main_cpp, "ts_2")
+    assert packed_ts_2 != 0
+    packed_ts_3 = _extract_packed_value(main_cpp, "ts_3")
+    assert packed_ts_3 != 0
diff --git a/tests/unit_tests/core/test_entity_helpers.py b/tests/unit_tests/core/test_entity_helpers.py
index 1169f5baa3..a68955fe08 100644
--- a/tests/unit_tests/core/test_entity_helpers.py
+++ b/tests/unit_tests/core/test_entity_helpers.py
@@ -9,6 +9,7 @@ import pytest
 
 from esphome.config_validation import Invalid
 from esphome.const import (
+    CONF_DEVICE_CLASS,
     CONF_DEVICE_ID,
     CONF_DISABLED_BY_DEFAULT,
     CONF_ENTITY_CATEGORY,
@@ -16,16 +17,26 @@ from esphome.const import (
     CONF_ID,
     CONF_INTERNAL,
     CONF_NAME,
+    CONF_UNIT_OF_MEASUREMENT,
 )
 from esphome.core import CORE, ID, entity_helpers
 from esphome.core.entity_helpers import (
+    _DC_SHIFT,
+    _DISABLED_BY_DEFAULT_SHIFT,
+    _ENTITY_CATEGORY_SHIFT,
+    _ICON_SHIFT,
+    _INTERNAL_SHIFT,
+    _UOM_SHIFT,
     _register_string,
     _setup_entity_impl,
     entity_duplicate_validator,
+    finalize_entity_strings,
     get_base_entity_object_id,
     register_device_class,
     register_icon,
+    setup_device_class,
     setup_entity,
+    setup_unit_of_measurement,
 )
 from esphome.cpp_generator import MockObj
 from esphome.helpers import sanitize, snake_case
@@ -309,8 +320,6 @@ def extract_object_id_from_expressions(expressions: list[str]) -> str | None:
 async def test_setup_entity_no_duplicates(setup_test_environment: list[str]) -> None:
     """Test setup_entity with unique names."""
 
-    setup_test_environment  # noqa: F841 - fixture initializes CORE state
-
     # Create mock entities
     var1 = MockObj("sensor1")
     var2 = MockObj("sensor2")
@@ -344,8 +353,6 @@ async def test_setup_entity_different_platforms(
 ) -> None:
     """Test that same name on different platforms doesn't conflict."""
 
-    setup_test_environment  # noqa: F841 - fixture initializes CORE state
-
     # Create mock entities
     sensor = MockObj("sensor1")
     binary_sensor = MockObj("binary_sensor1")
@@ -392,7 +399,6 @@ async def test_setup_entity_with_devices(
     setup_test_environment: list[str], mock_get_variable: dict[ID, MockObj]
 ) -> None:
     """Test that same name on different devices doesn't conflict."""
-    setup_test_environment  # noqa: F841 - fixture initializes CORE state
 
     # Create mock devices
     device1_id = ID("device1", type="Device")
@@ -433,8 +439,6 @@ async def test_setup_entity_with_devices(
 async def test_setup_entity_empty_name(setup_test_environment: list[str]) -> None:
     """Test setup_entity with empty entity name."""
 
-    setup_test_environment  # noqa: F841 - fixture initializes CORE state
-
     var = MockObj("sensor1")
 
     config = {
@@ -455,8 +459,6 @@ async def test_setup_entity_special_characters(
 ) -> None:
     """Test setup_entity with names containing special characters."""
 
-    setup_test_environment  # noqa: F841 - fixture initializes CORE state
-
     var = MockObj("sensor1")
 
     config = {
@@ -475,8 +477,6 @@ async def test_setup_entity_special_characters(
 async def test_setup_entity_with_icon(setup_test_environment: list[str]) -> None:
     """Test setup_entity sets icon correctly."""
 
-    setup_test_environment  # noqa: F841 - fixture initializes CORE state
-
     var = MockObj("sensor1")
 
     config = {
@@ -497,8 +497,6 @@ async def test_setup_entity_disabled_by_default(
 ) -> None:
     """Test setup_entity sets disabled_by_default correctly."""
 
-    added_expressions = setup_test_environment
-
     var = MockObj("sensor1")
 
     config = {
@@ -508,10 +506,8 @@ async def test_setup_entity_disabled_by_default(
 
     await _setup_entity_impl(var, config, "sensor")
 
-    # Check disabled_by_default was set
-    assert any(
-        "sensor1.set_disabled_by_default(true)" in expr for expr in added_expressions
-    )
+    # disabled_by_default is now packed into config for configure_entity_()
+    assert config.get("_entity_disabled_by_default") == 1
 
 
 def test_entity_duplicate_validator() -> None:
@@ -796,8 +792,8 @@ async def test_setup_entity_empty_name_with_device(
 
     entity_helpers.get_variable = original_get_variable
 
-    # Check that set_device was called
-    assert any("sensor1.set_device" in expr for expr in added_expressions)
+    # Check that set_device_ was called (separate protected call, accessible via friend)
+    assert any("sensor1.set_device_" in expr for expr in added_expressions)
 
     # For empty-name entities, Python stores hash 0 - C++ calculates hash at runtime
     assert config.get("_entity_name") == ""
@@ -813,7 +809,6 @@ async def test_setup_entity_empty_name_with_mac_suffix(
     For empty-name entities, Python passes 0 and C++ calculates the hash
     at runtime from friendly_name (bug-for-bug compatibility).
     """
-    setup_test_environment  # noqa: F841 - fixture initializes CORE state
 
     # Set up CORE.config with name_add_mac_suffix enabled
     CORE.config = {"name_add_mac_suffix": True}
@@ -844,7 +839,6 @@ async def test_setup_entity_empty_name_with_mac_suffix_no_friendly_name(
     at runtime. In this case C++ will hash the empty friendly_name
     (bug-for-bug compatibility).
     """
-    setup_test_environment  # noqa: F841 - fixture initializes CORE state
 
     # Set up CORE.config with name_add_mac_suffix enabled
     CORE.config = {"name_add_mac_suffix": True}
@@ -874,7 +868,6 @@ async def test_setup_entity_empty_name_no_mac_suffix_no_friendly_name(
     For empty-name entities, Python passes 0 and C++ calculates the hash
     at runtime from the device name.
     """
-    setup_test_environment  # noqa: F841 - fixture initializes CORE state
 
     # No MAC suffix (either not set or False)
     CORE.config = {}
@@ -942,7 +935,7 @@ def test_register_device_class_max_length() -> None:
 async def test_setup_entity_with_entity_category(
     setup_test_environment: list[str],
 ) -> None:
-    """Test setup_entity sets entity_category correctly."""
+    """Test entity_category is packed correctly through the full setup flow."""
     added_expressions = setup_test_environment
     var = MockObj("sensor1")
     config = {
@@ -951,9 +944,9 @@ async def test_setup_entity_with_entity_category(
         CONF_ENTITY_CATEGORY: "diagnostic",
     }
     await _setup_entity_impl(var, config, "sensor")
-    assert any(
-        'set_entity_category("diagnostic")' in expr for expr in added_expressions
-    )
+    finalize_entity_strings(var, config)
+    packed = _extract_packed_value(added_expressions)
+    assert (packed >> _ENTITY_CATEGORY_SHIFT) & 0x3 == 2
 
 
 @pytest.mark.asyncio
@@ -1002,3 +995,200 @@ async def test_setup_entity_decorator_mode(setup_test_environment: list[str]) ->
     assert body_called
     object_id = extract_object_id_from_expressions(added_expressions)
     assert object_id == "temperature"
+
+
+# Tests for finalize_entity_strings packing
+
+
+def _extract_packed_value(expressions: list[str]) -> int:
+    """Extract the third argument (packed value) from a configure_entity_() call."""
+    for expr in expressions:
+        if "configure_entity_" in expr:
+            # Match the last integer argument before the closing ");"
+            match = re.search(r",\s*(\d+)\s*\)", expr)
+            if match:
+                return int(match.group(1))
+    raise AssertionError("No configure_entity_ call found")
+
+
+@pytest.mark.asyncio
+async def test_finalize_no_flags(setup_test_environment: list[str]) -> None:
+    """Test entity with no special flags — packed value is 0, no comment."""
+    added_expressions = setup_test_environment
+    var = MockObj("sensor1")
+    config = {
+        CONF_NAME: "Test",
+        CONF_DISABLED_BY_DEFAULT: False,
+    }
+    await _setup_entity_impl(var, config, "sensor")
+    finalize_entity_strings(var, config)
+    packed = _extract_packed_value(added_expressions)
+    assert packed == 0
+    assert "//" not in added_expressions[0]
+
+
+@pytest.mark.asyncio
+async def test_finalize_internal(setup_test_environment: list[str]) -> None:
+    """Test entity with internal=True packs the internal bit."""
+    added_expressions = setup_test_environment
+    var = MockObj("sensor1")
+    config = {
+        CONF_NAME: "Test",
+        CONF_DISABLED_BY_DEFAULT: False,
+        CONF_INTERNAL: True,
+    }
+    await _setup_entity_impl(var, config, "sensor")
+    finalize_entity_strings(var, config)
+    packed = _extract_packed_value(added_expressions)
+    assert packed & (1 << _INTERNAL_SHIFT) != 0
+    assert packed == (1 << _INTERNAL_SHIFT)
+
+
+@pytest.mark.asyncio
+async def test_finalize_disabled_by_default(
+    setup_test_environment: list[str],
+) -> None:
+    """Test entity with disabled_by_default=True packs the bit."""
+    added_expressions = setup_test_environment
+    var = MockObj("sensor1")
+    config = {
+        CONF_NAME: "Test",
+        CONF_DISABLED_BY_DEFAULT: True,
+    }
+    await _setup_entity_impl(var, config, "sensor")
+    finalize_entity_strings(var, config)
+    packed = _extract_packed_value(added_expressions)
+    assert packed & (1 << _DISABLED_BY_DEFAULT_SHIFT) != 0
+    assert packed == (1 << _DISABLED_BY_DEFAULT_SHIFT)
+
+
+@pytest.mark.asyncio
+async def test_finalize_entity_category(
+    setup_test_environment: list[str],
+) -> None:
+    """Test entity_category values (diagnostic=2, config=1) are packed."""
+    added_expressions = setup_test_environment
+    var = MockObj("sensor1")
+
+    # Test diagnostic (value 2)
+    config = {
+        CONF_NAME: "Test",
+        CONF_DISABLED_BY_DEFAULT: False,
+        CONF_ENTITY_CATEGORY: "diagnostic",
+    }
+    await _setup_entity_impl(var, config, "sensor")
+    finalize_entity_strings(var, config)
+    packed = _extract_packed_value(added_expressions)
+    assert (packed >> _ENTITY_CATEGORY_SHIFT) & 0x3 == 2
+
+    # Test config (value 1)
+    added_expressions.clear()
+    config2 = {
+        CONF_NAME: "Test2",
+        CONF_DISABLED_BY_DEFAULT: False,
+        CONF_ENTITY_CATEGORY: "config",
+    }
+    await _setup_entity_impl(var, config2, "sensor")
+    finalize_entity_strings(var, config2)
+    packed = _extract_packed_value(added_expressions)
+    assert (packed >> _ENTITY_CATEGORY_SHIFT) & 0x3 == 1
+
+
+@pytest.mark.asyncio
+async def test_finalize_string_indices(
+    setup_test_environment: list[str],
+) -> None:
+    """Test device_class, unit_of_measurement, and icon are packed as indices."""
+    added_expressions = setup_test_environment
+    var = MockObj("sensor1")
+    config = {
+        CONF_NAME: "Test",
+        CONF_DISABLED_BY_DEFAULT: False,
+        CONF_DEVICE_CLASS: "temperature",
+        CONF_UNIT_OF_MEASUREMENT: "°C",
+        CONF_ICON: "mdi:thermometer",
+    }
+    await _setup_entity_impl(var, config, "sensor")
+    setup_device_class(config)
+    setup_unit_of_measurement(config)
+    finalize_entity_strings(var, config)
+    packed = _extract_packed_value(added_expressions)
+    # All three string indices should be non-zero
+    assert (packed >> _DC_SHIFT) & 0xFF != 0
+    assert (packed >> _UOM_SHIFT) & 0xFF != 0
+    assert (packed >> _ICON_SHIFT) & 0xFF != 0
+    # No flags set
+    assert (packed >> _INTERNAL_SHIFT) & 1 == 0
+    assert (packed >> _DISABLED_BY_DEFAULT_SHIFT) & 1 == 0
+    assert (packed >> _ENTITY_CATEGORY_SHIFT) & 0x3 == 0
+
+
+@pytest.mark.asyncio
+async def test_finalize_all_fields(
+    setup_test_environment: list[str],
+) -> None:
+    """Test all fields set: flags, string indices, and comment."""
+    added_expressions = setup_test_environment
+    var = MockObj("sensor1")
+    config = {
+        CONF_NAME: "Test",
+        CONF_DISABLED_BY_DEFAULT: True,
+        CONF_INTERNAL: True,
+        CONF_ENTITY_CATEGORY: "diagnostic",
+        CONF_DEVICE_CLASS: "temperature",
+        CONF_UNIT_OF_MEASUREMENT: "°C",
+        CONF_ICON: "mdi:thermometer",
+    }
+    await _setup_entity_impl(var, config, "sensor")
+    setup_device_class(config)
+    setup_unit_of_measurement(config)
+    finalize_entity_strings(var, config)
+    packed = _extract_packed_value(added_expressions)
+    # Verify flags
+    assert (packed >> _INTERNAL_SHIFT) & 1 == 1
+    assert (packed >> _DISABLED_BY_DEFAULT_SHIFT) & 1 == 1
+    assert (packed >> _ENTITY_CATEGORY_SHIFT) & 0x3 == 2
+    # Verify string indices are non-zero
+    assert (packed >> _DC_SHIFT) & 0xFF != 0
+    assert (packed >> _UOM_SHIFT) & 0xFF != 0
+    assert (packed >> _ICON_SHIFT) & 0xFF != 0
+    # Verify comment contains all flags with actual string values
+    comment_line = added_expressions[0]
+    assert (
+        "// internal, disabled_by_default, category:diagnostic,"
+        " dc:temperature, uom:°C, icon:mdi:thermometer" in comment_line
+    )
+
+
+@pytest.mark.asyncio
+async def test_finalize_comment_sanitization(
+    setup_test_environment: list[str],
+) -> None:
+    """Test that user strings in comments are sanitized against injection."""
+    added_expressions = setup_test_environment
+    var = MockObj("sensor1")
+    config = {
+        CONF_NAME: "Test",
+        CONF_DISABLED_BY_DEFAULT: False,
+        # Backslash at end would cause line splice eating next code line
+        CONF_ICON: "mdi:evil\\",
+    }
+    await _setup_entity_impl(var, config, "sensor")
+    finalize_entity_strings(var, config)
+    comment_line = added_expressions[0]
+    # Backslash must be replaced to prevent line splice
+    assert "\\" not in comment_line
+    assert "mdi:evil/" in comment_line
+
+    added_expressions.clear()
+    config2 = {
+        CONF_NAME: "Test2",
+        CONF_DISABLED_BY_DEFAULT: False,
+        CONF_ICON: "mdi:evil\nINJECTED_CODE();",
+    }
+    await _setup_entity_impl(var, config2, "sensor")
+    finalize_entity_strings(var, config2)
+    comment_line = added_expressions[0]
+    # Newline must be replaced to prevent breaking out of comment
+    assert "\n" not in comment_line
+    assert "INJECTED_CODE" in comment_line  # still visible but safe in comment