Revert early returns in process_active_iterator_()

The if/else pattern produces smaller code than early returns.

esphome/components/api/api_connection.cpp

@@ -219,35 +219,8 @@ void APIConnection::loop() {
     this->process_batch_();
   }
 
-  switch (this->active_iterator_) {
-    case ActiveIterator::LIST_ENTITIES:
-      if (this->iterator_storage_.list_entities.completed()) {
-        this->destroy_active_iterator_();
-        if (this->flags_.state_subscription) {
-          this->begin_iterator_(ActiveIterator::INITIAL_STATE);
-        }
-      } else {
-        this->process_iterator_batch_(this->iterator_storage_.list_entities);
-      }
-      break;
-    case ActiveIterator::INITIAL_STATE:
-      if (this->iterator_storage_.initial_state.completed()) {
-        this->destroy_active_iterator_();
-        // Process any remaining batched messages immediately
-        if (!this->deferred_batch_.empty()) {
-          this->process_batch_();
-        }
-        // Now that everything is sent, enable immediate sending for future state changes
-        this->flags_.should_try_send_immediately = true;
-        // Release excess memory from buffers that grew during initial sync
-        this->deferred_batch_.release_buffer();
-        this->helper_->release_buffers();
-      } else {
-        this->process_iterator_batch_(this->iterator_storage_.initial_state);
-      }
-      break;
-    case ActiveIterator::NONE:
-      break;
+  if (this->active_iterator_ != ActiveIterator::NONE) {
+    this->process_active_iterator_();
   }
 
   if (this->flags_.sent_ping) {
@@ -283,6 +256,49 @@ void APIConnection::loop() {
 #endif
 }
 
+void APIConnection::process_active_iterator_() {
+  // Caller ensures active_iterator_ != NONE
+  if (this->active_iterator_ == ActiveIterator::LIST_ENTITIES) {
+    if (this->iterator_storage_.list_entities.completed()) {
+      this->destroy_active_iterator_();
+      if (this->flags_.state_subscription) {
+        this->begin_iterator_(ActiveIterator::INITIAL_STATE);
+      }
+    } else {
+      this->process_iterator_batch_(this->iterator_storage_.list_entities);
+    }
+  } else {  // INITIAL_STATE
+    if (this->iterator_storage_.initial_state.completed()) {
+      this->destroy_active_iterator_();
+      // Process any remaining batched messages immediately
+      if (!this->deferred_batch_.empty()) {
+        this->process_batch_();
+      }
+      // Now that everything is sent, enable immediate sending for future state changes
+      this->flags_.should_try_send_immediately = true;
+      // Release excess memory from buffers that grew during initial sync
+      this->deferred_batch_.release_buffer();
+      this->helper_->release_buffers();
+    } else {
+      this->process_iterator_batch_(this->iterator_storage_.initial_state);
+    }
+  }
+}
+
+void APIConnection::process_iterator_batch_(ComponentIterator &iterator) {
+  size_t initial_size = this->deferred_batch_.size();
+  size_t max_batch = this->get_max_batch_size_();
+  while (!iterator.completed() && (this->deferred_batch_.size() - initial_size) < max_batch) {
+    iterator.advance();
+  }
+
+  // If the batch is full, process it immediately
+  // Note: iterator.advance() already calls schedule_batch_() via schedule_message_()
+  if (this->deferred_batch_.size() >= max_batch) {
+    this->process_batch_();
+  }
+}
+
 bool APIConnection::send_disconnect_response_() {
   // remote initiated disconnect_client
   // don't close yet, we still need to send the disconnect response

esphome/components/api/api_connection.h

@@ -15,6 +15,10 @@
 #include <limits>
 #include <vector>
 
+namespace esphome {
+class ComponentIterator;
+}  // namespace esphome
+
 namespace esphome::api {
 
 // Keepalive timeout in milliseconds
@@ -364,20 +368,13 @@ class APIConnection final : public APIServerConnectionBase {
     return this->client_supports_api_version(1, 14) ? MAX_INITIAL_PER_BATCH : MAX_INITIAL_PER_BATCH_LEGACY;
   }
 
-  // Helper method to process multiple entities from an iterator in a batch
-  template<typename Iterator> void process_iterator_batch_(Iterator &iterator) {
-    size_t initial_size = this->deferred_batch_.size();
-    size_t max_batch = this->get_max_batch_size_();
-    while (!iterator.completed() && (this->deferred_batch_.size() - initial_size) < max_batch) {
-      iterator.advance();
-    }
+  // Process active iterator (list_entities/initial_state) during connection setup.
+  // Extracted from loop() — only runs during initial handshake, NONE in steady state.
+  void __attribute__((noinline)) process_active_iterator_();
 
-    // If the batch is full, process it immediately
-    // Note: iterator.advance() already calls schedule_batch_() via schedule_message_()
-    if (this->deferred_batch_.size() >= max_batch) {
-      this->process_batch_();
-    }
-  }
+  // Helper method to process multiple entities from an iterator in a batch.
+  // Takes ComponentIterator base class reference to avoid duplicate template instantiations.
+  void process_iterator_batch_(ComponentIterator &iterator);
 
 #ifdef USE_BINARY_SENSOR
   static uint16_t try_send_binary_sensor_state(EntityBase *entity, APIConnection *conn, uint32_t remaining_size);

esphome/components/api/list_entities.h

@@ -94,7 +94,6 @@ class ListEntitiesIterator : public ComponentIterator {
   bool on_update(update::UpdateEntity *entity) override;
 #endif
   bool on_end() override;
-  bool completed() { return this->state_ == IteratorState::NONE; }
 
  protected:
   APIConnection *client_;

esphome/components/api/subscribe_state.h

@@ -88,7 +88,6 @@ class InitialStateIterator : public ComponentIterator {
 #ifdef USE_UPDATE
   bool on_update(update::UpdateEntity *entity) override;
 #endif
-  bool completed() { return this->state_ == IteratorState::NONE; }
 
  protected:
   APIConnection *client_;

esphome/components/cse7766/cse7766.cpp

@@ -16,8 +16,8 @@ void CSE7766Component::loop() {
   }
 
   // Early return prevents updating last_transmission_ when no data is available.
-  int avail = this->available();
-  if (avail <= 0) {
+  size_t avail = this->available();
+  if (avail == 0) {
     return;
   }
 
@@ -27,7 +27,7 @@ void CSE7766Component::loop() {
   // At 4800 baud (~480 bytes/sec) with ~122 Hz loop rate, typically ~4 bytes per call.
   uint8_t buf[CSE7766_RAW_DATA_SIZE];
   while (avail > 0) {
-    size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
+    size_t to_read = std::min(avail, sizeof(buf));
     if (!this->read_array(buf, to_read)) {
       break;
     }

esphome/components/dfplayer/dfplayer.cpp

@@ -133,10 +133,10 @@ void DFPlayer::send_cmd_(uint8_t cmd, uint16_t argument) {
 
 void DFPlayer::loop() {
   // Read all available bytes in batches to reduce UART call overhead.
-  int avail = this->available();
+  size_t avail = this->available();
   uint8_t buf[64];
   while (avail > 0) {
-    size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
+    size_t to_read = std::min(avail, sizeof(buf));
     if (!this->read_array(buf, to_read)) {
       break;
     }

esphome/components/dsmr/dsmr.cpp

@@ -120,9 +120,9 @@ void Dsmr::stop_requesting_data_() {
 
 void Dsmr::drain_rx_buffer_() {
   uint8_t buf[64];
-  int avail;
+  size_t avail;
   while ((avail = this->available()) > 0) {
-    if (!this->read_array(buf, std::min(static_cast<size_t>(avail), sizeof(buf)))) {
+    if (!this->read_array(buf, std::min(avail, sizeof(buf)))) {
       break;
     }
   }
@@ -140,9 +140,9 @@ void Dsmr::receive_telegram_() {
   while (this->available_within_timeout_()) {
     // Read all available bytes in batches to reduce UART call overhead.
     uint8_t buf[64];
-    int avail = this->available();
+    size_t avail = this->available();
     while (avail > 0) {
-      size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
+      size_t to_read = std::min(avail, sizeof(buf));
       if (!this->read_array(buf, to_read))
         return;
       avail -= to_read;
@@ -206,9 +206,9 @@ void Dsmr::receive_encrypted_telegram_() {
   while (this->available_within_timeout_()) {
     // Read all available bytes in batches to reduce UART call overhead.
     uint8_t buf[64];
-    int avail = this->available();
+    size_t avail = this->available();
     while (avail > 0) {
-      size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
+      size_t to_read = std::min(avail, sizeof(buf));
       if (!this->read_array(buf, to_read))
         return;
       avail -= to_read;

esphome/components/ld2410/ld2410.cpp

@@ -276,10 +276,10 @@ void LD2410Component::restart_and_read_all_info() {
 
 void LD2410Component::loop() {
   // Read all available bytes in batches to reduce UART call overhead.
-  int avail = this->available();
+  size_t avail = this->available();
   uint8_t buf[MAX_LINE_LENGTH];
   while (avail > 0) {
-    size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
+    size_t to_read = std::min(avail, sizeof(buf));
     if (!this->read_array(buf, to_read)) {
       break;
     }

esphome/components/ld2412/ld2412.cpp

@@ -311,10 +311,10 @@ void LD2412Component::restart_and_read_all_info() {
 
 void LD2412Component::loop() {
   // Read all available bytes in batches to reduce UART call overhead.
-  int avail = this->available();
+  size_t avail = this->available();
   uint8_t buf[MAX_LINE_LENGTH];
   while (avail > 0) {
-    size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
+    size_t to_read = std::min(avail, sizeof(buf));
     if (!this->read_array(buf, to_read)) {
       break;
     }

esphome/components/ld2450/ld2450.cpp

@@ -277,10 +277,10 @@ void LD2450Component::dump_config() {
 
 void LD2450Component::loop() {
   // Read all available bytes in batches to reduce UART call overhead.
-  int avail = this->available();
+  size_t avail = this->available();
   uint8_t buf[MAX_LINE_LENGTH];
   while (avail > 0) {
-    size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
+    size_t to_read = std::min(avail, sizeof(buf));
     if (!this->read_array(buf, to_read)) {
       break;
     }

esphome/components/modbus/modbus.cpp

@@ -20,10 +20,10 @@ void Modbus::loop() {
   const uint32_t now = App.get_loop_component_start_time();
 
   // Read all available bytes in batches to reduce UART call overhead.
-  int avail = this->available();
+  size_t avail = this->available();
   uint8_t buf[64];
   while (avail > 0) {
-    size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
+    size_t to_read = std::min(avail, sizeof(buf));
     if (!this->read_array(buf, to_read)) {
       break;
     }

esphome/components/nextion/nextion.cpp

@@ -398,10 +398,10 @@ bool Nextion::remove_from_q_(bool report_empty) {
 
 void Nextion::process_serial_() {
   // Read all available bytes in batches to reduce UART call overhead.
-  int avail = this->available();
+  size_t avail = this->available();
   uint8_t buf[64];
   while (avail > 0) {
-    size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
+    size_t to_read = std::min(avail, sizeof(buf));
     if (!this->read_array(buf, to_read)) {
       break;
     }

esphome/components/pipsolar/pipsolar.cpp

@@ -14,9 +14,9 @@ void Pipsolar::setup() {
 
 void Pipsolar::empty_uart_buffer_() {
   uint8_t buf[64];
-  int avail;
+  size_t avail;
   while ((avail = this->available()) > 0) {
-    if (!this->read_array(buf, std::min(static_cast<size_t>(avail), sizeof(buf)))) {
+    if (!this->read_array(buf, std::min(avail, sizeof(buf)))) {
       break;
     }
   }
@@ -97,10 +97,10 @@ void Pipsolar::loop() {
   }
 
   if (this->state_ == STATE_COMMAND || this->state_ == STATE_POLL) {
-    int avail = this->available();
+    size_t avail = this->available();
     while (avail > 0) {
       uint8_t buf[64];
-      size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
+      size_t to_read = std::min(avail, sizeof(buf));
       if (!this->read_array(buf, to_read)) {
         break;
       }

esphome/components/pylontech/pylontech.cpp

@@ -56,14 +56,14 @@ void PylontechComponent::setup() {
 void PylontechComponent::update() { this->write_str("pwr\n"); }
 
 void PylontechComponent::loop() {
-  int avail = this->available();
+  size_t avail = this->available();
   if (avail > 0) {
     // pylontech sends a lot of data very suddenly
     // we need to quickly put it all into our own buffer, otherwise the uart's buffer will overflow
     int recv = 0;
     uint8_t buf[64];
     while (avail > 0) {
-      size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
+      size_t to_read = std::min(avail, sizeof(buf));
       if (!this->read_array(buf, to_read)) {
         break;
       }

esphome/components/rd03d/rd03d.cpp

@@ -82,10 +82,10 @@ void RD03DComponent::dump_config() {
 
 void RD03DComponent::loop() {
   // Read all available bytes in batches to reduce UART call overhead.
-  int avail = this->available();
+  size_t avail = this->available();
   uint8_t buf[64];
   while (avail > 0) {
-    size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
+    size_t to_read = std::min(avail, sizeof(buf));
     if (!this->read_array(buf, to_read)) {
       break;
     }

esphome/components/rf_bridge/rf_bridge.cpp

@@ -136,10 +136,10 @@ void RFBridgeComponent::loop() {
     this->last_bridge_byte_ = now;
   }
 
-  int avail = this->available();
+  size_t avail = this->available();
   while (avail > 0) {
     uint8_t buf[64];
-    size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
+    size_t to_read = std::min(avail, sizeof(buf));
     if (!this->read_array(buf, to_read)) {
       break;
     }

esphome/components/seeed_mr24hpc1/seeed_mr24hpc1.cpp

@@ -107,10 +107,10 @@ void MR24HPC1Component::update_() {
 // main loop
 void MR24HPC1Component::loop() {
   // Read all available bytes in batches to reduce UART call overhead.
-  int avail = this->available();
+  size_t avail = this->available();
   uint8_t buf[64];
   while (avail > 0) {
-    size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
+    size_t to_read = std::min(avail, sizeof(buf));
     if (!this->read_array(buf, to_read)) {
       break;
     }

esphome/components/seeed_mr60bha2/seeed_mr60bha2.cpp

@@ -31,10 +31,10 @@ void MR60BHA2Component::dump_config() {
 // main loop
 void MR60BHA2Component::loop() {
   // Read all available bytes in batches to reduce UART call overhead.
-  int avail = this->available();
+  size_t avail = this->available();
   uint8_t buf[64];
   while (avail > 0) {
-    size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
+    size_t to_read = std::min(avail, sizeof(buf));
     if (!this->read_array(buf, to_read)) {
       break;
     }

esphome/components/seeed_mr60fda2/seeed_mr60fda2.cpp

@@ -50,10 +50,10 @@ void MR60FDA2Component::setup() {
 // main loop
 void MR60FDA2Component::loop() {
   // Read all available bytes in batches to reduce UART call overhead.
-  int avail = this->available();
+  size_t avail = this->available();
   uint8_t buf[64];
   while (avail > 0) {
-    size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
+    size_t to_read = std::min(avail, sizeof(buf));
     if (!this->read_array(buf, to_read)) {
       break;
     }

esphome/components/tuya/tuya.cpp

@@ -32,10 +32,10 @@ void Tuya::setup() {
 
 void Tuya::loop() {
   // Read all available bytes in batches to reduce UART call overhead.
-  int avail = this->available();
+  size_t avail = this->available();
   uint8_t buf[64];
   while (avail > 0) {
-    size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
+    size_t to_read = std::min(avail, sizeof(buf));
     if (!this->read_array(buf, to_read)) {
       break;
     }

esphome/components/web_server_idf/web_server_idf.cpp

@@ -344,15 +344,14 @@ bool AsyncWebServerRequest::authenticate(const char *username, const char *passw
   memcpy(user_info + user_len + 1, password, pass_len);
   user_info[user_info_len] = '\0';
 
-  // Base64 output size is ceil(input_len * 4/3) + 1, with input bounded to 256 bytes
-  // max output is ceil(256 * 4/3) + 1 = 343 bytes, use 350 for safety
-  constexpr size_t max_digest_len = 350;
-  char digest[max_digest_len];
-  size_t out;
-  esp_crypto_base64_encode(reinterpret_cast<uint8_t *>(digest), max_digest_len, &out,
+  size_t n = 0, out;
+  esp_crypto_base64_encode(nullptr, 0, &n, reinterpret_cast<const uint8_t *>(user_info), user_info_len);
+
+  auto digest = std::unique_ptr<char[]>(new char[n + 1]);
+  esp_crypto_base64_encode(reinterpret_cast<uint8_t *>(digest.get()), n, &out,
                            reinterpret_cast<const uint8_t *>(user_info), user_info_len);
 
-  return strcmp(digest, auth_str + auth_prefix_len) == 0;
+  return strcmp(digest.get(), auth_str + auth_prefix_len) == 0;
 }
 
 void AsyncWebServerRequest::requestAuthentication(const char *realm) const {
@@ -862,12 +861,12 @@ esp_err_t AsyncWebServer::handle_multipart_upload_(httpd_req_t *r, const char *c
     }
   });
 
-  // Process data - use stack buffer to avoid heap allocation
-  char buffer[MULTIPART_CHUNK_SIZE];
+  // Process data
+  std::unique_ptr<char[]> buffer(new char[MULTIPART_CHUNK_SIZE]);
   size_t bytes_since_yield = 0;
 
   for (size_t remaining = r->content_len; remaining > 0;) {
-    int recv_len = httpd_req_recv(r, buffer, std::min(remaining, MULTIPART_CHUNK_SIZE));
+    int recv_len = httpd_req_recv(r, buffer.get(), std::min(remaining, MULTIPART_CHUNK_SIZE));
 
     if (recv_len <= 0) {
       httpd_resp_send_err(r, recv_len == HTTPD_SOCK_ERR_TIMEOUT ? HTTPD_408_REQ_TIMEOUT : HTTPD_400_BAD_REQUEST,
@@ -875,7 +874,7 @@ esp_err_t AsyncWebServer::handle_multipart_upload_(httpd_req_t *r, const char *c
       return recv_len == HTTPD_SOCK_ERR_TIMEOUT ? ESP_ERR_TIMEOUT : ESP_FAIL;
     }
 
-    if (reader->parse(buffer, recv_len) != static_cast<size_t>(recv_len)) {
+    if (reader->parse(buffer.get(), recv_len) != static_cast<size_t>(recv_len)) {
       ESP_LOGW(TAG, "Multipart parser error");
       httpd_resp_send_err(r, HTTPD_400_BAD_REQUEST, nullptr);
       return ESP_FAIL;

esphome/core/component_iterator.h

@@ -26,6 +26,7 @@ class ComponentIterator {
  public:
   void begin(bool include_internal = false);
   void advance();
+  bool completed() const { return this->state_ == IteratorState::NONE; }
   virtual bool on_begin();
 #ifdef USE_BINARY_SENSOR
   virtual bool on_binary_sensor(binary_sensor::BinarySensor *binary_sensor) = 0;