From 3f6eafc88094956223229a2c62451238e96ea700 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Fri, 16 Oct 2026 13:39:46 -1000
Subject: [PATCH] Queue a stop/start sequence only when it fits whole

---
 esphome/components/dfrobot_sen0395/automation.h      |  3 +++
 .../components/dfrobot_sen0395/dfrobot_sen0395.cpp   |  9 +++++++++
 esphome/components/dfrobot_sen0395/dfrobot_sen0395.h |  2 ++
 tests/components/dfrobot_sen0395/settings_action.cpp | 12 ++++++++++++
 4 files changed, 26 insertions(+)

diff --git a/esphome/components/dfrobot_sen0395/automation.h b/esphome/components/dfrobot_sen0395/automation.h
index c4f742750e1..1f4d406e670 100644
--- a/esphome/components/dfrobot_sen0395/automation.h
+++ b/esphome/components/dfrobot_sen0395/automation.h
@@ -29,6 +29,9 @@ class DfrobotSen0395SettingsAction final : public Action<Ts...>, public Parented
   TEMPLATABLE_VALUE(float, det_max4)
 
   void play(const Ts &...x) override {
+    // Worst case: stop, factory reset, six settings, save, start
+    if (!this->parent_->has_queue_room(10))
+      return;
     this->parent_->enqueue(CommandType::COMMAND_TYPE_POWER, false);
     if (this->factory_reset_.has_value() && this->factory_reset_.value(x...) == true) {
       this->parent_->enqueue(CommandType::COMMAND_TYPE_FACTORY_RESET);
diff --git a/esphome/components/dfrobot_sen0395/dfrobot_sen0395.cpp b/esphome/components/dfrobot_sen0395/dfrobot_sen0395.cpp
index cda381b84e5..6c6e50c073d 100644
--- a/esphome/components/dfrobot_sen0395/dfrobot_sen0395.cpp
+++ b/esphome/components/dfrobot_sen0395/dfrobot_sen0395.cpp
@@ -57,6 +57,13 @@ bool DfrobotSen0395Component::enqueue(CommandType type, uint8_t arg) {
   return true;
 }
 
+bool DfrobotSen0395Component::has_queue_room(size_t count) const {
+  if (COMMAND_QUEUE_SIZE - this->cmd_queue_.size() >= count)
+    return true;
+  ESP_LOGE(TAG, "Command queue is full");
+  return false;
+}
+
 void DfrobotSen0395Component::enqueue_det_range_cfg(float min1, float max1, float min2, float max2, float min3,
                                                     float max3, float min4, float max4) {
   // TODO: Print warning when values are rounded
@@ -89,6 +96,8 @@ void DfrobotSen0395Component::enqueue_set_latency(float delay_after_detection, f
 
 void DfrobotSen0395Component::enqueue_saved_setting(CommandType type, bool value) {
   const bool was_active = this->active_;
+  if (!this->has_queue_room(was_active ? 4 : 2))
+    return;
   if (was_active)
     this->enqueue(CommandType::COMMAND_TYPE_POWER, false);
   this->enqueue(type, value);
diff --git a/esphome/components/dfrobot_sen0395/dfrobot_sen0395.h b/esphome/components/dfrobot_sen0395/dfrobot_sen0395.h
index e711a5b84db..fa20e250523 100644
--- a/esphome/components/dfrobot_sen0395/dfrobot_sen0395.h
+++ b/esphome/components/dfrobot_sen0395/dfrobot_sen0395.h
@@ -97,6 +97,8 @@ class DfrobotSen0395Component final : public uart::UARTDevice, public Component
 
   // Commands run one at a time from a queue, at least 1 s apart, so loop() never blocks
   bool enqueue(CommandType type, uint8_t arg = 0);
+  /// True when count more commands fit; logs when they do not, so a stop/start sequence is never queued in part
+  bool has_queue_room(size_t count) const;
   /// Queue a detection range config; segments are used up to the first one with a negative bound
   void enqueue_det_range_cfg(float min1, float max1, float min2, float max2, float min3, float max3, float min4,
                              float max4);
diff --git a/tests/components/dfrobot_sen0395/settings_action.cpp b/tests/components/dfrobot_sen0395/settings_action.cpp
index c5099220319..cee64e09e5d 100644
--- a/tests/components/dfrobot_sen0395/settings_action.cpp
+++ b/tests/components/dfrobot_sen0395/settings_action.cpp
@@ -142,4 +142,16 @@ TEST_F(SettingsActionTest, FloatTriggerUnpairedSegmentIsNotEvaluated) {
   EXPECT_EQ(call_record().segment_calls[0], 0);
 }
 
+TEST_F(SettingsActionTest, QueuesNothingWithoutRoomForWholeSequence) {
+  for (int i = 0; i < 11; i++)
+    ASSERT_TRUE(this->radar_.enqueue(CommandType::COMMAND_TYPE_SAVE_CFG));
+  DfrobotSen0395SettingsAction<> action;
+  action.set_parent(&this->radar_);
+  action.play();
+  EXPECT_TRUE(this->radar_.has_queue_room(9));
+  this->radar_.enqueue_saved_setting(CommandType::COMMAND_TYPE_LED_MODE, true);
+  EXPECT_TRUE(this->radar_.has_queue_room(7));
+  EXPECT_FALSE(this->radar_.has_queue_room(8));
+}
+
 }  // namespace esphome::dfrobot_sen0395::testing