Fix Core Room Size encoding and decoded value round-trip

LEVOIT_UART.md

@@ -361,7 +361,7 @@ Room sizes are transmitted as raw integer values derived from square feet.
 | Vital (tag `0x10`) | `raw = round(m² × 10.764 × 1.3)` | ESP→MCU |
 | Core / Core600S | `raw = round(m² × 10.764 × 3.15)` | ESP→MCU |
 
-Decode (MCU→ESP): `m² = raw / (10.764 × factor)` where factor = 1.3 (Vital) or 3.15 (Core).
+Decode (MCU→ESP): `m² = raw / (10.764 × factor)` where factor = 1.3 (Vital) or 3.15 (Core). Core status values are rounded to the nearest whole m² before publishing so values encoded with `round(m² × 10.764 × 3.15)` round-trip at range edges.
 
 ---
 

components/levoit/core_commands.cpp

@@ -2,6 +2,7 @@
 #include "levoit_message.h"
 #include "levoit.h"
 #include "number/levoit_number.h"
+#include "decoder_helpers.h"
 #include "esphome/core/log.h"
 
 namespace esphome
@@ -122,9 +123,8 @@ namespace esphome
                 auto *num = self->get_number(NumberType::EFFICIENCY_ROOM_SIZE);
                 if (num != nullptr)
                 {
-                    // Convert m² → raw MCU value: 1 m² = 10.764 sq ft, MCU uses sq_ft × 3.15
                     float m2 = num->state;
-                    uint32_t raw = static_cast<uint32_t>(m2 * 10.764f * 3.15f + 0.5f);
+                    uint32_t raw = encode_core_room_size_raw(m2);
                     uint8_t size_low = raw & 0xFF;
                     uint8_t size_high = (raw >> 8) & 0xFF;
 

components/levoit/core_status.cpp

@@ -110,7 +110,7 @@ namespace esphome
         bool child_lock     = payload[14] != 0;
         uint8_t fan_auto_mode = payload[15];
         uint16_t efficency_area = (uint16_t)((payload[17] << 8) | payload[16]);
-        float efficency_area_m2 = static_cast<float>(efficency_area) / (10.764f * 3.15f);
+        float efficency_area_m2 = decode_core_room_size_m2(efficency_area);
         bool light_detect   = payload[21] != 0;
 
         self->publish_text_sensor(TextSensorType::ERROR_MESSAGE, "Ok");
@@ -144,7 +144,7 @@ namespace esphome
       bool child_lock = payload[13] != 0;
       uint8_t fan_auto_mode = payload[14];
       uint16_t efficency_area = (payload[16] << 8) | payload[15];
-      float efficency_area_m2 = static_cast<float>(efficency_area) / (10.764f * 3.15f);
+      float efficency_area_m2 = decode_core_room_size_m2(efficency_area);
       bool display_on = false;
       uint8_t fan_speed = 0;
       if (model == ModelType::CORE300S)

components/levoit/decoder_helpers.h

@@ -1,6 +1,7 @@
 #pragma once
 #include <string>
 #include <cstdint>
+#include <cmath>
 
 namespace esphome
 {
@@ -36,5 +37,20 @@ namespace esphome
       return std::to_string(secs) + "s";
     }
 
+    static inline float core_room_size_factor()
+    {
+      return 10.764f * 3.15f;
+    }
+
+    static inline uint32_t encode_core_room_size_raw(float m2)
+    {
+      return static_cast<uint32_t>(std::round(m2 * core_room_size_factor()));
+    }
+
+    static inline float decode_core_room_size_m2(uint16_t raw)
+    {
+      return std::round(static_cast<float>(raw) / core_room_size_factor());
+    }
+
   } // namespace levoit
 } // namespace esphome

components/levoit/levoit.cpp

@@ -126,14 +126,13 @@ namespace esphome
 #endif
         }
 
-        void Levoit::publish_number(NumberType type, uint32_t value)
+        void Levoit::publish_number(NumberType type, float value)
         {
 #ifdef USE_NUMBER
             auto *nm = numbers_[nt_idx_(type)];
             if (!nm)
                 return;
-            float fvalue = static_cast<float>(value);
-            if (nm->has_state() && nm->state == fvalue)
+            if (nm->has_state() && nm->state == value)
                 return;
             nm->publish_state(value);
 #endif

components/levoit/levoit.h

@@ -44,7 +44,7 @@ class Levoit : public Component, public uart::UARTDevice {
 
   // called by decoder when device reports status
   void publish_switch(SwitchType type, bool state);
-  void publish_number(NumberType type, uint32_t value);
+  void publish_number(NumberType type, float value);
   void publish_sensor(SensorType type, uint32_t value);
   void publish_select(SelectType type, uint32_t value);
   void publish_text_sensor(TextSensorType type, const std::string &value);