Support kelvin light color-temp attributes (HA 2026.3+)

Hemera/Entities/Light/LightController.swift

@@ -35,11 +35,12 @@ final class LightController: LightControlling, ServiceCallErrorHandling {
 
     func setColorTemp(_ id: String, to mireds: Int) async {
         await performServiceCall("Failed to set color temp for \(id)") {
+            let kelvin = mireds > 0 ? 1_000_000 / mireds : 0
             try await serviceCaller.callService(
                 domain: Keys.domain,
                 service: Keys.turnOn,
                 entityId: id,
-                extraData: [Keys.colorTemp: mireds]
+                extraData: [Keys.colorTempKelvin: kelvin]
             )
         }
     }
@@ -61,6 +62,6 @@ private enum Keys {
     static let turnOn = "turn_on"
     static let turnOff = "turn_off"
     static let brightness = "brightness"
-    static let colorTemp = "color_temp"
+    static let colorTempKelvin = "color_temp_kelvin"
     static let hsColor = "hs_color"
 }

Hemera/Entities/Light/LightEntity.swift

@@ -78,14 +78,17 @@ final class LightEntity: StoredEntity {
         brightness = entity.attributes["brightness"] as? Int
         colorMode = entity.attributes["color_mode"] as? String
         colorTemp = entity.attributes["color_temp"] as? Int
+            ?? Self.miredsFromKelvin(entity.attributes["color_temp_kelvin"])
         if let hs = entity.attributes["hs_color"] as? [Any] {
             hsColor = hs.compactMap { ($0 as? NSNumber)?.doubleValue }
             if hsColor?.count != 2 { hsColor = nil }
         } else {
             hsColor = nil
         }
         let rawMinMireds = entity.attributes["min_mireds"] as? Int
+            ?? Self.miredsFromKelvin(entity.attributes["max_color_temp_kelvin"])
         let rawMaxMireds = entity.attributes["max_mireds"] as? Int
+            ?? Self.miredsFromKelvin(entity.attributes["min_color_temp_kelvin"])
         if let lo = rawMinMireds, let hi = rawMaxMireds {
             minMireds = Swift.min(lo, hi)
             maxMireds = Swift.max(lo, hi)
@@ -101,6 +104,20 @@ final class LightEntity: StoredEntity {
     }
 }
 
+// MARK: - Kelvin conversion
+
+private extension LightEntity {
+    /**
+     Converts a HA `*_color_temp_kelvin` attribute to mireds (their reciprocal).
+     Returns nil when the attribute is absent or non-positive so the caller can
+     fall back to the legacy mired attributes.
+    */
+    static func miredsFromKelvin(_ value: Any?) -> Int? {
+        guard let kelvin = value as? Int, kelvin > 0 else { return nil }
+        return 1_000_000 / kelvin
+    }
+}
+
 // MARK: - StoredEntity
 
 extension LightEntity {

HemeraTests/Entities/LightEntityTests.swift

@@ -52,4 +52,40 @@ struct LightEntityTests {
         #expect(entity.minMireds == nil)
         #expect(entity.maxMireds == nil)
     }
+
+    @Test
+    func update_withKelvinAttributes_derivesInvertedMireds() throws {
+        let entity = LightEntity(entityId: "light.test")
+        // HA 2026.3 drops mireds; only kelvin bounds are sent. min mired ↔ max kelvin.
+        let haEntity = try makeHAEntity(attributes: [
+            "color_temp_kelvin": 4000,
+            "min_color_temp_kelvin": 2000,
+            "max_color_temp_kelvin": 6535
+        ])
+
+        entity.update(from: haEntity)
+
+        #expect(entity.colorTemp == 1_000_000 / 4000)     // 250
+        #expect(entity.minMireds == 1_000_000 / 6535)     // 153, from the highest kelvin
+        #expect(entity.maxMireds == 1_000_000 / 2000)     // 500, from the lowest kelvin
+    }
+
+    @Test
+    func update_prefersLegacyMiredsOverKelvin() throws {
+        let entity = LightEntity(entityId: "light.test")
+        let haEntity = try makeHAEntity(attributes: [
+            "color_temp": 300,
+            "min_mireds": 153,
+            "max_mireds": 500,
+            "color_temp_kelvin": 4000,
+            "min_color_temp_kelvin": 2000,
+            "max_color_temp_kelvin": 6535
+        ])
+
+        entity.update(from: haEntity)
+
+        #expect(entity.colorTemp == 300)
+        #expect(entity.minMireds == 153)
+        #expect(entity.maxMireds == 500)
+    }
 }