leds: respect brightness setting and master toggle in achievement flash

Flash peaked at raw 1f brightness and left it there: the restore frame
matched the writer's stale dedup cache and got skipped, so LEDs stuck at
full white after an unlock. Flash now scales to the configured brightness,
requires the master toggle, invalidates the writer cache before restoring,
and suppresses ambient frames while flashing. stop() cancels an in-flight
flash. Achievement Flash setting hides with the master toggle off.

Author: tmgast

app/src/main/kotlin/com/nendo/argosy/hardware/AmbientLedManager.kt

@@ -145,6 +145,8 @@ class AmbientLedManager @Inject constructor(
     fun stop() {
         Log.i(TAG, "Stopping ambient LED manager")
         stopAudioCapture()
+        flashJob?.cancel()
+        flashActive = false
         ledController.setEnabled(false)
     }
 
@@ -301,36 +303,38 @@ class AmbientLedManager @Inject constructor(
     }
 
     private var flashJob: Job? = null
+    @Volatile private var flashActive = false
 
     fun flashAchievement(isHardcore: Boolean) {
-        if (!ledController.isAvailable || !achievementFlashEnabled) return
+        if (!ledController.isAvailable || !isEnabled || !achievementFlashEnabled) return
 
         flashJob?.cancel()
         flashJob = scope.launch {
-            val flashColor = if (isHardcore) {
-                Color(0xFFFFE566) // Bright gold/yellow for hardcore
-            } else {
-                Color(0xFFFFAA44) // Bright orange for casual
-            }
+            flashActive = true
+            val flashColor = if (isHardcore) HARDCORE_FLASH_COLOR else CASUAL_FLASH_COLOR
+            val peak = brightnessScalar
+            val dim = 0.2f * brightnessScalar
 
             repeat(3) {
                 ledController.setColor(flashColor)
-                ledController.setBrightness(1f)
+                ledController.setBrightness(peak)
                 delay(150)
-                ledController.setBrightness(0.2f)
+                ledController.setBrightness(dim)
                 delay(100)
             }
 
-            ledController.setBrightness(1f)
-            delay(50)
-
+            flashActive = false
+            writerCacheStale = true
             if (isEnabled) {
                 updateLeds()
+            } else {
+                ledController.setEnabled(false)
             }
         }
     }
 
     private fun updateLeds() {
+        if (flashActive) return
         val currentState = _state.value
         val (leftColor, rightColor) = when (currentState.context) {
             AmbientLedContext.ARGOSY_UI, AmbientLedContext.GAME_HOVER -> {
@@ -357,12 +361,20 @@ class AmbientLedManager @Inject constructor(
         ledFrames.trySend(LedFrame(leftColor, rightColor, brightness))
     }
 
+    @Volatile private var writerCacheStale = false
+
     private fun startLedWriter() {
         scope.launch(Dispatchers.IO) {
             var lastLeft: Color? = null
             var lastRight: Color? = null
             var lastBrightness = -1f
             for (frame in ledFrames) {
+                if (writerCacheStale) {
+                    writerCacheStale = false
+                    lastLeft = null
+                    lastRight = null
+                    lastBrightness = -1f
+                }
                 val colorChanged = lastLeft == null || lastRight == null ||
                     colorDelta(lastLeft, frame.left) > COLOR_EPSILON ||
                     colorDelta(lastRight, frame.right) > COLOR_EPSILON
@@ -513,5 +525,7 @@ class AmbientLedManager @Inject constructor(
         private const val MIN_WRITE_INTERVAL_MS = 33L
         private const val COLOR_EPSILON = 0.012f
         private const val BRIGHTNESS_EPSILON = 0.01f
+        private val HARDCORE_FLASH_COLOR = Color(0xFFFFE566)
+        private val CASUAL_FLASH_COLOR = Color(0xFFFFAA44)
     }
 }

app/src/main/kotlin/com/nendo/argosy/ui/screens/settings/sections/AmbientLedSection.kt

@@ -42,7 +42,8 @@ internal sealed class AmbientLedItem(
         visibleWhen = { it.ambientLedEnabled })
     data object CustomColorHue : AmbientLedItem("customColorHue", "general",
         visibleWhen = { it.ambientLedEnabled && it.ambientLedCustomColor })
-    data object AchievementFlash : AmbientLedItem("achievementFlash", "general")
+    data object AchievementFlash : AmbientLedItem("achievementFlash", "general",
+        visibleWhen = { it.ambientLedEnabled })
 
     // Cover Art
     data object CoverArtColors : AmbientLedItem("coverArtColors", "coverArt",