fix(audio): bypass toggle no longer greys out after being turned off

app/src/main/java/com/lastwave/app/playback/InternalDirectOutput.kt

@@ -65,6 +65,17 @@ data class InternalDirectAvailability(
 ) {
     val available: Boolean
         get() = reason == InternalDirectReason.AVAILABLE || reason == InternalDirectReason.ACTIVE
+
+    /**
+     * Whether the settings toggle may be switched on. Only a permanent
+     * impossibility (Android too old, native library missing) locks it.
+     * Route- or format-specific results (Bluetooth codec, one format mixed
+     * by Android, exclusive refused while something else held the output)
+     * can change on the next track or route, and the user must be able to
+     * turn the feature back on without restarting the app.
+     */
+    val canEnable: Boolean
+        get() = reason != InternalDirectReason.ANDROID_TOO_OLD && reason != InternalDirectReason.NATIVE_MISSING
 }
 
 /** The direct stream actually playing, for the signal-path page and the badge. */
@@ -169,6 +180,15 @@ class InternalDirectOutput @Inject constructor(
         if (!enabled) {
             synchronized(openLock) { closeLocked() }
             lastFailure = null
+        } else {
+            // Re-enabling is an explicit retry: forget what earlier attempts
+            // concluded (formats mixed by Android, a probe taken while our own
+            // stream held the output) so this output is tested again.
+            synchronized(openLock) {
+                openCache.clear()
+                mixedRoutes.clear()
+                cachedProbe = null
+            }
         }
         refreshAvailability()
     }

app/src/main/java/com/lastwave/app/ui/settings/SettingsScreen.kt

@@ -1013,10 +1013,10 @@ fun SettingsScreen(
                                     )
                                 },
                                 checked = internalDirectEnabled,
-                                // Greyed out when this output cannot be bypassed, but an
-                                // enabled toggle always stays reachable so it can be turned off.
-                                enabled = internalDirectEnabled || internalDirectAvailability.available ||
-                                    internalDirectAvailability.reason == com.lastwave.app.playback.InternalDirectReason.CHECKING,
+                                // Greyed out only when this device can never bypass the mixer.
+                                // A route- or format-specific refusal must not lock the toggle:
+                                // turning it off used to grey it out until the app restarted.
+                                enabled = internalDirectEnabled || internalDirectAvailability.canEnable,
                                 onCheckedChange = viewModel::setInternalDirectEnabled,
                                 position = position,
                                 isHighlighted = (highlightedSettingId == "audio.internal_direct"),

app/src/test/java/com/lastwave/app/playback/InternalDirectSignalPathTest.kt

@@ -254,4 +254,22 @@ class InternalDirectSignalPathTest {
         // A garbage source never reaches the loop.
         assertThat(InternalDirectOutput.fallbackRates(0, 44_100)).isEmpty()
     }
+    @Test
+    fun toggleStaysReachableUnlessTheDeviceCanNeverBypass() {
+        fun availability(reason: InternalDirectReason) =
+            InternalDirectAvailability(InternalRoute.SPEAKER, "Speaker", reason)
+        // Route- or format-specific results must not lock the toggle once it is turned off.
+        listOf(
+            InternalDirectReason.AVAILABLE,
+            InternalDirectReason.ACTIVE,
+            InternalDirectReason.CHECKING,
+            InternalDirectReason.BLUETOOTH,
+            InternalDirectReason.USB,
+            InternalDirectReason.EXCLUSIVE_REFUSED,
+            InternalDirectReason.NO_AAUDIO,
+            InternalDirectReason.MIXED_BY_ANDROID,
+        ).forEach { assertThat(availability(it).canEnable).isTrue() }
+        assertThat(availability(InternalDirectReason.ANDROID_TOO_OLD).canEnable).isFalse()
+        assertThat(availability(InternalDirectReason.NATIVE_MISSING).canEnable).isFalse()
+    }
 }