fix(battery): Seed charge ETA from quick-charge specs, hide projection while charging

- While charging, the gauge showed the bare runtime projection when no charge
  rate existed yet — "1% · 4m" next to a charging chip reads as a four-minute
  charge. The line now shows the "until charged" ETA or nothing
- Seed the charge rate from Apple's published quick-charge claims ("5 minutes
  in the case provides around 1 hour of listening"), normalized against the
  rated listening hours, so the ETA is present from the very first charge; a
  live fit still takes over within minutes

app/src/main/java/eu/darken/capod/main/ui/overview/cards/DualPodsCard.kt

@@ -240,7 +240,9 @@ private fun ColumnScope.DualPodsCardExpanded(
                     isMicrophone = device.isLeftPodMicrophone ?: false,
                     showMicrophone = device.hasDualMicrophone,
                     modifier = Modifier.weight(1f),
-                    timeRemaining = batteryEstimate?.left?.let { formatEstimateText(context, it) },
+                    timeRemaining = batteryEstimate?.left?.let {
+                        formatEstimateText(context, it, isCharging = device.isLeftPodCharging == true)
+                    },
                 )
 
                 PodGauge(
@@ -253,7 +255,9 @@ private fun ColumnScope.DualPodsCardExpanded(
                     isMicrophone = device.isRightPodMicrophone ?: false,
                     showMicrophone = device.hasDualMicrophone,
                     modifier = Modifier.weight(1f),
-                    timeRemaining = batteryEstimate?.right?.let { formatEstimateText(context, it) },
+                    timeRemaining = batteryEstimate?.right?.let {
+                        formatEstimateText(context, it, isCharging = device.isRightPodCharging == true)
+                    },
                 )
             }
 
@@ -406,14 +410,17 @@ private fun PodGauge(
 }
 
 /**
- * The gauge's small estimate line: while charging with a usable rate, the time until full
- * (language-neutral "⚡ 25m"); otherwise the usual time-remaining ("2h 15m"). Shared with
+ * The gauge's small estimate line: while charging, the time until full (language-neutral "⚡ 25m")
+ * or NOTHING — a bare runtime number next to a charging chip ("1% · 4m") inevitably reads as a
+ * four-minute charge. The runtime estimate only shows while not charging. Shared with
  * [SinglePodsCard] (same package).
  */
-internal fun formatEstimateText(context: Context, pod: BatteryEstimate.Pod): String =
-    pod.minutesUntilCharged
-        ?.let { context.getString(R.string.battery_time_until_charged_short, formatBatteryDurationShort(context, it)) }
-        ?: formatBatteryDurationShort(context, pod.minutesRemaining)
+internal fun formatEstimateText(context: Context, pod: BatteryEstimate.Pod, isCharging: Boolean): String? = when {
+    pod.minutesUntilCharged != null ->
+        context.getString(R.string.battery_time_until_charged_short, formatBatteryDurationShort(context, pod.minutesUntilCharged))
+    isCharging -> null
+    else -> formatBatteryDurationShort(context, pod.minutesRemaining)
+}
 
 @OptIn(ExperimentalLayoutApi::class)
 @Composable

app/src/main/java/eu/darken/capod/main/ui/overview/cards/SinglePodsCard.kt

@@ -267,10 +267,12 @@ private fun ColumnScope.SinglePodsCardExpanded(
                             MaterialTheme.colorScheme.onSurfaceVariant
                         },
                     )
-                    val headsetEstimate = batteryEstimate?.headset
+                    val headsetEstimate = batteryEstimate?.headset?.let {
+                        formatEstimateText(context, it, isCharging = device.isHeadsetBeingCharged == true)
+                    }
                     if (headsetEstimate != null) {
                         Text(
-                            text = formatEstimateText(context, headsetEstimate),
+                            text = headsetEstimate,
                             style = MaterialTheme.typography.labelMedium,
                             color = MaterialTheme.colorScheme.onSurfaceVariant,
                             maxLines = 1,

app/src/main/java/eu/darken/capod/monitor/core/battery/BatteryEstimator.kt

@@ -348,7 +348,13 @@ class BatteryEstimator @Inject constructor(
         val live = if (history.direction == SlotHistory.Direction.CHARGE) {
             DrainModel.chargeSlopeFractionPerHour(history.toList())
         } else null
-        val rate = live ?: learnedChargeRate(profileId, device, slot) ?: return null
+        // Rate preference mirrors the drain side: measured, then learned, then Apple's published
+        // quick-charge claim ("5 minutes in the case = ~1 hour of listening") — so an ETA exists
+        // even on the very first charge.
+        val rate = live
+            ?: learnedChargeRate(profileId, device, slot)
+            ?: device.model.batterySpec?.chargeFractionPerHour
+            ?: return null
 
         val lastRise = tracker.lastRiseMs[slot] ?: return null
         val step = if (device.liveReading(slot)?.second == DataSource.AAP) STEP_AAP else STEP_BLE

app/src/main/java/eu/darken/capod/pods/core/apple/PodModel.kt

@@ -27,7 +27,7 @@ enum class PodModel(
             hasMicrophoneMode = true,
             hasEarDetectionToggle = true,
         ),
-        batterySpec = BatterySpec(listeningHoursAncOff = 5f),
+        batterySpec = BatterySpec(listeningHoursAncOff = 5f, chargeFractionPerHour = 2.4f),
         modelNumbers = setOf("A1523", "A1722"), // L/R earphones
         leftPodIconRes = R.drawable.device_airpods_gen1_left,
         rightPodIconRes = R.drawable.device_airpods_gen1_right,
@@ -45,7 +45,7 @@ enum class PodModel(
             hasMicrophoneMode = true,
             hasEarDetectionToggle = true,
         ),
-        batterySpec = BatterySpec(listeningHoursAncOff = 5f),
+        batterySpec = BatterySpec(listeningHoursAncOff = 5f, chargeFractionPerHour = 2.4f),
         modelNumbers = setOf("A2031", "A2032"), // L/R earphones
         leftPodIconRes = R.drawable.device_airpods_gen1_left,
         rightPodIconRes = R.drawable.device_airpods_gen1_right,
@@ -67,7 +67,7 @@ enum class PodModel(
             hasMicrophoneMode = true,
             hasEarDetectionToggle = true,
         ),
-        batterySpec = BatterySpec(listeningHoursAncOff = 6f),
+        batterySpec = BatterySpec(listeningHoursAncOff = 6f, chargeFractionPerHour = 2.0f),
         modelNumbers = setOf("A2564", "A2565"), // L/R earphones
         leftPodIconRes = R.drawable.device_airpods_gen3_left,
         rightPodIconRes = R.drawable.device_airpods_gen3_right,
@@ -90,7 +90,7 @@ enum class PodModel(
             hasEarDetectionToggle = true,
             hasSleepDetection = true,
         ),
-        batterySpec = BatterySpec(listeningHoursAncOff = 5f),
+        batterySpec = BatterySpec(listeningHoursAncOff = 5f, chargeFractionPerHour = 2.4f),
         modelNumbers = setOf("A3050", "A3053", "A3054"), // earphones
         leftPodIconRes = R.drawable.device_airpods_gen3_left,
         rightPodIconRes = R.drawable.device_airpods_gen3_right,
@@ -122,7 +122,7 @@ enum class PodModel(
             hasStemConfig = true,
             hasSleepDetection = true,
         ),
-        batterySpec = BatterySpec(listeningHoursAncOn = 4f, listeningHoursAncOff = 5f),
+        batterySpec = BatterySpec(listeningHoursAncOn = 4f, listeningHoursAncOff = 5f, chargeFractionPerHour = 2.4f),
         modelNumbers = setOf("A3055", "A3056", "A3057"), // earphones
         leftPodIconRes = R.drawable.device_airpods_gen4anc_left,
         rightPodIconRes = R.drawable.device_airpods_gen4anc_right,
@@ -148,7 +148,7 @@ enum class PodModel(
             hasListeningModeCycle = true,
             hasAllowOffOption = true,
         ),
-        batterySpec = BatterySpec(listeningHoursAncOn = 4.5f, listeningHoursAncOff = 5f),
+        batterySpec = BatterySpec(listeningHoursAncOn = 4.5f, listeningHoursAncOff = 5f, chargeFractionPerHour = 2.4f),
         modelNumbers = setOf("A2083", "A2084"), // L/R earphones
         leftPodIconRes = R.drawable.device_airpods_pro2_left,
         rightPodIconRes = R.drawable.device_airpods_pro2_right,
@@ -182,7 +182,7 @@ enum class PodModel(
             hasStemConfig = true,
             hasSleepDetection = true,
         ),
-        batterySpec = BatterySpec(listeningHoursAncOn = 6f),
+        batterySpec = BatterySpec(listeningHoursAncOn = 6f, chargeFractionPerHour = 2.0f),
         modelNumbers = setOf("A2698", "A2699", "A2931"), // earphones
         leftPodIconRes = R.drawable.device_airpods_pro2_left,
         rightPodIconRes = R.drawable.device_airpods_pro2_right,
@@ -216,7 +216,7 @@ enum class PodModel(
             hasStemConfig = true,
             hasSleepDetection = true,
         ),
-        batterySpec = BatterySpec(listeningHoursAncOn = 6f),
+        batterySpec = BatterySpec(listeningHoursAncOn = 6f, chargeFractionPerHour = 2.0f),
         modelNumbers = setOf("A3047", "A3048", "A3049"), // earphones
         leftPodIconRes = R.drawable.device_airpods_pro2_left,
         rightPodIconRes = R.drawable.device_airpods_pro2_right,
@@ -251,7 +251,7 @@ enum class PodModel(
             hasSleepDetection = true,
             hasDynamicEndOfCharge = true,
         ),
-        batterySpec = BatterySpec(listeningHoursAncOn = 8f),
+        batterySpec = BatterySpec(listeningHoursAncOn = 8f, chargeFractionPerHour = 1.5f),
         modelNumbers = setOf("A3063", "A3064", "A3065"), // earphones
         leftPodIconRes = R.drawable.device_airpods_pro2_left,
         rightPodIconRes = R.drawable.device_airpods_pro2_right,
@@ -272,7 +272,7 @@ enum class PodModel(
             hasListeningModeCycle = true,
             hasAllowOffOption = true,
         ),
-        batterySpec = BatterySpec(listeningHoursAncOn = 20f),
+        batterySpec = BatterySpec(listeningHoursAncOn = 20f, chargeFractionPerHour = 0.9f),
         modelNumbers = setOf("A2096"), // headphones
     ),
 
@@ -290,7 +290,7 @@ enum class PodModel(
             hasListeningModeCycle = true,
             hasAllowOffOption = true,
         ),
-        batterySpec = BatterySpec(listeningHoursAncOn = 20f),
+        batterySpec = BatterySpec(listeningHoursAncOn = 20f, chargeFractionPerHour = 0.9f),
         modelNumbers = setOf("A3184"), // headphones
     ),
 
@@ -312,7 +312,7 @@ enum class PodModel(
             hasListeningModeCycle = true,
             hasAllowOffOption = true,
         ),
-        batterySpec = BatterySpec(listeningHoursAncOn = 20f),
+        batterySpec = BatterySpec(listeningHoursAncOn = 20f, chargeFractionPerHour = 0.9f),
         modelNumbers = setOf("A3454"), // headphones
     ),
 
@@ -606,5 +606,14 @@ enum class PodModel(
         val listeningHoursAncOn: Float? = null,
         /** Listening hours with noise control off, when Apple publishes a distinct figure; else null. */
         val listeningHoursAncOff: Float? = null,
+        /**
+         * Nominal charge rate (battery fraction gained per hour of charging), derived from Apple's
+         * published quick-charge claim: e.g. "5 minutes in the case provides around 1 hour of
+         * listening time" against a 6 h rating is (1/6) / (5/60) = 2.0/hr. Where the model has two
+         * listening ratings it's normalized against the LONGER one, so the seeded "until charged"
+         * never under-promises. Seeds the charge ETA on the very first charge, before any charge
+         * rate has been measured; a live fit takes over within minutes.
+         */
+        val chargeFractionPerHour: Float? = null,
     )
 }

app/src/test/java/eu/darken/capod/monitor/core/battery/BatteryEstimatorTest.kt

@@ -267,6 +267,16 @@ class BatteryEstimatorTest : BaseTest() {
         left.minutesUntilCharged shouldBe 28
     }
 
+    @Test
+    fun `the quick-charge rating seeds an ETA on the very first charge`() = runTest(UnconfinedTestDispatcher()) {
+        // Nothing measured, nothing stored — Apple's "5 minutes = ~1 hour of listening" claim
+        // (2.0/hr for a Pro 2) answers at once: 50% missing at 2.0/hr == 15 min.
+        val result = collectEstimate(
+            estimator(listOf(listOf(device("p1", left = 0.50f, right = 0.50f, charging = true, model = PodModel.AIRPODS_PRO2))))
+        )
+        result["p1"].shouldNotBeNull().left.shouldNotBeNull().minutesUntilCharged shouldBe 15
+    }
+
     @Test
     fun `a stored charge rate seeds time-until-charged immediately`() = runTest(UnconfinedTestDispatcher()) {
         // First charging emission, no live fit possible yet -> the persisted rate answers at once.

app/src/test/java/eu/darken/capod/pods/core/apple/ModelFeaturesTest.kt

@@ -155,6 +155,19 @@ class ModelFeaturesTest : BaseTest() {
         }
     }
 
+    @Test
+    fun `every battery spec carries a plausible quick-charge rate`() {
+        // Derived from Apple's published quick-charge claims; must sit inside the band the live
+        // fit is validated against, or the seed could never be corrected by a measurement.
+        PodModel.entries.forEach { model ->
+            val spec = model.batterySpec ?: return@forEach
+            withClue(model.name) {
+                val rate = spec.chargeFractionPerHour
+                (rate != null && rate in 0.25f..4.0f) shouldBe true
+            }
+        }
+    }
+
     private fun modelsWith(predicate: (PodModel.Features) -> Boolean): Set<PodModel> = PodModel.entries
         .filter { predicate(it.features) }
         .toSet()