refactor(car): consolidate shared utilities — eliminate duplicated logic

- Replace ConnectionStatus enum with core:model/ConnectionState directly
- Fix signal quality thresholds: use core's LoRa-correct SNR (-7/-15)
  and RSSI (-115/-126) instead of wrong 10/5/0 thresholds
- Replace manual formatLastHeard() with DateFormatter.formatRelativeTime()
  from core:common (already a dependency)
- Replace MeshStatusPanel time formatting with DateFormatter
- Remove unused time format string resources (car_time_just_now, etc.)
- Handle DeviceSleep as disconnected state in car UI

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

feature/car/src/main/kotlin/org/meshtastic/feature/car/model/CarUiModels.kt

@@ -16,20 +16,16 @@
  */
 package org.meshtastic.feature.car.model
 
+import org.meshtastic.core.model.ConnectionState
+
 data class CarSessionState(
-    val connectionStatus: ConnectionStatus,
+    val connectionStatus: ConnectionState,
     val onlineNodeCount: Int,
     val lastMessageTime: Long?,
     val activeEmergencies: List<EmergencyAlert>,
     val meshName: String?,
 )
 
-enum class ConnectionStatus {
-    CONNECTED,
-    CONNECTING,
-    DISCONNECTED,
-}
-
 data class MessagingUiState(
     val channels: List<ChannelUi>,
     val selectedChannelIndex: Int,

feature/car/src/main/kotlin/org/meshtastic/feature/car/panels/MeshStatusPanel.kt

@@ -20,8 +20,9 @@ import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.asStateFlow
 import org.koin.core.annotation.Single
+import org.meshtastic.core.common.util.DateFormatter
+import org.meshtastic.core.model.ConnectionState
 import org.meshtastic.feature.car.model.CarSessionState
-import org.meshtastic.feature.car.model.ConnectionStatus
 
 /**
  * Manages persistent mesh status state for the car display. Provides connection status, node count, and last message
@@ -33,7 +34,7 @@ class MeshStatusPanel {
     private val _state =
         MutableStateFlow(
             CarSessionState(
-                connectionStatus = ConnectionStatus.DISCONNECTED,
+                connectionStatus = ConnectionState.Disconnected,
                 onlineNodeCount = 0,
                 lastMessageTime = null,
                 activeEmergencies = emptyList(),
@@ -42,7 +43,7 @@ class MeshStatusPanel {
         )
     val state: StateFlow<CarSessionState> = _state.asStateFlow()
 
-    fun updateConnectionStatus(status: ConnectionStatus) {
+    fun updateConnectionStatus(status: ConnectionState) {
         _state.value = _state.value.copy(connectionStatus = status)
     }
 
@@ -61,29 +62,15 @@ class MeshStatusPanel {
     fun getStatusTitle(): String {
         val state = _state.value
         return when (state.connectionStatus) {
-            ConnectionStatus.CONNECTED -> "${state.onlineNodeCount} nodes online"
-            ConnectionStatus.CONNECTING -> "Connecting..."
-            ConnectionStatus.DISCONNECTED -> "Disconnected"
+            ConnectionState.Connected -> "${state.onlineNodeCount} nodes online"
+            ConnectionState.Connecting -> "Connecting..."
+            else -> "Disconnected"
         }
     }
 
     fun getStatusSubtitle(): String? {
         val state = _state.value
-        val lastMsg = state.lastMessageTime ?: return null
-        val elapsed = System.currentTimeMillis() - lastMsg
-        val timeAgo =
-            when {
-                elapsed < MILLIS_PER_MINUTE -> "just now"
-                elapsed < MILLIS_PER_HOUR -> "${elapsed / MILLIS_PER_MINUTE}m ago"
-                elapsed < MILLIS_PER_DAY -> "${elapsed / MILLIS_PER_HOUR}h ago"
-                else -> "${elapsed / MILLIS_PER_DAY}d ago"
-            }
-        return "Last msg: $timeAgo"
-    }
-
-    companion object {
-        private const val MILLIS_PER_MINUTE = 60_000L
-        private const val MILLIS_PER_HOUR = 3_600_000L
-        private const val MILLIS_PER_DAY = 86_400_000L
+        val lastMsg = state.lastMessageTime?.takeIf { it != 0L } ?: return null
+        return "Last msg: ${DateFormatter.formatRelativeTime(lastMsg)}"
     }
 }

feature/car/src/main/kotlin/org/meshtastic/feature/car/panels/MeshStatusSessionWiring.kt

@@ -20,7 +20,7 @@ import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Job
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.launch
-import org.meshtastic.feature.car.model.ConnectionStatus
+import org.meshtastic.core.model.ConnectionState
 
 /** Wires MeshStatusPanel to data sources during a car session. Attach in onCreateScreen, detach in onDestroy. */
 class MeshStatusSessionWiring(private val panel: MeshStatusPanel) {
@@ -30,7 +30,7 @@ class MeshStatusSessionWiring(private val panel: MeshStatusPanel) {
 
     fun attach(
         scope: CoroutineScope,
-        connectionFlow: Flow<ConnectionStatus>,
+        connectionFlow: Flow<ConnectionState>,
         nodeCountFlow: Flow<Int>,
         lastMessageTimeFlow: Flow<Long>,
         meshNameFlow: Flow<String?>,

feature/car/src/main/kotlin/org/meshtastic/feature/car/screens/HomeScreen.kt

@@ -39,8 +39,8 @@ import kotlinx.coroutines.SupervisorJob
 import kotlinx.coroutines.cancel
 import kotlinx.coroutines.flow.firstOrNull
 import kotlinx.coroutines.launch
+import org.meshtastic.core.model.ConnectionState
 import org.meshtastic.feature.car.R
-import org.meshtastic.feature.car.model.ConnectionStatus
 import org.meshtastic.feature.car.model.NodeUi
 import org.meshtastic.feature.car.model.SignalQuality
 import org.meshtastic.feature.car.service.CarStateCoordinator
@@ -73,7 +73,7 @@ class HomeScreen(carContext: CarContext, private val stateCoordinator: CarStateC
     @Suppress("ReturnCount")
     override fun onGetTemplate(): Template {
         val connectionStatus = stateCoordinator.sessionState.value.connectionStatus
-        if (connectionStatus == ConnectionStatus.DISCONNECTED) {
+        if (connectionStatus == ConnectionState.Disconnected || connectionStatus == ConnectionState.DeviceSleep) {
             return buildDisconnectedTemplate()
         }
         val messaging = stateCoordinator.messagingState.value

feature/car/src/main/kotlin/org/meshtastic/feature/car/screens/NodeDetailScreen.kt

@@ -24,6 +24,7 @@ import androidx.car.app.model.Pane
 import androidx.car.app.model.PaneTemplate
 import androidx.car.app.model.Row
 import androidx.car.app.model.Template
+import org.meshtastic.core.common.util.DateFormatter
 import org.meshtastic.feature.car.R
 import org.meshtastic.feature.car.model.NodeUi
 import org.meshtastic.feature.car.model.SignalQuality
@@ -107,23 +108,6 @@ class NodeDetailScreen(
 
     private fun formatLastHeard(epochMillis: Long): String {
         if (epochMillis == 0L) return carContext.getString(R.string.car_time_never)
-        val elapsed = System.currentTimeMillis() - epochMillis
-        return when {
-            elapsed < MILLIS_PER_MINUTE -> carContext.getString(R.string.car_time_just_now)
-
-            elapsed < MILLIS_PER_HOUR ->
-                carContext.getString(R.string.car_time_minutes_ago, (elapsed / MILLIS_PER_MINUTE).toInt())
-
-            elapsed < MILLIS_PER_DAY ->
-                carContext.getString(R.string.car_time_hours_ago, (elapsed / MILLIS_PER_HOUR).toInt())
-
-            else -> carContext.getString(R.string.car_time_days_ago, (elapsed / MILLIS_PER_DAY).toInt())
-        }
-    }
-
-    companion object {
-        private const val MILLIS_PER_MINUTE = 60_000L
-        private const val MILLIS_PER_HOUR = 3_600_000L
-        private const val MILLIS_PER_DAY = 86_400_000L
+        return DateFormatter.formatRelativeTime(epochMillis)
     }
 }

feature/car/src/main/kotlin/org/meshtastic/feature/car/service/CarStateCoordinator.kt

@@ -41,7 +41,6 @@ import org.meshtastic.core.repository.RadioConfigRepository
 import org.meshtastic.core.repository.ServiceRepository
 import org.meshtastic.feature.car.model.CarSessionState
 import org.meshtastic.feature.car.model.ChannelUi
-import org.meshtastic.feature.car.model.ConnectionStatus
 import org.meshtastic.feature.car.model.ConversationUi
 import org.meshtastic.feature.car.model.MessagingUiState
 import org.meshtastic.feature.car.model.NodeDashboardUiState
@@ -80,7 +79,7 @@ class CarStateCoordinator(
     private val _sessionState =
         MutableStateFlow(
             CarSessionState(
-                connectionStatus = ConnectionStatus.DISCONNECTED,
+                connectionStatus = ConnectionState.Disconnected,
                 onlineNodeCount = 0,
                 lastMessageTime = null,
                 activeEmergencies = emptyList(),
@@ -179,13 +178,7 @@ class CarStateCoordinator(
     private fun collectConnectionState() {
         scope.launch {
             serviceRepository.connectionState.collect { state ->
-                val status =
-                    when (state) {
-                        ConnectionState.Connected -> ConnectionStatus.CONNECTED
-                        ConnectionState.Connecting -> ConnectionStatus.CONNECTING
-                        else -> ConnectionStatus.DISCONNECTED
-                    }
-                _sessionState.value = _sessionState.value.copy(connectionStatus = status)
+                _sessionState.value = _sessionState.value.copy(connectionStatus = state)
             }
         }
     }
@@ -272,7 +265,7 @@ class CarStateCoordinator(
         nodeNum = num,
         longName = user.long_name.ifEmpty { "Unknown" },
         shortName = user.short_name.ifEmpty { "?" },
-        signalQuality = snrToSignalQuality(snr),
+        signalQuality = determineSignalQuality(snr, rssi),
         batteryPercent = batteryLevel?.takeIf { it in 1..BATTERY_MAX_PERCENT },
         isOnline = isOnline,
         lastHeard = lastHeard.toLong() * SECONDS_TO_MILLIS,
@@ -286,15 +279,20 @@ class CarStateCoordinator(
         private const val DATA_TYPE_TEXT = 1
         private const val SECONDS_TO_MILLIS = 1000L
         private const val BATTERY_MAX_PERCENT = 100
-        private const val SNR_EXCELLENT = 10f
-        private const val SNR_GOOD = 5f
-        private const val SNR_FAIR = 0f
 
-        private fun snrToSignalQuality(snr: Float): SignalQuality = when {
-            snr == Float.MAX_VALUE -> SignalQuality.UNKNOWN
-            snr >= SNR_EXCELLENT -> SignalQuality.EXCELLENT
-            snr >= SNR_GOOD -> SignalQuality.GOOD
-            snr >= SNR_FAIR -> SignalQuality.FAIR
+        // Thresholds aligned with core/ui LoraSignalIndicator.kt
+        private const val SNR_GOOD_THRESHOLD = -7f
+        private const val SNR_FAIR_THRESHOLD = -15f
+        private const val RSSI_GOOD_THRESHOLD = -115
+        private const val RSSI_FAIR_THRESHOLD = -126
+
+        @Suppress("MagicNumber")
+        private fun determineSignalQuality(snr: Float, rssi: Int): SignalQuality = when {
+            snr == Float.MAX_VALUE || rssi == Int.MAX_VALUE -> SignalQuality.UNKNOWN
+            snr > SNR_GOOD_THRESHOLD && rssi > RSSI_GOOD_THRESHOLD -> SignalQuality.EXCELLENT
+            snr > SNR_GOOD_THRESHOLD && rssi > RSSI_FAIR_THRESHOLD -> SignalQuality.GOOD
+            snr > SNR_FAIR_THRESHOLD && rssi > RSSI_GOOD_THRESHOLD -> SignalQuality.GOOD
+            snr > SNR_FAIR_THRESHOLD -> SignalQuality.FAIR
             else -> SignalQuality.POOR
         }
     }

feature/car/src/main/res/values/strings.xml

@@ -36,10 +36,6 @@
     <string name="car_status_status">Status</string>
     <string name="car_tab_messages">Messages</string>
     <string name="car_tab_nodes">Nodes</string>
-    <string name="car_time_days_ago">%dd ago</string>
-    <string name="car_time_hours_ago">%dh ago</string>
-    <string name="car_time_just_now">Just now</string>
-    <string name="car_time_minutes_ago">%dm ago</string>
     <string name="car_time_never">Never</string>
     <string name="car_unread_badge">%d unread</string>
     <string name="car_voice_reply">Reply</string>