chore: Integrate MQTT logging with Kermit and enhance PII sanitization (#5338)

app/src/fdroid/kotlin/org/meshtastic/app/analytics/FdroidPlatformAnalytics.kt

@@ -31,26 +31,21 @@ import org.meshtastic.core.repository.PlatformAnalytics
 class FdroidPlatformAnalytics : PlatformAnalytics {
     init {
         // For F-Droid builds we don't initialize external analytics services.
-        // In debug builds we attach a DebugTree for convenient local logging, but
-        // release builds rely on system logging only.
-        if (BuildConfig.DEBUG) {
-            Logger.setMinSeverity(Severity.Debug)
-            Logger.i { "F-Droid platform no-op analytics initialized (Debug mode)." }
-        } else {
-            Logger.setMinSeverity(Severity.Info)
-            Logger.i { "F-Droid platform no-op analytics initialized." }
+        // Configure Kermit logging: Debug level for debug builds, Info level for release builds.
+        Logger.setMinSeverity(if (BuildConfig.DEBUG) Severity.Debug else Severity.Info)
+        Logger.i {
+            "F-Droid platform no-op analytics initialized (${if (BuildConfig.DEBUG) "Debug" else "Info"} logging)."
         }
     }
 
     override fun setDeviceAttributes(firmwareVersion: String, model: String) {
-        // No-op for F-Droid
-        Logger.d { "Set device attributes called: firmwareVersion=$firmwareVersion, deviceHardware=$model" }
+        if (BuildConfig.DEBUG) Logger.d { "setDeviceAttributes: firmwareVersion=$firmwareVersion, model=$model" }
     }
 
     override val isPlatformServicesAvailable: Boolean
         get() = false
 
     override fun track(event: String, vararg properties: DataPair) {
-        Logger.d { "Track called: event=$event, properties=${properties.toList()}" }
+        // No-op for F-Droid
     }
 }

app/src/google/kotlin/org/meshtastic/app/analytics/GooglePlatformAnalytics.kt

@@ -343,7 +343,13 @@ class GooglePlatformAnalytics(private val context: Context, private val analytic
                 // Explicitly handle String
                 else -> bundle.putString(it.name, value.toString()) // Fallback for other types
             }
-            KermitLogger.withTag(TAG).d { "Analytics: track $event (${it.name} : $value)" }
+            KermitLogger.withTag(TAG).d {
+                if (BuildConfig.DEBUG) {
+                    "Analytics: track $event (${it.name} : $value)"
+                } else {
+                    "Analytics: track $event (${it.name})"
+                }
+            }
         }
         Firebase.analytics.logEvent(event, bundle)
     }

core/network/src/commonMain/kotlin/org/meshtastic/core/network/repository/KermitMqttLogger.kt

@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2026 Meshtastic LLC
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package org.meshtastic.core.network.repository
+
+import co.touchlab.kermit.Logger
+import org.meshtastic.mqtt.MqttLogLevel
+import org.meshtastic.mqtt.MqttLogger
+
+/**
+ * Adapter that implements [MqttLogger] to send MQTT client logs to Kermit's [Logger].
+ *
+ * This allows the MQTTastic library logging to integrate with the app's logging infrastructure, including any
+ * configured log sinks (Crashlytics, Datadog, etc.).
+ *
+ * The library's [tag] (e.g. "MqttClient", "MqttConnection") is forwarded as a structured Kermit tag so that Datadog
+ * receives it as an indexed attribute rather than freetext in the message body, enabling per-component filtering in log
+ * queries.
+ *
+ * Note: The production log level should be set to [MqttLogLevel.WARN] (not INFO) to prevent the library's own
+ * INFO-level messages (which include endpoint addresses and topic strings) from reaching remote analytics sinks.
+ */
+class KermitMqttLogger : MqttLogger {
+    override fun log(level: MqttLogLevel, tag: String, message: String, throwable: Throwable?) {
+        val logger = Logger.withTag(tag)
+        when (level) {
+            MqttLogLevel.TRACE -> logger.v(throwable) { message }
+            MqttLogLevel.DEBUG -> logger.d(throwable) { message }
+            MqttLogLevel.INFO -> logger.i(throwable) { message }
+            MqttLogLevel.WARN -> logger.w(throwable) { message }
+            MqttLogLevel.ERROR -> logger.e(throwable) { message }
+            MqttLogLevel.NONE -> return
+        }
+    }
+}

core/network/src/commonMain/kotlin/org/meshtastic/core/network/repository/MQTTRepositoryImpl.kt

@@ -47,6 +47,7 @@ import org.meshtastic.mqtt.ConnectionState
 import org.meshtastic.mqtt.MqttClient
 import org.meshtastic.mqtt.MqttEndpoint
 import org.meshtastic.mqtt.MqttException
+import org.meshtastic.mqtt.MqttLogLevel
 import org.meshtastic.mqtt.MqttMessage
 import org.meshtastic.mqtt.QoS
 import org.meshtastic.mqtt.packet.Subscription
@@ -57,6 +58,7 @@ import kotlin.concurrent.Volatile
 class MQTTRepositoryImpl(
     private val radioConfigRepository: RadioConfigRepository,
     private val nodeRepository: NodeRepository,
+    private val buildConfigProvider: org.meshtastic.core.common.BuildConfigProvider,
     dispatchers: CoroutineDispatchers,
 ) : MQTTRepository {
 
@@ -109,6 +111,11 @@ class MQTTRepositoryImpl(
                 autoReconnect = true
                 username = mqttConfig?.username
                 mqttConfig?.password?.let { password(it) }
+                logger = KermitMqttLogger()
+                // WARN for production: the library emits endpoint addresses and topic strings at
+                // INFO level. WARN messages (reconnect, timeout, retry) contain no PII and are
+                // exactly the signals needed for production diagnostics.
+                logLevel = if (buildConfigProvider.isDebug) MqttLogLevel.DEBUG else MqttLogLevel.WARN
             }
         client = newClient
 
@@ -139,7 +146,27 @@ class MQTTRepositoryImpl(
         launch { newClient.messages.collect { msg -> processMessage(msg) } }
 
         // Forward the client's connection state to the repo-level StateFlow for UI observation.
-        launch { newClient.connectionState.collect { _connectionState.value = it } }
+        // Also emit structured log messages on transitions so reconnect attempt counts and
+        // disconnect reason codes are visible in Crashlytics/Datadog without any PII.
+        launch {
+            newClient.connectionState.collect { state ->
+                _connectionState.value = state
+                when (state) {
+                    ConnectionState.Connecting -> Logger.i { "MQTT connecting" }
+
+                    ConnectionState.Connected -> Logger.i { "MQTT connected" }
+
+                    is ConnectionState.Reconnecting -> {
+                        val errorDetail = state.lastError?.message?.let { ": $it" } ?: ""
+                        Logger.w { "MQTT reconnecting (attempt ${state.attempt}$errorDetail)" }
+                    }
+
+                    is ConnectionState.Disconnected -> {
+                        state.reason?.let { Logger.w { "MQTT disconnected: ${it.message}" } }
+                    }
+                }
+            }
+        }
 
         // Retry the initial connect with exponential backoff. Once established,
         // autoReconnect handles subsequent drops and re-subscribes internally.
@@ -147,7 +174,9 @@ class MQTTRepositoryImpl(
             var reconnectDelay = INITIAL_RECONNECT_DELAY_MS
             while (true) {
                 val result = safeCatching {
-                    Logger.i { "MQTT Connecting to $endpoint" }
+                    Logger.i {
+                        if (buildConfigProvider.isDebug) "MQTT Connecting to $endpoint" else "MQTT Connecting..."
+                    }
                     newClient.connect(endpoint)
                     if (subscriptions.isNotEmpty()) {
                         Logger.d { "MQTT subscribing to ${subscriptions.size} topics" }
@@ -181,13 +210,11 @@ class MQTTRepositoryImpl(
     private fun ProducerScope<MqttClientProxyMessage>.processMessage(msg: MqttMessage) {
         val topic = msg.topic
         val payload = msg.payload.toByteArray()
-        Logger.d { "MQTT received message on topic $topic (size: ${payload.size} bytes)" }
 
         if (topic.contains("/json/")) {
             try {
                 val jsonStr = payload.decodeToString()
                 json.decodeFromString<MqttJsonPayload>(jsonStr)
-                Logger.d { "MQTT parsed JSON payload successfully" }
                 trySend(MqttClientProxyMessage(topic = topic, text = jsonStr, retained = msg.retain))
             } catch (e: JsonDecodingException) {
                 Logger.e(e) { "Failed to parse MQTT JSON: ${e.shortMessage} (path: ${e.path})" }
@@ -204,10 +231,15 @@ class MQTTRepositoryImpl(
     override fun publish(topic: String, data: ByteArray, retained: Boolean) {
         val currentClient = client
         if (currentClient == null) {
-            Logger.w { "MQTT publish to $topic dropped: client not connected" }
+            Logger.w {
+                if (buildConfigProvider.isDebug) {
+                    "MQTT publish to $topic dropped: client not connected"
+                } else {
+                    "MQTT publish dropped: client not connected"
+                }
+            }
             return
         }
-        Logger.d { "MQTT publishing message to topic $topic (size: ${data.size} bytes, retained: $retained)" }
         scope.launch {
             publishSemaphore.withPermit {
                 safeCatching {
@@ -215,7 +247,15 @@ class MQTTRepositoryImpl(
                         MqttMessage(topic = topic, payload = data, qos = QoS.AT_LEAST_ONCE, retain = retained),
                     )
                 }
-                    .onFailure { e -> Logger.w(e) { "MQTT publish to $topic failed" } }
+                    .onFailure { e ->
+                        Logger.w(e) {
+                            if (buildConfigProvider.isDebug) {
+                                "MQTT publish to $topic failed"
+                            } else {
+                                "MQTT publish (${data.size} bytes) failed"
+                            }
+                        }
+                    }
             }
         }
     }