Refactor command handling, enhance tests, and improve discovery logic (#4878)

Signed-off-by: James Rich <2199651+jamesarich@users.noreply.github.com>

core/network/src/commonTest/kotlin/org/meshtastic/core/network/repository/MQTTRepositoryImplTest.kt

@@ -20,6 +20,7 @@ import kotlinx.serialization.json.Json
 import org.meshtastic.core.model.MqttJsonPayload
 import kotlin.test.Test
 import kotlin.test.assertEquals
+import kotlin.test.assertTrue
 
 class MQTTRepositoryImplTest {
 
@@ -67,8 +68,8 @@ class MQTTRepositoryImplTest {
         val json = Json { ignoreUnknownKeys = true }
         val jsonStr = json.encodeToString(MqttJsonPayload.serializer(), payload)
 
-        assert(jsonStr.contains("\"type\":\"text\""))
-        assert(jsonStr.contains("\"from\":12345678"))
-        assert(jsonStr.contains("\"payload\":\"Hello World\""))
+        assertTrue(jsonStr.contains("\"type\":\"text\""))
+        assertTrue(jsonStr.contains("\"from\":12345678"))
+        assertTrue(jsonStr.contains("\"payload\":\"Hello World\""))
     }
 }

core/network/src/jvmMain/kotlin/org/meshtastic/core/network/repository/JvmServiceDiscovery.kt

@@ -25,6 +25,7 @@ import kotlinx.coroutines.flow.flowOn
 import org.koin.core.annotation.Single
 import java.io.IOException
 import java.net.InetAddress
+import java.net.NetworkInterface
 import javax.jmdns.JmDNS
 import javax.jmdns.ServiceEvent
 import javax.jmdns.ServiceListener
@@ -34,9 +35,14 @@ class JvmServiceDiscovery : ServiceDiscovery {
     @Suppress("TooGenericExceptionCaught")
     override val resolvedServices: Flow<List<DiscoveredService>> =
         callbackFlow {
+            trySend(emptyList()) // Emit initial empty list so downstream combine() is not blocked
+
+            val bindAddress = findLanAddress() ?: InetAddress.getLocalHost()
+            Logger.i { "JmDNS binding to ${bindAddress.hostAddress}" }
+
             val jmdns =
                 try {
-                    JmDNS.create(InetAddress.getLocalHost())
+                    JmDNS.create(bindAddress)
                 } catch (e: IOException) {
                     Logger.e(e) { "Failed to create JmDNS" }
                     null
@@ -93,4 +99,24 @@ class JvmServiceDiscovery : ServiceDiscovery {
             }
         }
             .flowOn(Dispatchers.IO)
+
+    companion object {
+        /**
+         * Finds a non-loopback, up, IPv4 LAN address for JmDNS to bind to. On many systems (especially Windows),
+         * [InetAddress.getLocalHost] resolves to `127.0.0.1` or `::1`, which prevents JmDNS from seeing multicast
+         * traffic on the actual LAN interface.
+         */
+        @Suppress("TooGenericExceptionCaught", "LoopWithTooManyJumpStatements")
+        internal fun findLanAddress(): InetAddress? = try {
+            NetworkInterface.getNetworkInterfaces()
+                ?.toList()
+                .orEmpty()
+                .filter { it.isUp && !it.isLoopback }
+                .flatMap { it.inetAddresses.toList() }
+                .firstOrNull { !it.isLoopbackAddress && it is java.net.Inet4Address }
+        } catch (e: Exception) {
+            Logger.w(e) { "Failed to enumerate network interfaces, falling back to getLocalHost()" }
+            null
+        }
+    }
 }

core/network/src/jvmTest/kotlin/org/meshtastic/core/network/repository/JvmServiceDiscoveryTest.kt

@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) 2025-2026 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 app.cash.turbine.test
+import kotlinx.coroutines.test.runTest
+import org.junit.Test
+import kotlin.test.assertNotNull
+import kotlin.test.assertTrue
+
+class JvmServiceDiscoveryTest {
+
+    @Test
+    fun `resolvedServices emits initial empty list immediately`() = runTest {
+        val discovery = JvmServiceDiscovery()
+        discovery.resolvedServices.test {
+            val first = awaitItem()
+            assertNotNull(first, "First emission should not be null")
+            assertTrue(first.isEmpty(), "First emission should be an empty list")
+            cancelAndIgnoreRemainingEvents()
+        }
+    }
+
+    @Test
+    fun `findLanAddress returns non-loopback address or null`() {
+        val address = JvmServiceDiscovery.findLanAddress()
+        // On CI machines there may be no LAN interface, so null is acceptable
+        if (address != null) {
+            assertTrue(!address.isLoopbackAddress, "Address should not be loopback")
+            assertTrue(address is java.net.Inet4Address, "Address should be IPv4")
+        }
+    }
+
+    @Test
+    fun `findLanAddress does not throw`() {
+        // Ensure the method handles exceptions gracefully
+        val result = runCatching { JvmServiceDiscovery.findLanAddress() }
+        assertTrue(result.isSuccess, "findLanAddress should not throw: ${result.exceptionOrNull()}")
+    }
+}