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

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

core/repository/src/commonMain/kotlin/org/meshtastic/core/repository/CommandSender.kt

@@ -23,7 +23,6 @@ import org.meshtastic.core.model.Position
 import org.meshtastic.proto.AdminMessage
 import org.meshtastic.proto.ChannelSet
 import org.meshtastic.proto.LocalConfig
-import org.meshtastic.proto.NeighborInfo
 
 /** Interface for sending commands and packets to the mesh network. */
 @Suppress("TooManyFunctions")
@@ -43,15 +42,6 @@ interface CommandSender {
     /** Generates a new unique packet ID. */
     fun generatePacketId(): Int
 
-    /** The latest neighbor info received from the connected radio. */
-    var lastNeighborInfo: NeighborInfo?
-
-    /** Start times of traceroute requests for duration calculation. */
-    val tracerouteStartTimes: MutableMap<Int, Long>
-
-    /** Start times of neighbor info requests for duration calculation. */
-    val neighborInfoStartTimes: MutableMap<Int, Long>
-
     /** Sets the session passkey for admin messages. */
     fun setSessionPasskey(key: ByteString)
 

core/repository/src/commonMain/kotlin/org/meshtastic/core/repository/HandshakeConstants.kt

@@ -0,0 +1,33 @@
+/*
+ * 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.repository
+
+/**
+ * Shared constants for the two-stage mesh handshake protocol.
+ *
+ * Stage 1 (`CONFIG_NONCE`): requests device config, module config, and channels. Stage 2 (`NODE_INFO_NONCE`): requests
+ * the full node database.
+ *
+ * Both [MeshConfigFlowManager] (consumer) and [MeshConnectionManager] (sender) reference these.
+ */
+object HandshakeConstants {
+    /** Nonce sent in `want_config_id` to request config-only (Stage 1). */
+    const val CONFIG_NONCE = 69420
+
+    /** Nonce sent in `want_config_id` to request node info only (Stage 2). */
+    const val NODE_INFO_NONCE = 69421
+}

core/repository/src/commonMain/kotlin/org/meshtastic/core/repository/NeighborInfoHandler.kt

@@ -18,12 +18,19 @@ package org.meshtastic.core.repository
 
 import kotlinx.coroutines.CoroutineScope
 import org.meshtastic.proto.MeshPacket
+import org.meshtastic.proto.NeighborInfo
 
 /** Interface for handling neighbor info responses from the mesh. */
 interface NeighborInfoHandler {
     /** Starts the neighbor info handler with the given coroutine scope. */
     fun start(scope: CoroutineScope)
 
+    /** Records the start time for a neighbor info request. */
+    fun recordStartTime(requestId: Int)
+
+    /** The latest neighbor info received from the connected radio. */
+    var lastNeighborInfo: NeighborInfo?
+
     /**
      * Processes a neighbor info packet.
      *

core/repository/src/commonMain/kotlin/org/meshtastic/core/repository/StoreForwardPacketHandler.kt

@@ -0,0 +1,43 @@
+/*
+ * 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.repository
+
+import kotlinx.coroutines.CoroutineScope
+import org.meshtastic.core.model.DataPacket
+import org.meshtastic.proto.MeshPacket
+
+/** Interface for handling Store & Forward (legacy) and SF++ packets. */
+interface StoreForwardPacketHandler {
+    /** Starts the handler with the given coroutine scope. */
+    fun start(scope: CoroutineScope)
+
+    /**
+     * Handles a legacy Store & Forward packet.
+     *
+     * @param packet The received mesh packet.
+     * @param dataPacket The decoded data packet.
+     * @param myNodeNum The local node number.
+     */
+    fun handleStoreAndForward(packet: MeshPacket, dataPacket: DataPacket, myNodeNum: Int)
+
+    /**
+     * Handles a Store Forward++ packet.
+     *
+     * @param packet The received mesh packet.
+     */
+    fun handleStoreForwardPlusPlus(packet: MeshPacket)
+}

core/repository/src/commonMain/kotlin/org/meshtastic/core/repository/TracerouteHandler.kt

@@ -25,6 +25,9 @@ interface TracerouteHandler {
     /** Starts the traceroute handler with the given coroutine scope. */
     fun start(scope: CoroutineScope)
 
+    /** Records the start time for a traceroute request. */
+    fun recordStartTime(requestId: Int)
+
     /**
      * Processes a traceroute packet.
      *