From 7adff025fedb7d74c08c57fb77d55ca5f298e929 Mon Sep 17 00:00:00 2001
From: Ben Batt <benbatt@gmail.com>
Date: Wed, 22 Jul 2026 21:12:14 +1000
Subject: [PATCH] Save room topic to a new "/room_prefs" file

---
 examples/simple_room_server/MyMesh.cpp | 46 ++++++++++++++++++++++++++
 examples/simple_room_server/MyMesh.h   |  8 ++---
 2 files changed, 50 insertions(+), 4 deletions(-)

diff --git a/examples/simple_room_server/MyMesh.cpp b/examples/simple_room_server/MyMesh.cpp
index 51e107b5e..faa59eaf4 100644
--- a/examples/simple_room_server/MyMesh.cpp
+++ b/examples/simple_room_server/MyMesh.cpp
@@ -714,6 +714,7 @@ void MyMesh::begin(FILESYSTEM *fs) {
   mesh::Mesh::begin();
   _fs = fs;
   // load persisted prefs
+  loadRoomPrefs();
   _cli.loadPrefs(_fs);
 
   acl.load(_fs, self_id);
@@ -747,6 +748,10 @@ void MyMesh::begin(FILESYSTEM *fs) {
   updateAdvertTimer();
   updateFloodAdvertTimer();
 
+  if (strlen(topic) > 0) {
+    topic_timestamp = getRTCClock()->getCurrentTimeUnique();
+  }
+
   board.setAdcMultiplier(_prefs.adc_multiplier);
 
 #if ENV_INCLUDE_GPS == 1
@@ -754,6 +759,45 @@ void MyMesh::begin(FILESYSTEM *fs) {
 #endif
 }
 
+#define PREFS_FILE_PATH "/room_prefs"
+
+void MyMesh::loadRoomPrefs() {
+#if defined(RP2040_PLATFORM)
+  File file = _fs->open(PREFS_FILE_PATH, "r");
+#else
+  File file = _fs->open(PREFS_FILE_PATH);
+#endif
+  if (file) {
+    file.read((uint8_t *)&topic[0], sizeof(topic));                     // 0
+    topic[MAX_TOPIC_TEXT_LEN] = '\0';
+    // next: 144
+
+    file.close();
+  }
+}
+
+void MyMesh::saveRoomPrefs() {
+#if defined(NRF52_PLATFORM) || defined(STM32_PLATFORM)
+  _fs->remove(PREFS_FILE_PATH);
+  File file = _fs->open(PREFS_FILE_PATH, FILE_O_WRITE);
+#elif defined(RP2040_PLATFORM)
+  File file = _fs->open(PREFS_FILE_PATH, "w");
+#else
+  File file = _fs->open(PREFS_FILE_PATH, "w", true);
+#endif
+  if (file) {
+    file.write((uint8_t *)&topic[0], sizeof(topic));                    // 0
+    // next: 144
+
+    file.close();
+  }
+}
+
+void MyMesh::savePrefs() {
+  saveRoomPrefs();
+  _cli.savePrefs(_fs);
+}
+
 void MyMesh::sendFloodScoped(const TransportKey& scope, mesh::Packet* pkt, uint32_t delay_millis, uint8_t path_hash_size) {
   if (scope.isNull()) {
     sendFlood(pkt, delay_millis, path_hash_size);
@@ -964,6 +1008,8 @@ void MyMesh::handleCommand(uint32_t sender_timestamp, char *command, char *reply
     strcpy(topic, new_topic);
     topic_timestamp = getRTCClock()->getCurrentTimeUnique();
 
+    saveRoomPrefs();
+
     sprintf(reply, "New topic set with length %d", len);
 
     return;
diff --git a/examples/simple_room_server/MyMesh.h b/examples/simple_room_server/MyMesh.h
index 73fe5ab23..398ffea7d 100644
--- a/examples/simple_room_server/MyMesh.h
+++ b/examples/simple_room_server/MyMesh.h
@@ -134,6 +134,9 @@ class MyMesh : public mesh::Mesh, public CommonCLICallbacks {
   File openAppend(const char* fname);
   int handleRequest(ClientInfo* sender, uint32_t sender_timestamp, uint8_t* payload, size_t payload_len);
 
+  void loadRoomPrefs();
+  void saveRoomPrefs();
+
 protected:
   float getAirtimeBudgetFactor() const override {
     return _prefs.airtime_factor;
@@ -194,13 +197,10 @@ public:
     return &_prefs;
   }
 
-  void savePrefs() override {
-    _cli.savePrefs(_fs);
-  }
-
   void sendFloodScoped(const TransportKey& scope, mesh::Packet* pkt, uint32_t delay_millis, uint8_t path_hash_size);
 
   // CommonCLICallbacks
+  void savePrefs() override;
   void applyTempRadioParams(float freq, float bw, uint8_t sf, uint8_t cr, int timeout_mins) override;
   bool formatFileSystem() override;
   void sendSelfAdvertisement(int delay_millis, bool flood) override;