Explicitly set LittleFS for uploadfs; log filesystem contents on boot

platformio.ini

@@ -25,6 +25,7 @@ board = esp32dev
 framework = arduino
 platform = espressif32
 monitor_speed = 115200
+board_build.filesystem = littlefs
 lib_deps =
 	tzapu/WiFiManager @ ^2.0.17
 	bblanchon/ArduinoJson @ ^7.4.3

src/main.cpp

@@ -461,7 +461,15 @@ static void applyFactoryResetIfNeeded(int count) {
 void setup() {
   Serial.begin(115200);
   Serial.println("\n\n=== ESP32 Device boot ===");
-  LittleFS.begin(true);
+  if (!LittleFS.begin(false)) {
+    Serial.println("[FS] mount failed, formatting...");
+    LittleFS.begin(true);
+  } else {
+    Serial.println("[FS] mounted OK");
+    File root = LittleFS.open("/");
+    File f = root.openNextFile();
+    while (f) { Serial.printf("[FS]  %s (%u bytes)\n", f.name(), f.size()); f = root.openNextFile(); }
+  }
 
   loadConfig();
   hostnameParam.setValue(hostname, sizeof(hostname) - 1);