From 4063b552709b912932438010528ad733a2b355ca Mon Sep 17 00:00:00 2001
From: Chris Morgan <chmorgan@gmail.com>
Date: Thu, 18 Jun 2026 21:52:46 -0400
Subject: [PATCH] Restore GAP device name after GATT reset

ESP-IDF NimBLE can reset the GAP Device Name when the standard GAP service is reinitialized during GATT server startup. NimBLEDevice::init(deviceName) calls NimBLEDevice::setDeviceName(deviceName), but that happens before the server is started. Later, starting advertising starts the server and resets/re-registers the GAP service, causing the C GAP name backing storage to be rebuilt from CONFIG_BT_NIMBLE_SVC_GAP_DEVICE_NAME. In projects where that Kconfig default remains "nimble", the advertised Local Name can be correct while the Generic Access Device Name characteristic reports "nimble".

The failing sequence is:

  -> pAdvertising->start()
     -> NimBLEAdvertising::start()
        -> NimBLEDevice::getServer()->start()
           -> NimBLEServer::resetGATT()
              -> ble_gatts_reset()
              -> ble_svc_gap_init()
                 -> ESP-IDF NimBLE resets GAP name to CONFIG_BT_NIMBLE_SVC_GAP_DEVICE_NAME
                 -> "nimble"
              -> ble_svc_gatt_init()

Fix this by saving the device name supplied through NimBLEDevice::setDeviceName() and reapplying it immediately after ble_svc_gap_init() in NimBLEServer::resetGATT(). This preserves the C++ wrapper contract that the configured device name remains effective even when the wrapper internally resets the GATT/GAP service tables.
---
 src/NimBLEDevice.cpp | 4 ++++
 src/NimBLEDevice.h   | 2 ++
 src/NimBLEServer.cpp | 4 ++++
 3 files changed, 10 insertions(+)

diff --git a/src/NimBLEDevice.cpp b/src/NimBLEDevice.cpp
index 06cb7865..db3f9d9d 100644
--- a/src/NimBLEDevice.cpp
+++ b/src/NimBLEDevice.cpp
@@ -95,6 +95,8 @@ bool                       NimBLEDevice::m_initialized{false};
 uint32_t                   NimBLEDevice::m_passkey{123456};
 bool                       NimBLEDevice::m_synced{false};
 ble_gap_event_listener     NimBLEDevice::m_listener{};
+std::string                NimBLEDevice::m_deviceName{};
+bool                       NimBLEDevice::m_deviceNameSet{false};
 std::vector<NimBLEAddress> NimBLEDevice::m_whiteList{};
 uint8_t                    NimBLEDevice::m_ownAddrType{BLE_OWN_ADDR_PUBLIC};
 
@@ -1326,6 +1328,8 @@ bool NimBLEDevice::setDeviceName(const std::string& deviceName) {
         return false;
     }
 # endif
+    m_deviceName    = deviceName;
+    m_deviceNameSet = true;
     return true;
 } // setDeviceName
 
diff --git a/src/NimBLEDevice.h b/src/NimBLEDevice.h
index fb64c83d..98ef8b77 100644
--- a/src/NimBLEDevice.h
+++ b/src/NimBLEDevice.h
@@ -219,6 +219,8 @@ class NimBLEDevice {
     static uint32_t                   m_passkey;
     static ble_gap_event_listener     m_listener;
     static uint8_t                    m_ownAddrType;
+    static std::string                m_deviceName;
+    static bool                       m_deviceNameSet;
     static std::vector<NimBLEAddress> m_whiteList;
     static NimBLEDeviceCallbacks*     m_pDeviceCallbacks;
     static NimBLEDeviceCallbacks      defaultDeviceCallbacks;
diff --git a/src/NimBLEServer.cpp b/src/NimBLEServer.cpp
index 1cab58ed..6c8616a9 100644
--- a/src/NimBLEServer.cpp
+++ b/src/NimBLEServer.cpp
@@ -891,6 +891,10 @@ bool NimBLEServer::resetGATT() {
 
     ble_gatts_reset();
     ble_svc_gap_init();
+    if (NimBLEDevice::m_deviceNameSet && !NimBLEDevice::setDeviceName(NimBLEDevice::m_deviceName)) {
+        return false;
+    }
+
     ble_svc_gatt_init();
 
     for (auto svcIt = m_svcVec.begin(); svcIt != m_svcVec.end();) {