From 541e6080d6e939230dead1a2bfc13208b298ccb7 Mon Sep 17 00:00:00 2001
From: Rob Dobson <rob@dobson.com>
Date: Sat, 24 Oct 2026 22:30:27 +0200
Subject: [PATCH] fix(winrtble): open GATT services before discovering their
 characteristics

Some peripherals' services refuse GetCharacteristicsWithCacheModeAsync with
GattCommunicationStatus::AccessDenied until the service has been opened, so
discover_services() returned the service with no characteristics. Open each
service with GattSharingMode::SharedReadAndWrite first. If opening fails,
discovery is tried as before.
---
 src/winrtble/ble/device.rs | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/src/winrtble/ble/device.rs b/src/winrtble/ble/device.rs
index aeba8276..579d0642 100644
--- a/src/winrtble/ble/device.rs
+++ b/src/winrtble/ble/device.rs
@@ -22,7 +22,7 @@ use windows::{
         BluetoothLEPreferredConnectionParameters,
         GenericAttributeProfile::{
             GattCharacteristic, GattCommunicationStatus, GattDescriptor, GattDeviceService,
-            GattDeviceServicesResult, GattSession,
+            GattDeviceServicesResult, GattSession, GattSharingMode,
         },
     },
     Foundation::TypedEventHandler,
@@ -129,6 +129,16 @@ impl BLEDevice {
     pub async fn get_characteristics(
         service: &GattDeviceService,
     ) -> Result<Vec<GattCharacteristic>> {
+        // Some services refuse characteristic discovery (AccessDenied) until they have been
+        // opened. Opening shared doesn't stop other apps using the service, and if it fails
+        // discovery is still tried as before.
+        match service.OpenAsync(GattSharingMode::SharedReadAndWrite) {
+            Ok(op) => match op.await {
+                Ok(status) => trace!("service open status {:?}", status),
+                Err(e) => debug!("service open failed {:?}", e),
+            },
+            Err(e) => debug!("service open failed {:?}", e),
+        }
         let async_result = match timeout(
             GATT_CACHE_TIMEOUT,
             service