From dd1348fa497020729fdbeabd8748ea3eba9ec941 Mon Sep 17 00:00:00 2001
From: Matt Hillsdon <matt.hillsdon@microbit.org>
Date: Thu, 22 Jan 2026 17:50:49 +0000
Subject: [PATCH] Wait for disconnect after partial flashing success

This seems to help significantly with reconnect on Android

Remove the retries for now - we might well reinstate but we need to do so with
more care as it's led to very long retries in the case where there is no device
due to app-level retries.
---
 lib/bluetooth-device-wrapper.ts | 41 ++++++++-------------------------
 lib/bluetooth.ts                |  4 ++++
 2 files changed, 13 insertions(+), 32 deletions(-)

diff --git a/lib/bluetooth-device-wrapper.ts b/lib/bluetooth-device-wrapper.ts
index 7461db0..524fe5b 100644
--- a/lib/bluetooth-device-wrapper.ts
+++ b/lib/bluetooth-device-wrapper.ts
@@ -36,9 +36,8 @@ import {
 import { UARTService } from "./uart-service.js";
 
 export const bondingTimeoutInMs = 40_000;
-export const connectTimeoutInMs = 4_000;
+export const connectTimeoutInMs = 10_000;
 export const scanningTimeoutInMs = 10_000;
-const connectionMaxAttempts = 4;
 
 export const isAndroid = () => Capacitor.getPlatform() === "android";
 
@@ -83,7 +82,7 @@ export class BluetoothDeviceWrapper implements Logging {
   // or reconnection itself.
   private duringExplicitConnectDisconnect: number = 0;
 
-  private connected = false;
+  connected = false;
   private isReconnect = false;
 
   // Only updated after the full connection flow completes not during bond handling.
@@ -153,11 +152,13 @@ export class BluetoothDeviceWrapper implements Logging {
     try {
       if (Capacitor.isNativePlatform()) {
         await this.connectHandlingBond();
+        // We need this on Android for reconnecting after DFU.
         await BleClient.discoverServices(this.device.deviceId);
       } else {
         await this.connectInternal();
       }
       await this.getBoardVersion();
+
       const events = this.currentEvents();
       const services = await BleClient.getServices(this.device.deviceId);
       this.serviceIds = new Set(services.map((s) => s.uuid));
@@ -200,33 +201,10 @@ export class BluetoothDeviceWrapper implements Logging {
 
   private async connectInternal() {
     this.waitingForDisconnectEventCallbacks.length = 0;
-
-    // Attempt multiple connection tries.
-    for (let i = 0; i < connectionMaxAttempts; i++) {
-      try {
-        // Fail immediately if disconnect occurs whilst connecting.
-        await this.raceDisconnectAndTimeout(
-          BleClient.connect(this.device.deviceId, this.handleDisconnectEvent),
-          {
-            actionName: "connect internal",
-            timeout: connectTimeoutInMs,
-            initiallyDisconnected: true,
-          },
-        );
-        this.connected = true;
-        return;
-      } catch (error) {
-        const attempts = i + 1;
-        if (attempts === connectionMaxAttempts) {
-          throw error;
-        }
-        const delayDuration = Math.pow(2, i) * 1000; // 1s, 2s, 4s
-        this.logging.log(
-          `Attempt ${attempts} failed, retrying in ${delayDuration}ms...`,
-        );
-        await delay(delayDuration);
-      }
-    }
+    await BleClient.connect(this.device.deviceId, this.handleDisconnectEvent, {
+      timeout: connectTimeoutInMs,
+    });
+    this.connected = true;
   }
 
   async disconnect(): Promise<void> {
@@ -433,10 +411,9 @@ export class BluetoothDeviceWrapper implements Logging {
     options: {
       actionName?: string;
       timeout?: number;
-      initiallyDisconnected?: boolean;
     } = {},
   ): Promise<T> {
-    if (!this.connected && !options.initiallyDisconnected) {
+    if (!this.connected) {
       throw new DisconnectError();
     }
     const actionName = options.actionName ?? "action";
diff --git a/lib/bluetooth.ts b/lib/bluetooth.ts
index 6f50838..3dcd10e 100644
--- a/lib/bluetooth.ts
+++ b/lib/bluetooth.ts
@@ -512,6 +512,10 @@ class MicrobitWebBluetoothConnectionImpl
 
         if (partialFlashResult === PartialFlashResult.AttemptFullFlash) {
           await fullFlash(connection, boardVersion, memoryMap, progress);
+        } else if (partialFlashResult === PartialFlashResult.Success) {
+          if (connection.connected) {
+            await connection.waitForDisconnect(10_000);
+          }
         }
       } catch (e) {
         this.error("Failed to flash", e);