From 1496ddba876a5b368c91ef8703288742bef8fb5e Mon Sep 17 00:00:00 2001
From: Daniel Hammer <daniel@nexlink.cloud>
Date: Wed, 8 Jul 2026 11:57:52 +0200
Subject: [PATCH] fix: A2DP reconnect fix

---
 kernel/src/Api/BuildNo.hpp                |  2 +-
 kernel/src/Drivers/USB/Bluetooth/A2dp.cpp | 13 ++++++++++---
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/kernel/src/Api/BuildNo.hpp b/kernel/src/Api/BuildNo.hpp
index e804708..46dfbd9 100644
--- a/kernel/src/Api/BuildNo.hpp
+++ b/kernel/src/Api/BuildNo.hpp
@@ -12,4 +12,4 @@
 
 #pragma once
 
-#define MONTAUK_BUILD_NUMBER 39
+#define MONTAUK_BUILD_NUMBER 42
diff --git a/kernel/src/Drivers/USB/Bluetooth/A2dp.cpp b/kernel/src/Drivers/USB/Bluetooth/A2dp.cpp
index 6ef3464..1963a82 100644
--- a/kernel/src/Drivers/USB/Bluetooth/A2dp.cpp
+++ b/kernel/src/Drivers/USB/Bluetooth/A2dp.cpp
@@ -1258,7 +1258,11 @@ namespace Drivers::USB::Bluetooth::A2dp {
                     rsp[3] = 6;
                     rsp[4] = (MEDIA_AUDIO << 4);
                     rsp[5] = CODEC_SBC;
-                    rsp[6] = 0x21;  // 44.1kHz | Joint Stereo
+                    rsp[6] = 0x11;  // 48kHz | Joint Stereo -- MUST match the
+                                    // encoder (fixed 48kHz) and our own
+                                    // SetConfig (oct0=0x11); advertising 44.1
+                                    // here let a remote-initiated config pick a
+                                    // rate we then don't actually send
                     rsp[7] = 0x15;  // 16 blocks (b4) | 8 subbands (b2) | Loudness (b0)
                     rsp[8] = 2;     // Min bitpool
                     rsp[9] = 53;    // Max bitpool
@@ -1267,9 +1271,12 @@ namespace Drivers::USB::Bluetooth::A2dp {
                 }
 
                 case AVDTP_SET_CONFIGURATION: {
-                    // Accept configuration from remote
+                    // Accept configuration from remote.  Payload after the
+                    // 2-byte header: [ACP SEID (ours)][INT SEID (theirs)] --
+                    // record THEIRS; our later START must address the sink's
+                    // SEID or it rejects with BAD_ACP_SEID (0x12).
                     if (len >= 4) {
-                        g_remoteSeid = (data[2] >> 2) & 0x3F;
+                        g_remoteSeid = (data[3] >> 2) & 0x3F;
                         g_state = State::Configured;
                         SendAvdtpResponse(txLabel, AVDTP_SET_CONFIGURATION, nullptr, 0);
                         KernelLogStream(OK, "BT-A2DP") << "Remote configured stream, SEID="