Rename playback device fix to SourceSwitchControl, drop the wire inversion

Rebased onto the current MDRProperty API (pending()/override() replace
submittedDirty()/commitOneShot(), renamed underneath this branch), and
renamed the public surface as requested in review: MDR_FEATURE_PLAYBACK_DEVICE_FIX
becomes MDR_FEATURE_SOURCE_SWITCH_CONTROL, mdrHeadphonesGet/SetPlaybackDeviceFixed
becomes mdrHeadphonesGet/SetSourceSwitchControl, MDRPlaybackFixResult becomes
MDRSourceSwitchControlResult - matching SOURCE_SWITCH_CONTROL and the packet
debugger instead of translating Sound Connect's Japanese-derived label.

libmdr now tracks the wire value directly (1 = switching free) instead of
mangling it into a "fixed" flag; the one inversion left lives in Client.cpp,
where "Fixing playback device" is a UI concept. Also dropped two MDR_LOG_DEBUG
calls in the SOURCE_SWITCH_CONTROL notify/param handlers, matching the other
protocol handlers, which don't log there either.

Co-Authored-By: Claude <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Qy2qqZHg5iaikSzDSNMT9o

Author: jkolo

client/Client.cpp

@@ -136,15 +136,15 @@ const char* FormatSpeakTimeout(MDRSpeakTimeout status)
     }
 }
 
-const char* FormatPlaybackFixResult(MDRPlaybackFixResult result)
+const char* FormatSourceSwitchControlResult(MDRSourceSwitchControlResult result)
 {
     switch (result)
     {
-    case MDR_PLAYBACK_FIX_FAILED_ON_CALL:
+    case MDR_SOURCE_SWITCH_CONTROL_FAILED_ON_CALL:
         return "The headphones refused: a call is in progress.";
-    case MDR_PLAYBACK_FIX_FAILED_NOT_CONNECTED:
+    case MDR_SOURCE_SWITCH_CONTROL_FAILED_NOT_CONNECTED:
         return "The headphones refused: the device has no audio connection.";
-    case MDR_PLAYBACK_FIX_FAILED_VOICE_ASSISTANT:
+    case MDR_SOURCE_SWITCH_CONTROL_FAILED_VOICE_ASSISTANT:
         return "The headphones refused: the voice assistant has priority.";
     default:
         return "The headphones refused the request.";
@@ -1343,10 +1343,12 @@ void DrawDeviceControlsDevices()
         action.device_id_size = static_cast<uint32_t>(std::strlen(mac));
         mdrHeadphonesSetPairedDevice(gDevice, &action);
     };
-    const bool supportFix = FeatureAvailable(MDR_FEATURE_PLAYBACK_DEVICE_FIX);
-    MDRBoolean playbackFixed = MDR_FALSE;
+    const bool supportFix = FeatureAvailable(MDR_FEATURE_SOURCE_SWITCH_CONTROL);
+    MDRBoolean switchControlEnabled = MDR_TRUE;
     if (supportFix)
-        mdrHeadphonesGetPlaybackDeviceFixed(gDevice, &playbackFixed);
+        mdrHeadphonesGetSourceSwitchControl(gDevice, &switchControlEnabled);
+    // Sound Connect's "Fixing playback device" is the negation of source switch control.
+    const bool playbackFixed = switchControlEnabled == MDR_FALSE;
     auto DrawDeviceElement = [&](const DeviceView& device, bool selected) -> bool
     {
         ImGui::PushID(device.mac.c_str());
@@ -1374,7 +1376,7 @@ void DrawDeviceControlsDevices()
                     StageDeviceAction(MDR_PAIRED_DEVICE_SELECT_PLAYBACK, device.mac.c_str());
                 if (canFix &&
                     ImModalButton(playbackFixed ? PSI_UNLOCK " Unfix Playback" : PSI_LOCK " Fix Playback", 2, columns))
-                    mdrHeadphonesSetPlaybackDeviceFixed(gDevice, playbackFixed ? MDR_FALSE : MDR_TRUE);
+                    mdrHeadphonesSetSourceSwitchControl(gDevice, playbackFixed ? MDR_TRUE : MDR_FALSE);
             }
             else
             {
@@ -1386,10 +1388,10 @@ void DrawDeviceControlsDevices()
             // After the button rows: Unpair shares a row, so an inline message would land beside it.
             if (supportFix && device.state.connected && device.state.playback_device)
             {
-                MDRPlaybackFixResult fixResult = MDR_PLAYBACK_FIX_SUCCESS;
-                mdrHeadphonesGetPlaybackDeviceFixResult(gDevice, &fixResult);
-                if (fixResult != MDR_PLAYBACK_FIX_SUCCESS)
-                    ImGui::TextWrapped(PSI_INFO_SIGN_ALT " %s", FormatPlaybackFixResult(fixResult));
+                MDRSourceSwitchControlResult fixResult = MDR_SOURCE_SWITCH_CONTROL_SUCCESS;
+                mdrHeadphonesGetSourceSwitchControlResult(gDevice, &fixResult);
+                if (fixResult != MDR_SOURCE_SWITCH_CONTROL_SUCCESS)
+                    ImGui::TextWrapped(PSI_INFO_SIGN_ALT " %s", FormatSourceSwitchControlResult(fixResult));
             }
         }
         ImGui::EndGroup();

libmdr/include/mdr-c/Headphones.h

@@ -45,7 +45,7 @@ typedef uint32_t MDRFeature;
 #define MDR_FEATURE_SHUTDOWN ((MDRFeature)26u)
 #define MDR_FEATURE_CONNECTION_MODE ((MDRFeature)27u)
 #define MDR_FEATURE_SAFE_LISTENING ((MDRFeature)28u)
-#define MDR_FEATURE_PLAYBACK_DEVICE_FIX ((MDRFeature)29u)
+#define MDR_FEATURE_SOURCE_SWITCH_CONTROL ((MDRFeature)29u)
 
 typedef uint32_t MDREvent;
 #define MDR_EVENT_NONE ((MDREvent)0u)
@@ -128,12 +128,12 @@ typedef uint32_t MDRPlaybackAction;
 #define MDR_PLAYBACK_NEXT ((MDRPlaybackAction)3u)
 #define MDR_PLAYBACK_PREVIOUS ((MDRPlaybackAction)4u)
 
-typedef uint32_t MDRPlaybackFixResult;
-#define MDR_PLAYBACK_FIX_SUCCESS ((MDRPlaybackFixResult)0u)
-#define MDR_PLAYBACK_FIX_FAILED ((MDRPlaybackFixResult)1u)
-#define MDR_PLAYBACK_FIX_FAILED_ON_CALL ((MDRPlaybackFixResult)2u)
-#define MDR_PLAYBACK_FIX_FAILED_NOT_CONNECTED ((MDRPlaybackFixResult)3u)
-#define MDR_PLAYBACK_FIX_FAILED_VOICE_ASSISTANT ((MDRPlaybackFixResult)4u)
+typedef uint32_t MDRSourceSwitchControlResult;
+#define MDR_SOURCE_SWITCH_CONTROL_SUCCESS ((MDRSourceSwitchControlResult)0u)
+#define MDR_SOURCE_SWITCH_CONTROL_FAILED ((MDRSourceSwitchControlResult)1u)
+#define MDR_SOURCE_SWITCH_CONTROL_FAILED_ON_CALL ((MDRSourceSwitchControlResult)2u)
+#define MDR_SOURCE_SWITCH_CONTROL_FAILED_NOT_CONNECTED ((MDRSourceSwitchControlResult)3u)
+#define MDR_SOURCE_SWITCH_CONTROL_FAILED_VOICE_ASSISTANT ((MDRSourceSwitchControlResult)4u)
 
 typedef uint32_t MDRNoiseMode;
 #define MDR_NOISE_MODE_OFF ((MDRNoiseMode)0u)
@@ -541,30 +541,26 @@ MDR_API MDRResult mdrHeadphonesGetPairing(
 MDR_API MDRResult mdrHeadphonesSetPairing(MDRHeadphones* headphones, const MDRPairing* pairing);
 
 /**
- * @brief Whether playback is pinned to the current playback device.
+ * @brief Whether the headphones may switch playback to the other multipoint device on their own.
  *
- * Mirrors Sound Connect's "Fixing playback device": while set, the headphones keep playing to the
- * device that holds the playback right instead of handing audio over to the other multipoint device.
- * The headphones drop the fixation on their own once that device disconnects.
- * Requires @ref MDR_FEATURE_PLAYBACK_DEVICE_FIX.
+ * Mirrors Sound Connect's "Fixing playback device", inverted: while enabled, switching is free and
+ * the headphones may hand audio over to the other multipoint device. While disabled, playback stays
+ * pinned to the device that currently holds the playback right - Sound Connect shows this as a
+ * padlock. The headphones re-enable switching on their own once that device disconnects.
+ * Requires @ref MDR_FEATURE_SOURCE_SWITCH_CONTROL.
  */
-MDR_API MDRResult mdrHeadphonesGetPlaybackDeviceFixed(
-    MDRHeadphones* headphones,
-    MDRBoolean* out_fixed
-);
-MDR_API MDRResult mdrHeadphonesSetPlaybackDeviceFixed(MDRHeadphones* headphones, MDRBoolean fixed);
+MDR_API MDRResult mdrHeadphonesGetSourceSwitchControl(MDRHeadphones* headphones, MDRBoolean* out_enabled);
+MDR_API MDRResult mdrHeadphonesSetSourceSwitchControl(MDRHeadphones* headphones, MDRBoolean enabled);
 
 /**
- * @brief Outcome the headphones reported for the last fix or playback switch request.
+ * @brief Outcome the headphones reported for the last source switch control request.
  *
  * A refused request leaves the previous state in place, so a caller watching only
- * @ref mdrHeadphonesGetPlaybackDeviceFixed cannot tell a refusal from a no-op. Staging a new
- * request resets this to @ref MDR_PLAYBACK_FIX_SUCCESS.
+ * @ref mdrHeadphonesGetSourceSwitchControl cannot tell a refusal from a no-op. Staging a new
+ * request resets this to @ref MDR_SOURCE_SWITCH_CONTROL_SUCCESS.
  */
-MDR_API MDRResult mdrHeadphonesGetPlaybackDeviceFixResult(
-    MDRHeadphones* headphones,
-    MDRPlaybackFixResult* out_result
-);
+MDR_API MDRResult mdrHeadphonesGetSourceSwitchControlResult(MDRHeadphones* headphones,
+                                                            MDRSourceSwitchControlResult* out_result);
 
 /* General settings and assignable controls. */
 MDR_API MDRResult mdrHeadphonesGetGeneralSettingInfo(

libmdr/src/Details.hpp

@@ -450,14 +450,12 @@ namespace mdr
         MDRProperty<String> mMultipointDeviceMac;
         MDRProperty<String> mPairedDeviceDisconnectMac, mPairedDeviceConnectMac, mPairedDeviceUnpairMac;
 
-        // Sound Connect's "Fixing playback device": pins playback to the current playback device so the
-        // headphones stop handing audio over to the other multipoint device. Carried by
-        // SOURCE_SWITCH_CONTROL's param byte, which is inverted against this flag - the wire value is 1
-        // while switching is free and 0 once the device is fixed (verified on WF-1000XM5).
-        MDRProperty<bool> mPlaybackDeviceFixed;
-        // Outcome of the last fix/switch attempt the headphones reported.
-        v2::t2::SourceSwitchControlResult mSourceSwitchControlResult{
-            v2::t2::SourceSwitchControlResult::SUCCESS};
+        // SOURCE_SWITCH_CONTROL's param byte: 1 while playback may switch to the other multipoint
+        // device on its own, 0 once it's pinned to the current device (verified on WF-1000XM5). This
+        // is Sound Connect's "Fixing playback device", inverted.
+        MDRProperty<bool> mSourceSwitchControlEnabled;
+        // Outcome of the last source switch control request the headphones reported.
+        v2::t2::SourceSwitchControlResult mSourceSwitchControlResult{v2::t2::SourceSwitchControlResult::SUCCESS};
 
         MDRProperty<bool> mSafeListeningPreviewMode;
 #pragma endregion

libmdr/src/Headphones.cpp

@@ -80,7 +80,7 @@ namespace mdr
             mSupport.contains(T2::PAIRING_DEVICE_MANAGEMENT_WITH_BLUETOOTH_CLASS_OF_DEVICE_CLASSIC_LE);
         features[MDR_FEATURE_PAIRED_DEVICE_MANAGEMENT] = pairing;
         features[MDR_FEATURE_PAIRING_MODE] = pairing;
-        features[MDR_FEATURE_PLAYBACK_DEVICE_FIX] = mSupport.contains(T2::SOURCE_SWITCH_CONTROL);
+        features[MDR_FEATURE_SOURCE_SWITCH_CONTROL] = mSupport.contains(T2::SOURCE_SWITCH_CONTROL);
         features[MDR_FEATURE_GENERAL_SETTINGS] =
             mSupport.contains(T1::GENERAL_SETTING_1) || mSupport.contains(T1::GENERAL_SETTING_2) ||
             mSupport.contains(T1::GENERAL_SETTING_3) || mSupport.contains(T1::GENERAL_SETTING_4);
@@ -235,7 +235,7 @@ namespace mdr
         dirty |= mEqPresetId.dirty() || mEqClearBass.dirty() || mEqConfig.dirty();
         dirty |= mVoiceGuidanceEnabled.dirty() || mVoiceGuidanceVolume.dirty() || mPairingMode.dirty();
         dirty |= mMultipointDeviceMac.dirty() || mSafeListeningPreviewMode.dirty();
-        dirty |= mPlaybackDeviceFixed.dirty();
+        dirty |= mSourceSwitchControlEnabled.dirty();
         dirty |= mPairedDeviceConnectMac.dirty() || mPairedDeviceDisconnectMac.dirty() || mPairedDeviceUnpairMac.
             dirty();
         return dirty;
@@ -1084,7 +1084,7 @@ MDRResult mdrHeadphonesGetFeature(
     if (!headphones || !outAvailability)
         return MDR_RESULT_ERROR_INVALID_ARGUMENT;
     // Keep the upper bound on the last MDR_FEATURE_* id, or newly added features read as invalid.
-    if (feature < MDR_FEATURE_IDENTITY || feature > MDR_FEATURE_PLAYBACK_DEVICE_FIX)
+    if (feature < MDR_FEATURE_IDENTITY || feature > MDR_FEATURE_SOURCE_SWITCH_CONTROL)
         return MDR_RESULT_ERROR_INVALID_ARGUMENT;
     const auto& h = *Impl(headphones);
     if (!h.mNeutralInitialized)
@@ -1549,47 +1549,47 @@ MDRResult mdrHeadphonesSetPairing(MDRHeadphones* headphones, const MDRPairing* p
     return MDR_RESULT_OK;
 }
 
-MDRResult mdrHeadphonesGetPlaybackDeviceFixed(MDRHeadphones* headphones, MDRBoolean* outFixed)
+MDRResult mdrHeadphonesGetSourceSwitchControl(MDRHeadphones* headphones, MDRBoolean* outEnabled)
 {
-    if (!headphones || !outFixed)
+    if (!headphones || !outEnabled)
         return MDR_RESULT_ERROR_INVALID_ARGUMENT;
-    *outFixed = static_cast<MDRBoolean>(Impl(headphones)->mPlaybackDeviceFixed.current);
+    *outEnabled = static_cast<MDRBoolean>(Impl(headphones)->mSourceSwitchControlEnabled.current);
     return MDR_RESULT_OK;
 }
 
-MDRResult mdrHeadphonesSetPlaybackDeviceFixed(MDRHeadphones* headphones, MDRBoolean fixed)
+MDRResult mdrHeadphonesSetSourceSwitchControl(MDRHeadphones* headphones, MDRBoolean enabled)
 {
-    if (!headphones || !ValidBoolean(fixed))
+    if (!headphones || !ValidBoolean(enabled))
         return MDR_RESULT_ERROR_INVALID_ARGUMENT;
     auto* h = Impl(headphones);
-    if (!h->mSupport.contains(MDR_FEATURE_PLAYBACK_DEVICE_FIX))
+    if (!h->mSupport.contains(MDR_FEATURE_SOURCE_SWITCH_CONTROL))
         return MDR_RESULT_ERROR_NOT_SUPPORTED;
     h->mSourceSwitchControlResult = mdr::v2::t2::SourceSwitchControlResult::SUCCESS;
-    h->mPlaybackDeviceFixed.stage(fixed != MDR_FALSE);
+    h->mSourceSwitchControlEnabled.stage(enabled != MDR_FALSE);
     return MDR_RESULT_OK;
 }
 
-MDRResult mdrHeadphonesGetPlaybackDeviceFixResult(MDRHeadphones* headphones, MDRPlaybackFixResult* outResult)
+MDRResult mdrHeadphonesGetSourceSwitchControlResult(MDRHeadphones* headphones, MDRSourceSwitchControlResult* outResult)
 {
     if (!headphones || !outResult)
         return MDR_RESULT_ERROR_INVALID_ARGUMENT;
     using enum mdr::v2::t2::SourceSwitchControlResult;
     switch (Impl(headphones)->mSourceSwitchControlResult)
     {
     case SUCCESS:
-        *outResult = MDR_PLAYBACK_FIX_SUCCESS;
+        *outResult = MDR_SOURCE_SWITCH_CONTROL_SUCCESS;
         break;
     case FAIL_CALLING:
-        *outResult = MDR_PLAYBACK_FIX_FAILED_ON_CALL;
+        *outResult = MDR_SOURCE_SWITCH_CONTROL_FAILED_ON_CALL;
         break;
     case FAIL_A2DP_NOT_CONNECT:
-        *outResult = MDR_PLAYBACK_FIX_FAILED_NOT_CONNECTED;
+        *outResult = MDR_SOURCE_SWITCH_CONTROL_FAILED_NOT_CONNECTED;
         break;
     case FAIL_GIVE_PRIORITY_TO_VOICE_ASSISTANT:
-        *outResult = MDR_PLAYBACK_FIX_FAILED_VOICE_ASSISTANT;
+        *outResult = MDR_SOURCE_SWITCH_CONTROL_FAILED_VOICE_ASSISTANT;
         break;
     default:
-        *outResult = MDR_PLAYBACK_FIX_FAILED;
+        *outResult = MDR_SOURCE_SWITCH_CONTROL_FAILED;
         break;
     }
     return MDR_RESULT_OK;

libmdr/src/HeadphonesV2.cpp

@@ -160,8 +160,7 @@ namespace mdr
         /* Source Switch Control */
         if (mSupport.contains(t2::FunctionType::SOURCE_SWITCH_CONTROL))
         {
-            SendCommandACK(t2::PeripheralGetParam,
-                           {.inquiredType = t2::PeripheralInquiredType::SOURCE_SWITCH_CONTROL});
+            SendCommandACK(t2::PeripheralGetParam, {.inquiredType = t2::PeripheralInquiredType::SOURCE_SWITCH_CONTROL});
         }
 
         /* Speak To Chat */
@@ -339,7 +338,7 @@ namespace mdr
         mVoiceGuidanceVolume.submit();
         mPairingMode.submit();
         mMultipointDeviceMac.submit();
-        mPlaybackDeviceFixed.submit();
+        mSourceSwitchControlEnabled.submit();
         mPairedDeviceDisconnectMac.submit();
         mPairedDeviceConnectMac.submit();
         mPairedDeviceUnpairMac.submit();
@@ -467,20 +466,19 @@ namespace mdr
             }
         }
 
-        /* Playback Device Fixation */
-        if (mPlaybackDeviceFixed.submittedDirty())
+        /* Source Switch Control */
+        if (mSourceSwitchControlEnabled.pending())
         {
             using namespace t2;
             if (mSupport.contains(t2::FunctionType::SOURCE_SWITCH_CONTROL))
             {
                 PeripheralSetParamSourceSwitchControl res;
-                // Inverted: the wire flag says "switching is free", we track "device is fixed".
-                res.value = mPlaybackDeviceFixed.submitted ? 0 : 1;
+                res.value = mSourceSwitchControlEnabled.submitted ? 1 : 0;
                 SendCommandACK(PeripheralSetParamSourceSwitchControl, res);
-                mPlaybackDeviceFixed.commit();
+                mSourceSwitchControlEnabled.commit();
             }
             else
-                mPlaybackDeviceFixed.commitOneShot(false);
+                mSourceSwitchControlEnabled.override(true);
         }
 
         /* Connection Ops */

libmdr/src/HeadphonesV2T2.cpp

@@ -150,21 +150,19 @@ namespace mdr
             return MDR_EVENT_PAIRED_DEVICES_CHANGED;
         }
         case SOURCE_SWITCH_CONTROL:
-        {
-            const auto command = static_cast<Command>(cmd[0]);
-            if (command == Command::PERI_NTFY_PARAM)
             {
-                Deserialize(PeripheralNotifyParamSourceSwitchControl, res, cmd);
-                self->mPlaybackDeviceFixed.overwrite(res.value1 == 0);
-                self->mSourceSwitchControlResult = res.result;
-                MDR_LOG_DEBUG("SourceSwitchControl notify: value1={} result={}", res.value1, res.result);
+                const auto command = static_cast<Command>(cmd[0]);
+                if (command == Command::PERI_NTFY_PARAM)
+                {
+                    Deserialize(PeripheralNotifyParamSourceSwitchControl, res, cmd);
+                    self->mSourceSwitchControlEnabled.overwrite(res.value1 != 0);
+                    self->mSourceSwitchControlResult = res.result;
+                    return MDR_EVENT_PAIRED_DEVICES_CHANGED;
+                }
+                Deserialize(PeripheralRetParamSourceSwitchControl, res, cmd);
+                self->mSourceSwitchControlEnabled.overwrite(res.value != 0);
                 return MDR_EVENT_PAIRED_DEVICES_CHANGED;
             }
-            Deserialize(PeripheralRetParamSourceSwitchControl, res, cmd);
-            self->mPlaybackDeviceFixed.overwrite(res.value == 0);
-            MDR_LOG_DEBUG("SourceSwitchControl param: value={}", res.value);
-            return MDR_EVENT_PAIRED_DEVICES_CHANGED;
-        }
         case PAIRING_DEVICE_MANAGEMENT_WITH_BLUETOOTH_CLASS_OF_DEVICE:
         {
             const auto command = static_cast<Command>(cmd[0]);