fix(windows): finalize WGC recordings safely

electron/native/bin/win32-x64/helpers-manifest.json

@@ -5,10 +5,10 @@
   "helpers": {
     "wgc-capture": {
       "binaryName": "wgc-capture.exe",
-      "binarySha256": "72d8f0703a5360a0e911a95bf8839354c877df5fa51294af75ded83a17c0c32e",
+      "binarySha256": "5f364b07b016c597288f90a9b61c581e6559d6d32b79ffadceb37859bbea8dd2",
       "sourceDir": "electron/native/wgc-capture",
-      "sourceFingerprint": "f30dee6b4956a5b57f4fc4d8d586f3470c793c8f7e3242f4160394debbb3f3be",
-      "updatedAt": "2026-03-28T05:17:10.449Z"
+      "sourceFingerprint": "9e9bce082266ca5968cf5f0b535b469d47c4ec3a775a93726171c0dfdbcdaa44",
+      "updatedAt": "2026-03-28T05:48:46.587Z"
     },
     "cursor-monitor": {
       "binaryName": "cursor-monitor.exe",

electron/native/wgc-capture/src/main.cpp

@@ -13,6 +13,7 @@
 #include <mutex>
 #include <condition_variable>
 #include <chrono>
+#include <cstdio>
 
 static std::atomic<bool> g_stopRequested{false};
 static std::atomic<bool> g_pauseRequested{false};
@@ -249,6 +250,7 @@ int main(int argc, char* argv[]) {
 
     // Set up frame callback
     std::atomic<int64_t> frameCount{0};
+    std::atomic<bool> recordingStartedAnnounced{false};
     session.setFrameCallback([&](ID3D11Texture2D* texture, int64_t timestampHns) {
         g_lastFrameTimestampHns = timestampHns;
         if (g_stopRequested) return;
@@ -269,7 +271,11 @@ int main(int argc, char* argv[]) {
         }
 
         if (encoder.writeFrame(texture, adjustedTimestampHns)) {
-            frameCount++;
+            const int64_t writtenFrames = frameCount.fetch_add(1) + 1;
+            if (writtenFrames == 1 && !recordingStartedAnnounced.exchange(true)) {
+                std::cout << "Recording started" << std::endl;
+                std::cout.flush();
+            }
         }
     });
 
@@ -312,9 +318,6 @@ int main(int argc, char* argv[]) {
         micActive = micCapture.start();
     }
 
-    std::cout << "Recording started" << std::endl;
-    std::cout.flush();
-
     // Wait for stop signal while pausing/resuming audio tracks in lockstep.
     while (!g_stopRequested) {
         if (g_pauseRequested) {
@@ -333,7 +336,17 @@ int main(int argc, char* argv[]) {
     session.stopCapture();
     if (audioActive) loopback.stop();
     if (micActive) micCapture.stop();
-    encoder.finalize();
+
+    if (frameCount.load() <= 0) {
+        std::cerr << "ERROR: No video frames were captured before stop" << std::endl;
+        DeleteFileW(outputPathW.c_str());
+        return 1;
+    }
+
+    if (!encoder.finalize()) {
+        std::cerr << "ERROR: Failed to finalize Media Foundation encoder" << std::endl;
+        return 1;
+    }
 
     std::cout << "Recording stopped. Output path: " << config.outputPath << std::endl;
     if (audioActive) {

electron/native/wgc-capture/src/mf_encoder.cpp

@@ -22,6 +22,8 @@ MFEncoder::~MFEncoder() {
 
 bool MFEncoder::initialize(const std::wstring& outputPath, int width, int height, int fps,
                            ID3D11Device* device, ID3D11DeviceContext* context) {
+    std::lock_guard<std::mutex> lock(mutex_);
+
     if (initialized_) return false;
 
     if (width % 2 != 0 || height % 2 != 0) {
@@ -124,6 +126,8 @@ bool MFEncoder::initialize(const std::wstring& outputPath, int width, int height
 }
 
 bool MFEncoder::writeFrame(ID3D11Texture2D* texture, int64_t timestampHns) {
+    std::lock_guard<std::mutex> lock(mutex_);
+
     if (!initialized_ || !sinkWriter_) return false;
 
     context_->CopyResource(stagingTexture_.Get(), texture);
@@ -186,20 +190,28 @@ bool MFEncoder::writeFrame(ID3D11Texture2D* texture, int64_t timestampHns) {
     sample->SetSampleDuration(10000000LL / fps_);
 
     hr = sinkWriter_->WriteSample(streamIndex_, sample.Get());
+    if (FAILED(hr)) {
+        std::cerr << "ERROR: WriteSample failed: 0x" << std::hex << hr << std::endl;
+    }
     return SUCCEEDED(hr);
 }
 
 bool MFEncoder::finalize() {
-    if (!initialized_) return false;
-    initialized_ = false;
+    std::lock_guard<std::mutex> lock(mutex_);
 
+    if (!initialized_) return false;
+    if (!sinkWriter_) return false;
+
+    HRESULT hr = sinkWriter_->Finalize();
+    if (FAILED(hr)) {
+        std::cerr << "ERROR: SinkWriter Finalize failed: 0x" << std::hex << hr << std::endl;
+    }
+
+    initialized_ = false;
+    sinkWriter_.Reset();
     stagingTexture_.Reset();
     nv12Buffer_.clear();
     nv12Buffer_.shrink_to_fit();
-
-    if (!sinkWriter_) return false;
-    HRESULT hr = sinkWriter_->Finalize();
-    sinkWriter_.Reset();
     MFShutdown();
     return SUCCEEDED(hr);
 }