Fix silent I/O failures and harden whisper model handling

app.go

@@ -144,14 +144,16 @@ func (a *App) Quit() {
 	wailsruntime.Quit(a.ctx)
 }
 
-var lastToggle time.Time
+var lastToggleUnixNano int64
 
 func (a *App) ToggleRecording() {
 	// Debounce toggle calls to prevent rapid firing from double-binds or Wayland glitches
-	if time.Since(lastToggle) < 500*time.Millisecond {
+	now := time.Now().UnixNano()
+	last := atomic.LoadInt64(&lastToggleUnixNano)
+	if last != 0 && time.Duration(now-last) < 500*time.Millisecond {
 		return
 	}
-	lastToggle = time.Now()
+	atomic.StoreInt64(&lastToggleUnixNano, now)
 
 	if atomic.LoadInt32(&a.recording) == 1 {
 		a.StopRecording()

internal/audio/recorder/recorder.go

@@ -289,23 +289,49 @@ func (r *AudioRecorder) writeWAVHeader(dataSize uint32) error {
 	blockAlign := numChannels * (bitsPerSample / 8)
 
 	// RIFF chunk
-	r.outputFile.Write([]byte("RIFF"))
+	if _, err := r.outputFile.Write([]byte("RIFF")); err != nil {
-	binary.Write(r.outputFile, binary.LittleEndian, uint32(36+dataSize))
+		return err
-	r.outputFile.Write([]byte("WAVE"))
+	}
+	if err := binary.Write(r.outputFile, binary.LittleEndian, uint32(36+dataSize)); err != nil {
+		return err
+	}
+	if _, err := r.outputFile.Write([]byte("WAVE")); err != nil {
+		return err
+	}
 
 	// fmt sub-chunk
-	r.outputFile.Write([]byte("fmt "))
+	if _, err := r.outputFile.Write([]byte("fmt ")); err != nil {
-	binary.Write(r.outputFile, binary.LittleEndian, uint32(16)) // Subchunk1Size
+		return err
-	binary.Write(r.outputFile, binary.LittleEndian, uint16(1))  // AudioFormat (PCM)
+	}
-	binary.Write(r.outputFile, binary.LittleEndian, numChannels)
+	if err := binary.Write(r.outputFile, binary.LittleEndian, uint32(16)); err != nil { // Subchunk1Size
-	binary.Write(r.outputFile, binary.LittleEndian, sampleRate)
+		return err
-	binary.Write(r.outputFile, binary.LittleEndian, byteRate)
+	}
-	binary.Write(r.outputFile, binary.LittleEndian, blockAlign)
+	if err := binary.Write(r.outputFile, binary.LittleEndian, uint16(1)); err != nil { // AudioFormat (PCM)
-	binary.Write(r.outputFile, binary.LittleEndian, bitsPerSample)
+		return err
+	}
+	if err := binary.Write(r.outputFile, binary.LittleEndian, numChannels); err != nil {
+		return err
+	}
+	if err := binary.Write(r.outputFile, binary.LittleEndian, sampleRate); err != nil {
+		return err
+	}
+	if err := binary.Write(r.outputFile, binary.LittleEndian, byteRate); err != nil {
+		return err
+	}
+	if err := binary.Write(r.outputFile, binary.LittleEndian, blockAlign); err != nil {
+		return err
+	}
+	if err := binary.Write(r.outputFile, binary.LittleEndian, bitsPerSample); err != nil {
+		return err
+	}
 
 	// data sub-chunk
-	r.outputFile.Write([]byte("data"))
+	if _, err := r.outputFile.Write([]byte("data")); err != nil {
-	binary.Write(r.outputFile, binary.LittleEndian, dataSize)
+		return err
+	}
+	if err := binary.Write(r.outputFile, binary.LittleEndian, dataSize); err != nil {
+		return err
+	}
 
 	return nil
 }

internal/config/config.go

@@ -89,7 +89,7 @@ func Save(c *Config, configPath string) error {
 
 	// Ensure the directory exists
 	dir := filepath.Dir(configPath)
-	if err := os.MkdirAll(dir, 0755); err != nil {
+	if err := os.MkdirAll(dir, 0700); err != nil {
 		return err
 	}
 
@@ -98,7 +98,7 @@ func Save(c *Config, configPath string) error {
 		return err
 	}
 
-	return os.WriteFile(configPath, data, 0644)
+	return os.WriteFile(configPath, data, 0600)
 }
 
 // GetConfigPath returns the default configuration file path.

internal/services/whisper/whisper.go

@@ -74,7 +74,12 @@ func (m *Manager) IsInstalled() bool {
 		return false
 	}
 
-	modelPath := filepath.Join(m.installDir, Models[info.Model].Filename)
+	modelInfo, ok := Models[info.Model]
+	if !ok || modelInfo.Filename == "" {
+		return false
+	}
+
+	modelPath := filepath.Join(m.installDir, modelInfo.Filename)
 	if _, err := os.Stat(modelPath); os.IsNotExist(err) {
 		return false
 	}
@@ -265,9 +270,13 @@ func (m *Manager) Transcribe(audioPath string) (string, error) {
 	if err != nil {
 		return "", fmt.Errorf("failed to get installation info: %w", err)
 	}
+	modelInfo, ok := Models[info.Model]
+	if !ok || modelInfo.Filename == "" {
+		return "", fmt.Errorf("invalid installed model: %q", info.Model)
+	}
 
 	binaryPath := m.getBinaryPath()
-	modelFilename := Models[info.Model].Filename
+	modelFilename := modelInfo.Filename
 
 	// Check for model in Release directory first, then main directory
 	modelPath := filepath.Join(m.installDir, "Release", modelFilename)
@@ -424,7 +433,9 @@ func downloadFile(url, dest string, progress chan<- DownloadProgress) error {
 	for {
 		n, err := resp.Body.Read(buf)
 		if n > 0 {
-			out.Write(buf[:n])
+			if _, writeErr := out.Write(buf[:n]); writeErr != nil {
+				return writeErr
+			}
 			downloaded += int64(n)
 			if progress != nil && total > 0 {
 				progress <- DownloadProgress{
@@ -444,5 +455,3 @@ func downloadFile(url, dest string, progress chan<- DownloadProgress) error {
 
 	return nil
 }
-
-