Add WhisperX configuration contract

internal/config/load.go

@@ -15,6 +15,7 @@ func LoadPipeline(path string) (*PipelineConfig, error) {
 	if err := decodeStrictYAML("pipeline", path, &cfg); err != nil {
 		return nil, fmt.Errorf("load pipeline config: %w", err)
 	}
+	applyPipelineDefaults(&cfg)
 	return &cfg, nil
 }
 
@@ -75,3 +76,36 @@ func shortName(path, fallback string) string {
 	}
 	return base
 }
+
+func applyPipelineDefaults(cfg *PipelineConfig) {
+	if cfg == nil {
+		return
+	}
+	applyWhisperXDefaults(&cfg.WhisperX)
+}
+
+func applyWhisperXDefaults(cfg *WhisperXConfig) {
+	if cfg == nil {
+		return
+	}
+	if cfg.Language == "" {
+		cfg.Language = "en"
+	}
+	if cfg.Timeout == "" {
+		cfg.Timeout = "30m"
+	}
+	if cfg.RetryDelay == "" {
+		cfg.RetryDelay = "2s"
+	}
+	if cfg.Concurrency == nil {
+		cfg.Concurrency = intPtr(2)
+	}
+	if cfg.Retries == nil {
+		cfg.Retries = intPtr(3)
+	}
+}
+
+func intPtr(v int) *int {
+	p := v
+	return &p
+}