diff --git a/internal/config/config.go b/internal/config/config.go
index fd9d785..a18886e 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -99,7 +99,7 @@ type RefinementConfig struct {
 	MinCandidateSNRDb float64 `yaml:"min_candidate_snr_db" json:"min_candidate_snr_db"`
 	MinSpanHz         float64 `yaml:"min_span_hz" json:"min_span_hz"`
 	MaxSpanHz         float64 `yaml:"max_span_hz" json:"max_span_hz"`
-	AutoSpan          bool    `yaml:"auto_span" json:"auto_span"`
+	AutoSpan          *bool   `yaml:"auto_span" json:"auto_span"`
 }
 
 type ResourceConfig struct {
@@ -178,7 +178,7 @@ func Default() Config {
 			MinCandidateSNRDb: 0,
 			MinSpanHz:         0,
 			MaxSpanHz:         0,
-			AutoSpan:          true,
+			AutoSpan:          boolPtr(true),
 		},
 		Resources: ResourceConfig{
 			PreferGPU:           true,
@@ -364,6 +364,9 @@ func applyDefaults(cfg Config) Config {
 	if cfg.Refinement.MaxSpanHz > 0 && cfg.Refinement.MinSpanHz > cfg.Refinement.MaxSpanHz {
 		cfg.Refinement.MaxSpanHz = cfg.Refinement.MinSpanHz
 	}
+	if cfg.Refinement.AutoSpan == nil {
+		cfg.Refinement.AutoSpan = boolPtr(true)
+	}
 	if cfg.Resources.MaxRefinementJobs <= 0 {
 		cfg.Resources.MaxRefinementJobs = cfg.Refinement.MaxConcurrent
 	}
diff --git a/internal/config/config_test.go b/internal/config/config_test.go
index 97bb592..be87026 100644
--- a/internal/config/config_test.go
+++ b/internal/config/config_test.go
@@ -41,6 +41,9 @@ func TestLoadConfig(t *testing.T) {
 	if !cfg.Refinement.Enabled {
 		t.Fatalf("refinement default not applied")
 	}
+	if cfg.Refinement.AutoSpan == nil || !*cfg.Refinement.AutoSpan {
+		t.Fatalf("refinement auto_span default not applied")
+	}
 	if cfg.EventPath == "" {
 		t.Fatalf("event path default not applied")
 	}
diff --git a/internal/config/helpers.go b/internal/config/helpers.go
new file mode 100644
index 0000000..acb5ac2
--- /dev/null
+++ b/internal/config/helpers.go
@@ -0,0 +1,12 @@
+package config
+
+func BoolValue(v *bool, fallback bool) bool {
+	if v == nil {
+		return fallback
+	}
+	return *v
+}
+
+func boolPtr(v bool) *bool {
+	return &v
+}
diff --git a/internal/pipeline/policy.go b/internal/pipeline/policy.go
index cabf6d0..d9a1fd4 100644
--- a/internal/pipeline/policy.go
+++ b/internal/pipeline/policy.go
@@ -43,7 +43,7 @@ func PolicyFromConfig(cfg config.Config) Policy {
 		MinCandidateSNRDb:   cfg.Refinement.MinCandidateSNRDb,
 		RefinementMinSpanHz: cfg.Refinement.MinSpanHz,
 		RefinementMaxSpanHz: cfg.Refinement.MaxSpanHz,
-		RefinementAutoSpan:  cfg.Refinement.AutoSpan,
+		RefinementAutoSpan:  config.BoolValue(cfg.Refinement.AutoSpan, true),
 		PreferGPU:           cfg.Resources.PreferGPU,
 	}
 }