diff --git a/internal/runtime/runtime.go b/internal/runtime/runtime.go
index d397bb5..30f31f1 100644
--- a/internal/runtime/runtime.go
+++ b/internal/runtime/runtime.go
@@ -34,6 +34,7 @@ type DetectorUpdate struct {
 	CFARRank        *int     `json:"cfar_rank"`
 	CFARScaleDb     *float64 `json:"cfar_scale_db"`
 	CFARWrapAround  *bool    `json:"cfar_wrap_around"`
+	EdgeMarginDb    *float64 `json:"edge_margin_db"`
 }
 
 type SettingsUpdate struct {
@@ -195,6 +196,13 @@ func (m *Manager) ApplyConfig(update ConfigUpdate) (config.Config, error) {
 		if update.Detector.CFARScaleDb != nil {
 			next.Detector.CFARScaleDb = *update.Detector.CFARScaleDb
 		}
+		if update.Detector.EdgeMarginDb != nil {
+			v := *update.Detector.EdgeMarginDb
+			if math.IsNaN(v) || math.IsInf(v, 0) || v < 0 {
+				return m.cfg, errors.New("edge_margin_db must be >= 0")
+			}
+			next.Detector.EdgeMarginDb = v
+		}
 	}
 	if update.Recorder != nil {
 		if update.Recorder.Enabled != nil {
diff --git a/web/app.js b/web/app.js
index d1ee8e4..2aebd36 100644
--- a/web/app.js
+++ b/web/app.js
@@ -42,6 +42,7 @@ const emaAlphaInput = qs('emaAlphaInput');
 const hysteresisInput = qs('hysteresisInput');
 const stableFramesInput = qs('stableFramesInput');
 const gapToleranceInput = qs('gapToleranceInput');
+const edgeMarginInput = qs('edgeMarginInput');
 const agcToggle = qs('agcToggle');
 const dcToggle = qs('dcToggle');
 const iqToggle = qs('iqToggle');
@@ -418,6 +419,7 @@ function applyConfigToUI(cfg) {
   if (hysteresisInput) hysteresisInput.value = cfg.detector.hysteresis_db ?? 3;
   if (stableFramesInput) stableFramesInput.value = cfg.detector.min_stable_frames ?? 3;
   if (gapToleranceInput) gapToleranceInput.value = cfg.detector.gap_tolerance_ms ?? cfg.detector.hold_ms;
+  if (edgeMarginInput) edgeMarginInput.value = cfg.detector.edge_margin_db ?? 3.0;
   agcToggle.checked = !!cfg.agc;
   dcToggle.checked = !!cfg.dc_block;
   iqToggle.checked = !!cfg.iq_balance;
@@ -1416,6 +1418,10 @@ if (gapToleranceInput) gapToleranceInput.addEventListener('change', () => {
   const v = parseInt(gapToleranceInput.value, 10);
   if (Number.isFinite(v)) queueConfigUpdate({ detector: { gap_tolerance_ms: v } });
 });
+if (edgeMarginInput) edgeMarginInput.addEventListener('change', () => {
+  const v = parseFloat(edgeMarginInput.value);
+  if (Number.isFinite(v)) queueConfigUpdate({ detector: { edge_margin_db: v } });
+});
 
 agcToggle.addEventListener('change', () => queueSettingsUpdate({ agc: agcToggle.checked }));
 dcToggle.addEventListener('change', () => queueSettingsUpdate({ dc_block: dcToggle.checked }));
diff --git a/web/index.html b/web/index.html
index 1b932c2..c75478e 100644
--- a/web/index.html
+++ b/web/index.html
@@ -197,6 +197,7 @@
               <label class="field"><span>Hysteresis (dB)</span><input id="hysteresisInput" type="number" step="1" min="0" /></label>
               <label class="field"><span>Min Stable Frames</span><input id="stableFramesInput" type="number" step="1" min="1" /></label>
               <label class="field"><span>Gap Tolerance (ms)</span><input id="gapToleranceInput" type="number" step="50" min="0" /></label>
+              <label class="field"><span>Edge Margin (dB)</span><input id="edgeMarginInput" type="number" step="0.5" min="0" /></label>
               <label class="field"><span>CFAR Mode</span>
                 <select id="cfarModeSelect">
                   <option value="OFF">Off</option>