diff --git a/pm2d/line_matcher.py b/pm2d/line_matcher.py
index eae4d50..360a82d 100644
--- a/pm2d/line_matcher.py
+++ b/pm2d/line_matcher.py
@@ -954,7 +954,7 @@ class LineShapeMatcher:
         # variante e' quantizzato a multipli di angle_step (5 deg default).
         # Refine angolare e' essenziale per orientamento sub-step.
         if search_radius is None:
-            search_radius = self._effective_angle_step() / 2.0
+            search_radius = self._effective_angle_step()
 
         h, w = template_gray.shape
         sw = max(16, int(round(w * scale)))
@@ -1042,8 +1042,11 @@ class LineShapeMatcher:
         # Score all'origine come riferimento (ang offset 0)
         s0, cx0_s, cy0_s = _score_at_angle(0.0)
         best = (angle_deg, s0, cx0_s, cy0_s)
-        tol = 0.1  # gradi
-        for _ in range(8):
+        # Precisione angolare: tol piu' stretto + piu' iterazioni golden.
+        # 16 iter golden coprono ~1e-3 della search_radius -> precisione
+        # ~0.005 deg per step=10 deg.
+        tol = 0.02
+        for _ in range(16):
             if s1 > best[1]:
                 best = (angle_deg + x1, s1, cx1, cy1)
             if s2 > best[1]:
@@ -1060,6 +1063,22 @@ class LineShapeMatcher:
                 x1 = x2; s1 = s2; cx1 = cx2; cy1 = cy2
                 x2 = a_lo + _GOLDEN * (a_hi - a_lo)
                 s2, cx2, cy2 = _score_at_angle(x2)
+        # Parabolic fit finale sui 3 punti vicini al best per refinement
+        # sub-step ulteriore (precisione <0.01 deg quando lo score map e'
+        # smooth attorno al picco).
+        best_off = best[0] - angle_deg
+        delta = max(0.05, abs(a_hi - a_lo) * 0.5)
+        sm, _, _ = _score_at_angle(best_off - delta)
+        sp, _, _ = _score_at_angle(best_off + delta)
+        # Vertice parabola su 3 punti (sm, sb, sp) a (-delta, 0, +delta)
+        denom = sm - 2 * best[1] + sp
+        if abs(denom) > 1e-9:
+            shift = 0.5 * (sm - sp) / denom * delta
+            shift = max(-delta, min(delta, shift))
+            new_off = best_off + shift
+            sn, cxn, cyn = _score_at_angle(new_off)
+            if sn >= best[1]:
+                return (angle_deg + new_off, sn, cxn, cyn)
         return best
 
     def _get_view_template(
@@ -1825,7 +1844,10 @@ class LineShapeMatcher:
                 ang_f, score_f, cx_f, cy_f = self._refine_angle(
                     spread0, bit_active_full, self.template_gray, cx_f, cy_f,
                     var.angle_deg, var.scale, mask_full,
-                    search_radius=self._effective_angle_step() / 2.0,
+                    # Search radius esteso allo step pieno (era step/2):
+                    # copre il caso peggiore in cui il picco vero e' all'estremo
+                    # del bin angolare della variante grezza.
+                    search_radius=self._effective_angle_step(),
                     original_score=score,
                 )
             # Halcon SubPixel='least_squares_high': refinement iterativo
diff --git a/pm2d/web/static/index.html b/pm2d/web/static/index.html
index 442a9b3..4d23bc6 100644
--- a/pm2d/web/static/index.html
+++ b/pm2d/web/static/index.html
@@ -102,8 +102,8 @@
     <div class="field">
       <label>Simmetria</label>
       <select id="p-simmetria">
+        <option value="nessuna" selected>Nessuna (0..360°)</option>
         <option value="invariante">Invariante (cerchi — no rotazione)</option>
-        <option value="nessuna">Nessuna (0..360°)</option>
         <option value="bilaterale">Bilaterale (speculare 180°)</option>
         <option value="rot_3">Rotazionale 3× (120°)</option>
         <option value="rot_4">Rotazionale 4× (90°)</option>