diff --git a/pm2d/web/server.py b/pm2d/web/server.py
index cc1ddf7..893ada4 100644
--- a/pm2d/web/server.py
+++ b/pm2d/web/server.py
@@ -163,6 +163,7 @@ class TuneParams(BaseModel):
 # ---------- User-facing (simple) params ----------
 
 SYMMETRY_TO_ANGLE_MAX = {
+    "invariante": 0.0,   # oggetto simmetrico a rotazione totale (cerchi): 1 variante
     "nessuna": 360.0,
     "bilaterale": 180.0,
     "rot_3": 120.0,
diff --git a/pm2d/web/static/app.js b/pm2d/web/static/app.js
index bf9865b..3b2b06b 100644
--- a/pm2d/web/static/app.js
+++ b/pm2d/web/static/app.js
@@ -202,7 +202,7 @@ async function doMatch() {
   let body;
   if (hasAdv) {
     // Merge simple → tecnici base, poi overrides
-    const SYM_MAP = {nessuna:360, bilaterale:180, rot_3:120,
+    const SYM_MAP = {invariante:0, nessuna:360, bilaterale:180, rot_3:120,
                      rot_4:90, rot_6:60, rot_8:45};
     const SCALE_MAP = {fissa:[1,1,0.1], mini:[0.9,1.1,0.05],
                        medio:[0.75,1.25,0.05], max:[0.5,1.5,0.05]};
diff --git a/pm2d/web/static/index.html b/pm2d/web/static/index.html
index 6be8a23..364a4ef 100644
--- a/pm2d/web/static/index.html
+++ b/pm2d/web/static/index.html
@@ -50,6 +50,7 @@
     <div class="field">
       <label>Simmetria</label>
       <select id="p-simmetria">
+        <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>