diff --git a/data_only_viz/action_head_pub.py b/data_only_viz/action_head_pub.py
index 674649d..d08a46f 100644
--- a/data_only_viz/action_head_pub.py
+++ b/data_only_viz/action_head_pub.py
@@ -165,8 +165,11 @@ class ActionHeadPublisher(threading.Thread):
                 rkp = getattr(self.state, "right_hand_kp", None)
                 hands = [h for h in (lkp, rkp) if h is not None and len(h) > 0]
                 chirality = []
+        stab = getattr(self, "_stab", None)
+        fist_enabled = stab.active_flags() if stab is not None else (True, True)
         feats = self._hand_ext.step(hands, chirality or None,
-                                    swap=getattr(self, "_hand_swap_lr", False))
+                                    swap=getattr(self, "_hand_swap_lr", False),
+                                    fist_enabled=fist_enabled)
         with self.state.lock():
             self.state.hand_feats = feats
         self.bridge.send_hands(feats, t_now)
diff --git a/data_only_viz/hand_features.py b/data_only_viz/hand_features.py
index e47c095..491aaa1 100644
--- a/data_only_viz/hand_features.py
+++ b/data_only_viz/hand_features.py
@@ -79,7 +79,8 @@ class HandFeatureExtractor:
         buf.append((cx, cy))
         return _clamp(spd, 0.0, 1.0)
 
-    def step(self, hands: list, chirality=None, swap: bool = False) -> dict:
+    def step(self, hands: list, chirality=None, swap: bool = False,
+             fist_enabled: tuple = (True, True)) -> dict:
         from data_only_viz.hand_slots import route_hands
         # swap must mirror the gesture path (HAND_SWAP_LR) or per-voice
         # L/R mods contradict pinch/strike in the same performance.
@@ -95,6 +96,8 @@ class HandFeatureExtractor:
 
         if left_lm is not None:
             lf = self._features(left_lm)
+            if not fist_enabled[0]:
+                lf["fist"] = 0.0
             lf["speed"] = self._speed(0, lf["cx"], lf["cy"])
             out_l = lf
         else:
@@ -102,6 +105,8 @@ class HandFeatureExtractor:
 
         if right_lm is not None:
             rf = self._features(right_lm)
+            if not fist_enabled[1]:
+                rf["fist"] = 0.0
             rf["speed"] = self._speed(1, rf["cx"], rf["cy"])
             out_r = rf
         else:
diff --git a/data_only_viz/tests/test_hand_features.py b/data_only_viz/tests/test_hand_features.py
index 2033fb6..bf8dfeb 100644
--- a/data_only_viz/tests/test_hand_features.py
+++ b/data_only_viz/tests/test_hand_features.py
@@ -153,3 +153,53 @@ def test_no_swap_keeps_source_chirality():
     out = ext.step([a, b], [1, 0], swap=False)
     assert out["L"]["cx"] == pytest.approx(0.70, abs=0.01)   # chir 0 -> L
     assert out["R"]["cx"] == pytest.approx(0.30, abs=0.01)
+
+
+# ---------------------------------------------------------------------------
+# fist_enabled gate
+# ---------------------------------------------------------------------------
+
+def test_fist_enabled_false_zeroes_fist_preserves_openness():
+    """fist_enabled=(False, False) forces fist=0 but leaves openness intact."""
+    ext = HandFeatureExtractor()
+    h = _fist_hand(0.20)   # all curled -> fist > 0.9 normally
+    out = ext.step([h], fist_enabled=(False, False))
+    hand = out["L"] or out["R"]
+    assert hand["fist"] == 0.0, "fist must be zeroed when disabled"
+    assert hand["openness"] < 0.2, "openness unaffected"
+
+
+def test_fist_enabled_true_computes_fist():
+    """fist_enabled=(True, True) leaves fist computation unchanged."""
+    ext = HandFeatureExtractor()
+    h = _fist_hand(0.20)
+    out = ext.step([h], fist_enabled=(True, True))
+    hand = out["L"] or out["R"]
+    assert hand["fist"] > 0.9
+
+
+def test_fist_enabled_per_slot_independence():
+    """fist_enabled masks only the specified slot."""
+    ext = HandFeatureExtractor()
+    # Build two 21-kp hands with distinct wrist positions for L/R routing
+    # Left hand: cx~0.2, all fingers curled (fist)
+    h_fist = _fist_hand(0.20)
+    h_fist[0] = LM(0.2, 0.6)
+    h_fist[9] = LM(0.2, 0.5)
+    for mcp in (5, 13, 17):
+        h_fist[mcp] = LM(0.2, 0.5)
+    for tip in (8, 12, 16, 20):
+        h_fist[tip] = LM(0.2 + 0.20 * 0.10, 0.5)
+    # Right hand: cx~0.8, fingers extended (open)
+    h_open = _fist_hand(0.80)
+    h_open[0] = LM(0.8, 0.6)
+    h_open[9] = LM(0.8, 0.5)
+    for mcp in (5, 13, 17):
+        h_open[mcp] = LM(0.8, 0.5)
+    for tip in (8, 12, 16, 20):
+        h_open[tip] = LM(0.8 + 0.80 * 0.10, 0.5)
+    out = ext.step([h_fist, h_open], fist_enabled=(False, True))
+    # L slot (cx~0.2) should have fist=0 even though it's curled
+    assert out["L"]["fist"] == 0.0
+    # R slot (cx~0.8) should compute normally (open -> fist < 0.1)
+    assert out["R"]["fist"] < 0.1