diff --git a/src/components/three/XRGrabbable.tsx b/src/components/three/XRGrabbable.tsx
index 69acba7..1876124 100644
--- a/src/components/three/XRGrabbable.tsx
+++ b/src/components/three/XRGrabbable.tsx
@@ -21,6 +21,8 @@ interface SingleGrabRecord {
   hand: 'left' | 'right';
   /** Offset (world) = groupWorldPos - controllerWorldPos at grab start. */
   offsetWorld: THREE.Vector3;
+  /** Altura Y de mundo da peça no momento em que o grab iniciou, para travar horizontalmente */
+  startWorldY: number;
 }
 
 interface DualGrabRecord {
@@ -44,8 +46,8 @@ const _tmpQuat = new THREE.Quaternion();
 /**
  * Touch Plus grip mapping (Meta Quest 3):
  *
- *  • One-hand grip  → **PAN ONLY** (translação). A rotação e a escala
- *    da peça NÃO mudam — o grip simples só arrasta.
+ *  • One-hand grip  → **PAN ONLY (RESTRICTED HORIZONTALLY)** (translação). A rotação e a escala
+ *    da peça NÃO mudam — o grip simples só arrasta no plano horizontal X/Z para preservar a altura Y calibrada.
  *  • Two-hand grip  → ORBIT (eixo entre as mãos) + ZOOM uniforme
  *    (distância entre os controles). O zoom está sempre ligado.
  *
@@ -144,7 +146,7 @@ export function XRGrabbable({ allowScale = true, lockedActive = false, onGrabSta
       dual.current = null;
     }
 
-    // ─── One-hand mode (PAN ONLY) ────────────────────────────────
+    // ─── One-hand mode (PAN ONLY - HORIZONTAL X/Z) ────────────────
     const activeHand: 'left' | 'right' | null = lActive ? 'left' : rActive ? 'right' : null;
     if (activeHand) {
       const slot = activeHand === 'left' ? L : R;
@@ -154,14 +156,21 @@ export function XRGrabbable({ allowScale = true, lockedActive = false, onGrabSta
         group.updateMatrixWorld();
         const groupWorldPos = new THREE.Vector3().setFromMatrixPosition(group.matrixWorld);
         const offsetWorld = new THREE.Vector3().subVectors(groupWorldPos, ctrlPos);
-        single.current = { hand: activeHand, offsetWorld };
+        
+        // Salva a altura Y original de mundo
+        const startWorldY = groupWorldPos.y;
+        
+        single.current = { hand: activeHand, offsetWorld, startWorldY };
         if (!everGrabbed.current) { everGrabbed.current = true; onGrabStart?.(); }
-        console.log(`[XR][grab] ● ONE-HAND start (${activeHand}) — pan only`);
+        console.log(`[XR][grab] ● ONE-HAND start (${activeHand}) — horizontal pan`);
       }
 
       // Target world position = controller + initial offset
       const targetWorldPos = new THREE.Vector3().addVectors(ctrlPos, single.current.offsetWorld);
 
+      // Trava a translação no plano horizontal (XZ de mundo), preservando a altura Y original de calibração!
+      targetWorldPos.y = single.current.startWorldY;
+
       // Convert to parent-local position (preserve current rotation/scale)
       if (group.parent) {
         group.parent.updateMatrixWorld();
diff --git a/src/components/three/XRHudInWorld.tsx b/src/components/three/XRHudInWorld.tsx
index c0d0538..fa2afab 100644
--- a/src/components/three/XRHudInWorld.tsx
+++ b/src/components/three/XRHudInWorld.tsx
@@ -615,6 +615,9 @@ function GridFloorRow() {
   const setGridAutoFollow = useModelStore((s) => s.setGridAutoFollow);
   const setGridY = useModelStore((s) => s.setGridY);
   const nudgeGridY = useModelStore((s) => s.nudgeGridY);
+  const gridCalibMode = useModelStore((s) => s.gridCalibMode);
+  const setGridCalibMode = useModelStore((s) => s.setGridCalibMode);
+
   const placeAtFloor = () => {
     // Headset eye Y minus avg standing eye height (1.6 m)
     const floor = camera.position.y - 1.6;
@@ -635,6 +638,8 @@ function GridFloorRow() {
         onClick={() => nudgeGridY(0.01)} />
       <XR3DButton position={[0.07, -0.175, 0]} size={[0.075, 0.022]} label="Pousar chão"
         onClick={placeAtFloor} />
+      <XR3DButton position={[0.155, -0.175, 0]} size={[0.075, 0.022]} label={gridCalibMode ? "Calibrando" : "Calibrar"}
+        active={gridCalibMode} onClick={() => setGridCalibMode(!gridCalibMode)} />
     </group>
   );
 }
diff --git a/src/pages/XRSession.tsx b/src/pages/XRSession.tsx
index 3ca7cea..6e3bf45 100644
--- a/src/pages/XRSession.tsx
+++ b/src/pages/XRSession.tsx
@@ -233,7 +233,19 @@ function XRModel({ sceneModel }: { sceneModel: import('@/stores/useModelStore').
       onClick={(e) => {
         e.stopPropagation();
 
-        // Calibração XR: captura normal da face do modelo em espaço de mundo.
+        // Calibração do Grid em AR (clonando os mesmos princípios do modo viewer)
+        const gridCalibMode = useModelStore.getState().gridCalibMode;
+        if (gridCalibMode && e.point) {
+          useModelStore.setState({
+            gridY: e.point.y - 0.001,
+            gridAutoFollow: false,
+            gridCalibMode: false,
+            showGrid: true,
+          });
+          return;
+        }
+
+        // Calibração XR da Peça: captura normal da face do modelo em espaço de mundo.
         if (
           xrCalibration.modelId === sceneModel.id &&
           (xrCalibration.step === 'await-model-1' || xrCalibration.step === 'await-model-2' || xrCalibration.step === 'await-model-3') &&
@@ -328,8 +340,8 @@ function ControllerFineTuning({ freeMove }: { freeMove: boolean }) {
     for (const source of inputSources) {
       const gp = source.gamepad;
       if (!gp) continue;
-      const gripBtn = gp.buttons[2];
-      const trigBtn = gp.buttons[1];
+      const trigBtn = gp.buttons[0];
+      const gripBtn = gp.buttons[1];
       const gripVal = gripBtn ? (gripBtn.value || (gripBtn.pressed ? 1 : 0)) : 0;
       if (gripBtn?.pressed) gripHeld = true;
       if (gripVal > 0.3) anyGripHeld = true; // matches grab hysteresis OFF