diff --git a/public/js/exhibit.js b/public/js/exhibit.js
index 5dbd805..8680053 100644
--- a/public/js/exhibit.js
+++ b/public/js/exhibit.js
@@ -5,7 +5,7 @@
  */
 import * as THREE from 'three';
 import { createDetector, detectMarkers, quadArea } from './ar/detect.js';
-import { PoseEstimator } from './ar/pose.js';
+import { PoseEstimator, ROT_MODES, setRotMode, getRotMode } from './ar/pose.js';
 import { WorldFuser } from './ar/fuse.js';
 import { buildGhost } from './ghosts/loader.js';
 import { ghostTransform } from './ghosts/behavior.js';
@@ -14,15 +14,19 @@ import { renderMarkdown } from './md.js';
 
 const $ = (s) => document.querySelector(s);
 
-/* The fused pose is a camera-in-world transform in OpenCV convention
- * (+X right, +Y DOWN, +Z FORWARD along the view axis). A Three.js camera uses
- * OpenGL convention (+X right, +Y UP, looks down LOCAL -Z). The correct change of
- * basis between them is a 180° rotation about the camera's local Y axis: it flips
- * the forward axis (+Z_cv view -> three.js -Z) AND the up axis (+Y_cv down ->
- * three.js +Y up) together, leaving roll correct. (A 180° about X fixes the view
- * axis too but leaves roll inverted — ghosts render upside-down when the phone is
- * upright.) Applied after copying the fused quaternion each frame. */
-const CV_TO_GL = new THREE.Quaternion().setFromAxisAngle(new THREE.Vector3(0, 1, 0), Math.PI);
+/* Camera-frame correction applied to the fused quaternion (see pose.js for the
+ * rotation-frame conjugation that happens upstream). Switchable for on-device A/B:
+ * once pose.js conjugates the rotation correctly, the right camera correction here
+ * may be identity, Y180, X180, or Z180 depending on the net convention. The debug
+ * overlay cycles CAM_MODES. */
+const CAM_CORR = {
+  none: new THREE.Quaternion(),
+  y180: new THREE.Quaternion().setFromAxisAngle(new THREE.Vector3(0, 1, 0), Math.PI),
+  x180: new THREE.Quaternion().setFromAxisAngle(new THREE.Vector3(1, 0, 0), Math.PI),
+  z180: new THREE.Quaternion().setFromAxisAngle(new THREE.Vector3(0, 0, 1), Math.PI),
+};
+const CAM_MODES = ['none', 'y180', 'x180', 'z180'];
+let camMode = 'none';   // default: none — rely on pose.js conjugation alone
 
 let info = { mode: 'dev' };
 let scene3, camera3, renderer, video, canvas2d, ctx2d;
@@ -50,6 +54,7 @@ function updateDbg(fusedQuat, markerCount) {
   const up = _dbgV.set(0, 1, 0).applyQuaternion(camera3.quaternion).clone();
   const v3 = v => `(${v.x.toFixed(2)},${v.y.toFixed(2)},${v.z.toFixed(2)})`;
   dbgEl.textContent =
+    `rot ${getRotMode()}  cam ${camMode}   (tap to cycle)\n` +
     `markers ${markerCount}\n${rawLine}\nview ${v3(view)}\nup   ${v3(up)}\n` +
     `pos  ${v3(camera3.position)}`;
 }
@@ -131,8 +136,25 @@ async function start() {
   detector = createDetector();
   fuser = new WorldFuser();
 
-  // dev-mode pose readout
-  if (info.mode === 'dev') { dbgEl = $('#dbg'); if (dbgEl) dbgEl.style.display = 'block'; }
+  // dev-mode pose readout + tap-to-cycle correction modes
+  if (info.mode === 'dev') {
+    dbgEl = $('#dbg');
+    if (dbgEl) {
+      dbgEl.style.display = 'block';
+      dbgEl.style.pointerEvents = 'auto';
+      // tap top ~60% cycles rotation mode; tap bottom cycles camera mode
+      dbgEl.addEventListener('click', (ev) => {
+        const r = dbgEl.getBoundingClientRect();
+        if ((ev.clientY - r.top) < r.height * 0.5) {
+          const i = ROT_MODES.indexOf(getRotMode());
+          setRotMode(ROT_MODES[(i + 1) % ROT_MODES.length]);
+        } else {
+          const i = CAM_MODES.indexOf(camMode);
+          camMode = CAM_MODES[(i + 1) % CAM_MODES.length];
+        }
+      });
+    }
+  }
 
   // network
   const net = new ExhibitNet();
@@ -241,8 +263,9 @@ function loop(t) {
       const fused = fuser.fuse(estimates);
       if (fused) {
         camera3.position.copy(fused.position);
-        // convert OpenCV camera frame -> Three.js (OpenGL) camera frame
-        camera3.quaternion.copy(fused.quaternion).multiply(CV_TO_GL);
+        // pose.js already conjugated rotation into the three.js frame; apply any
+        // residual camera-frame correction (switchable via overlay)
+        camera3.quaternion.copy(fused.quaternion).multiply(CAM_CORR[camMode]);
         updateDbg(fused.quaternion, fused.markerCount);
       }
     }