diff --git a/public/js/exhibit.js b/public/js/exhibit.js
index c1a94bf..3323f3e 100644
--- a/public/js/exhibit.js
+++ b/public/js/exhibit.js
@@ -4,7 +4,7 @@
  *
  * v3 ships two runtime-switchable tracking engines (HUD overlay, tap top third):
  *   opencv (default) — joint multi-marker board solve (solve-cv.js). All detected
- *                      corners -> one solvePnP -> camera pose. Non-coplanar wall
+ *                      corners -> one solvePnP -> camera pose. A non-coplanar
  *                      crest removes planar ambiguity outright.
  *   posit            — the v2 per-marker POS-IT + fuseWorld path, kept intact for
  *                      on-table A/B until the new engine is confirmed. Delete later.
@@ -86,6 +86,13 @@ const focalPxFor = (w, h) => (Math.max(w, h) / 2) / Math.tan(THREE.MathUtils.deg
  * ~20Hz tracks hand movement fine and the 1e filter smooths between updates,
  * while rendering stays at full frame rate. Override: localStorage 'nbx.detectHz'. */
 const DETECT_HZ = parseFloat(localStorage.getItem('nbx.detectHz')) || 20;
+
+/* Long-edge resolution of the detection canvas. At 960 a 60mm crest filling the
+ * usual framing already gets ~23px per marker cell, well above ArUco's needs —
+ * so raising this is NOT an obvious cure for crests that fail to decode, and it
+ * costs CPU roughly linearly (960 -> 1280 is +78% pixels). Exposed as a knob to
+ * test that empirically rather than assume: localStorage 'nbx.detectLong'. */
+const DETECT_LONG = parseFloat(localStorage.getItem('nbx.detectLong')) || 960;
 const DETECT_INTERVAL_MS = 1000 / DETECT_HZ;
 let lastDetectAt = 0;
 let fps = 0, fpsFrames = 0, fpsAt = 0;
@@ -99,7 +106,8 @@ function dbgStatus() {
   const ws = netRef && netRef.ws ? ['conn','open','closing','closed'][netRef.ws.readyState] : 'none';
   return `ws ${ws}  rx ${rxLog.join(',') || '-'}\n` +
          `scene ${sceneLoaded ? anchorCount + ' anchors' : 'NOT LOADED'}  ghost recs ${activeGhosts.size}\n` +
-         `${fps} fps  detect ${DETECT_HZ}Hz  fov ${camera3 ? camera3.fov.toFixed(0) : '?'}\n`;
+         `${fps} fps  detect ${DETECT_HZ}Hz@${DETECT_LONG}  fov ${camera3 ? camera3.fov.toFixed(0) : '?'}` +
+         `${cvSolver && cvSolver.lastReject ? '  REJ:' + cvSolver.lastReject : ''}\n`;
 }
 function paintDbg() { if (dbgEl) dbgEl.textContent = dbgStatus() + dbgPose + dbgAim; }
 
@@ -472,11 +480,11 @@ function loop(t) {
 
   if (video && video.readyState >= 2 && (t - lastDetectAt) >= DETECT_INTERVAL_MS) {
     lastDetectAt = t;
-    /* Downscale for detection speed, capping the LONG side. Fixing the WIDTH at
-     * 960 quietly tripled the work on a portrait stream (960x1707 = 1.6M px vs
-     * 960x540 = 0.5M), which is most of the cost of a frame. */
+    /* Downscale for detection, capping the LONG side. Fixing the WIDTH quietly
+     * tripled the work on a portrait stream (960x1707 vs 960x540), which is most
+     * of the cost of a frame. */
     const vw = video.videoWidth, vh = video.videoHeight;
-    const LONG = 960;
+    const LONG = DETECT_LONG;
     const W = vw >= vh ? LONG : Math.round(LONG * vw / vh);
     const H = vw >= vh ? Math.round(LONG * vh / vw) : LONG;
     if (canvas2d.width !== W || canvas2d.height !== H) { canvas2d.width = W; canvas2d.height = H; }