fix(tour): scrim only paints when highlight target is actually measured

Author: jddunn

src/dashboard/src/components/tour/GuidedTour.tsx

@@ -386,26 +386,28 @@ export function GuidedTour({ activeTab, chatEnabled = true, onTabChange, onClose
 
   return (
     <>
-      {/* Dim overlay with cutout around highlighted element. Mounts
-       * only while the tour is active (App.tsx gates this whole
-       * component on `tourActive`). */}
-      <div data-tour-overlay className={styles.svgOverlay}>
-        <svg width="100%" height="100%" className={styles.svgFill}>
-          <defs>
-            <mask id="tour-mask">
-              <rect width="100%" height="100%" fill="white" />
-              {rect && (
+      {/* Dim overlay with cutout around highlighted element. Painted
+       * only when a `rect` is measured — without that gate the scrim
+       * renders solid dim with no hole (no target found / wrong tab),
+       * which is what the user saw as "full-page dim with no tour info"
+       * after navigating to a tab the current step doesn't target. */}
+      {rect && (
+        <div data-tour-overlay className={styles.svgOverlay}>
+          <svg width="100%" height="100%" className={styles.svgFill}>
+            <defs>
+              <mask id="tour-mask">
+                <rect width="100%" height="100%" fill="white" />
                 <rect
                   x={rect.left - pad} y={rect.top - pad}
                   width={rect.width + pad * 2} height={rect.height + pad * 2}
                   rx="10" fill="black"
                 />
-              )}
-            </mask>
-          </defs>
-          <rect width="100%" height="100%" fill="rgba(0,0,0,0.55)" mask="url(#tour-mask)" />
-        </svg>
-      </div>
+              </mask>
+            </defs>
+            <rect width="100%" height="100%" fill="rgba(0,0,0,0.55)" mask="url(#tour-mask)" />
+          </svg>
+        </div>
+      )}
 
       {/* Click-away layer */}
       <div data-tour-overlay className={styles.clickAway} onClick={handleClose} />