fix(heal): eliminate boundary seams by windowing inpaint clusters to 1:1 scale and smoothing feather transition

docker/frontend/src/engine/exportEngine.ts

@@ -1326,20 +1326,43 @@ function clusterHealSpots(
       }
     }
   }
+
+  // Maximum dimension of a cluster's bounding box so that the inpaint crop
+  // runs at ~1:1 native resolution (avoiding heavy downscale/upscale blur & edge seams)
+  const isMob = typeof navigator !== 'undefined' && /iPad|iPhone|iPod|Android|Mobile/i.test(navigator.userAgent || '');
+  const maxSpan = isMob ? 240 : 380;
   const visited = new Uint8Array(n);
   const clusters: { x: number; y: number; r: number }[][] = [];
+
   for (let i = 0; i < n; i++) {
     if (visited[i]) continue;
     visited[i] = 1;
     const cluster: { x: number; y: number; r: number }[] = [spots[i]];
+    let minX = spots[i].x * width;
+    let maxX = minX;
+    let minY = spots[i].y * height;
+    let maxY = minY;
     const queue = [i];
+
     while (queue.length > 0) {
-      const curr = queue.pop()!;
+      const curr = queue.shift()!;
       for (const neighbor of adj[curr]) {
         if (!visited[neighbor]) {
-          visited[neighbor] = 1;
-          cluster.push(spots[neighbor]);
-          queue.push(neighbor);
+          const nx = spots[neighbor].x * width;
+          const ny = spots[neighbor].y * height;
+          const newMinX = Math.min(minX, nx);
+          const newMaxX = Math.max(maxX, nx);
+          const newMinY = Math.min(minY, ny);
+          const newMaxY = Math.max(maxY, ny);
+          if (newMaxX - newMinX <= maxSpan && newMaxY - newMinY <= maxSpan) {
+            visited[neighbor] = 1;
+            cluster.push(spots[neighbor]);
+            minX = newMinX;
+            maxX = newMaxX;
+            minY = newMinY;
+            maxY = newMaxY;
+            queue.push(neighbor);
+          }
         }
       }
     }
@@ -1503,7 +1526,7 @@ function clusterHealSpots(
         const my1 = Math.max(...cYs) + cWidest;
         const margin = Math.max(
           16,
-          Math.min(64, Math.round(Math.max(cWidest * 1.5, 0.25 * Math.max(mx1 - mx0, my1 - my0))))
+          Math.min(64, Math.round(cWidest * 1.5))
         );
         const srcLeft = Math.max(boxLeft, Math.floor(mx0 - margin));
         const srcTop = Math.max(boxTop, Math.floor(my0 - margin));