fix: domino endpoint hit radius increased + only check active endpoints

- Snap radius 45→60 for easier endpoint tapping
- hitTestEndpoints only checks currently active (highlighted) endpoints
- Empty board returns hit on any canvas tap when endpoint is active
- Simplified pointerdown handler (no early endpoint intercept)
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

public/js/modules/domino/canvas/board.js

@@ -118,6 +118,8 @@ export class DominoBoard {
   }
 
   hitTestEndpoints(screenX, screenY) {
+    if (!this.activeEndpoint) return null;
+
     const rect = this.canvas.getBoundingClientRect();
     const canvasX = (screenX - rect.left) * (this.width / rect.width);
     const canvasY = (screenY - rect.top) * (this.height / rect.height);
@@ -130,15 +132,23 @@ export class DominoBoard {
 
     const leftEp = this.layout.endpoints.left;
     const rightEp = this.layout.endpoints.right;
-    const radius = getSnapRadius() / this.zoom;
+    const radius = getSnapRadius();
 
-    // Empty board: tap anywhere = center placement
-    if (!leftEp && !rightEp && this.activeEndpoint) {
+    // Empty board: tap anywhere on canvas = center placement
+    if (!leftEp && !rightEp) {
       return { end: 'right', value: null };
     }
 
-    if (leftEp && dist(worldX, worldY, leftEp.x, leftEp.y) < radius) return { end: 'left', value: leftEp.value };
-    if (rightEp && dist(worldX, worldY, rightEp.x, rightEp.y) < radius) return { end: 'right', value: rightEp.value };
+    // Check which endpoints are active
+    const checkLeft = this.activeEndpoint === 'left' || this.activeEndpoint === 'both';
+    const checkRight = this.activeEndpoint === 'right' || this.activeEndpoint === 'both';
+
+    if (checkLeft && leftEp && dist(worldX, worldY, leftEp.x, leftEp.y) < radius) {
+      return { end: 'left', value: leftEp.value };
+    }
+    if (checkRight && rightEp && dist(worldX, worldY, rightEp.x, rightEp.y) < radius) {
+      return { end: 'right', value: rightEp.value };
+    }
     return null;
   }
 
@@ -274,14 +284,6 @@ export class DominoBoard {
     let lastPanX = 0, lastPanY = 0;
 
     this.canvas.addEventListener('pointerdown', (e) => {
-      // Check endpoint tap first
-      if (this.activeEndpoint && this.onEndpointTap) {
-        const hit = this.hitTestEndpoints(e.clientX, e.clientY);
-        if (hit) {
-          this.onEndpointTap(hit);
-          return;
-        }
-      }
       startX = e.clientX;
       startY = e.clientY;
       lastPanX = this.pan.x;

public/js/modules/domino/logic/layout.js

@@ -155,7 +155,7 @@ function getEndpoint(tiles, chain, side) {
   return { x: ex, y: ey, value: endValue, end: side };
 }
 
-export function getSnapRadius() { return 45; }
+export function getSnapRadius() { return 60; }
 
 export function hitTestEndpoint(px, py, endpoint) {
   if (!endpoint) return false;