fix: improve magnifier zoom smoothness and debug panel

- Remove immediate snap threshold in useMagnifierZoom - always animate smoothly with react-spring even for large zoom changes (e.g., 14.8× → 313.8× when approaching Vatican City)
- Add smooth cubic falloff for region importance (1 - (d/50)³) to prevent sudden jumps when regions enter detection box
- Reduce size boost from 2.0× to 1.5× and make conditional (only applies when distanceWeight > 0.1) to prevent tiny edge regions from dominating
- Expand detection radius from 75px to 100px for smoother transitions
- Add minimum zoom constraint to ensure magnifier viewport never exceeds detection box size (minZoom >= svgRect.height / 50)
- Compress debug panel Region Analysis: show top 3 regions instead of 5, single-line format
- Fix React duplicate key warning by deduplicating regionDecisions before rendering and using namespaced keys
- Revert to bounding box detection for performance (geometry-based detection was too expensive)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

apps/web/src/arcade-games/know-your-world/components/MapRenderer.tsx

@@ -2247,65 +2247,33 @@ export function MapRenderer({
                     </div>
 
                     <div style={{ marginTop: '8px' }}>
-                      <strong>Region Analysis:</strong>
+                      <strong>Region Analysis (top 3):</strong>
                     </div>
-                    {zoomSearchDebugInfo.regionDecisions
+                    {Array.from(
+                      new Map(
+                        zoomSearchDebugInfo.regionDecisions.map((d) => [d.regionId, d])
+                      ).values()
+                    )
                       .sort((a, b) => b.importance - a.importance)
-                      .slice(0, 5)
+                      .slice(0, 3)
                       .map((decision) => {
-                        const bgColor = decision.wasAccepted
-                          ? 'rgba(0, 255, 0, 0.15)'
-                          : 'rgba(128, 128, 128, 0.1)'
-                        const textColor = decision.wasAccepted ? '#0f0' : '#ccc'
-
+                        const marker = decision.wasAccepted ? '✓' : '✗'
+                        const color = decision.wasAccepted ? '#0f0' : '#888'
                         return (
                           <div
-                            key={decision.regionId}
+                            key={`decision-${decision.regionId}`}
                             style={{
                               fontSize: '9px',
                               marginLeft: '8px',
-                              marginTop: '4px',
-                              padding: '4px',
-                              backgroundColor: bgColor,
-                              borderLeft: `2px solid ${textColor}`,
-                              paddingLeft: '6px',
+                              color,
                             }}
                           >
-                            <div style={{ fontWeight: 'bold', color: textColor }}>
-                              {decision.regionId} (importance: {decision.importance.toFixed(2)})
-                            </div>
-                            <div>
-                              Size: {decision.currentSize.width.toFixed(1)}×
-                              {decision.currentSize.height.toFixed(1)}px
-                            </div>
-                            {decision.testedZoom && (
-                              <>
-                                <div>
-                                  @ {decision.testedZoom.toFixed(1)}×: {decision.magnifiedSize?.width.toFixed(0)}×
-                                  {decision.magnifiedSize?.height.toFixed(0)}px
-                                </div>
-                                <div>
-                                  Ratio: {((decision.sizeRatio?.width ?? 0) * 100).toFixed(1)}% ×{' '}
-                                  {((decision.sizeRatio?.height ?? 0) * 100).toFixed(1)}%
-                                </div>
-                              </>
-                            )}
-                            {decision.rejectionReason && (
-                              <div style={{ color: '#f88', fontStyle: 'italic' }}>
-                                ✗ {decision.rejectionReason}
-                              </div>
-                            )}
-                            {decision.wasAccepted && (
-                              <div style={{ color: '#0f0', fontWeight: 'bold' }}>✓ ACCEPTED</div>
-                            )}
+                            {marker} {decision.regionId}: {decision.currentSize.width.toFixed(0)}×
+                            {decision.currentSize.height.toFixed(0)}px
+                            {decision.rejectionReason && ` (${decision.rejectionReason})`}
                           </div>
                         )
                       })}
-                    {zoomSearchDebugInfo.regionDecisions.length > 5 && (
-                      <div style={{ fontSize: '9px', marginLeft: '8px', color: '#888', marginTop: '4px' }}>
-                        ...and {zoomSearchDebugInfo.regionDecisions.length - 5} more regions
-                      </div>
-                    )}
                   </>
                 )}
 

apps/web/src/arcade-games/know-your-world/hooks/useMagnifierZoom.ts

@@ -222,21 +222,10 @@ export function useMagnifierZoom(options: UseMagnifierZoomOptions): UseMagnifier
         console.log('[useMagnifierZoom] ▶️  Resuming - target zoom is below threshold')
       }
 
-      // If current zoom is very far from target (>100× difference), snap immediately
-      // This prevents slow animations when recovering from stuck states
-      const zoomDifference = Math.abs(currentZoom - targetZoom)
-      const shouldSnapImmediate = zoomDifference > 100
-
-      if (shouldSnapImmediate) {
-        console.log(
-          `[useMagnifierZoom] ⚡ Snapping immediately from ${currentZoom.toFixed(1)}× to ${targetZoom.toFixed(1)}× (diff: ${zoomDifference.toFixed(1)}×)`
-        )
-        magnifierApi.start({ zoom: targetZoom, immediate: true })
-      } else {
+      // Always animate smoothly - react-spring will handle the transition
       console.log('[useMagnifierZoom] 🎬 Starting/updating animation to:', targetZoom.toFixed(1))
       magnifierApi.start({ zoom: targetZoom })
     }
-    }
   }, [
     targetZoom, // Effect runs when target zoom changes
     pointerLocked, // Effect runs when pointer lock state changes

apps/web/src/arcade-games/know-your-world/hooks/useRegionDetection.ts

@@ -1,42 +1,18 @@
 /**
  * Region Detection Hook
  *
- * Detects which regions are near the cursor using actual SVG path geometry.
- * Uses isPointInFill() to test if sample points within the detection box
- * intersect with the actual region shapes (not just bounding boxes).
+ * Detects which regions are near the cursor using bounding box overlap.
+ * Uses isPointInFill() to determine which region is directly under the cursor.
  *
  * Returns information about detected regions including:
- * - Which regions overlap with the detection box (using actual geometry)
- * - Which region is directly under the cursor (using actual geometry)
+ * - Which regions overlap with the detection box (using bounding box)
+ * - Which region is directly under the cursor (using isPointInFill)
  * - Size information for adaptive cursor dampening
  * - Whether there are small regions requiring magnifier zoom
- *
- * CRITICAL: All detection uses SVG path geometry via isPointInFill(), not
- * bounding boxes. This prevents false positives from irregularly shaped regions.
  */
 
 import { useState, useCallback, useRef, useEffect, type RefObject } from 'react'
 import type { MapData } from '../types'
-import { Polygon, Box, point as Point } from '@flatten-js/core'
-
-/**
- * Sample points along an SVG path element to create a Polygon for geometric operations.
- * Uses SVG's native getPointAtLength() to sample the actual path geometry.
- */
-function pathToPolygon(pathElement: SVGGeometryElement, samplesCount = 50): Polygon {
-  const pathLength = pathElement.getTotalLength()
-  const points: Array<[number, number]> = []
-
-  // Sample points evenly along the path
-  for (let i = 0; i <= samplesCount; i++) {
-    const distance = (pathLength * i) / samplesCount
-    const pt = pathElement.getPointAtLength(distance)
-    points.push([pt.x, pt.y])
-  }
-
-  // Create polygon from points
-  return new Polygon(points.map(([x, y]) => Point(x, y)))
-}
 
 export interface DetectionBox {
   left: number
@@ -120,13 +96,22 @@ export function useRegionDetection(options: UseRegionDetectionOptions): UseRegio
 
   const [hoveredRegion, setHoveredRegion] = useState<string | null>(null)
 
-  // Cache polygons to avoid expensive recomputation on every mouse move
-  const polygonCache = useRef<Map<string, Polygon>>(new Map())
+  // Cache path elements to avoid repeated querySelector calls
+  const pathElementCache = useRef<Map<string, SVGGeometryElement>>(new Map())
 
-  // Clear cache when map data changes
+  // Populate path element cache when SVG is available
   useEffect(() => {
-    polygonCache.current.clear()
-  }, [mapData])
+    const svgElement = svgRef.current
+    if (!svgElement) return
+
+    pathElementCache.current.clear()
+    for (const region of mapData.regions) {
+      const path = svgElement.querySelector(`path[data-region-id="${region.id}"]`)
+      if (path && path instanceof SVGGeometryElement) {
+        pathElementCache.current.set(region.id, path)
+      }
+    }
+  }, [svgRef, mapData])
 
   /**
    * Detect regions at the given cursor position.
@@ -205,24 +190,21 @@ export function useRegionDetection(options: UseRegionDetectionOptions): UseRegio
         const dy = screenCenter.y - cursorClientY
         const distanceSquared = dx * dx + dy * dy
 
-        // Skip regions whose centers are far from the detection box
-        // Use generous threshold to avoid false negatives (detection box is 50px, so check 150px)
-        const MAX_DISTANCE = 150
+        // Skip regions whose centers are very far from the detection box
+        // Detection box is 50px, but we check 100px radius to provide smooth transitions
+        // Regions at 50-100px will have very low importance (smooth cubic falloff)
+        const MAX_DISTANCE = 100
         if (distanceSquared > MAX_DISTANCE * MAX_DISTANCE) {
           return // Region is definitely too far away
         }
 
-        // Region is close enough - now do proper DOM-based checks
-        const regionPath = svgElement.querySelector(`path[data-region-id="${region.id}"]`)
-        if (!regionPath || !(regionPath instanceof SVGGeometryElement)) return
+        // Get cached path element (populated in useEffect)
+        const regionPath = pathElementCache.current.get(region.id)
+        if (!regionPath) return
 
         const pathRect = regionPath.getBoundingClientRect()
 
-        // CRITICAL: Use actual SVG path geometry, not bounding box
-        // Sample multiple points within the detection box to check for intersection
-        // This prevents false positives from irregularly shaped regions
-
-        // Second check: does bounding box overlap? (fast rejection)
+        // Check if bounding box overlaps with detection box
         const regionLeft = pathRect.left
         const regionRight = pathRect.right
         const regionTop = pathRect.top
@@ -239,92 +221,19 @@ export function useRegionDetection(options: UseRegionDetectionOptions): UseRegio
           return
         }
 
-        // Bounding box overlaps - now check actual path geometry using flatten-js
-        let overlaps = false
-        let cursorInRegion = false
+        // SIMPLE AND FAST: Use bounding box overlap for detection
+        // If bounding box overlaps, the region is detected
+        const overlaps = boundingBoxOverlaps
 
-        // Get the transformation matrix to convert screen coordinates to SVG coordinates
-        const screenCTM = svgElement.getScreenCTM()
-        if (!screenCTM) {
-          // Fallback to bounding box if we can't get coordinate transform
-          overlaps = true
-          cursorInRegion =
-            cursorClientX >= regionLeft &&
-            cursorClientX <= regionRight &&
-            cursorClientY >= regionTop &&
-            cursorClientY <= regionBottom
-        } else {
+        // Use the screenCTM we already got at the top (guaranteed non-null)
         const inverseMatrix = screenCTM.inverse()
 
-          // Check if cursor point is inside the actual region path
+        // Check if cursor point is inside the actual region path (for "region under cursor")
         let svgPoint = svgElement.createSVGPoint()
         svgPoint.x = cursorClientX
         svgPoint.y = cursorClientY
         svgPoint = svgPoint.matrixTransform(inverseMatrix)
-          cursorInRegion = regionPath.isPointInFill(svgPoint)
-
-          // For overlap detection, use flatten-js for precise geometric intersection
-          try {
-            // Get or create cached polygon for this region
-            let regionPolygon = polygonCache.current.get(region.id)
-            if (!regionPolygon) {
-              regionPolygon = pathToPolygon(regionPath)
-              polygonCache.current.set(region.id, regionPolygon)
-            }
-
-            // Convert detection box to SVG coordinates
-            const boxTopLeft = svgElement.createSVGPoint()
-            boxTopLeft.x = boxLeft
-            boxTopLeft.y = boxTop
-            const boxBottomRight = svgElement.createSVGPoint()
-            boxBottomRight.x = boxRight
-            boxBottomRight.y = boxBottom
-
-            const svgTopLeft = boxTopLeft.matrixTransform(inverseMatrix)
-            const svgBottomRight = boxBottomRight.matrixTransform(inverseMatrix)
-
-            // Create detection box in SVG coordinates
-            const detectionBox = new Box(
-              Math.min(svgTopLeft.x, svgBottomRight.x),
-              Math.min(svgTopLeft.y, svgBottomRight.y),
-              Math.max(svgTopLeft.x, svgBottomRight.x),
-              Math.max(svgTopLeft.y, svgBottomRight.y)
-            )
-
-            // Check for intersection or containment
-            const intersects = regionPolygon.intersect(detectionBox).length > 0
-            const boxContainsRegion = detectionBox.contains(regionPolygon.box)
-
-            overlaps = intersects || boxContainsRegion
-          } catch (error) {
-            // If flatten-js fails (e.g., complex path), fall back to point sampling
-            console.warn('flatten-js intersection failed, using fallback:', error)
-
-            // Fallback: check 9 strategic points
-            const testPoints = [
-              { x: boxLeft, y: boxTop },
-              { x: boxRight, y: boxTop },
-              { x: boxLeft, y: boxBottom },
-              { x: boxRight, y: boxBottom },
-              { x: cursorClientX, y: cursorClientY },
-              { x: (boxLeft + boxRight) / 2, y: boxTop },
-              { x: (boxLeft + boxRight) / 2, y: boxBottom },
-              { x: boxLeft, y: (boxTop + boxBottom) / 2 },
-              { x: boxRight, y: (boxTop + boxBottom) / 2 },
-            ]
-
-            for (const point of testPoints) {
-              const pt = svgElement.createSVGPoint()
-              pt.x = point.x
-              pt.y = point.y
-              const svgPt = pt.matrixTransform(inverseMatrix)
-              if (regionPath.isPointInFill(svgPt)) {
-                overlaps = true
-                break
-              }
-            }
-          }
-        }
+        const cursorInRegion = regionPath.isPointInFill(svgPoint)
 
         // If cursor is inside region, track it as region under cursor
         if (cursorInRegion) {

apps/web/src/arcade-games/know-your-world/utils/adaptiveZoomSearch.ts

@@ -209,17 +209,27 @@ function calculateRegionImportance(
     (cursorClientX - regionCenterX) ** 2 + (cursorClientY - regionCenterY) ** 2
   )
 
-  // Normalize distance to 0-1 range (0 = at cursor, 1 = 50px away or more)
-  // Use 50px as reference since that's our detection box size
+  // SMOOTH EDGE FALLOFF: Create a continuous importance curve
+  // - At cursor (0px): importance = 1.0 (maximum)
+  // - At 25px: importance ≈ 0.5 (half)
+  // - At 50px (edge): importance ≈ 0.0 (minimal, but not zero for continuity)
+  //
+  // Use smooth cubic falloff: (1 - (d/50)^3)
+  // This provides:
+  // - Slow decrease near cursor (plateau at center)
+  // - Faster decrease at mid-range
+  // - Very gradual approach to zero at edge (no discontinuity)
   const normalizedDistance = Math.min(distanceToCursor / 50, 1)
-  const distanceWeight = 1 - normalizedDistance // Invert: closer = higher weight
+  const distanceWeight = Math.max(0, 1 - Math.pow(normalizedDistance, 3))
 
   // 2. Size factor: Smaller regions get boosted importance
   // This ensures San Marino can be targeted even when Italy is closer to cursor
-  const sizeWeight = region.isVerySmall ? 2.0 : 1.0
+  // HOWEVER: Only apply boost if region has meaningful distance weight (> 0.1)
+  // This prevents tiny regions at the edge from suddenly dominating
+  const sizeBoost = region.isVerySmall && distanceWeight > 0.1 ? 1.5 : 1.0
 
   // Combined importance score
-  return distanceWeight * sizeWeight
+  return distanceWeight * sizeBoost
 }
 
 /**
@@ -280,6 +290,23 @@ export function findOptimalZoom(context: AdaptiveZoomSearchContext): AdaptiveZoo
   // Convert cursor position to SVG coordinates
   const scaleX = viewBoxWidth / svgRect.width
   const scaleY = viewBoxHeight / svgRect.height
+
+  // CRITICAL: Calculate minimum zoom to ensure magnified viewport doesn't exceed detection box
+  // Detection box is 50px, so magnified area should not show more than 50px of screen space
+  // At zoom Z, the magnifier shows svgRect.height/Z pixels vertically
+  // We need: svgRect.height/minZoom <= 50
+  // Therefore: minZoom >= svgRect.height/50
+  const calculatedMinZoom = Math.max(svgRect.height / 50, minZoom)
+
+  if (pointerLocked) {
+    console.log('[Zoom Search] Min zoom constraint:', {
+      svgHeight: svgRect.height,
+      detectionBox: 50,
+      calculatedMinZoom,
+      providedMinZoom: minZoom,
+      finalMinZoom: calculatedMinZoom,
+    })
+  }
   const cursorSvgX = (cursorX - (svgRect.left - containerRect.left)) * scaleX + viewBoxX
   const cursorSvgY = (cursorY - (svgRect.top - containerRect.top)) * scaleY + viewBoxY
 
@@ -363,7 +390,7 @@ export function findOptimalZoom(context: AdaptiveZoomSearchContext): AdaptiveZoo
   let optimalZoom = maxZoom
   let foundGoodZoom = false
 
-  for (let testZoom = maxZoom; testZoom >= minZoom; testZoom *= zoomStep) {
+  for (let testZoom = maxZoom; testZoom >= calculatedMinZoom; testZoom *= zoomStep) {
     // Calculate the SVG viewport that will be shown in the magnifier at this zoom
     const magnifiedViewBoxWidth = viewBoxWidth / testZoom
     const magnifiedViewBoxHeight = viewBoxHeight / testZoom
@@ -509,10 +536,10 @@ export function findOptimalZoom(context: AdaptiveZoomSearchContext): AdaptiveZoo
   }
 
   if (!foundGoodZoom) {
-    // Didn't find a good zoom - use minimum
-    optimalZoom = minZoom
+    // Didn't find a good zoom - use calculated minimum
+    optimalZoom = calculatedMinZoom
     if (pointerLocked) {
-      console.log(`[Zoom Search] ⚠️ No good zoom found, using minimum: ${minZoom}x`)
+      console.log(`[Zoom Search] ⚠️ No good zoom found, using calculated minimum: ${calculatedMinZoom}x`)
     }
   }