diff --git a/frontend/src/lib/components/HandwriteCanvas.svelte b/frontend/src/lib/components/HandwriteCanvas.svelte
index d4c9c83..c99b4dc 100644
--- a/frontend/src/lib/components/HandwriteCanvas.svelte
+++ b/frontend/src/lib/components/HandwriteCanvas.svelte
@@ -18,7 +18,6 @@
    *     (전체 지우기 버튼은 별도)
    */
   import { onMount, onDestroy } from 'svelte';
-  import { getStroke } from 'perfect-freehand';
   import { Eraser, Pencil, Undo2, Redo2, Trash2 } from 'lucide-svelte';
   import IconButton from '$lib/components/ui/IconButton.svelte';
 
@@ -118,24 +117,30 @@
     redraw();
   }
 
-  // ── render ──
-  function strokeToPath(_stroke: Stroke): Path2D {
-    const outlinePoints = getStroke(_stroke.points, {
-      size: baseSize,
-      thinning: 0.3,           // 시작 부분이 너무 얇아지지 않게 (0.5 → 0.3)
-      smoothing: 0.5,
-      streamline: 0.4,
-      simulatePressure: true,  // pressure 0 으로 들어오는 케이스 방어
-      last: true,              // 진행 중에도 양쪽 outline + cap 완성 (polygon 닫힘 보장)
-    });
-    const path = new Path2D();
-    if (outlinePoints.length === 0) return path;
-    path.moveTo(outlinePoints[0][0], outlinePoints[0][1]);
-    for (let i = 1; i < outlinePoints.length; i++) {
-      path.lineTo(outlinePoints[i][0], outlinePoints[i][1]);
+  // ── render — 단순 ctx.stroke() 로 갈아치움 (perfect-freehand 미사용).
+  // 이유: perfect-freehand 의 polygon fill 이 그려지지 않는 보고. 단순 line 으로
+  // 안정성 확보 후 문제 격리. 압력 효과는 lineWidth 변경으로 흉내.
+  function drawStroke(ctx: CanvasRenderingContext2D, s: Stroke) {
+    if (s.points.length === 0) return;
+    ctx.beginPath();
+    ctx.lineCap = 'round';
+    ctx.lineJoin = 'round';
+    ctx.lineWidth = baseSize;
+    ctx.strokeStyle = strokeColor;
+    if (s.points.length === 1) {
+      // 점 하나만 있으면 작은 원
+      const [x, y] = s.points[0];
+      ctx.beginPath();
+      ctx.fillStyle = strokeColor;
+      ctx.arc(x, y, baseSize / 2, 0, Math.PI * 2);
+      ctx.fill();
+      return;
     }
-    path.closePath();
-    return path;
+    ctx.moveTo(s.points[0][0], s.points[0][1]);
+    for (let i = 1; i < s.points.length; i++) {
+      ctx.lineTo(s.points[i][0], s.points[i][1]);
+    }
+    ctx.stroke();
   }
 
   function drawTraceBackground(ctx: CanvasRenderingContext2D) {
@@ -156,12 +161,11 @@
     if (!ctx) return;
     ctx.clearRect(0, 0, cssWidth, cssHeight);
     drawTraceBackground(ctx);
-    ctx.fillStyle = strokeColor;
     for (const s of strokes) {
-      ctx.fill(strokeToPath(s));
+      drawStroke(ctx, s);
     }
     if (inflight) {
-      ctx.fill(strokeToPath(inflight));
+      drawStroke(ctx, inflight);
     }
   }
 
@@ -169,7 +173,14 @@
   function getLocalXY(e: PointerEvent): [number, number] {
     if (!canvas) return [0, 0];
     const rect = canvas.getBoundingClientRect();
-    return [e.clientX - rect.left, e.clientY - rect.top];
+    // canvas 의 실제 표시 크기와 attribute 크기가 다른 경우 (ResizeObserver 가 아직 못 따라잡은 케이스)
+    // 비율로 보정. rect.width 가 canvas 의 실제 표시 width.
+    const scaleX = rect.width === 0 ? 1 : cssWidth / rect.width;
+    const scaleY = rect.height === 0 ? 1 : cssHeight / rect.height;
+    return [
+      (e.clientX - rect.left) * scaleX,
+      (e.clientY - rect.top) * scaleY,
+    ];
   }
 
   function isPenLike(e: PointerEvent): boolean {