Refine external signing flow and mobile PDF placement

frontend/src/components/ui/PdfSignaturePlacer.jsx

@@ -1,4 +1,4 @@
-import { useState, useRef, useCallback } from 'react';
+import { useEffect, useRef, useState } from 'react';
 import { Document, Page, pdfjs } from 'react-pdf';
 import 'react-pdf/dist/Page/AnnotationLayer.css';
 import 'react-pdf/dist/Page/TextLayer.css';
@@ -31,10 +31,33 @@ export default function PdfSignaturePlacer({
   const [numPages, setNumPages] = useState(null);
   const [currentPage, setCurrentPage] = useState(1);
   const [sigBox, setSigBox] = useState(null); // { x, y } in container px
+  const stageRef = useRef(null);
   const containerRef = useRef(null);
   const [pageSize, setPageSize] = useState(null); // rendered px size
+  const [pageRenderWidth, setPageRenderWidth] = useState(600);
   const signatureWidth = getSignatureWidth(signatureStyle, signerName);
 
+  useEffect(() => {
+    const stage = stageRef.current;
+    if (!stage) return undefined;
+
+    const updateWidth = () => {
+      const nextWidth = Math.max(280, Math.min(600, Math.floor(stage.clientWidth || 600)));
+      setPageRenderWidth(nextWidth);
+    };
+
+    updateWidth();
+
+    if (typeof ResizeObserver === 'undefined') {
+      window.addEventListener('resize', updateWidth);
+      return () => window.removeEventListener('resize', updateWidth);
+    }
+
+    const observer = new ResizeObserver(() => updateWidth());
+    observer.observe(stage);
+    return () => observer.disconnect();
+  }, []);
+
   const getCanvasMetrics = () => {
     const container = containerRef.current;
     const canvas = container?.querySelector('.react-pdf__Page__canvas');
@@ -59,12 +82,12 @@ export default function PdfSignaturePlacer({
     setPageSize({ width: page.width, height: page.height });
   };
 
-  const handleContainerClick = (e) => {
+  const handlePointerDown = (event) => {
     const metrics = getCanvasMetrics();
     if (!metrics) return;
 
-    const x = e.clientX - metrics.canvasRect.left;
-    const y = e.clientY - metrics.canvasRect.top;
+    const x = event.clientX - metrics.canvasRect.left;
+    const y = event.clientY - metrics.canvasRect.top;
     const clampedX = Math.min(Math.max(x, 0), metrics.width - signatureWidth);
     const clampedY = Math.min(Math.max(y, 0), metrics.height - SIG_H);
 
@@ -177,35 +200,37 @@ export default function PdfSignaturePlacer({
         </div>
       </div>
 
-      <div
-        ref={containerRef}
-        className="pdf-placer-canvas"
-        onClick={handleContainerClick}
-        style={{ cursor: 'crosshair', position: 'relative', display: 'inline-block' }}
-      >
-        <Document file={pdfBlob} onLoadSuccess={handleDocLoad}>
-          <Page
-            pageNumber={currentPage}
-            width={600}
-            onLoadSuccess={(p) => setPageSize({
-              width: p.width, height: p.height,
-              pdfWidth: p.originalWidth, pdfHeight: p.originalHeight,
-            })}
-          />
-        </Document>
+      <div ref={stageRef} className="pdf-placer-stage">
+        <div
+          ref={containerRef}
+          className="pdf-placer-canvas"
+          onPointerDown={handlePointerDown}
+          style={{ cursor: 'crosshair', position: 'relative', display: 'inline-block' }}
+        >
+          <Document file={pdfBlob} onLoadSuccess={handleDocLoad}>
+            <Page
+              pageNumber={currentPage}
+              width={pageRenderWidth}
+              onLoadSuccess={(p) => setPageSize({
+                width: p.width, height: p.height,
+                pdfWidth: p.originalWidth, pdfHeight: p.originalHeight,
+              })}
+            />
+          </Document>
 
-        {sigBox && (
-          <div
-            className={`sig-preview-box sig-preview-box--${signatureStyle}`}
-            data-background={signatureStyle === 'qr' ? qrBackground : undefined}
-            data-border={signatureStyle === 'qr' ? qrBorder : undefined}
-            style={{ left: sigBox.x, top: sigBox.y, width: signatureWidth, height: SIG_H }}
-            onClick={(e) => e.stopPropagation()}
-          >
-            {signatureStyle === 'classic' && <div className="sig-preview-bar" />}
-            {renderPreview()}
-          </div>
-        )}
+          {sigBox && (
+            <div
+              className={`sig-preview-box sig-preview-box--${signatureStyle}`}
+              data-background={signatureStyle === 'qr' ? qrBackground : undefined}
+              data-border={signatureStyle === 'qr' ? qrBorder : undefined}
+              style={{ left: sigBox.x, top: sigBox.y, width: signatureWidth, height: SIG_H }}
+              onPointerDown={(e) => e.stopPropagation()}
+            >
+              {signatureStyle === 'classic' && <div className="sig-preview-bar" />}
+              {renderPreview()}
+            </div>
+          )}
+        </div>
       </div>
 
       {sigBox && (

frontend/src/index.css

@@ -1425,6 +1425,10 @@ select {
 .pdf-placer-pages { display: flex; align-items: center; gap: 8px; }
 .pdf-placer-pages .btn { color: #fff; border-color: rgba(255,255,255,.2); padding: 4px 10px; }
 
+.pdf-placer-stage {
+  width: 100%;
+}
+
 .pdf-placer-canvas {
   border: 2px dashed var(--primary);
   border-radius: 0 0 8px 8px;
@@ -2323,6 +2327,7 @@ select {
 
   .pdf-placer-canvas {
     overflow: auto;
+    max-width: 100%;
   }
 
   .pdf-placer-canvas .react-pdf__Page,