feat: QR export as SVG and PDF with selectable error correction

All QR endpoints (/api/qr/:code, /api/qr/custom GET+POST) accept
format=png|svg|pdf, ec=L|M|Q|H, and download=1 for attachment responses,
unified behind a shared qr_response() renderer. SVG is generated as a true
vector (one path of modules, crispEdges) with an optional logo embedded as
a data URI over a cleared centre tile; PDF wraps the raster render for
print. A logo always forces error correction H. Dot styles remain
raster-only.

QR Studio: format and error-correction selectors, PDF previews as PNG,
format-aware download button with contextual hints.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

app.py

@@ -478,15 +478,27 @@ def get_user_monthly_clicks(conn, user_id):
 # QR Generator
 # ─────────────────────────────────────────────
 
+def _qr_ec_constant(qrc, ec: str, logo_bytes=None):
+    """Map an L/M/Q/H letter to a qrcode error-correction constant.
+    A logo overlay always forces H so the covered modules stay recoverable."""
+    if logo_bytes:
+        return qrc.constants.ERROR_CORRECT_H
+    return {
+        'L': qrc.constants.ERROR_CORRECT_L,
+        'M': qrc.constants.ERROR_CORRECT_M,
+        'Q': qrc.constants.ERROR_CORRECT_Q,
+        'H': qrc.constants.ERROR_CORRECT_H,
+    }.get((ec or 'M').upper(), qrc.constants.ERROR_CORRECT_M)
+
+
 def generate_qr_png(data: str, size: int = 300, fg=(0,0,0), bg=(255,255,255),
-                    style: str = 'square', logo_bytes: bytes = None) -> bytes:
+                    style: str = 'square', logo_bytes: bytes = None, ec: str = 'M') -> bytes:
     """Generate QR PNG. Supports dot styles and logo overlay when qrcode[pil] is installed."""
     try:
         import qrcode as qrc
         from PIL import Image
 
-        ec = qrc.constants.ERROR_CORRECT_H if logo_bytes else qrc.constants.ERROR_CORRECT_M
+        qr = qrc.QRCode(error_correction=_qr_ec_constant(qrc, ec, logo_bytes), border=2)
-        qr = qrc.QRCode(error_correction=ec, border=2)
         qr.add_data(data)
         qr.make(fit=True)
 
@@ -591,6 +603,105 @@ def generate_qr_png(data: str, size: int = 300, fg=(0,0,0), bg=(255,255,255),
             + png_chunk(b'IEND', b''))
 
 
+def _sniff_image_mime(data: bytes) -> str:
+    if data[:8] == b'\x89PNG\r\n\x1a\n': return 'image/png'
+    if data[:2] == b'\xff\xd8':          return 'image/jpeg'
+    if data[:6] in (b'GIF87a', b'GIF89a'): return 'image/gif'
+    if data[:4] == b'RIFF' and data[8:12] == b'WEBP': return 'image/webp'
+    return 'image/png'
+
+
+def generate_qr_svg(data: str, size: int = 300, fg: str = '#000000', bg: str = '#ffffff',
+                    ec: str = 'M', logo_bytes: bytes = None) -> bytes:
+    """Generate a vector QR as SVG (print-ready, scales losslessly).
+    A logo, when given, is embedded as a data URI over a cleared centre tile.
+    Dot styles are raster-only; SVG always renders square modules."""
+    import qrcode as qrc
+    qr = qrc.QRCode(error_correction=_qr_ec_constant(qrc, ec, logo_bytes), border=2)
+    qr.add_data(data)
+    qr.make(fit=True)
+    matrix = qr.get_matrix()
+    n = len(matrix)
+    path = ''.join(
+        f'M{x} {y}h1v1h-1z'
+        for y, row in enumerate(matrix)
+        for x, dark in enumerate(row) if dark
+    )
+    logo_svg = ''
+    if logo_bytes:
+        # Mirror the PNG renderer: clear a centre tile (logo = 1/4 of the code,
+        # plus a small gutter) and place the logo inside it.
+        logo_units = n / 4
+        pad        = max(0.5, n / 100)
+        zone       = logo_units + pad * 2
+        cx         = (n - zone) / 2
+        b64        = base64.b64encode(logo_bytes).decode()
+        mime       = _sniff_image_mime(logo_bytes)
+        logo_svg = (
+            f'<rect x="{cx:.2f}" y="{cx:.2f}" width="{zone:.2f}" height="{zone:.2f}" fill="{bg}"/>'
+            f'<image href="data:{mime};base64,{b64}" x="{cx + pad:.2f}" y="{cx + pad:.2f}" '
+            f'width="{logo_units:.2f}" height="{logo_units:.2f}" preserveAspectRatio="xMidYMid meet"/>'
+        )
+    svg = (
+        f'<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 {n} {n}" '
+        f'width="{size}" height="{size}" shape-rendering="crispEdges">'
+        f'<rect width="{n}" height="{n}" fill="{bg}"/>'
+        f'<path d="{path}" fill="{fg}"/>{logo_svg}</svg>'
+    )
+    return svg.encode('utf-8')
+
+
+def png_to_pdf(png_bytes: bytes) -> bytes:
+    """Wrap a rendered QR PNG in a single-page PDF (requires Pillow)."""
+    from PIL import Image
+    img = Image.open(io.BytesIO(png_bytes)).convert('RGB')
+    buf = io.BytesIO()
+    img.save(buf, 'PDF')
+    return buf.getvalue()
+
+
+def qr_response(data_str: str, params, logo_bytes: bytes = None,
+                filename: str = 'qr', cache: bool = False):
+    """Shared QR endpoint renderer — handles format (png/svg/pdf), colours,
+    size, style, error-correction, and optional attachment download."""
+    fmt      = (params.get('format') or 'png').lower()
+    ec       = (params.get('ec') or 'M').upper()
+    fg_hex   = (params.get('fg') or '000000').lstrip('#')
+    bg_hex   = (params.get('bg') or 'ffffff').lstrip('#')
+    size     = min(int(params.get('size', 300) or 300), 1000)
+    style    = params.get('style') or 'square'
+    download = str(params.get('download') or '').lower() in ('1', 'true')
+
+    if fmt == 'svg':
+        try:
+            body = generate_qr_svg(data_str, size=size, fg='#'+fg_hex, bg='#'+bg_hex,
+                                   ec=ec, logo_bytes=logo_bytes)
+        except ImportError:
+            return jsonify({'error': 'SVG output requires the qrcode library'}), 501
+        mime, ext = 'image/svg+xml', 'svg'
+    elif fmt == 'pdf':
+        png = generate_qr_png(data_str, size=size, fg=hex_to_rgb(fg_hex), bg=hex_to_rgb(bg_hex),
+                              style=style, logo_bytes=logo_bytes, ec=ec)
+        try:
+            body = png_to_pdf(png)
+        except ImportError:
+            return jsonify({'error': 'PDF output requires Pillow'}), 501
+        mime, ext = 'application/pdf', 'pdf'
+    elif fmt == 'png':
+        body = generate_qr_png(data_str, size=size, fg=hex_to_rgb(fg_hex), bg=hex_to_rgb(bg_hex),
+                               style=style, logo_bytes=logo_bytes, ec=ec)
+        mime, ext = 'image/png', 'png'
+    else:
+        return jsonify({'error': 'format must be png, svg, or pdf'}), 400
+
+    headers = {}
+    if cache:
+        headers['Cache-Control'] = 'public, max-age=3600'
+    if download:
+        headers['Content-Disposition'] = f'attachment; filename="{filename}.{ext}"'
+    return Response(body, mimetype=mime, headers=headers)
+
+
 # ─────────────────────────────────────────────
 # Shared helpers
 # ─────────────────────────────────────────────
@@ -1372,19 +1483,17 @@ def stats():
 # QR Routes
 # ─────────────────────────────────────────────
 
+# All QR endpoints accept: format=png|svg|pdf, ec=L|M|Q|H, fg, bg, size,
+# style (raster formats only), download=1 for an attachment response.
+
 @app.route('/api/qr/<code>')
 def qr_code(code):
-    fg_hex = request.args.get('fg', '000000')
-    bg_hex = request.args.get('bg', 'ffffff')
-    size   = min(int(request.args.get('size', 300)), 1000)
-    style  = request.args.get('style', 'square')
     with get_db() as conn:
         link = conn.execute('SELECT 1 FROM links WHERE code=? AND is_active=1', (code,)).fetchone()
     if not link:
         return jsonify({'error': 'Not found'}), 404
-    png = generate_qr_png(f"{BASE_URL}/{code}", size=size,
+    return qr_response(f"{BASE_URL}/{code}", request.args,
-                          fg=hex_to_rgb(fg_hex), bg=hex_to_rgb(bg_hex), style=style)
+                       filename=f'qr-{code}', cache=True)
-    return Response(png, mimetype='image/png', headers={'Cache-Control': 'public, max-age=3600'})
 
 
 @app.route('/api/qr/custom', methods=['GET'])
@@ -1392,12 +1501,7 @@ def qr_custom():
     url = request.args.get('url', '').strip()
     if not url or not validate_url(url):
         return jsonify({'error': 'Valid URL required'}), 400
-    fg_hex = request.args.get('fg', '000000')
+    return qr_response(url, request.args, filename='qrcode')
-    bg_hex = request.args.get('bg', 'ffffff')
-    size   = min(int(request.args.get('size', 300)), 1000)
-    style  = request.args.get('style', 'square')
-    png = generate_qr_png(url, size=size, fg=hex_to_rgb(fg_hex), bg=hex_to_rgb(bg_hex), style=style)
-    return Response(png, mimetype='image/png')
 
 
 @app.route('/api/qr/custom', methods=['POST'])
@@ -1406,10 +1510,6 @@ def qr_custom_post():
     url  = (data.get('url') or '').strip()
     if not url or not validate_url(url):
         return jsonify({'error': 'Valid URL required'}), 400
-    fg_hex = (data.get('fg') or '000000').lstrip('#')
-    bg_hex = (data.get('bg') or 'ffffff').lstrip('#')
-    size   = min(int(data.get('size', 300)), 1000)
-    style  = data.get('style', 'square')
     logo_bytes = None
     logo_b64   = data.get('logo', '')
     if logo_b64:
@@ -1417,9 +1517,7 @@ def qr_custom_post():
             logo_bytes = base64.b64decode(logo_b64)
         except Exception:
             return jsonify({'error': 'Invalid logo data'}), 400
-    png = generate_qr_png(url, size=size, fg=hex_to_rgb(fg_hex), bg=hex_to_rgb(bg_hex),
+    return qr_response(url, data, logo_bytes=logo_bytes, filename='qrcode')
-                          style=style, logo_bytes=logo_bytes)
-    return Response(png, mimetype='image/png')
 
 
 # ─────────────────────────────────────────────

index.html

@@ -697,6 +697,26 @@ input[type="range"]::-webkit-slider-thumb { -webkit-appearance:none; width:16px;
           <button class="style-btn" data-style="horizontal">▬ H-Bars</button>
         </div>
       </div>
+      <div class="color-row" style="margin-bottom:18px">
+        <div>
+          <label class="field-label">FORMAT</label>
+          <select class="field-input" id="qr-format">
+            <option value="png" selected>PNG — raster</option>
+            <option value="svg">SVG — vector (print)</option>
+            <option value="pdf">PDF — print-ready</option>
+          </select>
+          <div style="font-size:10px;color:var(--muted);font-family:var(--font-mono);margin-top:4px">Dot styles apply to PNG &amp; PDF only</div>
+        </div>
+        <div>
+          <label class="field-label">ERROR CORRECTION</label>
+          <select class="field-input" id="qr-ec">
+            <option value="L">L — 7% (densest)</option>
+            <option value="M" selected>M — 15% (default)</option>
+            <option value="Q">Q — 25%</option>
+            <option value="H">H — 30% (logos)</option>
+          </select>
+        </div>
+      </div>
       <div style="margin-bottom:18px">
         <label class="field-label">LOGO / ICON <span style="font-weight:400;color:var(--muted)">(optional — centered overlay)</span></label>
         <div class="logo-row">
@@ -713,7 +733,7 @@ input[type="range"]::-webkit-slider-thumb { -webkit-appearance:none; width:16px;
       <div id="qr-preview-wrap"><div class="qr-placeholder">Enter a URL and click Generate</div></div>
       <div id="qr-dl-row" style="display:none;flex-direction:column;align-items:center;gap:8px;width:100%">
         <a class="btn-primary" id="qr-download-link" download="qrcode.png" style="text-decoration:none;display:inline-block;text-align:center">↓ Download PNG</a>
-        <div style="font-size:11px;color:var(--muted);font-family:var(--font-mono)">Right-click to save</div>
+        <div style="font-size:11px;color:var(--muted);font-family:var(--font-mono)" id="qr-dl-hint">Right-click to save</div>
       </div>
     </div>
   </div>
@@ -722,6 +742,22 @@ input[type="range"]::-webkit-slider-thumb { -webkit-appearance:none; width:16px;
 
 <!-- ── ADMIN ── -->
 <div class="view" id="view-admin">
+  <!-- Platform overview -->
+  <div class="section-head" style="margin-bottom:18px">
+    <div><div class="section-title">Platform Overview</div><div style="color:var(--muted);font-size:13px;margin-top:3px">All users, links, and clicks across the instance</div></div>
+    <button class="btn-sm" onclick="loadAdminOverview()">↻ Refresh</button>
+  </div>
+  <div class="stats-strip" id="admin-stats">
+    <div class="stat-card"><div class="stat-value" id="astat-users">—</div><div class="stat-label">USERS</div></div>
+    <div class="stat-card"><div class="stat-value" id="astat-orgs">—</div><div class="stat-label">ORGS</div></div>
+    <div class="stat-card"><div class="stat-value" id="astat-links">—</div><div class="stat-label">ACTIVE LINKS</div></div>
+    <div class="stat-card"><div class="stat-value" id="astat-clicks30">—</div><div class="stat-label">CLICKS / 30D</div></div>
+  </div>
+  <div class="panel" style="margin-bottom:32px">
+    <h3>QUOTA USAGE</h3>
+    <div id="admin-usage"><div style="color:var(--muted);font-size:12px;font-family:var(--font-mono)">Loading…</div></div>
+  </div>
+
   <!-- Users -->
   <div class="section-head" style="margin-bottom:24px">
     <div><div class="section-title">User Management</div><div style="color:var(--muted);font-size:13px;margin-top:3px">Create and manage user accounts</div></div>
@@ -1831,37 +1867,52 @@ function clearQrLogo() {
   document.getElementById('qr-logo-clear').style.display = 'none';
 }
 
+async function postQrBlob(body) {
+  const resp = await authFetch(`${BASE}/api/qr/custom`, {method:'POST', body:JSON.stringify(body)});
+  if (!resp.ok) throw new Error('QR generation failed');
+  return await resp.blob();
+}
+
 document.getElementById('qr-generate-btn').addEventListener('click', async () => {
   const url = document.getElementById('qr-url-input').value.trim();
   if (!url) { toast('Please enter a URL','error'); return; }
   const fg   = qrFgH.value.replace('#','') || '000000';
   const bg   = qrBgH.value.replace('#','') || 'ffffff';
   const size = parseInt(qrSz.value);
+  const fmt  = document.getElementById('qr-format').value;
+  const ec   = document.getElementById('qr-ec').value;
   const btn  = document.getElementById('qr-generate-btn');
+  const dlLink = document.getElementById('qr-download-link');
+  // PDFs can't render in an <img> — preview those as PNG, download as PDF
+  const previewFmt = fmt === 'pdf' ? 'png' : fmt;
 
-  if (qrLogoBase64 || qrStyle !== 'square') {
   btn.disabled = true; btn.textContent = 'Generating...';
   try {
-      const body = { url, fg, bg, size, style: qrStyle };
+    let previewUrl, dlUrl;
-      if (qrLogoBase64) body.logo = qrLogoBase64;
+    if (qrLogoBase64) {
-      const resp = await authFetch(`${BASE}/api/qr/custom`, {method:'POST', body:JSON.stringify(body)});
+      const params = { url, fg, bg, size, style: qrStyle, ec, logo: qrLogoBase64 };
-      if (!resp.ok) { toast('Failed to generate QR','error'); return; }
+      const previewBlob = await postQrBlob({...params, format: previewFmt});
-      const blob   = await resp.blob();
+      previewUrl = URL.createObjectURL(previewBlob);
-      const blobUrl = URL.createObjectURL(blob);
+      dlUrl = fmt === 'pdf'
-      document.getElementById('qr-preview-wrap').innerHTML =
+        ? URL.createObjectURL(await postQrBlob({...params, format: 'pdf'}))
-        `<div class="qr-preview-img"><img src="${blobUrl}" width="${Math.min(size,300)}" height="${Math.min(size,300)}" alt="QR"></div>`;
+        : previewUrl;
-      document.getElementById('qr-dl-row').style.display = 'flex';
-      document.getElementById('qr-download-link').href = blobUrl;
-    } catch(e) { toast('Network error','error'); }
-    finally { btn.disabled = false; btn.textContent = 'Generate QR Code'; }
     } else {
-    const qrUrl = `${BASE}/api/qr/custom?url=${encodeURIComponent(url)}&fg=${fg}&bg=${bg}&size=${size}&t=${Date.now()}`;
+      const qs = `url=${encodeURIComponent(url)}&fg=${fg}&bg=${bg}&size=${size}&style=${qrStyle}&ec=${ec}`;
-    document.getElementById('qr-preview-wrap').innerHTML =
+      previewUrl = `${BASE}/api/qr/custom?${qs}&format=${previewFmt}&t=${Date.now()}`;
-      `<div class="qr-preview-img"><img src="${qrUrl}" width="${Math.min(size,300)}" height="${Math.min(size,300)}" alt="QR"></div>`;
+      dlUrl      = `${BASE}/api/qr/custom?${qs}&format=${fmt}&download=1`;
-    document.getElementById('qr-dl-row').style.display = 'flex';
-    document.getElementById('qr-download-link').href = qrUrl;
     }
+    document.getElementById('qr-preview-wrap').innerHTML =
+      `<div class="qr-preview-img"><img src="${previewUrl}" width="${Math.min(size,300)}" height="${Math.min(size,300)}" alt="QR"></div>`;
+    document.getElementById('qr-dl-row').style.display = 'flex';
+    dlLink.href = dlUrl;
+    dlLink.download = `qrcode.${fmt}`;
+    dlLink.textContent = `↓ Download ${fmt.toUpperCase()}`;
+    document.getElementById('qr-dl-hint').textContent =
+      fmt === 'svg' ? 'Vector — scales losslessly for print' :
+      fmt === 'pdf' ? 'Print-ready single-page PDF' : 'Right-click to save';
     toast('QR generated!');
+  } catch(e) { toast('Failed to generate QR','error'); }
+  finally { btn.disabled = false; btn.textContent = 'Generate QR Code'; }
 });
 
 // ── Select Mode & Bulk Ops ─────────────────────────