diff --git a/app/app.py b/app/app.py
index e20597d..ce6f90e 100644
--- a/app/app.py
+++ b/app/app.py
@@ -1,6 +1,7 @@
 import io
 import json
 import os
+import re
 import shutil
 import subprocess
 import threading
@@ -663,6 +664,44 @@ def upload_file():
     return redirect(url_for("browse", subpath=subpath) if subpath else url_for("browse"))
 
 
+# ── Vérification des conflits avant redimensionnement ────────────────
+
+@app.route("/check-resize", methods=["POST"])
+def check_resize():
+    redir = _require_admin()
+    if redir:
+        return redir
+
+    subpath    = request.form.get("path", "").strip()
+    raw_sizes  = request.form.getlist("sizes")
+    raw_formats = request.form.getlist("formats")
+
+    if not subpath:
+        return jsonify({"conflicts": []})
+
+    target = _safe_path(subpath)
+    if not target.is_file():
+        return jsonify({"conflicts": []})
+
+    try:
+        sizes = [int(s) for s in raw_sizes if int(s) in RESIZE_SIZES]
+    except (ValueError, TypeError):
+        return jsonify({"conflicts": []})
+
+    formats = [f for f in raw_formats if f in RESIZE_FORMATS]
+    stem    = re.sub(r"_\d+x\d+$", "", target.stem)
+    parent  = target.parent
+
+    conflicts = []
+    for fmt in formats:
+        for size in sizes:
+            out_name = f"{stem}_{size}x{size}.{fmt}"
+            if (parent / out_name).exists():
+                conflicts.append(out_name)
+
+    return jsonify({"conflicts": conflicts})
+
+
 # ── Redimensionnement d'images ────────────────────────────────────────
 
 @app.route("/resize", methods=["POST"])
@@ -704,7 +743,7 @@ def resize_image():
         conflict = "skip"
 
     is_svg = ext == ".svg"
-    stem   = target.stem
+    stem   = re.sub(r"_\d+x\d+$", "", target.stem)
     parent = target.parent
     created, errors = [], []
 
diff --git a/app/templates/preview_image.html b/app/templates/preview_image.html
index 00c9641..fb76e26 100644
--- a/app/templates/preview_image.html
+++ b/app/templates/preview_image.html
@@ -122,33 +122,25 @@
       </div>
     </div>
 
-    <div class="resize-group">
-      <div class="resize-group-label">Si le fichier existe déjà</div>
-      <div class="resize-chips resize-chips--radio">
-        <label class="chip">
-          <input type="radio" name="conflict" value="backup" checked>
-          <span>Backup</span>
-        </label>
-        <label class="chip">
-          <input type="radio" name="conflict" value="overwrite">
-          <span>Écraser</span>
-        </label>
-        <label class="chip">
-          <input type="radio" name="conflict" value="rename">
-          <span>Renommer la copie</span>
-        </label>
-        <label class="chip">
-          <input type="radio" name="conflict" value="skip">
-          <span>Ignorer</span>
-        </label>
-      </div>
-    </div>
-
     <div class="resize-actions">
       <button id="resize-btn" class="btn btn-primary" disabled>Générer les copies</button>
       <span class="resize-hint">Les fichiers sont créés dans le même dossier</span>
     </div>
 
+    <div id="resize-conflict-panel" class="conflict-panel" style="display:none">
+      <p class="conflict-title">⚠ Ces fichiers existent déjà : <strong id="resize-conflict-list"></strong></p>
+      <div class="resize-chips resize-chips--radio">
+        <label class="chip"><input type="radio" name="resize-conflict" value="backup" checked><span>Backup</span></label>
+        <label class="chip"><input type="radio" name="resize-conflict" value="overwrite"><span>Écraser</span></label>
+        <label class="chip"><input type="radio" name="resize-conflict" value="rename"><span>Renommer</span></label>
+        <label class="chip"><input type="radio" name="resize-conflict" value="skip"><span>Ignorer</span></label>
+      </div>
+      <div class="conflict-actions">
+        <button type="button" id="resize-confirm" class="btn btn-primary">Confirmer la génération</button>
+        <button type="button" id="resize-cancel-conflict" class="btn-rename-cancel">Annuler</button>
+      </div>
+    </div>
+
     <div id="resize-result" class="resize-result" style="display:none"></div>
 
   </div>
@@ -205,11 +197,17 @@
   });
 
   /* ── Resize ── */
-  const szCbs  = document.querySelectorAll('.resize-sz');
-  const fmtCbs = document.querySelectorAll('.resize-fmt');
-  const btn    = document.getElementById('resize-btn');
-  const result = document.getElementById('resize-result');
-  const RESIZE_URL = {{ url_for('resize_image') | tojson }};
+  const szCbs         = document.querySelectorAll('.resize-sz');
+  const fmtCbs        = document.querySelectorAll('.resize-fmt');
+  const btn           = document.getElementById('resize-btn');
+  const result        = document.getElementById('resize-result');
+  const conflictPanel = document.getElementById('resize-conflict-panel');
+  const conflictList  = document.getElementById('resize-conflict-list');
+  const confirmBtn    = document.getElementById('resize-confirm');
+  const cancelConflict= document.getElementById('resize-cancel-conflict');
+  const RESIZE_URL      = {{ url_for('resize_image')  | tojson }};
+  const CHECK_RESIZE_URL= {{ url_for('check_resize')  | tojson }};
+  let resizeResolved = false;
 
   function canSubmit() {
     return Array.from(szCbs).some(c => c.checked)
@@ -217,10 +215,11 @@
   }
   [...szCbs, ...fmtCbs].forEach(c => c.addEventListener('change', () => {
     btn.disabled = !canSubmit();
+    conflictPanel.style.display = 'none';
+    resizeResolved = false;
   }));
 
-  btn.addEventListener('click', async () => {
-    const conflict = document.querySelector('input[name="conflict"]:checked')?.value || 'skip';
+  async function doResize(conflict) {
     const fd = new FormData();
     fd.append('path',     FILE_PATH);
     fd.append('conflict', conflict);
@@ -235,7 +234,6 @@
       const resp = await fetch(RESIZE_URL, { method: 'POST', body: fd });
       const data = await resp.json();
       let html = '';
-
       if (data.created && data.created.length) {
         html += '<p class="resize-ok-title">✓ ' + data.created.length + ' fichier(s) créé(s)</p>';
         html += '<ul class="resize-list">';
@@ -257,10 +255,43 @@
     } catch (_) {
       result.innerHTML = '<p class="resize-err-title">Erreur réseau.</p>';
     }
-
     result.style.display = 'block';
     btn.textContent = 'Générer les copies';
     btn.disabled = !canSubmit();
+    resizeResolved = false;
+  }
+
+  btn.addEventListener('click', async () => {
+    const fd = new FormData();
+    fd.append('path', FILE_PATH);
+    szCbs.forEach(c  => { if (c.checked) fd.append('sizes',   c.value); });
+    fmtCbs.forEach(c => { if (c.checked) fd.append('formats', c.value); });
+
+    let conflicts = [];
+    try {
+      const resp = await fetch(CHECK_RESIZE_URL, { method: 'POST', body: fd });
+      const data = await resp.json();
+      conflicts = data.conflicts || [];
+    } catch (_) { /* réseau : on génère directement */ }
+
+    if (!conflicts.length) {
+      doResize('overwrite');
+      return;
+    }
+
+    conflictList.textContent = conflicts.join(', ');
+    conflictPanel.style.display = 'block';
+    conflictPanel.scrollIntoView({ behavior: 'smooth', block: 'nearest' });
+  });
+
+  confirmBtn.addEventListener('click', () => {
+    const strategy = document.querySelector('input[name="resize-conflict"]:checked')?.value || 'skip';
+    conflictPanel.style.display = 'none';
+    doResize(strategy);
+  });
+
+  cancelConflict.addEventListener('click', () => {
+    conflictPanel.style.display = 'none';
   });
 })();
 </script>