diff --git a/backend/static/js/pages/dog-profile.js b/backend/static/js/pages/dog-profile.js
index fdf69ca..6d72005 100644
--- a/backend/static/js/pages/dog-profile.js
+++ b/backend/static/js/pages/dog-profile.js
@@ -133,14 +133,19 @@ window.Page_dog_profile = (() => {
               <div style="font-weight:500;font-size:var(--text-sm)">${dog.gewicht_kg} kg</div>
             </div>
           ` : ''}
-          ${dog.chip_nr ? `
-            <div class="card" style="padding:var(--space-3)">
-              <div style="font-size:var(--text-xs);color:var(--c-text-secondary);
-                          margin-bottom:2px"><svg class="ph-icon" aria-hidden="true"><use href="/icons/phosphor.svg#tag"></use></svg> Chip-Nr.</div>
-              <div style="font-size:var(--text-xs);font-weight:500;
-                          word-break:break-all">${_esc(dog.chip_nr)}</div>
+          <div class="card" style="padding:var(--space-3)">
+            <div style="font-size:var(--text-xs);color:var(--c-text-secondary);
+                        margin-bottom:2px">
+              <svg class="ph-icon" aria-hidden="true"><use href="/icons/phosphor.svg#wave-sine"></use></svg> Transponder
             </div>
-          ` : ''}
+            ${dog.chip_nr
+              ? `<div style="font-size:var(--text-xs);font-weight:500;word-break:break-all">${_esc(dog.chip_nr)}</div>`
+              : `<div style="font-size:var(--text-xs);color:var(--c-text-muted)">nicht eingetragen
+                   <button class="btn btn-link btn-sm" id="dp-chip-edit-btn"
+                           style="padding:0 0 0 var(--space-1);font-size:var(--text-xs)">Eintragen</button>
+                 </div>`
+            }
+          </div>
         </div>
 
         ${dog.bio ? `
@@ -230,9 +235,46 @@ window.Page_dog_profile = (() => {
       }
     });
 
+    // Transponder "Eintragen"-Button
+    document.getElementById('dp-chip-edit-btn')?.addEventListener('click', () => {
+      _showChipEdit(dog);
+    });
+
     // Edit- und Add-Klicks laufen über Event-Delegation in init() — keine direkten Listener nötig.
   }
 
+  function _showChipEdit(dog) {
+    UI.modal.open({
+      title: 'Transpondernummer',
+      body: `
+        <div class="mb-3">
+          <label class="form-label">Chip-Nummer (15-stellig)</label>
+          <input id="chip-edit-input" class="form-control" type="text"
+                 value="${_esc(dog.chip_nr || '')}" placeholder="z.B. 276009200123456" maxlength="20">
+        </div>`,
+      footer: `
+        <button class="btn btn-secondary" onclick="UI.modal.close()">Abbrechen</button>
+        <button class="btn btn-primary" id="chip-edit-save-btn">Speichern</button>`,
+    });
+    document.getElementById('chip-edit-save-btn').addEventListener('click', async () => {
+      const nr  = document.getElementById('chip-edit-input').value.trim() || null;
+      const btn = document.getElementById('chip-edit-save-btn');
+      UI.setLoading(btn, true);
+      try {
+        await API.dogs.update(dog.id, { chip_nr: nr });
+        dog.chip_nr = nr;
+        _appState.activeDog = { ..._appState.activeDog, chip_nr: nr };
+        _appState.dogs = _appState.dogs.map(d => d.id === dog.id ? _appState.activeDog : d);
+        UI.modal.close();
+        UI.toast.success('Transpondernummer gespeichert.');
+        _renderProfile(_appState.activeDog);
+      } catch (e) {
+        UI.setLoading(btn, false);
+        UI.toast.error('Fehler beim Speichern.');
+      }
+    });
+  }
+
   // ----------------------------------------------------------
   // NEU ANLEGEN (direkt auf der Seite, kein Modal)
   // ----------------------------------------------------------
diff --git a/backend/static/js/ui.js b/backend/static/js/ui.js
index 1b6cf14..22f66d0 100644
--- a/backend/static/js/ui.js
+++ b/backend/static/js/ui.js
@@ -259,6 +259,15 @@ const UI = (() => {
     `;
   }
 
+  function escape(str) {
+    if (!str) return '';
+    return String(str)
+      .replace(/&/g, '&amp;')
+      .replace(/</g, '&lt;')
+      .replace(/>/g, '&gt;')
+      .replace(/"/g, '&quot;');
+  }
+
   // Öffentliche API
   return {
     toast, modal,
@@ -267,6 +276,7 @@ const UI = (() => {
     emptyState, time,
     setupPhotoPreview, scrollTop, skeleton,
     icon: _svgIcon,
+    escape,
   };
 
 })();
diff --git a/backend/static/sw.js b/backend/static/sw.js
index 223defb..aec02ba 100644
--- a/backend/static/sw.js
+++ b/backend/static/sw.js
@@ -3,7 +3,7 @@
    Offline-Cache + Push Notifications + Tile-Cache
    ============================================================ */
 
-const CACHE_VERSION = 'by-v142';
+const CACHE_VERSION = 'by-v143';
 const CACHE_STATIC  = `${CACHE_VERSION}-static`;
 const CACHE_TILES   = 'ban-yaro-tiles-v1';  // bleibt über SW-Updates erhalten