diff --git a/pkg/appview/src/js/repository.js b/pkg/appview/src/js/repository.js
index 23f9548..a2d9934 100644
--- a/pkg/appview/src/js/repository.js
+++ b/pkg/appview/src/js/repository.js
@@ -299,11 +299,38 @@ function initTabController() {
         const selector = document.getElementById('tag-selector');
         if (!content || !selector || !to) return;
         const currentTag = selector.value;
+        // Backstop: syncDiffMenu() hides the current tag's entry, but keep the
+        // guard in case it's reached some other way (keyboard, stale DOM).
         if (!currentTag || to === currentTag) return;
         window.location.href = '/diff/' + content.dataset.owner + '/' + content.dataset.repo +
             '?from=' + encodeURIComponent(currentTag) + '&to=' + encodeURIComponent(to);
     };
 
+    // Hide the currently-selected tag from the "Diff" menu — diffing a tag
+    // against itself is a no-op (see the guard in diffToTag above), so the
+    // entry is dead weight in the menu.
+    //
+    // This has to live in JS, not the template: #diff-dropdown sits OUTSIDE
+    // #tag-content and is never re-rendered, so a template-side filter would
+    // be right on first paint and stale after the first htmx tag swap. Called
+    // from initTabs(), which runs on load and again on every tag swap.
+    //
+    // The template guards the whole dropdown with {{ if gt (len .AllTags) 1 }}
+    // and tags are unique per repo (tags PK is did+repository+tag), so hiding
+    // exactly one entry always leaves at least one behind — never an empty menu.
+    function syncDiffMenu() {
+        const selector = document.getElementById('tag-selector');
+        const menu = document.getElementById('diff-dropdown');
+        if (!selector || !menu) return;
+        const currentTag = selector.value;
+        menu.querySelectorAll('[data-action="diff-to"]').forEach(btn => {
+            const item = btn.closest('li') || btn;
+            // Inline style, matching filterTags() above: beats the daisyUI
+            // menu's own display rules without a specificity fight.
+            item.style.display = (btn.dataset.diffTo === currentTag) ? 'none' : '';
+        });
+    }
+
     window.switchRepoTab = function(tabId) {
         window._activeRepoTab = tabId;
         const section = document.getElementById('tag-content');
@@ -338,6 +365,8 @@ function initTabController() {
     function initTabs() {
         loaded = {};
 
+        syncDiffMenu();
+
         const prefetch = [
             ['artifacts-tab-btn', 'artifacts-content', tagsUrl],
             ['layers-tab-btn', 'layers-content', () => contentUrl('layers')],