Update previous links

webextension/popup.js

@@ -142,6 +142,24 @@ async function populateCurrentTab() {
   urlInput.value = tab.url || '';
 }
 
+async function checkExistingLink() {
+  const settings = await getSettings();
+  if (!settings.backendUrl || !settings.accessToken || !titleInput.value || !urlInput.value) return;
+  try {
+    const response = await fetch(`${settings.backendUrl}/api/links/check?${new URLSearchParams({
+      title: titleInput.value,
+      url: removeKnownTrackingParams(urlInput.value),
+    })}`, {
+      headers: {'Authorization': `Bearer ${settings.accessToken}`},
+    });
+    if (response.ok && (await response.json()).exists) {
+      setStatus(t('duplicateLinkWarning'), true);
+    }
+  } catch (error) {
+    // Duplicate checking is advisory; submission remains available.
+  }
+}
+
 async function handleSubmit(event) {
   event.preventDefault();
   setStatus(t('submitting'), false);
@@ -190,7 +208,8 @@ async function handleSubmit(event) {
       throw new Error(t('submissionFailed'));
     }
 
-    setStatus(t('linkSaved'));
+    const result = await response.json();
+    setStatus(result.duplicate ? t('linkAlreadyExists') : t('linkSaved'), Boolean(result.duplicate));
   } catch (error) {
     setStatus(t('submissionFailedConnection'), true);
   }
@@ -199,6 +218,6 @@ async function handleSubmit(event) {
 openSettingsButton.addEventListener('click', () => browser.runtime.openOptionsPage());
 warningSettingsButton.addEventListener('click', () => browser.runtime.openOptionsPage());
 form.addEventListener('submit', handleSubmit);
-populateCurrentTab();
+populateCurrentTab().then(checkExistingLink);
 loadExistingTags();
 updateFeedLink();