diff --git a/src/lib/api.js b/src/lib/api.js
index e3ed34f..206fb1d 100644
--- a/src/lib/api.js
+++ b/src/lib/api.js
@@ -46,6 +46,12 @@ export const anthropicApi = {
           throw new Error(`API Error: ${response.status} ${response.statusText} - ${JSON.stringify(errData)}`);
         }
 
+        // Detect auth portal session expiry: the portal returns HTML instead of JSON
+        const contentType = response.headers.get('content-type') || '';
+        if (!contentType.includes('application/json')) {
+          throw new Error('Your session has expired. Please refresh the page and log in again.');
+        }
+
         const data = await response.json();
         return data.content[0].text;
       } catch (error) {
diff --git a/src/lib/pb.js b/src/lib/pb.js
index 03fa049..6c82e7e 100644
--- a/src/lib/pb.js
+++ b/src/lib/pb.js
@@ -4,3 +4,13 @@ const pbUrl = import.meta.env.VITE_PB_URL ||
   (typeof window !== 'undefined' ? window.location.origin : 'http://localhost:8090');
 
 export const pb = new PocketBase(pbUrl);
+
+// Detect auth portal session expiry: the portal returns HTML instead of JSON.
+// This prevents cryptic "Unexpected token '<'" errors when the session expires.
+pb.afterSend = function (response, data) {
+  const contentType = response.headers.get('content-type') || '';
+  if (contentType.includes('text/html')) {
+    throw new Error('Your session has expired. Please refresh the page and log in again.');
+  }
+  return data;
+};