diff --git a/bincio/serve/routers/me.py b/bincio/serve/routers/me.py
index 4809b52..bd6c76c 100644
--- a/bincio/serve/routers/me.py
+++ b/bincio/serve/routers/me.py
@@ -317,3 +317,26 @@ async def me_change_password(
         raise HTTPException(400, "New password must be at least 8 characters")
     _change_password(deps._get_db(), user.handle, new_pw)
     return JSONResponse({"ok": True})
+
+
+@router.get("/api/me/sync-status")
+async def get_sync_status(
+    bincio_session: str | None = Cookie(default=None),
+) -> JSONResponse:
+    """Return the last sync status for Strava and Garmin for the logged-in user."""
+    user = deps._require_user(bincio_session)
+    user_dir = deps._get_data_dir() / user.handle
+
+    def _read_status(filename: str) -> dict | None:
+        p = user_dir / filename
+        try:
+            return json.loads(p.read_text(encoding="utf-8"))
+        except (OSError, json.JSONDecodeError):
+            return None
+
+    strava = _read_status("_strava_sync_status.json")
+    garmin = _read_status("_garmin_sync_status.json")
+    return JSONResponse({
+        "strava": strava,
+        "garmin": garmin,
+    })
diff --git a/site/src/layouts/Base.astro b/site/src/layouts/Base.astro
index 0a62e14..c5f1c93 100644
--- a/site/src/layouts/Base.astro
+++ b/site/src/layouts/Base.astro
@@ -663,6 +663,25 @@ try {
             if (wikiElM) wikiElM.style.display = '';
           }
 
+          // Sync error: turn upload button orange if Strava or Garmin auth failed
+          try {
+            const sr = await fetch('/api/me/sync-status', { credentials: 'include' });
+            if (sr.ok) {
+              const ss = await sr.json();
+              const errServices = [
+                ss.strava?.status === 'auth_error' ? 'Strava' : null,
+                ss.garmin?.status === 'auth_error' ? 'Garmin' : null,
+              ].filter(Boolean);
+              if (errServices.length > 0) {
+                const btn = document.getElementById('upload-btn');
+                if (btn) {
+                  btn.style.color = '#f97316';
+                  btn.title = `${errServices.join(' & ')} connection lost — open to reconnect`;
+                }
+              }
+            }
+          } catch (_) {}
+
           // Admin: show admin link and poll for active jobs
           if (user.is_admin) {
             const adminLink = document.getElementById('nav-admin');