CBP ref fallback chain: own entry -> upline sponsor's entry -> company (Marty's rule)

Endpoint walks one hop up ref_by when the member's own program-73 entry is
empty; response carries source: self|sponsor. Calculator shows an adapted
nudge on upline fallback (alignment held, but claim your own referrals).
Hub invite still aligns to the SHARER either way.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

index.html

@@ -2370,9 +2370,16 @@ function updateHubLinks() {
   }
 }
 
-function showSponsorNudge() {
+function showSponsorNudge(kind) {
   const el = document.getElementById('sponsorNudge');
-  if (el) el.style.display = 'block';
+  if (!el) return;
+  if (kind === 'sponsor') {
+    // Endpoint resolved the CBP ref from the member's UPLINE sponsor's entry
+    // (fallback chain: own entry → upline's entry → company). Alignment held,
+    // but the sharer should still claim their own referrals.
+    el.innerHTML = '⚠️ This sponsor hasn’t added their own ClickBaitPays username in CryptoTeamBuild yet, so sign-ups credit their upline sponsor for now. <strong>Sponsors:</strong> log into CryptoTeamBuild → Downline Builder → ClickBaitPays → enter your ClickBaitPays username, and your links switch to you automatically.';
+  }
+  el.style.display = 'block';
 }
 
 async function resolveIdentity() {
@@ -2387,6 +2394,7 @@ async function resolveIdentity() {
       if (r.found) {
         IDENT.cbp = r.cbpUsername;
         IDENT.ctb = r.ctbUsername;
+        if (r.source === 'sponsor') IDENT.uplineFallback = true;
       } else {
         const rv = await fetch(`${CTB_LOOKUP_URL}?cbp=${encodeURIComponent(ctbParam)}`).then(x => x.json());
         if (rv.found) {
@@ -2413,6 +2421,7 @@ async function resolveIdentity() {
         if (f.found) {
           IDENT.cbp = f.cbpUsername;
           IDENT.ctb = f.ctbUsername;
+          if (f.source === 'sponsor') IDENT.uplineFallback = true;
         }
       }
     }
@@ -2423,6 +2432,7 @@ async function resolveIdentity() {
   updateSharedLinkBox();
   updateHubLinks();
   if (IDENT.fallback) showSponsorNudge();
+  else if (IDENT.uplineFallback) showSponsorNudge('sponsor');
 }
 
 function getBaseUrl() {