From 4f24ac2733ba312d63c86ff569d7fe4e1b94cdae Mon Sep 17 00:00:00 2001
From: BoulderBadgeDad <batmanesignal@gmail.com>
Date: Tue, 23 Jun 2026 10:00:52 -0700
Subject: [PATCH] video discover: stop duplicate 'Recommended for you' rows
 stacking on rail rebuild

Toggling service/language chips calls reloadRails(), which clears the shelves synchronously
but the personalized loaders (foryou/gaps/morelike) fetch async and insertAdjacentHTML afterbegin.
Rapid re-toggles let superseded in-flight fetches prepend anyway -> N 'Recommended for you' rows
piled up. Each rebuild now bumps state.railGen and every loader bails if its captured gen is
stale before prepending; chip-driven rebuilds are also debounced (350ms) so multi-select
coalesces into one rebuild. The 'On your streaming services' rail itself was building fine -
it was just buried under the duplicates.
---
 webui/static/video/video-discover.js | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/webui/static/video/video-discover.js b/webui/static/video/video-discover.js
index 53a815b4..53390494 100644
--- a/webui/static/video/video-discover.js
+++ b/webui/static/video/video-discover.js
@@ -383,9 +383,11 @@
 
     // ── "More like <owned title>" rails (pre-filled, prepended above the stack) ─
     function loadMoreLike() {
+        var gen = state.railGen || 0;
         fetch('/api/video/discover/morelike', { headers: { Accept: 'application/json' } })
             .then(function (r) { return r.ok ? r.json() : null; })
             .then(function (d) {
+                if (gen !== (state.railGen || 0)) return;   // a newer rebuild superseded this
                 var rails = (d && d.rails) || [];
                 var host = $('[data-vdsc-shelves]');
                 if (!rails.length || !host) return;
@@ -411,9 +413,11 @@
     // ── "What am I missing?" gap rails — franchises you've started but not finished,
     //    and more from the directors/creators you own the most (prepended on top). ──
     function loadGaps() {
+        var gen = state.railGen || 0;
         fetch('/api/video/discover/gaps', { headers: { Accept: 'application/json' } })
             .then(function (r) { return r.ok ? r.json() : null; })
             .then(function (d) {
+                if (gen !== (state.railGen || 0)) return;   // a newer rebuild superseded this
                 var rails = (d && d.rails) || [];
                 var host = $('[data-vdsc-shelves]');
                 if (!rails.length || !host) return;
@@ -438,9 +442,11 @@
 
     // ── "Recommended for you" — one wall blended from across your library, prepended on top ─
     function loadForYou() {
+        var gen = state.railGen || 0;
         fetch('/api/video/discover/foryou', { headers: { Accept: 'application/json' } })
             .then(function (r) { return r.ok ? r.json() : null; })
             .then(function (d) {
+                if (gen !== (state.railGen || 0)) return;   // a newer rebuild superseded this
                 var items = (d && d.items) || [];
                 var host = $('[data-vdsc-shelves]');
                 if (items.length < 6 || !host) return;
@@ -462,12 +468,21 @@
     }
 
     // Rebuild the whole rail stack (genre/curated shelves + the prepended personalized rows).
+    // Each rebuild bumps railGen; in-flight personalized loaders from a superseded rebuild check
+    // it before prepending, so rapid re-toggles can't stack duplicate "Recommended for you" rows.
     function reloadRails() {
+        state.railGen = (state.railGen || 0) + 1;
         renderShelves();
         loadMoreLike();
         loadGaps();
         loadForYou();
     }
+    // Coalesce rapid chip toggles (e.g. picking 3 services) into a single rebuild.
+    var _reloadTimer;
+    function reloadRailsSoon() {
+        clearTimeout(_reloadTimer);
+        _reloadTimer = setTimeout(reloadRails, 350);
+    }
 
     // ── shelves (lazy rails) ──────────────────────────────────────────────────
     function renderShelves() {
@@ -727,7 +742,7 @@
                 fetch('/api/video/discover/languages', {
                     method: 'POST', headers: { 'Content-Type': 'application/json' },
                     body: JSON.stringify({ languages: langs }),
-                }).then(function () { reloadRails(); }).catch(function () { /* ignore */ });
+                }).then(function () { reloadRailsSoon(); }).catch(function () { /* ignore */ });
             });
         }
         // 'My streaming services' preference — multi-select; drives the 'On your services' rail.
@@ -752,7 +767,7 @@
                 fetch('/api/video/discover/providers-pref', {
                     method: 'POST', headers: { 'Content-Type': 'application/json' },
                     body: JSON.stringify({ providers: provs }),
-                }).then(function () { reloadRails(); }).catch(function () { /* ignore */ });
+                }).then(function () { reloadRailsSoon(); }).catch(function () { /* ignore */ });
             });
         }
         // Infinite scroll: a sentinel near the grid bottom pulls the next page.