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Keep active sidebar item visible across navigation #380

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ehfeng wants to merge 3 commits into from
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Keep active sidebar item visible across navigation #380

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8af0335
Keep active sidebar item visible across navigation
ehfeng May 27, 2026
5d56cf8
Trim explanatory comments in sidebar-scroll.js
ehfeng May 27, 2026
e2ef311
Trigger sidebar scroll on data-current-path mutation
ehfeng May 27, 2026
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50 changes: 50 additions & 0 deletions sidebar-scroll.js
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Original file line number Diff line number Diff line change
@@ -0,0 +1,50 @@
(function () {
if (typeof window === "undefined") return;

// Mintlify's markup is not a stable contract; take the first scrollable match.
function findSidebar() {
var candidates = document.querySelectorAll(
"aside, nav[aria-label='Sidebar'], aside[aria-label='Sidebar'], #sidebar"
);
for (var i = 0; i < candidates.length; i++) {
if (candidates[i].scrollHeight > candidates[i].clientHeight + 1) {
return candidates[i];
}
}
return null;
}

function showActive() {
var sb = findSidebar();
if (!sb) return;
var link = sb.querySelector(
"a[aria-current='page'], a[aria-current='true'], a[data-active='true']"
);
// Guard against acting on the previous page's link before the DOM updates.
if (!link || link.pathname !== location.pathname) return;
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@cursor cursor Bot May 27, 2026

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No retry after race condition guard causes silent failure

Medium Severity

On SPA navigation, data-current-path on <html> triggers the MutationObserver, which schedules a single requestAnimationFrame(showActive). If Mintlify's React render cycle hasn't yet updated aria-current on sidebar links by the time that frame fires, the guard on line 24 (link.pathname !== location.pathname) correctly bails out to avoid acting on the old link — but there is no retry. The feature silently becomes a no-op for that navigation. The PR description mentions "polling until the sidebar mounts plus one 150ms re-apply" but neither mechanism is actually implemented.

Additional Locations (1)
Fix in Cursor Fix in Web

Reviewed by Cursor Bugbot for commit e2ef311. Configure here.


var sbRect = sb.getBoundingClientRect();
var linkRect = link.getBoundingClientRect();
var margin = 24;

if (linkRect.top < sbRect.top + margin) {
sb.scrollTop -= sbRect.top + margin - linkRect.top;
} else if (linkRect.bottom > sbRect.bottom - margin) {
sb.scrollTop += linkRect.bottom - (sbRect.bottom - margin);
}
}

// Mintlify has no navigation event, but it rewrites data-current-path on
// <html> on every client-side route change. That mutation is our signal.
var html = document.documentElement;
var last = html.getAttribute("data-current-path");
new MutationObserver(function () {
var cur = html.getAttribute("data-current-path");
if (cur === last) return;
last = cur;
requestAnimationFrame(showActive);
}).observe(html, { attributes: true, attributeFilter: ["data-current-path"] });

if (document.readyState === "complete") showActive();
else window.addEventListener("load", showActive);
})();
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