docs: record dropdown scroll fix + language picker search gotchas

AGENTS.md

@@ -1444,6 +1444,19 @@ session with **no other memory of this project**. So:
   also add `min-w-0` to truncating flex/grid children. `/stats` also gained a
   **Top Shops** leaderboard (`topShops` in `useGrowthStats`; `PERSIST_BUSTER` → v6)
   alongside Top Mappers (spots).
+- **Dropdown menu scroll gotcha (2026-10-08):** the shared `DropdownMenuContent`
+  (`components/ui/dropdown-menu.tsx`) shipped `overflow-hidden` with **no
+  max-height**, so any menu taller than the viewport was clipped and could not
+  scroll to its last items (the language picker, now 22 locales, was cut off at
+  the bottom). It now carries
+  `max-h-[var(--radix-dropdown-menu-content-available-height)]` +
+  `overflow-y-auto overflow-x-hidden` (canonical shadcn). Radix exposes that var
+  but nothing applies it. Keep it if you add more long menus. The language picker
+  (`LanguageToggle`) also gained a **search input** in both the header dropdown
+  (sticky above the scrolling list; input stops `keyDown`/`pointerDown`
+  propagation so Radix typeahead does not hijack typing) and the inline/mobile
+  variant; keys `nav.searchLanguages`/`nav.noLanguages` live in en/es only (other
+  locales fall back). The Settings `LanguageSelector` grid is searchless by design.
 - **Community stats (`/stats`, 2026-10-01):** `useGrowthStats` + `CommunityStatsPage`.
   - ⚠️ **A relay outage used to render a board of ZEROS as truth** — every
     sub-query ended in `.catch(() => [])`. The queryFn now counts failures (a