fix: enforce a single open user profile preview across ProfilePreview instances (#27578)

src/lib/components/channel/Messages/Message/ProfilePreview.svelte

@@ -1,6 +1,17 @@
+<script context="module" lang="ts">
+	/**
+	 * At most one user profile preview may be open across all ProfilePreview
+	 * instances. bits-ui's safe-polygon close only re-evaluates on pointermove,
+	 * so a preview can be left open when the pointer stops on a neighboring
+	 * row while still inside the previous row's grace area; opening a preview
+	 * therefore force-closes whichever one is still up.
+	 */
+	let closeActiveProfilePreview: (() => void) | null = null;
+</script>
+
 <script lang="ts">
 	import { LinkPreview } from 'bits-ui';
-	import { getContext } from 'svelte';
+	import { getContext, onDestroy } from 'svelte';
 
 	const i18n = getContext('i18n');
 	import UserStatus from './UserStatus.svelte';
@@ -13,6 +24,23 @@
 	export let sideOffset = 8;
 
 	let openPreview = false;
+
+	const closeProfilePreview = () => {
+		if (openPreview) {
+			openPreview = false;
+		}
+	};
+
+	$: if (openPreview && closeActiveProfilePreview !== closeProfilePreview) {
+		closeActiveProfilePreview?.();
+		closeActiveProfilePreview = closeProfilePreview;
+	}
+
+	onDestroy(() => {
+		if (closeActiveProfilePreview === closeProfilePreview) {
+			closeActiveProfilePreview = null;
+		}
+	});
 </script>
 
 <LinkPreview.Root openDelay={0} closeDelay={200} bind:open={openPreview}>