From 0041e8f2d2b057544af9d000b61806186ddbde69 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=98yvind=20Eikeland?= <oyvind@eikeland.me>
Date: Mon, 3 Aug 2026 09:07:25 +0200
Subject: [PATCH 1/2] fix(filter): refactor selected count calculation in
 FilterOptionHeader

---
 packages/filter/src/components/filter/FilterOptionHeader.tsx | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/packages/filter/src/components/filter/FilterOptionHeader.tsx b/packages/filter/src/components/filter/FilterOptionHeader.tsx
index 2f7cdafcf..3e9178209 100644
--- a/packages/filter/src/components/filter/FilterOptionHeader.tsx
+++ b/packages/filter/src/components/filter/FilterOptionHeader.tsx
@@ -14,6 +14,8 @@ type FilterHeaderProps = {
   readonly title: string;
 };
 
+const getSelectedCount = (selection?: Set<unknown>): number => selection?.size ?? 0;
+
 const Styled = {
   Root: styled.div`
     display: flex;
@@ -63,7 +65,7 @@ export const FilterOptionHeader = (props: FilterHeaderProps): ReactElement => {
   const { options$, selection$ } = useFilterOptionContext();
   const optionCount = Object.keys(useObservableState(options$).value || {}).length;
   const { value: selectedCount } = useObservableState(
-    useObservableSelector(selection$, (x) => (x ?? new Set()).size),
+    useObservableSelector(selection$, getSelectedCount),
     { initial: 0 },
   );
 

From 0318e17fab7214731eeaa0bb9f52b3d04e8bbca5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=98yvind=20Eikeland?= <oyvind@eikeland.me>
Date: Mon, 3 Aug 2026 09:11:16 +0200
Subject: [PATCH 2/2] fix(filter): prevent infinite render loop in
 FilterOptionHeader

---
 .changeset/stable-filter-selector.md | 5 +++++
 1 file changed, 5 insertions(+)
 create mode 100644 .changeset/stable-filter-selector.md

diff --git a/.changeset/stable-filter-selector.md b/.changeset/stable-filter-selector.md
new file mode 100644
index 000000000..274c288f3
--- /dev/null
+++ b/.changeset/stable-filter-selector.md
@@ -0,0 +1,5 @@
+---
+"@equinor/fusion-react-filter": patch
+---
+
+Prevent `FilterOptionHeader` from entering an infinite render loop after upgrading `@equinor/fusion-observable` by keeping its selection count selector stable across renders.