From 402641b6058f5a2d97b94667f1921a7208e749fa Mon Sep 17 00:00:00 2001
From: Marie Lucca <francinelucca@github.com>
Date: Wed, 28 Jan 2026 16:16:50 -0500
Subject: [PATCH 1/3] remove primer_react_overlay_overflow FF from the codebase

---
 .../react/src/FeatureFlags/DefaultFeatureFlags.ts  |  1 -
 packages/react/src/Overlay/Overlay.test.tsx        | 14 --------------
 packages/react/src/Overlay/Overlay.tsx             |  4 +---
 3 files changed, 1 insertion(+), 18 deletions(-)

diff --git a/packages/react/src/FeatureFlags/DefaultFeatureFlags.ts b/packages/react/src/FeatureFlags/DefaultFeatureFlags.ts
index 4a2c0896f50..6b84dfc8215 100644
--- a/packages/react/src/FeatureFlags/DefaultFeatureFlags.ts
+++ b/packages/react/src/FeatureFlags/DefaultFeatureFlags.ts
@@ -4,7 +4,6 @@ export const DefaultFeatureFlags = FeatureFlagScope.create({
   primer_react_action_list_item_as_button: false,
   primer_react_breadcrumbs_overflow_menu: false,
   primer_react_css_has_selector_perf: false,
-  primer_react_overlay_overflow: false,
   primer_react_select_panel_fullscreen_on_narrow: false,
   primer_react_select_panel_order_selected_at_top: false,
   primer_react_select_panel_remove_active_descendant: false,
diff --git a/packages/react/src/Overlay/Overlay.test.tsx b/packages/react/src/Overlay/Overlay.test.tsx
index d6dde8d506e..f1d6400d4ab 100644
--- a/packages/react/src/Overlay/Overlay.test.tsx
+++ b/packages/react/src/Overlay/Overlay.test.tsx
@@ -352,18 +352,4 @@ describe('Overlay', () => {
     const container = getByRole('dialog')
     expect(container).not.toHaveAttribute('data-reflow-container')
   })
-
-  it('should `data-reflow-container` if FF is enabled', async () => {
-    const user = userEvent.setup()
-    const {getByRole} = render(
-      <FeatureFlags flags={{primer_react_overlay_overflow: true}}>
-        <TestComponent />
-      </FeatureFlags>,
-    )
-
-    await user.click(getByRole('button', {name: 'open overlay'}))
-
-    const container = getByRole('dialog')
-    expect(container).toHaveAttribute('data-reflow-container')
-  })
 })
diff --git a/packages/react/src/Overlay/Overlay.tsx b/packages/react/src/Overlay/Overlay.tsx
index 9f588146323..362083945e2 100644
--- a/packages/react/src/Overlay/Overlay.tsx
+++ b/packages/react/src/Overlay/Overlay.tsx
@@ -8,7 +8,6 @@ import Portal from '../Portal'
 import {useRefObjectAsForwardedRef} from '../hooks/useRefObjectAsForwardedRef'
 import type {AnchorSide} from '@primer/behaviors'
 import type {ForwardRefComponent as PolymorphicForwardRefComponent} from '../utils/polymorphic'
-import {useFeatureFlag} from '../FeatureFlags'
 import classes from './Overlay.module.css'
 import {clsx} from 'clsx'
 
@@ -230,13 +229,12 @@ const Overlay = React.forwardRef<HTMLDivElement, internalOverlayProps>(
     // To be backwards compatible with the old Overlay, we need to set the left prop if x-position is not specified
     const leftPosition = left === undefined && right === undefined ? 0 : left
 
-    const overflowEnabled = useFeatureFlag('primer_react_overlay_overflow')
     return (
       <Portal containerName={portalContainerName}>
         <BaseOverlay
           role={role}
           width={width}
-          data-reflow-container={overflowEnabled || !preventOverflow ? true : undefined}
+          data-reflow-container={!preventOverflow ? true : undefined}
           ref={overlayRef}
           left={leftPosition}
           right={right}

From f1cda330b8cc7abfc06fdeea2776dfe0300febea Mon Sep 17 00:00:00 2001
From: Marie Lucca <francinelucca@github.com>
Date: Wed, 28 Jan 2026 16:24:59 -0500
Subject: [PATCH 2/3] remove unused import

---
 packages/react/src/Overlay/Overlay.test.tsx | 1 -
 1 file changed, 1 deletion(-)

diff --git a/packages/react/src/Overlay/Overlay.test.tsx b/packages/react/src/Overlay/Overlay.test.tsx
index f1d6400d4ab..b43ecc99e93 100644
--- a/packages/react/src/Overlay/Overlay.test.tsx
+++ b/packages/react/src/Overlay/Overlay.test.tsx
@@ -7,7 +7,6 @@ import Overlay from '../Overlay'
 import Text from '../Text'
 import BaseStyles from '../BaseStyles'
 import {NestedOverlays, MemexNestedOverlays, MemexIssueOverlay, PositionedOverlays} from './Overlay.features.stories'
-import {FeatureFlags} from '../FeatureFlags'
 import {implementsClassName} from '../utils/testing'
 import classes from './Overlay.module.css'
 

From 2330a0be421c76c371d6c6f5dce3e689c8ba1ad6 Mon Sep 17 00:00:00 2001
From: Marie Lucca <40550942+francinelucca@users.noreply.github.com>
Date: Wed, 28 Jan 2026 16:25:14 -0500
Subject: [PATCH 3/3] Create flat-gifts-swim.md

---
 .changeset/flat-gifts-swim.md | 5 +++++
 1 file changed, 5 insertions(+)
 create mode 100644 .changeset/flat-gifts-swim.md

diff --git a/.changeset/flat-gifts-swim.md b/.changeset/flat-gifts-swim.md
new file mode 100644
index 00000000000..c43a24d9e5d
--- /dev/null
+++ b/.changeset/flat-gifts-swim.md
@@ -0,0 +1,5 @@
+---
+"@primer/react": patch
+---
+
+remove primer_react_overlay_overflow FF from the codebase