Evaluate existing major bumps of backpack dependency for v39

[Faye-Xiao]

🧭 Backpack v39 Major dependency Bump PRs Review Summary

PR	Title	Core Change	Impact Assessment	Key Reasoning	Note	Status
#3994	Bump react & @types/react	Upgraded React 18.3.1 → 19.2.0 (+ types).	Breaking: React 19 removes defaultProps on FCs, Legacy Context, string refs; requires new JSX transform; useId IDs changed.	React 19 is still under internal evaluation	Deferred it until we decide to upgrade it to 19.x	Evaluated and deferred it.
#3996	Bump react-dom & @types/react-dom	Upgraded react-dom 18.3.1 → 19.2.0 (+ types).	Breaking: Removed ReactDOM.render/hydrate/unmountComponentAtNode; SSR & Suspense behavior changed; useId ID format changed.	It should be aligned with React, and React 19 is still under internal evaluation	Deferred it until we upgrade react to 19.x.	Evaluated and deferred it.
#3997	Bump @types/react-window 1.8.8 → 2.0.0	Type-only upgrade (devDependency)	External: None. Internal: Possible new TS hints in examples.	Adopting the type upgrade only would cause a type mismatch with the react-window@18.x, while upgrading both requires a code change. Deserved a careful validation.	Its version should be aligned with the react-window's version.	Evaluated and deferred it.
#3995	Bump @percy/storybook 6.0.3 → 9.1.0	Visual regression tooling upgrade	External: None. Internal: CI screenshot config may change.	CI tooling only; no runtime effect.	🔹 Downgrade to minor + Re-baseline Percy snapshots.	✅
#3865	Bump Storybook 8.6 → 9.0	Dev/documentation environment upgrade	External: None. Internal: Config migration required.	Developer docs only; not user-facing.	🔹 Downgrade to minor + Validate Storybook build and addons.	✅
#3992	Bump glob 10.4.5 → 11.0.3	Drops Node < 20	External: None (not runtime). Internal: Requires Node 20+.	Affects build scripts only; Node version compatibility risk.	🔹 Downgrade to minor + Ensure CI uses Node 20 or pin to ^10.	✅
#3794	Bump normalize.css 4.2.0 → 8.0.1	Major CSS reset evolution (4→8)	External: Potentially breaking if distributed styles include it. Internal: Storybook/Docs may show visual drift.	normalize.css changed base resets significantly; could affect visual baselines.	⚠️ Keep as major if exported styles; minor if docs-only + Verify via Percy diff.	🧪 To be tested

🧭 Confirmed Major Change PRs for Backpack v39

PR	Title	Core Change	Impact	How to Use / Migration	Status	Note
#4007	Deprecate SCSS @import in Backpack Clean up	Removed legacy SCSS @import usages, removed node-sass dependency, switched all mixins to stable bpk-mixins instead of unstable__bpk­-mixins. oai_citation:0‡GitHub	Breaking for consumers who still use @import or import from unstable__bpk-mixins. Build/config may fail or styles may be missing.	Consumers must change all @import to @use, and update any import paths from unstable__bpk-mixins → bpk-mixins. oai_citation:1‡GitHub	approved + tested	Major change: mark as breaking.
#3990	[BpkCardList] use negative margin to remove bottom padding	Adjusted internal padding/margin of BpkCardListCarousel: removed top 0.25 rem padding, removed bottom 1 rem padding when accessory is not rendered; switched to a consistent positive padding + negative margin technique. oai_citation:2‡GitHub	Breaking layout for consumers relying on the old built-in bottom padding; will alter spacing when accessory not present.	If you used BpkCardList in ROW or RAIL layout without accessory, you may need to add your own 1 rem bottom spacing to maintain previous layout. oai_citation:3‡GitHub	approved + tested	Major change: layout impact.
#3979	Deprecate SCSS @import in Backpack (Modern Sass API)	Similar to #4007: removed all @import, switched to @use, consolidated mixins. oai_citation:4‡GitHub	Breaking for styling consumers using @import or unstable__bpk-mixins.	Consumers must change import syntax to @use and update paths to bpk-mixins. oai_citation:5‡GitHub	approved + tested	Major change; schedule for v39.
#3965	[BpkBottomSheet] adding padding types style	Added a prop paddingType (none/base/small/medium/large) to BpkBottomSheet; default “small” equals 1.5 rem (24px) and changed from previous static 16px. oai_citation:6‡GitHub	Minor breaking: default padding changed from 16px to 24px (“small”). Some consumers may notice increased vertical space.	If you used BpkBottomSheet and relied on old padding, you may now want to explicitly pass a paddingType="none" or adjust CSS to override.	approved + tested	Non-breaking in API but visual difference.

[Faye-Xiao]

I have deferred these PRs #3994, #3996, and #3997 after a detailed assessment.

• PR Bump react and @types/react #3994 and Bump react-dom and @types/react-dom #3996 introduce major changes to react/react-dom. We need to conduct an internal evaluation before adopting these changes.
• PR Bump @types/react-window from 1.8.8 to 2.0.0 #3997 only includes the type/react-window, which we actively use in the BpkScrollableCalendarGridList. We need to upgrade both(type/react-window and react-window to V2) at the same time and perform careful validation, as they are used in the calendar component and react-window introduces some breaking changes(https://github.com/bvaughn/react-window/blob/master/CHANGELOG.md).

[Faye-Xiao]

We conducted an internal visual regression test in Backpack and identified a visual issue that requires manual modification. This will necessitate further testing in the downstream web mirsciteion regression test, along with additional modifications. After discussing the matter, we decided to exclude issue #3794 from versions v38.2x.0 and v39.

[Faye-Xiao]

I have deferred these PRs #3994, #3996, and #3997 after a detailed assessment.

• PR Bump react and @types/react #3994 and Bump react-dom and @types/react-dom #3996 introduce major changes to react/react-dom. We need to conduct an internal evaluation before adopting these changes.
• PR Bump @types/react-window from 1.8.8 to 2.0.0 #3997 only includes the type/react-window, which we actively use in the BpkScrollableCalendarGridList. We need to upgrade both(type/react-window and react-window to V2) at the same time and perform careful validation, as they are used in the calendar component and react-window introduces some breaking changes(https://github.com/bvaughn/react-window/blob/master/CHANGELOG.md).

These changes were released in version 38.21.0 before version 39, to ensure that version 39 remains a manageable size.