Add optimistic updates for admin mutations

[Lakes41]

Summary

Improve the admin experience by adding optimistic updates and rollback handling for role and policy changes.

Current Behaviour

Admin actions such as assigning roles or changing policies depend on mutation completion before the UI reflects changes. Failure behaviour is minimal, and users may not clearly see whether data is pending, saved, or reverted.

Expected Behaviour

Admin changes should feel responsive while remaining correct if the server rejects a mutation.

Suggested Implementation

Use React Query mutation lifecycle hooks to update cached members and policies optimistically. Add rollback logic in onError, cache invalidation in onSettled, and visible pending or failed state indicators.

Files or Areas Likely Affected

• app/admin/members/page.tsx
• app/admin/policies/page.tsx
• lib/api/types.ts
• lib/api/live.ts
• lib/api/mock.ts
• components/ui/

Acceptance Criteria

• Role assignment updates the visible member list optimistically
• Policy edits update visible policy values optimistically
• Failed mutations rollback to the previous cached state
• Pending saves are visibly indicated
• Successful saves produce clear feedback
• Tests cover success and rollback behaviour

Additional Notes

Do not hide backend validation errors. Rollback should be paired with a useful error message.

[Chigybillionz]

Good morning!!

I would like to work on this issue.

I have experience with React Query, Next.js, TypeScript, state management, and building responsive admin dashboards. I can implement optimistic updates for role assignments and policy changes, add proper rollback handling on failed mutations, and provide clear pending, success, and error feedback to users.

My focus will be on improving admin responsiveness while maintaining data consistency through React Query mutation lifecycle hooks, cache invalidation, and comprehensive tests covering both successful updates and rollback scenarios.

[grantfox-oss]

🦊 GrantFox — @Chigybillionz has been assigned to this issue as part of the Official Campaign campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #22)
2. Your PR will be reviewed by the Adamantine-guild maintainers

Good luck! Track your progress on GrantFox.