## ADDED Requirements ### Requirement: Navigation transitions SHALL use a maintainable baseline motion system The frontend SHALL provide route and panel transition effects using a baseline motion mechanism suitable for long-term maintenance. #### Scenario: Route transition feedback - **WHEN** a user navigates between report modules - **THEN** the shell SHALL provide consistent transition feedback - **THEN** transitions SHALL NOT block route completion or data loading ### Requirement: Motion behavior SHALL support reduced-motion accessibility The motion system SHALL respect reduced-motion user preferences. #### Scenario: Reduced-motion preference - **WHEN** user agent indicates reduced motion preference - **THEN** non-essential animations SHALL be minimized or disabled - **THEN** primary interactions SHALL remain fully usable ### Requirement: Motion effects SHALL preserve functional correctness Animation implementation SHALL NOT alter data correctness, query timing semantics, or interaction outcomes. #### Scenario: Interactive action during motion - **WHEN** users perform filtering, refresh, or drill-down actions during transitions - **THEN** resulting API calls and state updates SHALL remain functionally equivalent to non-animated execution