# Module Contracts: Frontend Style Unification

## [DEF:FrontendStyleSystem:Module]
@TIER: CRITICAL  
@PURPOSE: Define and enforce unified visual primitives and page-shell rules across targeted frontend routes.  
@RELATION: DEPENDS_ON -> [DEF:Std:UI_Svelte]  
@RELATION: DEPENDS_ON -> [DEF:Std:Semantics]  
@RELATION: BINDS_TO -> [DEF:StyleTokenGroup:Entity]  
@RELATION: BINDS_TO -> [DEF:UIPatternRule:Entity]  
@PRE: Target routes/components for unification are identified and included in scope.  
@PRE: Existing behavior-critical user flows remain available for validation.  
@POST: Shared visual primitives and shell patterns are applied consistently in targeted scope.  
@POST: No critical functional flow is removed by style refactor.  
@UX_STATE: Default -> Users see consistent hierarchy (title/actions/content) across targeted pages.  
@UX_STATE: Loading -> Loading visuals appear in consistent zones without disruptive layout jumps.  
@UX_STATE: Error -> Error blocks use consistent emphasis and include a clear recovery action.  
@UX_STATE: Success -> Confirmation messages follow one tone/placement pattern.  
@INVARIANT: Unified styling must not regress accessibility-visible focus and readable contrast behavior.

---

## [DEF:RouteShellContract:Component]
@TIER: CRITICAL  
@PURPOSE: Standardize route shell structure for primary pages (dashboards, tasks, reports, settings).  
@RELATION: DEPENDS_ON -> [DEF:FrontendStyleSystem:Module]  
@PRE: Route provides title context and action area metadata.  
@POST: Route renders canonical shell order: context/breadcrumbs, title block, action region, content container.  
@UX_STATE: Default -> Primary action location is discoverable quickly and consistently.  
@UX_STATE: Empty -> Empty-state container is visually aligned with shell and includes next-step guidance.  
@UX_RECOVERY: Empty -> User can recover using explicit action (refresh/filter adjust/create flow).

---

## [DEF:StateFeedbackContract:Component]
@TIER: CRITICAL  
@PURPOSE: Normalize loading/empty/error/success feedback rendering and wording across modules.  
@RELATION: DEPENDS_ON -> [DEF:StatePresentationPattern:Entity]  
@PRE: Module can expose current state category (loading/empty/error/success).  
@POST: State-specific UI uses canonical placement, tone, and recovery behavior.  
@UX_STATE: Loading -> Consistent indicator style and placement with stable layout rhythm.  
@UX_STATE: Empty -> Neutral message + guidance action rendered in standard block.  
@UX_STATE: Error -> Actionable error messaging with retry/fix path.  
@UX_STATE: Success -> Concise confirmation in standard visual language.  
@UX_FEEDBACK: Error -> Emphasis clearly distinguishes failure from neutral status.  
@UX_RECOVERY: Error -> Retry or corrective action is always visible when recoverable.  
@INVARIANT: State texts use canonical terminology and remain i18n-compatible.

---

## [DEF:TerminologyConsistencyContract:Module]
@TIER: STANDARD  
@PURPOSE: Keep user-facing wording consistent across page shells and state blocks.  
@RELATION: DEPENDS_ON -> [DEF:Std:Constitution]  
@PRE: Canonical term list for targeted flows is defined.  
@POST: Targeted modules avoid mixed synonyms for the same concept.  
@UX_STATE: Default -> UI labels and status texts remain concise and confidence-building.  
@INVARIANT: User-facing text remains compatible with existing localization workflow.

---

## Contract Usage Simulation (Key Scenario)

**Scenario**: User navigates from dashboards to reports and encounters a failed data load.

1. `RouteShellContract` ensures both pages keep identical shell rhythm and action placement.
2. `FrontendStyleSystem` ensures shared primitives (spacing/typography/cards/buttons) are consistent.
3. `StateFeedbackContract` renders failure using canonical error block with explicit retry action.
4. `TerminologyConsistencyContract` ensures error wording and action labels are aligned across pages.

**Continuity Check**: No interface mismatch detected between shell-level structure and state-level feedback contracts.