diff --git a/src/web/src/store/slices/ui.slice.ts b/src/web/src/store/slices/ui.slice.ts
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+++ b/src/web/src/store/slices/ui.slice.ts
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+import { createSlice, PayloadAction } from '@reduxjs/toolkit'; // @reduxjs/toolkit ^1.9.5
+import { ApiStatus } from '../../types/common.types';
+
+/**
+ * Interface defining the shape of the UI state managed by this slice
+ */
+interface UIState {
+  isLoading: boolean;
+  sidebarOpen: boolean;
+  modals: Record<string, boolean>;
+  activeView: string;
+  theme: string;
+}
+
+/**
+ * Initial state for the UI slice
+ */
+const initialState: UIState = {
+  isLoading: false,
+  sidebarOpen: true, // Default to open
+  modals: {},
+  activeView: 'dashboard', // Default view
+  theme: 'light', // Default theme
+};
+
+/**
+ * Redux slice for managing UI-related state in the Refunds Service application.
+ * Handles common UI elements like loading indicators, modal visibility, sidebar state,
+ * theme settings, and active view tracking.
+ */
+const uiSlice = createSlice({
+  name: 'ui',
+  initialState,
+  reducers: {
+    /**
+     * Sets the global loading state
+     * Can be used with ApiStatus.LOADING or ApiStatus.IDLE for consistent state management
+     */
+    setLoading: (state, action: PayloadAction<boolean>) => {
+      state.isLoading = action.payload;
+    },
+    
+    /**
+     * Shows a modal by ID
+     */
+    showModal: (state, action: PayloadAction<string>) => {
+      state.modals[action.payload] = true;
+    },
+    
+    /**
+     * Hides a modal by ID
+     */
+    hideModal: (state, action: PayloadAction<string>) => {
+      state.modals[action.payload] = false;
+    },
+    
+    /**
+     * Toggles the sidebar open/closed state
+     */
+    toggleSidebar: (state) => {
+      state.sidebarOpen = !state.sidebarOpen;
+    },
+    
+    /**
+     * Sets the active view or screen
+     */
+    setActiveView: (state, action: PayloadAction<string>) => {
+      state.activeView = action.payload;
+    },
+    
+    /**
+     * Sets the theme (light/dark)
+     */
+    setTheme: (state, action: PayloadAction<string>) => {
+      state.theme = action.payload;
+    },
+  },
+});
+
+// Extract the action creators
+export const uiActions = uiSlice.actions;
+
+// Extract the reducer
+export const uiReducer = uiSlice.reducer;
+
+/**
+ * Selector function to get the global loading state from the Redux store
+ */
+export const selectLoading = (state: { ui: UIState }): boolean => state.ui.isLoading;
+
+/**
+ * Selector function to check if a specific modal is currently visible
+ */
+export const selectModalVisible = (state: { ui: UIState }, modalId: string): boolean => 
+  Boolean(state.ui.modals[modalId]);
+
+/**
+ * Selector function to get the sidebar open state
+ */
+export const selectSidebarOpen = (state: { ui: UIState }): boolean => state.ui.sidebarOpen;
+
+/**
+ * Selector function to get the currently active view or screen
+ */
+export const selectActiveView = (state: { ui: UIState }): string => state.ui.activeView;
+
+/**
+ * Selector function to get the current theme setting
+ */
+export const selectTheme = (state: { ui: UIState }): string => state.ui.theme;
+
+// Default export for the slice
+export default uiSlice;
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