fix(ui): fix library selection state for single-library users (#4686)

* fix: validate library selection state for single-library users

Fixes issues where users with a single library see no content when
selectedLibraries in localStorage contains library IDs they no longer
have access to (e.g., after removing libraries or switching accounts).

Changes:
- libraryReducer: Validate selectedLibraries when SET_USER_LIBRARIES
  is dispatched, filtering out invalid IDs and resetting to empty for
  single-library users (empty means 'all accessible libraries')
- wrapperDataProvider: Add defensive validation in getSelectedLibraries
  to check against current user libraries before applying filters
- Add comprehensive test coverage for reducer validation logic

Fixes #4553, #4508, #4569

* style: format code with prettier

ui/src/reducers/libraryReducer.js

@@ -8,18 +8,39 @@ const initialState = {
 export const libraryReducer = (previousState = initialState, payload) => {
   const { type, data } = payload
   switch (type) {
-    case SET_USER_LIBRARIES:
+    case SET_USER_LIBRARIES: {
+      const newUserLibraryIds = data.map((lib) => lib.id)
+
+      // Validate and filter selected libraries to only include IDs that exist in new user libraries
+      const validatedSelection = previousState.selectedLibraries.filter((id) =>
+        newUserLibraryIds.includes(id),
+      )
+
+      // Determine the final selection:
+      // 1. If first time setting libraries (no previous user libraries), select all
+      // 2. If user now has only one library, reset to empty (no filter needed)
+      // 3. Otherwise, use validated selection (may be empty if all previous selections were invalid)
+      let finalSelection
+      if (
+        previousState.selectedLibraries.length === 0 &&
+        previousState.userLibraries.length === 0
+      ) {
+        // First time: select all libraries
+        finalSelection = newUserLibraryIds
+      } else if (newUserLibraryIds.length === 1) {
+        // Single library: reset selection (empty means "all accessible")
+        finalSelection = []
+      } else {
+        // Multiple libraries: use validated selection
+        finalSelection = validatedSelection
+      }
+
       return {
         ...previousState,
         userLibraries: data,
-        // If this is the first time setting user libraries and no selection exists,
-        // default to all libraries
-        selectedLibraries:
-          previousState.selectedLibraries.length === 0 &&
-          previousState.userLibraries.length === 0
-            ? data.map((lib) => lib.id)
-            : previousState.selectedLibraries,
+        selectedLibraries: finalSelection,
       }
+    }
     case SET_SELECTED_LIBRARIES:
       return {
         ...previousState,