fix(ui): use single-select for user filter and add tests

The user entity type's backend endpoint only accepts a single user_id,
so the filter now uses single-select mode instead of multi-select.
Added tests for the new user entity type in EntityUsage and
UsageViewSelect. Updated CLAUDE.md and AGENTS.md with guidance on
UI/backend contract consistency and test coverage for new entity types.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

AGENTS.md

@@ -174,6 +174,8 @@ When opening issues or pull requests, follow these templates:
 3. **Rate Limits**: Respect provider rate limits in tests
 4. **Memory Usage**: Be mindful of memory usage in streaming scenarios
 5. **Dependencies**: Keep dependencies minimal and well-justified
+6. **UI/Backend Contract Mismatch**: When adding a new entity type to the UI, always check whether the backend endpoint accepts a single value or an array. Match the UI control accordingly (single-select vs. multi-select) to avoid silently dropping user selections
+7. **Missing Tests for New Entity Types**: When adding a new entity type (e.g., in `EntityUsage`, `UsageViewSelect`), always add corresponding tests in the existing test files and update any icon/component mocks
 
 ## HELPFUL RESOURCES
 

CLAUDE.md

@@ -97,6 +97,10 @@ LiteLLM is a unified interface for 100+ LLM providers with two main components:
 - Integration tests for each provider in `tests/llm_translation/`
 - Proxy tests in `tests/proxy_unit_tests/`
 - Load tests in `tests/load_tests/`
+- **Always add tests when adding new entity types or features** — if the existing test file covers other entity types, add corresponding tests for the new one
+
+### UI / Backend Consistency
+- When wiring a new UI entity type to an existing backend endpoint, verify the backend API contract (single value vs. array, required vs. optional params) and ensure the UI controls match — e.g., use a single-select dropdown when the backend accepts a single value, not a multi-select
 
 ### Database Migrations
 - Prisma handles schema migrations

ui/litellm-dashboard/src/components/EntityUsageExport/UsageExportHeader.tsx

@@ -17,6 +17,7 @@ interface UsageExportHeaderProps {
   selectedFilters?: string[];
   onFiltersChange?: (filters: string[]) => void;
   filterOptions?: Array<{ label: string; value: string }>;
+  filterMode?: "multiple" | "single";
   customTitle?: string;
   compactLayout?: boolean;
   teams?: Team[];
@@ -32,6 +33,7 @@ const UsageExportHeader: React.FC<UsageExportHeaderProps> = ({
   selectedFilters = [],
   onFiltersChange,
   filterOptions = [],
+  filterMode = "multiple",
   customTitle,
   compactLayout = false,
   teams = [],
@@ -59,11 +61,17 @@ const UsageExportHeader: React.FC<UsageExportHeaderProps> = ({
             <div>
               {filterLabel && <Text className="mb-2">{filterLabel}</Text>}
               <Select
-                mode="multiple"
+                mode={filterMode === "single" ? undefined : "multiple"}
                 style={{ width: "100%" }}
                 placeholder={filterPlaceholder}
-                value={selectedFilters}
-                onChange={onFiltersChange}
+                value={filterMode === "single" ? (selectedFilters[0] ?? undefined) : selectedFilters}
+                onChange={(value: any) => {
+                  if (filterMode === "single") {
+                    onFiltersChange?.(value ? [value] : []);
+                  } else {
+                    onFiltersChange?.(value);
+                  }
+                }}
                 options={filterOptions}
                 allowClear
               />

ui/litellm-dashboard/src/components/UsagePage/components/EntityUsage/EntityUsage.test.tsx

@@ -20,6 +20,7 @@ vi.mock("../../../networking", () => ({
   organizationDailyActivityCall: vi.fn(),
   customerDailyActivityCall: vi.fn(),
   agentDailyActivityCall: vi.fn(),
+  userDailyActivityCall: vi.fn(),
 }));
 
 // Mock the child components to simplify testing
@@ -58,6 +59,7 @@ describe("EntityUsage", () => {
   const mockOrganizationDailyActivityCall = vi.mocked(networking.organizationDailyActivityCall);
   const mockCustomerDailyActivityCall = vi.mocked(networking.customerDailyActivityCall);
   const mockAgentDailyActivityCall = vi.mocked(networking.agentDailyActivityCall);
+  const mockUserDailyActivityCall = vi.mocked(networking.userDailyActivityCall);
 
   const mockSpendData = {
     results: [
@@ -146,11 +148,13 @@ describe("EntityUsage", () => {
     mockOrganizationDailyActivityCall.mockClear();
     mockCustomerDailyActivityCall.mockClear();
     mockAgentDailyActivityCall.mockClear();
+    mockUserDailyActivityCall.mockClear();
     mockTagDailyActivityCall.mockResolvedValue(mockSpendData);
     mockTeamDailyActivityCall.mockResolvedValue(mockSpendData);
     mockOrganizationDailyActivityCall.mockResolvedValue(mockSpendData);
     mockCustomerDailyActivityCall.mockResolvedValue(mockSpendData);
     mockAgentDailyActivityCall.mockResolvedValue(mockSpendData);
+    mockUserDailyActivityCall.mockResolvedValue(mockSpendData);
   });
 
   it("should render with tag entity type and display spend metrics", async () => {
@@ -232,6 +236,21 @@ describe("EntityUsage", () => {
     });
   });
 
+  it("should render with user entity type and call user API", async () => {
+    render(<EntityUsage {...defaultProps} entityType="user" />);
+
+    await waitFor(() => {
+      expect(mockUserDailyActivityCall).toHaveBeenCalled();
+    });
+
+    expect(screen.getByText("User Spend Overview")).toBeInTheDocument();
+
+    await waitFor(() => {
+      const spendElements = screen.getAllByText("$100.50");
+      expect(spendElements.length).toBeGreaterThan(0);
+    });
+  });
+
   it("should switch between tabs", async () => {
     render(<EntityUsage {...defaultProps} />);
 

ui/litellm-dashboard/src/components/UsagePage/components/EntityUsage/EntityUsage.tsx

@@ -401,6 +401,7 @@ const EntityUsage: React.FC<EntityUsageProps> = ({ accessToken, entityType, enti
         selectedFilters={selectedTags}
         onFiltersChange={setSelectedTags}
         filterOptions={getAllTags() || undefined}
+        filterMode={entityType === "user" ? "single" : "multiple"}
         teams={teams || []}
       />
       <TabGroup>

ui/litellm-dashboard/src/components/UsagePage/components/UsageViewSelect/UsageViewSelect.test.tsx

@@ -79,6 +79,7 @@ vi.mock("@ant-design/icons", async () => {
     ShoppingCartOutlined: Icon,
     TagsOutlined: Icon,
     RobotOutlined: Icon,
+    UserOutlined: Icon,
     LineChartOutlined: Icon,
     BarChartOutlined: Icon,
   };