perf(pb,frontend): cascadeDelete bunk_assignments_draft on scenario delete

.pip-audit-ignore

@@ -4,3 +4,4 @@
 # Format: CVE-ID  # reason — added YYYY-MM-DD, remove by YYYY-MM-DD
 
 CVE-2026-4539  # pygments ReDoS in AdlLexer (archetype.py) — local-only, no upstream fix yet — added 2026-03-24, remove by 2026-04-24
+CVE-2026-3219  # pip handles concatenated tar/ZIP files as ZIP — install-time only, no fix released yet — added 2026-04-25, remove by 2026-05-25

frontend/src/components/ScenarioManagementModal.test.tsx

@@ -0,0 +1,96 @@
+/**
+ * Regression test for the "list vanishes during delete" bug reported in
+ * staff testing (April 2026). See ScenarioContext.test.tsx for full context.
+ *
+ * The modal must keep rendering the scenario cards while a delete mutation
+ * is pending — only the initial query-fetch state should swap the list for
+ * a "Loading scenarios..." placeholder.
+ */
+import { describe, it, expect, vi } from 'vitest'
+import { render, screen } from '@testing-library/react'
+import { QueryClient, QueryClientProvider } from '@tanstack/react-query'
+import type { ReactNode } from 'react'
+import { Toaster } from 'react-hot-toast'
+
+// Mock useSyncStatusAPI — modal uses it for the CampMinder "synced" line.
+vi.mock('../hooks/useSyncStatusAPI', () => ({
+  useSyncStatusAPI: () => ({ data: undefined }),
+}))
+
+// Mock useYear — modal reads currentYear for clear-scenario calls.
+vi.mock('../hooks/useCurrentYear', async () => {
+  const actual = await vi.importActual<object>('../hooks/useCurrentYear')
+  return { ...actual, useYear: () => 2026 }
+})
+
+// Render the modal without its child modals doing anything.
+vi.mock('./ScenarioEditModal', () => ({ default: () => null }))
+vi.mock('./NewScenarioModal', () => ({ default: () => null }))
+
+import ScenarioManagementModal from './ScenarioManagementModal'
+import { ScenarioContext } from '../hooks/useScenario'
+import type { ScenarioContextType, Scenario } from '../hooks/useScenario'
+
+function makeContext(overrides: Partial<ScenarioContextType>): ScenarioContextType {
+  const scenarios: Scenario[] = [
+    {
+      id: 'scenario-1',
+      name: 'Dorm Cabin Plan A',
+      session_cm_id: 1000001,
+      is_active: true,
+      description: '',
+      created: '2026-04-01T00:00:00Z',
+      updated: '2026-04-01T00:00:00Z',
+    },
+  ]
+  return {
+    currentScenario: null,
+    isProductionMode: true,
+    scenarios,
+    loading: false,
+    isLoading: false,
+    isMutating: false,
+    error: null,
+    loadScenarios: vi.fn().mockResolvedValue(undefined),
+    createScenario: vi.fn(),
+    selectScenario: vi.fn(),
+    updateScenario: vi.fn().mockResolvedValue(undefined),
+    deleteScenario: vi.fn().mockResolvedValue(undefined),
+    clearScenario: vi.fn().mockResolvedValue(undefined),
+    ...overrides,
+  }
+}
+
+function renderModal(ctx: ScenarioContextType) {
+  const qc = new QueryClient({
+    defaultOptions: { queries: { retry: false }, mutations: { retry: false } },
+  })
+  const wrapper = ({ children }: { children: ReactNode }) => (
+    <QueryClientProvider client={qc}>
+      <ScenarioContext.Provider value={ctx}>{children}</ScenarioContext.Provider>
+      <Toaster />
+    </QueryClientProvider>
+  )
+  return render(<ScenarioManagementModal sessionId={1000001} onClose={vi.fn()} />, { wrapper })
+}
+
+describe('ScenarioManagementModal loading state', () => {
+  it('shows "Loading scenarios..." during initial query fetch', () => {
+    // Matches what ScenarioContext produces when the query is first loading:
+    // loading=true AND isLoading=true (scenarios list not yet fetched).
+    renderModal(makeContext({ loading: true, isLoading: true, scenarios: [] }))
+    expect(screen.getByText('Loading scenarios...')).toBeInTheDocument()
+  })
+
+  it('keeps scenario cards visible while a delete mutation is pending', () => {
+    // Simulates real context state mid-delete: the combined loading flag
+    // is true (because isMutating is true), but the query has already
+    // resolved (isLoading=false). Prior to the fix, the modal consumed the
+    // combined `loading` and swapped the list for the placeholder — this
+    // test asserts the fix by requiring the cards to remain visible.
+    renderModal(makeContext({ loading: true, isLoading: false, isMutating: true }))
+
+    expect(screen.getByText('Dorm Cabin Plan A')).toBeInTheDocument()
+    expect(screen.queryByText('Loading scenarios...')).not.toBeInTheDocument()
+  })
+})

frontend/src/components/ScenarioManagementModal.tsx

@@ -30,14 +30,18 @@ export default function ScenarioManagementModal({
   onClose,
 }: ScenarioManagementModalProps) {
   const currentYear = useYear()
+  // Read `isLoading` (initial query fetch) rather than the combined
+  // `loading` flag — otherwise the scenario list is replaced with a
+  // "Loading scenarios..." placeholder while a delete/clear is in flight,
+  // making the list appear to vanish behind the confirmation dialog.
   const {
     scenarios,
     currentScenario,
     selectScenario,
     updateScenario,
     deleteScenario,
     clearScenario,
-    loading,
+    isLoading,
   } = useScenario()
   const { data: syncStatus } = useSyncStatusAPI()
 
@@ -157,7 +161,7 @@ export default function ScenarioManagementModal({
 
           {/* Scenarios List */}
           <div className="flex-1 space-y-3 overflow-y-auto p-6 pt-4">
-            {loading ? (
+            {isLoading ? (
               <div className="text-muted-foreground py-8 text-center">Loading scenarios...</div>
             ) : scenarios.length === 0 ? (
               <div className="py-8 text-center">

frontend/src/contexts/ScenarioContext.test.tsx

@@ -0,0 +1,152 @@
+/**
+ * Tests for ScenarioContext loading/mutation state split.
+ *
+ * Regression: staff testing (April 2026) reported that clicking "Delete" on a
+ * scenario caused the entire list in ScenarioManagementModal to vanish — only
+ * the hardcoded "CampMinder" card remained visible behind the confirmation
+ * prompt. Root cause: the provider's single `loading` flag went true for any
+ * pending mutation (create / update / delete / clear), and the modal rendered
+ * a "Loading scenarios..." placeholder in that branch, replacing the scenario
+ * cards. The fix exposes `isLoading` (initial query fetch) separately from
+ * `isMutating` (any mutation pending) so consumers can distinguish the two.
+ */
+import { describe, it, expect, vi, beforeEach } from 'vitest'
+import { renderHook, act, waitFor } from '@testing-library/react'
+import type { ReactNode } from 'react'
+import { QueryClient, QueryClientProvider } from '@tanstack/react-query'
+
+// Mock pocketbase before importing the context
+vi.mock('../lib/pocketbase', () => {
+  const collections: Record<string, unknown> = {}
+  return {
+    pb: {
+      collection: vi.fn((name: string) => {
+        collections[name] ??= {
+          getFullList: vi.fn().mockResolvedValue([]),
+          getOne: vi.fn(),
+          create: vi.fn(),
+          update: vi.fn(),
+          delete: vi.fn(),
+        }
+        return collections[name]
+      }),
+    },
+    getCurrentUser: vi.fn(() => ({ id: 'user-1', email: 'user@example.com' })),
+  }
+})
+
+// Mock auth so useSavedScenarios doesn't gate on isLoading
+vi.mock('./AuthContext', () => ({
+  useAuth: () => ({ isLoading: false }),
+}))
+
+// Mock useYear so provider gets a stable year
+vi.mock('../hooks/useCurrentYear', async () => {
+  const actual = await vi.importActual<object>('../hooks/useCurrentYear')
+  return {
+    ...actual,
+    useYear: () => 2026,
+  }
+})
+
+import { pb } from '../lib/pocketbase'
+import type { Mock } from 'vitest'
+import { ScenarioProvider } from './ScenarioContext'
+import { useScenario } from '../hooks/useScenario'
+
+interface CollectionMock {
+  getFullList: Mock
+  getOne: Mock
+  create: Mock
+  update: Mock
+  delete: Mock
+}
+
+function getCollection(name: string): CollectionMock {
+  return (pb.collection as Mock)(name) as CollectionMock
+}
+
+function createWrapper() {
+  const qc = new QueryClient({
+    defaultOptions: { mutations: { retry: false }, queries: { retry: false } },
+  })
+  return ({ children }: { children: ReactNode }) => (
+    <QueryClientProvider client={qc}>
+      <ScenarioProvider>{children}</ScenarioProvider>
+    </QueryClientProvider>
+  )
+}
+
+beforeEach(() => {
+  vi.clearAllMocks()
+})
+
+describe('ScenarioContext loading vs mutating', () => {
+  it('exposes isLoading (query fetch) separately from isMutating (mutation pending)', () => {
+    const { result } = renderHook(() => useScenario(), { wrapper: createWrapper() })
+    // Both flags must exist on the public context shape.
+    expect(result.current).toHaveProperty('isLoading')
+    expect(result.current).toHaveProperty('isMutating')
+  })
+
+  it('does not flip isLoading to true during a delete mutation', async () => {
+    const savedScenarios = getCollection('saved_scenarios')
+    const drafts = getCollection('bunk_assignments_draft')
+
+    savedScenarios.getFullList.mockResolvedValue([
+      {
+        id: 'scenario-1',
+        name: 'Test Scenario',
+        session: 'pb-session-1',
+        year: 2026,
+        is_active: true,
+        description: '',
+        created: '2026-04-01T00:00:00Z',
+        updated: '2026-04-01T00:00:00Z',
+        collectionId: 'c1',
+        collectionName: 'saved_scenarios',
+        expand: { session: { cm_id: 1000001 } },
+      },
+    ])
+
+    // Delete path: getFullList for drafts, then delete scenario.
+    // Keep the delete promise pending so we can observe state mid-flight.
+    drafts.getFullList.mockResolvedValue([])
+    let resolveScenarioDelete: (value?: unknown) => void = () => {}
+    savedScenarios.delete.mockImplementation(
+      () =>
+        new Promise((resolve) => {
+          resolveScenarioDelete = resolve
+        })
+    )
+
+    const { result } = renderHook(() => useScenario(), { wrapper: createWrapper() })
+
+    // Let the initial query settle.
+    await act(async () => {
+      await result.current.loadScenarios(1000001)
+    })
+    await waitFor(() => expect(result.current.scenarios).toHaveLength(1))
+    expect(result.current.isLoading).toBe(false)
+
+    // Start the delete but do NOT await it yet — we want to observe the
+    // in-flight state.
+    let deletePromise: Promise<void> = Promise.resolve()
+    act(() => {
+      deletePromise = result.current.deleteScenario('scenario-1')
+    })
+
+    // While the delete is pending: isMutating true, isLoading stays false.
+    await waitFor(() => expect(result.current.isMutating).toBe(true))
+    expect(result.current.isLoading).toBe(false)
+
+    // Resolve and drain.
+    await act(async () => {
+      resolveScenarioDelete()
+      await deletePromise
+    })
+
+    await waitFor(() => expect(result.current.isMutating).toBe(false))
+    expect(result.current.isLoading).toBe(false)
+  })
+})

frontend/src/contexts/ScenarioContext.tsx

@@ -46,14 +46,21 @@ export const ScenarioProvider: FC<ScenarioProviderProps> = ({ children }) => {
     clearScenarioMutation.error?.message ??
     null
 
-  // Combined loading state
-  const loading =
-    isLoading ||
+  // Any mutation in flight. Tracked separately from `isLoading` so UI that
+  // renders list content (e.g. ScenarioManagementModal) doesn't replace the
+  // list with a placeholder while a delete/clear is processing.
+  const isMutating =
     createScenarioMutation.isPending ||
     updateScenarioMutation.isPending ||
     deleteScenarioMutation.isPending ||
     clearScenarioMutation.isPending
 
+  // Combined loading state (initial fetch OR mutation pending). Kept for
+  // backward compatibility with any consumer that just needs a unified
+  // "busy" signal. Consumers that drive empty-state/placeholder UI should
+  // read `isLoading` instead.
+  const loading = isLoading || isMutating
+
   // Load scenarios for a session
   const loadScenarios = useCallback(async (sessionId: number) => {
     setCurrentSessionId(sessionId)
@@ -232,6 +239,8 @@ export const ScenarioProvider: FC<ScenarioProviderProps> = ({ children }) => {
     isProductionMode,
     scenarios,
     loading,
+    isLoading,
+    isMutating,
     error,
     loadScenarios,
     createScenario,

frontend/src/hooks/useSavedScenariosMutation.test.ts

@@ -23,7 +23,7 @@ vi.mock('../lib/pocketbase', () => {
 })
 
 import { pb } from '../lib/pocketbase'
-import { useCreateScenario } from './useSavedScenariosMutation'
+import { useCreateScenario, useDeleteScenario } from './useSavedScenariosMutation'
 import type { SavedScenario } from '../types/app-types'
 
 function createWrapper() {
@@ -219,3 +219,23 @@ describe('Bug B: copyScenarioToScenario copies ALL source assignments without lo
     })
   })
 })
+
+describe('useDeleteScenario: relies on server-side cascade', () => {
+  it('deletes only the saved_scenarios row — does not pre-delete draft assignments', async () => {
+    const savedScenarios = getCollection('saved_scenarios')
+    const drafts = getCollection('bunk_assignments_draft')
+    savedScenarios.delete.mockResolvedValue(true)
+
+    const { result } = renderHook(() => useDeleteScenario(), { wrapper: createWrapper() })
+
+    await act(async () => {
+      await result.current.mutateAsync('scenario-to-delete')
+    })
+
+    // Single server call — no N+1 pre-delete loop.
+    expect(savedScenarios.delete).toHaveBeenCalledTimes(1)
+    expect(savedScenarios.delete).toHaveBeenCalledWith('scenario-to-delete')
+    expect(drafts.getFullList).not.toHaveBeenCalled()
+    expect(drafts.delete).not.toHaveBeenCalled()
+  })
+})

frontend/src/hooks/useSavedScenariosMutation.ts

@@ -201,17 +201,11 @@ export function useDeleteScenario() {
 
   return useMutation({
     mutationFn: async (scenarioId: string) => {
-      // Must delete all draft assignments first (PocketBase enforces referential integrity)
-      const draftAssignments = await pb.collection('bunk_assignments_draft').getFullList({
-        filter: `scenario = "${scenarioId}"`,
-      })
-
-      // Delete in batches to avoid overwhelming the server
-      for (const assignment of draftAssignments) {
-        await pb.collection('bunk_assignments_draft').delete(assignment.id)
-      }
-
-      // Now delete the scenario
+      // PocketBase cascades bunk_assignments_draft rows via
+      // cascadeDelete: true on the scenario relation (migration
+      // 1500000098). One server-side call replaces the previous N+1
+      // client-side pre-delete loop that made scenario deletion take
+      // several seconds on real sessions.
       return await pb.collection<SavedScenario>('saved_scenarios').delete(scenarioId)
     },
     onSuccess: () => {

frontend/src/hooks/useScenario.ts

@@ -18,7 +18,15 @@ export interface ScenarioContextType {
   scenarios: Scenario[]
 
   // Loading states
+  // `isLoading` reflects the initial React Query fetch — use this for
+  // empty/placeholder UI. `isMutating` reflects any in-flight mutation
+  // (create/update/delete/clear) — don't use it to hide list content, since
+  // doing so causes the list to "vanish" mid-mutation. `loading` is the
+  // combined flag, retained for existing consumers that only care that
+  // *something* is happening.
   loading: boolean
+  isLoading: boolean
+  isMutating: boolean
   error: string | null
 
   // Actions