feat: add case deletion for admins with inline confirmation

- Add DELETE /cases/{case_id} endpoint (admin-only) with cascading
  cleanup of DisclosureRequests and audit trail preservation
- Add useCaseDelete() mutation hook with cache invalidation
- Add delete button in CaseDetail sheet with inline confirmation UI

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/app/api/cases.py

@@ -14,6 +14,7 @@ from sqlalchemy.orm import Session
 
 from app.core.dependencies import get_current_user, require_admin
 from app.database import get_db
+from app.models.audit import DisclosureRequest
 from app.models.case import Case
 from app.models.user import User
 from app.schemas.case import (
@@ -554,6 +555,61 @@ def update_case(
     return case
 
 
+# ---------------------------------------------------------------------------
+# Delete case (admin only)
+# ---------------------------------------------------------------------------
+
+
+@router.delete("/{case_id}", status_code=status.HTTP_204_NO_CONTENT)
+def delete_case(
+    case_id: int,
+    request: Request,
+    db: Session = Depends(get_db),
+    user: User = Depends(require_admin),
+):
+    """Permanently delete a case and its related records (admin only).
+
+    Cascading behaviour:
+    - CaseICDCode records are deleted automatically (DB CASCADE).
+    - DisclosureRequest records are deleted manually (no DB CASCADE).
+    - AuditLog entries are kept (no FK constraint) as a deletion trace.
+    """
+    case = db.query(Case).filter(Case.id == case_id).first()
+    if not case:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail="Case not found",
+        )
+
+    fall_id = case.fall_id
+    case_info = {
+        "fall_id": fall_id,
+        "nachname": case.nachname,
+        "vorname": case.vorname,
+        "kvnr": case.kvnr,
+        "fallgruppe": case.fallgruppe,
+        "jahr": case.jahr,
+        "kw": case.kw,
+    }
+
+    # Remove DisclosureRequests first (no DB cascade)
+    db.query(DisclosureRequest).filter(DisclosureRequest.case_id == case_id).delete()
+
+    db.delete(case)
+    db.commit()
+
+    log_action(
+        db,
+        user_id=user.id,
+        action="case_deleted",
+        entity_type="case",
+        entity_id=case_id,
+        old_values=case_info,
+        ip_address=request.client.host if request.client else None,
+        user_agent=request.headers.get("user-agent"),
+    )
+
+
 # ---------------------------------------------------------------------------
 # ICD entry
 # ---------------------------------------------------------------------------

frontend/src/hooks/useCases.ts

@@ -68,3 +68,15 @@ export function useIcdUpdate() {
     },
   })
 }
+
+export function useCaseDelete() {
+  const queryClient = useQueryClient()
+  return useMutation({
+    mutationFn: (id: number) =>
+      api.delete(`/cases/${id}`),
+    onSuccess: () => {
+      queryClient.invalidateQueries({ queryKey: ['cases'] })
+      queryClient.invalidateQueries({ queryKey: ['dashboard'] })
+    },
+  })
+}

frontend/src/pages/CasesPage.tsx

@@ -5,7 +5,7 @@ import {
 } from 'lucide-react'
 import type { Case } from '@/types'
 import { useAuth } from '@/context/AuthContext'
-import { useCases, usePendingIcdCases, useIcdUpdate, type CaseFilters } from '@/hooks/useCases'
+import { useCases, usePendingIcdCases, useIcdUpdate, useCaseDelete, type CaseFilters } from '@/hooks/useCases'
 import api from '@/services/api'
 import { useFilterPresets, useCreateFilterPreset, useDeleteFilterPreset } from '@/hooks/useFilterPresets'
 import { Input } from '@/components/ui/input'
@@ -472,7 +472,10 @@ export function CasesPage({ pendingIcdOnly = false }: CasesPageProps) {
       <Sheet open={sheetOpen} onOpenChange={setSheetOpen}>
         <SheetContent className="w-full sm:max-w-lg overflow-y-auto">
           {selectedCase && (
-            <CaseDetail caseData={selectedCase} />
+            <CaseDetail
+              caseData={selectedCase}
+              onDeleted={() => { setSheetOpen(false); setSelectedCase(null) }}
+            />
           )}
         </SheetContent>
       </Sheet>
@@ -590,7 +593,7 @@ function StatusBadges({ c }: { c: Case }) {
   )
 }
 
-function CaseDetail({ caseData }: { caseData: Case }) {
+function CaseDetail({ caseData, onDeleted }: { caseData: Case; onDeleted?: () => void }) {
   const { isAdmin } = useAuth()
   const {
     editing, formValues, saving, error, success,
@@ -603,10 +606,15 @@ function CaseDetail({ caseData }: { caseData: Case }) {
   const [icdError, setIcdError] = useState('')
   const [icdSuccess, setIcdSuccess] = useState(false)
 
+  // Delete state
+  const deleteMutation = useCaseDelete()
+  const [confirmDelete, setConfirmDelete] = useState(false)
+
   useEffect(() => {
     setIcdValue(caseData.icd || '')
     setIcdError('')
     setIcdSuccess(false)
+    setConfirmDelete(false)
   }, [caseData.id, caseData.icd])
 
   const saveIcd = async () => {
@@ -621,6 +629,15 @@ function CaseDetail({ caseData }: { caseData: Case }) {
     }
   }
 
+  const handleDelete = async () => {
+    try {
+      await deleteMutation.mutateAsync(caseData.id)
+      onDeleted?.()
+    } catch {
+      // error is visible via deleteMutation.isError
+    }
+  }
+
   return (
     <>
       <SheetHeader>
@@ -654,6 +671,34 @@ function CaseDetail({ caseData }: { caseData: Case }) {
           )}
         </div>
 
+        {/* Delete button (admin only) */}
+        {isAdmin && !editing && (
+          <div className="flex items-center gap-2">
+            {!confirmDelete ? (
+              <Button size="sm" variant="outline" className="text-destructive hover:text-destructive" onClick={() => setConfirmDelete(true)}>
+                <Trash2 className="size-4 mr-1" />
+                Löschen
+              </Button>
+            ) : (
+              <div className="flex items-center gap-2 p-2 border border-destructive/30 rounded-lg bg-destructive/5">
+                <span className="text-sm text-destructive">Fall endgültig löschen?</span>
+                <Button size="sm" variant="destructive" onClick={handleDelete} disabled={deleteMutation.isPending}>
+                  {deleteMutation.isPending ? 'Löschen...' : 'Ja, löschen'}
+                </Button>
+                <Button size="sm" variant="outline" onClick={() => setConfirmDelete(false)} disabled={deleteMutation.isPending}>
+                  Abbrechen
+                </Button>
+              </div>
+            )}
+          </div>
+        )}
+
+        {deleteMutation.isError && (
+          <Alert variant="destructive">
+            <AlertDescription>Fehler beim Löschen des Falls.</AlertDescription>
+          </Alert>
+        )}
+
         {error && (
           <Alert variant="destructive">
             <AlertDescription>{error}</AlertDescription>