feat(cases): enforce purpose-bound case governance

webui/src/features/cases/CasesPage.tsx

@@ -1,5 +1,6 @@
 import { Search } from "lucide-react";
 import { useEffect, useMemo, useState, type FormEvent } from "react";
+import { useSearchParams } from "react-router";
 import { Button,
   DocumentationHelpLink,
   DismissibleAlert,
@@ -18,6 +19,7 @@ import { Button,
   type PlatformRouteContext
 } from "@govoplan/core-webui";
 import {
+  DEFAULT_CASE_ACCESS_PURPOSE,
   listCaseCatalog,
   listCases,
   type CaseCatalog,
@@ -28,8 +30,12 @@ import { CASES_DOCUMENTATION, CASES_I18N } from "./interfacePatterns";
 
 export default function CasesPage({ settings }: PlatformRouteContext) {
   const navigate = useGuardedNavigate();
+  const [searchParams] = useSearchParams();
+  const initialPurpose = searchParams.get("purpose")?.trim() || DEFAULT_CASE_ACCESS_PURPOSE;
   const [query, setQuery] = useState("");
   const [submittedQuery, setSubmittedQuery] = useState("");
+  const [purpose, setPurpose] = useState(initialPurpose);
+  const [submittedPurpose, setSubmittedPurpose] = useState(initialPurpose);
   const [status, setStatus] = useState("");
   const [cases, setCases] = useState<CaseRecord[]>([]);
   const [catalog, setCatalog] = useState<CaseCatalog>({ statuses: [], types: [] });
@@ -46,6 +52,7 @@ export default function CasesPage({ settings }: PlatformRouteContext) {
       listCases(settings, {
         query: submittedQuery,
         statuses: status ? [status] : undefined,
+        purpose: submittedPurpose,
         limit: 200
       }, controller.signal),
       listCaseCatalog(settings, controller.signal)
@@ -62,7 +69,7 @@ export default function CasesPage({ settings }: PlatformRouteContext) {
       }).
       finally(() => setLoading(false));
     return () => controller.abort();
-  }, [reloadKey, settings, status, submittedQuery]);
+  }, [reloadKey, settings, status, submittedPurpose, submittedQuery]);
 
   const statusLabels = useMemo(
     () => new Map(catalog.statuses.map((item) => [item.status_key, item])),
@@ -76,6 +83,7 @@ export default function CasesPage({ settings }: PlatformRouteContext) {
   function submit(event: FormEvent) {
     event.preventDefault();
     setSubmittedQuery(query.trim());
+    setSubmittedPurpose(purpose.trim());
   }
 
   return (
@@ -96,6 +104,14 @@ export default function CasesPage({ settings }: PlatformRouteContext) {
               aria-label="Search cases"
               placeholder="Search cases"
             />
+            <input
+              value={purpose}
+              onChange={(event) => setPurpose(event.target.value)}
+              aria-label="Case access purpose"
+              placeholder="Case access purpose"
+              data-help-context-id="cases.field.access-purpose"
+              required
+            />
             <Button
               type="submit"
               variant="primary"
@@ -135,7 +151,7 @@ export default function CasesPage({ settings }: PlatformRouteContext) {
                   <SelectionListItem
                     selected={false}
                     key={item.reference.object_id}
-                    onClick={() => navigate(`/cases/${encodeURIComponent(item.reference.object_id)}`)}>
+                    onClick={() => navigate(`/cases/${encodeURIComponent(item.reference.object_id)}?purpose=${encodeURIComponent(submittedPurpose)}`)}>
                     <SelectionListItemContent title={item.title} description={`${item.case_number} · ${typeLabels.get(item.case_type_key) ?? humanize(item.case_type_key)} · ${formatDate(item.deadline_at)}`} />
                     <StatusBadge
                       status={statusDefinition?.terminal ? "inactive" : "active"}