feat(ai-sdk): legal-corpus structure endpoint + coverage page

Expose GET /sdk/v1/rag/legal-corpus, which scrolls the eur-lex legal
corpus (filtered to a few hundred points regardless of total size) and
aggregates each ingested act's composition: distinct articles, annexes,
recitals and chunk count. Surface it as a new section on /sdk/coverage so
the ingested corpus is no longer a black box — a developer SEES what each
act actually contains, not only its name.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

admin-compliance/app/sdk/coverage/page.tsx

@@ -3,6 +3,7 @@ import Link from 'next/link'
 import {
   type UseCaseRow,
   type CorpusOverview,
+  type LegalCorpus,
   licenseTierBadgeClass,
   commercialBadgeClass,
   groupUseCases,
@@ -11,28 +12,46 @@ import {
 
 const BACKEND_URL =
   process.env.COMPLIANCE_BACKEND_URL || 'http://backend-compliance:8002'
+// The legal-corpus structure comes from the Go SDK (it owns the vector store).
+const SDK_URL = process.env.SDK_URL || 'http://ai-compliance-sdk:8090'
 
 export const dynamic = 'force-dynamic'
 
+// Fetched from the SDK and isolated in its own try/catch so a vector-store
+// hiccup degrades to "no structure shown" instead of blanking the whole page.
+async function fetchLegalCorpus(): Promise<LegalCorpus | null> {
+  try {
+    const res = await fetch(`${SDK_URL}/sdk/v1/rag/legal-corpus`, {
+      cache: 'no-store',
+    })
+    return res.ok ? await res.json() : null
+  } catch {
+    return null
+  }
+}
+
 async function getData(): Promise<{
   useCases: UseCaseRow[]
   corpus: CorpusOverview | null
+  legalCorpus: LegalCorpus | null
 }> {
   try {
-    const [ucRes, corpusRes] = await Promise.all([
+    const [ucRes, corpusRes, legalCorpus] = await Promise.all([
       fetch(`${BACKEND_URL}/api/compliance/v1/controls/use-cases`, {
         cache: 'no-store',
       }),
       fetch(`${BACKEND_URL}/api/compliance/v1/controls/corpus`, {
         cache: 'no-store',
       }),
+      fetchLegalCorpus(),
     ])
     return {
       useCases: ucRes.ok ? await ucRes.json() : [],
       corpus: corpusRes.ok ? await corpusRes.json() : null,
+      legalCorpus,
     }
   } catch {
-    return { useCases: [], corpus: null }
+    return { useCases: [], corpus: null, legalCorpus: null }
   }
 }
 
@@ -46,7 +65,7 @@ function Stat({ label, value }: { label: string; value: string | number }) {
 }
 
 export default async function CoveragePage() {
-  const { useCases, corpus } = await getData()
+  const { useCases, corpus, legalCorpus } = await getData()
   const groups = groupUseCases(useCases)
   const totalRelevant = useCases.reduce((s, u) => s + u.atom_relevant, 0)
   const totalAtoms = useCases.reduce((s, u) => s + u.atom_total, 0)
@@ -221,6 +240,67 @@ export default async function CoveragePage() {
         </div>
       </section>
 
+      {legalCorpus?.regulations?.length ? (
+        <section className="space-y-2">
+          <h2 className="text-lg font-semibold text-gray-900">
+            Ingestierter Rechtskorpus – Struktur ({legalCorpus.totals.regulations}{' '}
+            Rechtsakte)
+          </h2>
+          <p className="text-xs text-gray-500">
+            Woraus jeder ingestierte eur-lex-Rechtsakt tatsächlich besteht:
+            Artikel (§), Anhänge, Erwägungsgründe und retrievbare Chunks — direkt
+            aus dem Vektorspeicher, damit kein Black-Box-Korpus entsteht.
+          </p>
+          <div className="overflow-auto rounded-lg border border-gray-200">
+            <table className="min-w-full divide-y divide-gray-200 text-sm">
+              <thead className="bg-gray-50 text-left text-xs uppercase text-gray-500">
+                <tr>
+                  <th className="px-4 py-2">Rechtsakt</th>
+                  <th className="px-4 py-2 text-right">Artikel (§)</th>
+                  <th className="px-4 py-2 text-right">Anhänge</th>
+                  <th className="px-4 py-2 text-right">Erwägungsgründe</th>
+                  <th className="px-4 py-2 text-right">Chunks</th>
+                </tr>
+              </thead>
+              <tbody className="divide-y divide-gray-100 bg-white">
+                {legalCorpus.regulations.map((r) => (
+                  <tr key={r.regulation_short}>
+                    <td className="px-4 py-2 text-gray-900">
+                      <span className="font-medium">{r.regulation_short}</span>
+                      {r.regulation_name !== r.regulation_short ? (
+                        <span className="ml-2 text-xs text-gray-500">
+                          {r.regulation_name}
+                        </span>
+                      ) : null}
+                    </td>
+                    <td className="px-4 py-2 text-right font-semibold">
+                      {r.articles.toLocaleString('de-DE')}
+                    </td>
+                    <td className="px-4 py-2 text-right">
+                      {r.annexes > 0 ? (
+                        r.annexes.toLocaleString('de-DE')
+                      ) : (
+                        <span className="text-gray-300">—</span>
+                      )}
+                    </td>
+                    <td className="px-4 py-2 text-right text-gray-500">
+                      {r.recitals > 0 ? (
+                        r.recitals.toLocaleString('de-DE')
+                      ) : (
+                        <span className="text-gray-300">—</span>
+                      )}
+                    </td>
+                    <td className="px-4 py-2 text-right text-gray-500">
+                      {r.chunks.toLocaleString('de-DE')}
+                    </td>
+                  </tr>
+                ))}
+              </tbody>
+            </table>
+          </div>
+        </section>
+      ) : null}
+
       {corpus?.license_catalog?.length ? (
         <section className="space-y-2">
           <h2 className="text-lg font-semibold text-gray-900">