Wire Azure AI Search into dobetternorge-tools

health.php: Add azure_search check — calls /$count endpoint and
  reports doc count in the index. Reads DBN_AZURE_SEARCH_{ENDPOINT,KEY,INDEX}.

corpus-search.php: Add azure mode — semantic + vector hybrid search
  via Azure AI Search bnl-legal-v2. Embeds query with LiteLLM
  nomic-embed-text; expands keepCats to include government-policy,
  health-law, social-services, labour-law, immigration (previously
  blocked by contamination workaround, now safe to include).

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

api/corpus-search.php

@@ -9,7 +9,7 @@ dbnToolsRequireAuth();
 $input    = dbnToolsJsonInput(4000);
 $query    = trim(dbnToolsString($input, 'query', 1000));
 $rawMode  = $input['mode'] ?? 'hybrid';
-$mode     = in_array($rawMode, ['hybrid', 'bm25', 'vector'], true) ? $rawMode : 'hybrid';
+$mode     = in_array($rawMode, ['hybrid', 'bm25', 'vector', 'azure'], true) ? $rawMode : 'hybrid';
 $language = dbnToolsNormalizeLanguage($input['language'] ?? 'en');
 $limit    = max(1, min(20, (int)($input['limit'] ?? 8)));
 $category = isset($input['category']) && $input['category'] !== '' ? trim((string)$input['category']) : null;
@@ -160,6 +160,91 @@ try {
         dbnToolsRespond(['ok' => true, 'hits' => $hits, 'mode' => 'vector', 'query' => $query]);
     }
 
+    // ── AZURE AI SEARCH: semantic + vector via Azure AI Search ────────────────
+    if ($mode === 'azure') {
+        $searchEndpoint = rtrim((string)dbnToolsEnv('DBN_AZURE_SEARCH_ENDPOINT', ''), '/');
+        $searchKey      = (string)dbnToolsEnv('DBN_AZURE_SEARCH_KEY', '');
+        $searchIndex    = (string)dbnToolsEnv('DBN_AZURE_SEARCH_INDEX', 'bnl-legal-v2');
+
+        if (!$searchEndpoint || !$searchKey) {
+            dbnToolsError('Azure AI Search is not configured on this server.', 503, 'azure_search_not_configured');
+        }
+
+        // Try to embed the query for hybrid (semantic + vector) search
+        $vector = null;
+        $embeddings = dbnToolsLiteLLMEmbedBatch([$query]);
+        if (!empty($embeddings) && is_array($embeddings[0])) {
+            $vector = $embeddings[0];
+        }
+
+        // Expanded keep-list: original 11 + government-policy, health-law,
+        // social-services, labour-law, immigration (unblocked after contamination cleanup)
+        $keepCats = [
+            'child-welfare', 'echr-case-law', 'child-abduction', 'legislation',
+            'anti-discrimination', 'legal', 'children-rights', 'family-law',
+            'civil-litigation', 'patient-rights', 'parliamentary',
+            'government-policy', 'health-law', 'social-services', 'labour-law', 'immigration',
+        ];
+        $catFilter = implode(' or ', array_map(fn($c) => "category eq '$c'", $keepCats));
+        if ($category !== null) {
+            $catFilter = "category eq '$category'";
+        }
+
+        $payload = [
+            'search'                => $query,
+            'top'                   => $limit,
+            'select'                => 'id,chunk_id,content,title,section_title,category,source_url',
+            'queryType'             => 'semantic',
+            'semanticConfiguration' => 'bnl-semantic',
+            'filter'                => $catFilter,
+        ];
+        if ($vector) {
+            $payload['vectorQueries'] = [[
+                'kind'   => 'vector',
+                'vector' => $vector,
+                'fields' => 'content_vector',
+                'k'      => $limit,
+            ]];
+        }
+
+        $url = "$searchEndpoint/indexes/" . rawurlencode($searchIndex) . '/docs/search?api-version=2024-05-01-preview';
+        $ch  = curl_init($url);
+        curl_setopt_array($ch, [
+            CURLOPT_POST           => true,
+            CURLOPT_RETURNTRANSFER => true,
+            CURLOPT_TIMEOUT        => 15,
+            CURLOPT_HTTPHEADER     => ['Content-Type: application/json', "api-key: $searchKey"],
+            CURLOPT_POSTFIELDS     => json_encode($payload, JSON_UNESCAPED_SLASHES),
+        ]);
+        $resp = curl_exec($ch);
+        $code = (int)curl_getinfo($ch, CURLINFO_RESPONSE_CODE);
+        $curlErr = curl_error($ch);
+        curl_close($ch);
+
+        if ($curlErr) dbnToolsError("Azure Search unreachable: $curlErr", 502, 'azure_search_error');
+        if ($code !== 200) {
+            $errBody = json_decode((string)$resp, true);
+            $errMsg  = $errBody['error']['message'] ?? "HTTP $code";
+            dbnToolsError("Azure AI Search error: $errMsg", 502, 'azure_search_error');
+        }
+
+        $data = json_decode((string)$resp, true);
+        $hits = array_map(fn($d) => [
+            'title'       => trim(implode(' — ', array_filter([$d['title'] ?? '', $d['section_title'] ?? '']))),
+            'category'    => $d['category'] ?? '',
+            'section'     => $d['section_title'] ?? null,
+            'excerpt'     => mb_substr((string)($d['content'] ?? ''), 0, 600, 'UTF-8'),
+            'score'       => round((float)($d['@search.rerankerScore'] ?? $d['@search.score'] ?? 0), 4),
+            'document_id' => null,
+            'chunk_id'    => $d['chunk_id'] ?? $d['id'] ?? null,
+            'source_url'  => $d['source_url'] ?? null,
+            'language'    => null,
+        ], $data['value'] ?? []);
+
+        $hits = array_values(array_filter($hits, fn($h) => !str_contains($h['source_url'] ?? '', EXCLUDED_DOMAIN)));
+        dbnToolsRespond(['ok' => true, 'hits' => $hits, 'mode' => 'azure', 'query' => $query]);
+    }
+
     dbnToolsError('Unknown search mode.', 422, 'invalid_mode');
 } catch (DbnToolsHttpException $e) {
     throw $e;

api/health.php

@@ -66,6 +66,29 @@ try {
     $checks['family_legal_subscription'] = ['ok' => false, 'detail' => 'Not checked'];
 }
 
+$searchEndpoint = rtrim((string)dbnToolsEnv('DBN_AZURE_SEARCH_ENDPOINT', ''), '/');
+$searchKey      = (string)dbnToolsEnv('DBN_AZURE_SEARCH_KEY', '');
+$searchIndex    = (string)dbnToolsEnv('DBN_AZURE_SEARCH_INDEX', '');
+if ($searchEndpoint && $searchKey && $searchIndex) {
+    $countUrl = "$searchEndpoint/indexes/$searchIndex/docs/\$count?api-version=2024-05-01-preview";
+    $ch = curl_init($countUrl);
+    curl_setopt_array($ch, [
+        CURLOPT_RETURNTRANSFER => true,
+        CURLOPT_TIMEOUT        => 8,
+        CURLOPT_HTTPHEADER     => ["api-key: $searchKey"],
+    ]);
+    $resp = curl_exec($ch);
+    $code = (int)curl_getinfo($ch, CURLINFO_RESPONSE_CODE);
+    curl_close($ch);
+    $count = is_numeric(trim((string)$resp)) ? (int)trim($resp) : null;
+    $checks['azure_search'] = [
+        'ok'     => $code === 200 && $count !== null,
+        'detail' => $code === 200 ? "$count docs in $searchIndex" : "HTTP $code",
+    ];
+} else {
+    $checks['azure_search'] = ['ok' => false, 'detail' => 'Azure Search env vars not configured'];
+}
+
 $logPath = dbnToolsMetadataLogPath();
 $dir = dirname($logPath);
 $checks['metadata_log'] = [