Real JSON null for empty product feature; SSR warm-cache button and CLI

Ticket 0068-FE: ProductFeatureJsonRenderer returned json_encode(null), which headless passes on as the STRING null (it only decodes object/array-looking strings) and crashed the front end. It now returns an empty string and the TypoScript field sets ifEmptyReturnNull = 1, giving a real JSON null. No other renderer used the pattern. Ticket 0066-FE: SsrPurgeService::warm() posts to the node /__warm endpoint (derived from SSR_PURGE_ENDPOINT, same secret), exposed as a Warm cache button with confirmation in the VITEC SSR module, a Cache warming progress row fed by /__health, and the CLI vitec:ssr-warm [paths]. Warm runs are deliberately not written to the purge log. Verified: two-path run 2/2 done, affected page delivers productfeature null.

Co-Authored-By: Claude Fable 5.2 <noreply@anthropic.com>

packages/vitec/Classes/Service/SsrPurgeService.php

@@ -76,6 +76,79 @@ final class SsrPurgeService
         return max(1, (int)($this->getConfig()['SSR_FAILOVER_AFTER'] ?? 2));
     }
 
+    /**
+     * POST /__warm on the node (contract 0066-FE), derived from
+     * SSR_PURGE_ENDPOINT; SSR_WARM_ENDPOINT overrides explicitly.
+     */
+    public function getWarmEndpoint(): string
+    {
+        $explicit = $this->getConfig()['SSR_WARM_ENDPOINT'] ?? '';
+        if ($explicit !== '') {
+            return $explicit;
+        }
+        $purge = $this->getConfig()['SSR_PURGE_ENDPOINT'] ?? '';
+        return $purge === '' ? '' : str_replace('/__purge', '/__warm', $purge);
+    }
+
+    /**
+     * Starts a background warm run on the node: no paths (or '*') = every
+     * page of sitemap.xml, otherwise exactly the given paths. The node
+     * answers at once and renders in the background; progress shows up as
+     * "warming" in /__health and /__stats. Not written to the purge log -
+     * a warm run evicts nothing, and the log feeds the purge statistics.
+     *
+     * @param string[] $paths
+     * @return array{success:bool, httpCode:int, message:string, data:array}
+     */
+    public function warm(array $paths = []): array
+    {
+        if (!$this->isConfigured()) {
+            return ['success' => false, 'httpCode' => 0, 'message' => 'not configured (var/vitec-ssr-purge.env missing)', 'data' => []];
+        }
+        $paths = $this->normalize($paths);
+        $payload = ($paths === [] || $paths === ['*']) ? ['source' => 'sitemap'] : ['paths' => $paths];
+        try {
+            $response = $this->requestFactory->request($this->getWarmEndpoint(), 'POST', [
+                'headers' => [
+                    'X-Purge-Secret' => $this->getConfig()['SSR_PURGE_SECRET'],
+                    'Content-Type' => 'application/json',
+                ],
+                'body' => json_encode($payload, JSON_THROW_ON_ERROR),
+                // The node reads the sitemap (index + sub-sitemaps) before
+                // it answers; the pages themselves are not awaited.
+                'timeout' => 30,
+                'connect_timeout' => 3,
+                'http_errors' => false,
+            ]);
+            $code = $response->getStatusCode();
+            $body = (string)$response->getBody();
+            $data = json_decode($body, true);
+            $data = is_array($data) ? $data : [];
+            if ($code === 200 && !empty($data['started'])) {
+                $message = sprintf(
+                    'Warm run started: %d pages queued (source: %s, %d at a time)',
+                    (int)($data['queued'] ?? 0),
+                    (string)($data['source'] ?? '?'),
+                    (int)($data['concurrency'] ?? 0)
+                );
+                return ['success' => true, 'httpCode' => $code, 'message' => $message, 'data' => $data];
+            }
+            if ($code === 200 && !empty($data['running'])) {
+                $w = (array)($data['warming'] ?? []);
+                $message = sprintf(
+                    'A warm run is already active: %d of %d pages done',
+                    (int)($w['done'] ?? 0) + (int)($w['skipped'] ?? 0) + (int)($w['failed'] ?? 0),
+                    (int)($w['queued'] ?? 0)
+                );
+                return ['success' => true, 'httpCode' => $code, 'message' => $message, 'data' => $data];
+            }
+            $message = 'HTTP ' . $code . ' - ' . (string)($data['error'] ?? substr($body, 0, 200));
+            return ['success' => false, 'httpCode' => $code, 'message' => $message, 'data' => $data];
+        } catch (\Throwable $e) {
+            return ['success' => false, 'httpCode' => 0, 'message' => substr($e->getMessage(), 0, 200), 'data' => []];
+        }
+    }
+
     /**
      * Normalizes, dedupes and sends the paths; logs the outcome.
      * Never throws - editors' saves must not fail on a purge problem.