[BUGFIX] Flush frontend cache when AI label metadata changes

[achimfritz]

No description provided.

[o-ba]

The bug is real and I even reproduced it. But most of the diff is IMOunnecessary. TYPO3’s DataHandler already flushes the page-cache tag sys_file_metadata_<uid> on every write to that table, with no feature flag involved. What’s missing is only the tag on the page-cache entry. On a fresh v14 install the bug doesn’t occur at all, because core’s frontend.cache.autoTagging is on there.

So I see following options:

1. Only configuration, zero code: Set frontend.cache.autoTagging = true and document it. Core then tags every page cache entry with sys_file_metadata_<uid> from ResourceStorage::getPublicUrl() and DataHandler flushes it. The flag is on for instances installed on v13.3+, manual for upgraded ones.

2. Keep one extension-side tag and drop the rest: Classes/Service/CacheHelper.php, keep addCacheTag(), delete invalidate(), getServerRequestInterface() and the CacheManager dependency, rename to something that says what it does (FrontendCacheTagger or similar), and take the request as an argument:

public function addCacheTag(FileReference $fileReference, ?ServerRequestInterface $request): void
{
    // Unconditional, also for unflagged files: a file that gets flagged later must
    // invalidate the pages that already rendered it.
    $metadataUid = $fileReference->hasProperty('metadata_uid')
        ? (int)$fileReference->getProperty('metadata_uid')
        : 0;
    $collector = $request?->getAttribute('frontend.cache.collector');
    if ($metadataUid <= 0 || !$collector instanceof CacheDataCollector) {
        return;
    }
    // Core's own tag name, the one ResourceStorage::getPublicUrl() emits under
    // frontend.cache.autoTagging, and the one DataHandler already flushes on every
    // sys_file_metadata write. So nothing here has to flush anything itself.
    $collector->addCacheTags(new CacheTag('sys_file_metadata_' . $metadataUid));
}

FileMetadataViewHelper:

$this->cacheTagger->addCacheTag(
    $fileReference,
    $this->renderingContext->hasAttribute(ServerRequestInterface::class)
        ? $this->renderingContext->getAttribute(ServerRequestInterface::class)
        : null
);

What Option 2 doesn’t cover, and the README should say: the tag is only added where a template calls <ailabel:fileMetadata>. Only Option 1 covers those, which is why the feature flag is the primary fix and the tag the fallback.