fix(AmazonS3#getMetaData): preserve storage_mtime after parent clobbers it

Common::getMetaData (Common.php:667) always sets storage_mtime = mtime before
returning. For S3 virtual directories this is wrong: mtime can be bumped by
child propagation while storage_mtime should remain the actual last S3 change.

When the scanner later calls getMetaData() it compares data['storage_mtime']
against cacheData['storage_mtime']. If they differ it writes the value back,
triggering View::getCacheEntry to fire propagateChange on every read even when
nothing on S3 changed.

Override getMetaData() to restore storage_mtime from the live cache entry (or,
for non-root directories not yet in the cache, from the S3 directory marker
LastModified header) after the parent call.

Assisted-by: ClaudeCode:claude-sonnet-4-6
Signed-off-by: Maksim Sukharev <antreesy.web@gmail.com>

Author: Antreesy

apps/files_external/lib/Lib/Storage/AmazonS3.php

@@ -359,6 +359,25 @@ private function getLastModified(string $path): string {
 		return 'now';
 	}
 
+	public function getMetaData(string $path): ?array {
+		$data = parent::getMetaData($path);
+		if ($data !== null && $data['mimetype'] === FileInfo::MIMETYPE_FOLDER) {
+			// Common::getMetaData sets storage_mtime = mtime, but for S3 virtual directories
+			// mtime may have been updated by mtime propagation while storage_mtime should
+			// reflect the actual last storage change. Without this override the scanner sees
+			// data['storage_mtime'] != cacheData['storage_mtime'] and re-writes the cache,
+			// causing View::getCacheEntry to trigger propagateChange on every read.
+			$path = $this->normalizePath($path);
+			$cacheEntry = $this->getCache()->get($this->getCachePath($path));
+			if ($cacheEntry instanceof CacheEntry) {
+				$data['storage_mtime'] = $cacheEntry->getStorageMTime();
+			} elseif (!$this->isRoot($path) && $directoryMarker = $this->headObject($path . '/')) {
+				$data['storage_mtime'] = strtotime($directoryMarker['LastModified']);
+			}
+		}
+		return $data;
+	}
+
 	public function is_dir(string $path): bool {
 		$path = $this->normalizePath($path);
 

apps/files_external/tests/Storage/Amazons3Test.php

@@ -64,4 +64,30 @@ public function testStatRootPreservesStorageMtimeFromCache(): void {
 		);
 	}
 
+	/**
+	 * Regression test: Common::getMetaData sets storage_mtime = mtime, but for S3 virtual
+	 * directories mtime may have been bumped by propagation while storage_mtime should stay
+	 * stable. The override restores storage_mtime from the cache entry so the scanner does
+	 * not see a spurious mismatch and re-write the cache on every scan.
+	 */
+	public function testGetMetaDataDirectoryPreservesStorageMtimeSeparateFromMtime(): void {
+		$this->instance->getScanner()->scan('', Scanner::SCAN_SHALLOW);
+
+		$cachedRoot = $this->instance->getCache()->get('');
+		$this->assertNotFalse($cachedRoot, 'Root entry must exist in cache after scan');
+
+		// Simulate propagation bumping mtime without touching storage_mtime
+		$originalStorageMtime = $cachedRoot['storage_mtime'];
+		$this->instance->getCache()->update($cachedRoot->getId(), [
+			'mtime' => $originalStorageMtime + 9999,
+		]);
+
+		$meta = $this->instance->getMetaData('');
+		$this->assertNotNull($meta, 'getMetaData(\'\') must return data');
+		$this->assertEquals(
+			$originalStorageMtime,
+			$meta['storage_mtime'],
+			'getMetaData must return storage_mtime from cache, not the propagated mtime'
+		);
+	}
 }