fix(theming): fix broken custom images introduced in 32.0.9

PR #58224 introduced a raster→SVG conversion path in ImageManager::getImage()
that breaks display of custom theming images. The root cause is a three-part
bug chain:

1. getImage() attempted to convert raster images (PNG/JPEG) to SVG format,
   which Imagick cannot do meaningfully and produces broken output.
2. getMimeType() returns 'application/octet-stream' for extensionless stored
   files, so the Content-Type response header was wrong.
3. Stale .svg cache files persisted after image replacement, causing
   subsequent requests to serve the wrong format.

Fix by:
- Restricting the Imagick conversion to SVG→PNG only (not raster→SVG)
- Reading the stored MIME type from IAppConfig for extensionless files in
  ThemingController::getImage()
- Deleting .svg cache files in ImageManager::delete()
- Injecting IAppConfig into ImageManager and reading the cachebuster via
  IAppConfig::getAppValueInt() so the URL returned after upload always
  carries the freshly-incremented value (IConfig::getAppValue() can return
  a stale cached value within the same request)
- Updating the FileInputField Vue component to use a reactive cacheKey ref
  that increments on every upload, so the thumbnail refreshes even when the
  MIME type of the new image is the same as the old one

AI-Assisted-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Signed-off-by: Anna Larch <anna@nextcloud.com>

Author: miaulalala

apps/theming/lib/Controller/ThemingController.php

@@ -356,7 +356,13 @@ public function getImage(string $key, bool $useSvg = true) {
 		$csp->allowInlineStyle();
 		$response->setContentSecurityPolicy($csp);
 		$response->cacheFor(3600);
-		$response->addHeader('Content-Type', $file->getMimeType());
+		// The original stored file has no extension (e.g. "logo"), so getMimeType() returns
+		// application/octet-stream for it. Use the config-stored MIME type for the original
+		// file, and getMimeType() only for converted files which have a proper extension.
+		$mimeType = $file->getName() === $key
+			? $this->appConfig->getAppValueString($key . 'Mime', '')
+			: $file->getMimeType();
+		$response->addHeader('Content-Type', $mimeType);
 		$response->addHeader('Content-Disposition', 'attachment; filename="' . $key . '"');
 		return $response;
 	}
@@ -435,7 +441,7 @@ public function getThemeStylesheet(string $themeId, bool $plain = false, bool $w
 	#[BruteForceProtection(action: 'manifest')]
 	#[OpenAPI(scope: OpenAPI::SCOPE_DEFAULT)]
 	public function getManifest(string $app): JSONResponse {
-		$cacheBusterValue = $this->config->getAppValue('theming', 'cachebuster', '0');
+		$cacheBusterValue = $this->appConfig->getAppValueString('cachebuster', '0');
 		if ($app === 'core' || $app === 'settings') {
 			$name = $this->themingDefaults->getName();
 			$shortName = $this->themingDefaults->getName();

apps/theming/lib/ImageManager.php

@@ -8,6 +8,7 @@
 
 use OCA\Theming\AppInfo\Application;
 use OCA\Theming\Service\BackgroundService;
+use OCP\AppFramework\Services\IAppConfig;
 use OCP\Files\IAppData;
 use OCP\Files\NotFoundException;
 use OCP\Files\NotPermittedException;
@@ -30,6 +31,7 @@ public function __construct(
 		private LoggerInterface $logger,
 		private ITempManager $tempManager,
 		private BackgroundService $backgroundService,
+		private IAppConfig $appConfig,
 	) {
 	}
 
@@ -40,7 +42,7 @@ public function __construct(
 	 * @return string the image url
 	 */
 	public function getImageUrl(string $key): string {
-		$cacheBusterCounter = $this->config->getAppValue(Application::APP_ID, 'cachebuster', '0');
+		$cacheBusterCounter = (string)$this->appConfig->getAppValueInt(ConfigLexicon::CACHE_BUSTER);
 		if ($this->hasImage($key)) {
 			return $this->urlGenerator->linkToRoute('theming.Theming.getImage', [ 'key' => $key ]) . '?v=' . $cacheBusterCounter;
 		} elseif ($key === 'backgroundDark' && $this->hasImage('background')) {
@@ -85,31 +87,14 @@ public function getImageUrlAbsolute(string $key): string {
 	public function getImage(string $key, bool $useSvg = true): ISimpleFile {
 		$mime = $this->config->getAppValue('theming', $key . 'Mime', '');
 		$folder = $this->getRootFolder()->getFolder('images');
-		$useSvg = $useSvg && $this->canConvert('SVG');
 
 		if ($mime === '' || !$folder->fileExists($key)) {
 			throw new NotFoundException();
 		}
-		// if SVG was requested and is supported
-		if ($useSvg) {
-			if (!$folder->fileExists($key . '.svg')) {
-				try {
-					$finalIconFile = new \Imagick();
-					$finalIconFile->setBackgroundColor('none');
-					$finalIconFile->readImageBlob($folder->getFile($key)->getContent());
-					$finalIconFile->setImageFormat('SVG');
-					$svgFile = $folder->newFile($key . '.svg');
-					$svgFile->putContent($finalIconFile->getImageBlob());
-					return $svgFile;
-				} catch (\ImagickException $e) {
-					$this->logger->info('The image was requested to be no SVG file, but converting it to SVG failed: ' . $e->getMessage());
-				}
-			} else {
-				return $folder->getFile($key . '.svg');
-			}
-		}
-		// if SVG was not requested, but PNG is supported
-		if (!$useSvg && $this->canConvert('PNG')) {
+		// only convert SVG originals to PNG when SVG output is not desired;
+		// converting raster images to SVG produces broken output and is not useful
+		$isOriginalSvg = ($mime === 'image/svg+xml' || $mime === 'image/svg');
+		if ($isOriginalSvg && !$useSvg && $this->canConvert('SVG') && $this->canConvert('PNG')) {
 			if (!$folder->fileExists($key . '.png')) {
 				try {
 					$finalIconFile = new \Imagick();
@@ -120,13 +105,12 @@ public function getImage(string $key, bool $useSvg = true): ISimpleFile {
 					$pngFile->putContent($finalIconFile->getImageBlob());
 					return $pngFile;
 				} catch (\ImagickException $e) {
-					$this->logger->info('The image was requested to be no SVG file, but converting it to PNG failed: ' . $e->getMessage());
+					$this->logger->info('Converting SVG to PNG failed: ' . $e->getMessage());
 				}
 			} else {
 				return $folder->getFile($key . '.png');
 			}
 		}
-		// fallback to the original file
 		return $folder->getFile($key);
 	}
 
@@ -157,7 +141,7 @@ public function getCustomImages(): array {
 	 * @throws NotPermittedException
 	 */
 	public function getCacheFolder(): ISimpleFolder {
-		$cacheBusterValue = $this->config->getAppValue('theming', 'cachebuster', '0');
+		$cacheBusterValue = (string)$this->appConfig->getAppValueInt(ConfigLexicon::CACHE_BUSTER);
 		try {
 			$folder = $this->getRootFolder()->getFolder($cacheBusterValue);
 		} catch (NotFoundException $e) {
@@ -214,6 +198,12 @@ public function delete(string $key): void {
 		} catch (NotFoundException $e) {
 		} catch (NotPermittedException $e) {
 		}
+		try {
+			$file = $this->getRootFolder()->getFolder('images')->getFile($key . '.svg');
+			$file->delete();
+		} catch (NotFoundException $e) {
+		} catch (NotPermittedException $e) {
+		}
 
 		if ($key === 'logo') {
 			$this->config->deleteAppValue('theming', 'logoDimensions');

lib/private/Server.php

@@ -1030,6 +1030,11 @@ public function __construct($webRoot, \OC\Config $config) {
 					$c->get(LoggerInterface::class),
 					$c->get(ITempManager::class),
 					$backgroundService,
+					new AppConfig(
+						$c->get(IConfig::class),
+						$c->get(IAppConfig::class),
+						'theming',
+					),
 				);
 				return new ThemingDefaults(
 					$c->get(\OCP\IConfig::class),