fix: store content type at upload time instead of guessing from extension

Previously FileService fell back to extension-based MIME detection, causing
TIFF, HEIC, DOCX and other unlisted types to be served as octet-stream
(forced download instead of inline display).

- Add content_type column to documents (V3 migration)
- Store file.getContentType() in DocumentService on upload and file replace
- MassImportService uses Files.probeContentType() for local files
- DocumentController prefers doc.getContentType() over S3-reported type
- FileService: remove extension-based fallback (no longer needed)
- DocumentService: replace leftover ResponseStatusException with DomainException

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

backend/src/main/java/org/raddatz/familienarchiv/controller/DocumentController.java

@@ -57,8 +57,13 @@ public class DocumentController {
         try {
             FileService.S3FileDownload download = fileService.downloadFile(doc.getFilePath());
 
+            // Prefer the content type stored at upload time; fall back to whatever S3 reports
+            String contentType = (doc.getContentType() != null && !doc.getContentType().isBlank())
+                    ? doc.getContentType()
+                    : download.contentType();
+
             return ResponseEntity.ok()
-                    .contentType(MediaType.parseMediaType(download.contentType()))
+                    .contentType(MediaType.parseMediaType(contentType))
                     .header(HttpHeaders.CONTENT_DISPOSITION, "inline; filename=\"" + doc.getOriginalFilename() + "\"")
                     .body(download.resource());
         } catch (FileService.StorageFileNotFoundException e) {

backend/src/main/java/org/raddatz/familienarchiv/model/Document.java

@@ -32,6 +32,10 @@ public class Document {
     @Column(name = "file_path")
     private String filePath;
 
+    // MIME-Type, gespeichert beim Upload (z.B. "application/pdf", "image/jpeg")
+    @Column(name = "content_type")
+    private String contentType;
+
     // Originaler Dateiname beim Upload (z.B. "Brief_Oma_1940.pdf")
     @Column(name = "original_filename", nullable = false)
     private String originalFilename;

backend/src/main/java/org/raddatz/familienarchiv/service/DocumentService.java

@@ -13,11 +13,11 @@ import org.raddatz.familienarchiv.repository.PersonRepository;
 import org.raddatz.familienarchiv.repository.TagRepository;
 import org.springframework.data.domain.Sort;
 import org.springframework.data.jpa.domain.Specification;
-import org.springframework.http.HttpStatus;
+import org.raddatz.familienarchiv.exception.DomainException;
+import org.raddatz.familienarchiv.exception.ErrorCode;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 import org.springframework.web.multipart.MultipartFile;
-import org.springframework.web.server.ResponseStatusException;
 
 import java.io.IOException;
 import java.time.LocalDate;
@@ -69,6 +69,7 @@ public class DocumentService {
 
         // 3. Update Database
         document.setFilePath(s3Key);
+        document.setContentType(file.getContentType());
         if (document.getStatus() == DocumentStatus.PLACEHOLDER) {
             document.setStatus(DocumentStatus.UPLOADED);
         }
@@ -79,7 +80,7 @@ public class DocumentService {
     @Transactional
     public Document updateDocument(UUID id, DocumentUpdateDTO dto, MultipartFile newFile) throws IOException {
         Document doc = documentRepository.findById(id)
-                .orElseThrow(() -> new ResponseStatusException(HttpStatus.NOT_FOUND, "Dokument nicht gefunden"));
+                .orElseThrow(() -> DomainException.notFound(ErrorCode.DOCUMENT_NOT_FOUND, "Document not found: " + id));
 
         // 1. Einfache Felder Update
         doc.setTitle(dto.getTitle());
@@ -125,6 +126,7 @@ public class DocumentService {
 
             doc.setFilePath(s3Key);
             doc.setOriginalFilename(newFile.getOriginalFilename());
+            doc.setContentType(newFile.getContentType());
             doc.setStatus(DocumentStatus.UPLOADED);
         }
 

backend/src/main/java/org/raddatz/familienarchiv/service/FileService.java

@@ -66,21 +66,10 @@ public class FileService {
 
         ResponseInputStream<GetObjectResponse> s3Object = s3Client.getObject(getObjectRequest);
 
-        // 1. Versuche Content-Type von S3 zu bekommen
+        // Use whatever content type S3 has stored (set at upload time)
         String contentType = s3Object.response().contentType();
-
-        // 2. FIX: Wenn S3 "octet-stream" sagt (oder null ist), raten wir anhand der Endung
-        if (contentType == null || contentType.isEmpty() || contentType.equals("application/octet-stream")) {
-            String keyLower = s3Key.toLowerCase();
-            if (keyLower.endsWith(".pdf")) {
-                contentType = "application/pdf";
-            } else if (keyLower.endsWith(".jpg") || keyLower.endsWith(".jpeg")) {
-                contentType = "image/jpeg";
-            } else if (keyLower.endsWith(".png")) {
-                contentType = "image/png";
-            } else {
-                contentType = "application/octet-stream"; // Fallback
-            }
+        if (contentType == null || contentType.isBlank()) {
+            contentType = "application/octet-stream";
         }
 
         return new S3FileDownload(new InputStreamResource(s3Object), contentType);

backend/src/main/java/org/raddatz/familienarchiv/service/MassImportService.java

@@ -140,12 +140,22 @@ public class MassImportService {
             return;
         }
 
+        // Detect MIME type from the local file
+        String contentType;
+        try {
+            contentType = Files.probeContentType(file.toPath());
+        } catch (IOException e) {
+            contentType = null;
+        }
+        if (contentType == null) contentType = "application/octet-stream";
+
         // Upload zu S3
         String s3Key = "documents/" + UUID.randomUUID() + "_" + file.getName();
         try {
             s3Client.putObject(PutObjectRequest.builder()
                     .bucket(bucketName)
                     .key(s3Key)
+                    .contentType(contentType)
                     .build(),
                     RequestBody.fromFile(file));
         } catch (Exception e) {
@@ -160,6 +170,7 @@ public class MassImportService {
                 .build());
 
         doc.setFilePath(s3Key);
+        doc.setContentType(contentType);
         doc.setStatus(DocumentStatus.UPLOADED); // Jetzt ist es da!
         doc.setDocumentDate(date);
         doc.setLocation(location);

backend/src/main/resources/db/migration/V3__add_content_type_to_documents.sql

@@ -0,0 +1 @@
+ALTER TABLE documents ADD COLUMN content_type character varying(255);