diff --git a/backend/src/main/java/org/raddatz/familienarchiv/document/DocumentService.java b/backend/src/main/java/org/raddatz/familienarchiv/document/DocumentService.java
index 44b0a0d9..ed37a2c2 100644
--- a/backend/src/main/java/org/raddatz/familienarchiv/document/DocumentService.java
+++ b/backend/src/main/java/org/raddatz/familienarchiv/document/DocumentService.java
@@ -431,7 +431,11 @@ public class DocumentService {
             doc.setScriptType(dto.getScriptType());
         }
 
-        // 4. Datei austauschen (nur wenn eine neue ausgewählt wurde)
+        // 4. Datei austauschen (nur wenn eine neue ausgewählt wurde).
+        // NB (#726): this reassigns originalFilename to the uploaded file's name. The title's index
+        // segment is originalFilename, so after a replace the stored title no longer matches
+        // build(currentState) and the row is treated as manual — neither save-time nor backfill
+        // rewrites it. Accepted fail-safe (ADR-031), and autoTitleBefore was already captured above.
         boolean fileReplaced = newFile != null && !newFile.isEmpty();
         if (fileReplaced) {
             FileService.UploadResult upload = fileService.uploadFile(newFile, newFile.getOriginalFilename());
@@ -479,44 +483,49 @@ public class DocumentService {
     }
 
     /**
-     * The document state the regenerated title is built from, mirroring {@code updateDocument}'s
-     * setter asymmetry exactly: {@code documentDate}/{@code location} are overwritten from the DTO
-     * (a null value clears the field), while precision/end/raw are taken from the DTO only when
-     * non-null and otherwise kept from the stored entity (see {@link #applyDatePrecision}). The
-     * index ({@code originalFilename}) is never touched by a metadata edit. A mismatch here would
-     * silently produce a wrong label, so it is kept lock-step with the real setters.
+     * The document state the regenerated title is built from. It is composed from the SAME
+     * resolvers the real setters use — {@code documentDate}/{@code location} overwritten from the
+     * DTO (a null value clears the field), precision/end/raw resolved skip-null via
+     * {@link #effectivePrecision}/{@link #effectiveMetaDateEnd}/{@link #effectiveMetaDateRaw} — so
+     * the projection cannot drift from {@link #updateDocument}. The index ({@code originalFilename})
+     * is never touched by a metadata edit.
      */
     private Document projectedState(Document doc, DocumentUpdateDTO dto) {
         return Document.builder()
                 .originalFilename(doc.getOriginalFilename())
                 .documentDate(dto.getDocumentDate())
                 .location(dto.getLocation())
-                .metaDatePrecision(dto.getMetaDatePrecision() != null
-                        ? dto.getMetaDatePrecision() : doc.getMetaDatePrecision())
-                .metaDateEnd(dto.getMetaDateEnd() != null
-                        ? dto.getMetaDateEnd() : doc.getMetaDateEnd())
-                .metaDateRaw(dto.getMetaDateRaw() != null
-                        ? dto.getMetaDateRaw() : doc.getMetaDateRaw())
+                .metaDatePrecision(effectivePrecision(doc, dto))
+                .metaDateEnd(effectiveMetaDateEnd(doc, dto))
+                .metaDateRaw(effectiveMetaDateRaw(doc, dto))
                 .build();
     }
 
     /**
-     * Applies the three date-precision fields only when the DTO carries them.
-     * A null field means "not submitted" — overwriting the stored value with null
-     * would fabricate a precision the user never chose, the exact dishonesty #666
-     * exists to prevent. A row with a genuinely-unknown precision must keep it when
-     * an unrelated edit (e.g. a location typo) is saved.
+     * Applies the three date-precision fields skip-null: a null DTO field means "not submitted",
+     * so the stored value is kept rather than overwritten with null — which would fabricate a
+     * precision the user never chose, the exact dishonesty #666 exists to prevent. Expressed via
+     * the shared {@code effective*} resolvers so {@link #projectedState} stays lock-step (writing
+     * the stored value back when the DTO omits a field is a harmless no-op).
      */
     private void applyDatePrecision(Document doc, DocumentUpdateDTO dto) {
-        if (dto.getMetaDatePrecision() != null) {
-            doc.setMetaDatePrecision(dto.getMetaDatePrecision());
-        }
-        if (dto.getMetaDateEnd() != null) {
-            doc.setMetaDateEnd(dto.getMetaDateEnd());
-        }
-        if (dto.getMetaDateRaw() != null) {
-            doc.setMetaDateRaw(dto.getMetaDateRaw());
-        }
+        doc.setMetaDatePrecision(effectivePrecision(doc, dto));
+        doc.setMetaDateEnd(effectiveMetaDateEnd(doc, dto));
+        doc.setMetaDateRaw(effectiveMetaDateRaw(doc, dto));
+    }
+
+    // Skip-null date-field resolution shared by applyDatePrecision (the real setters) and
+    // projectedState (the title projection) — the single rule keeps them from diverging (#726).
+    private static DatePrecision effectivePrecision(Document doc, DocumentUpdateDTO dto) {
+        return dto.getMetaDatePrecision() != null ? dto.getMetaDatePrecision() : doc.getMetaDatePrecision();
+    }
+
+    private static LocalDate effectiveMetaDateEnd(Document doc, DocumentUpdateDTO dto) {
+        return dto.getMetaDateEnd() != null ? dto.getMetaDateEnd() : doc.getMetaDateEnd();
+    }
+
+    private static String effectiveMetaDateRaw(Document doc, DocumentUpdateDTO dto) {
+        return dto.getMetaDateRaw() != null ? dto.getMetaDateRaw() : doc.getMetaDateRaw();
     }
 
     /**