fix: Repair foreign keys on columns that also carry a unique claim (#151)

packages/serverpod_offline_sync/lib/src/database/database.dart

@@ -477,6 +477,9 @@ class OfflineSyncDatabase implements Database {
           tx,
           projectionUnchanged: projection.projectionUnchanged,
           domainBeforeUpsert: projection.domain,
+          upsertRows: updateColumns == null && projection.domain.isNotEmpty
+              ? prepared.rows
+              : const [],
         );
         if (noReturn) return <T>[];
         _stripStampedRows(result, prepared);

packages/serverpod_offline_sync/lib/src/database/merge_utils/foreign_key_projector.dart

@@ -2120,12 +2120,24 @@ class CrdtForeignKeyProjector {
         if (state.pendingInsertKeys.contains(row.key)) continue;
         for (final column in _uniqueResolver.uniqueColumnNamesFor(row.key.$1)) {
           final key = (row.key.$1, row.key.$2, column);
-          row.values[column] = canonicalDomainValue(
+          final localValue = canonicalDomainValue(
             authoredOverlays.containsKey(key)
                 ? authoredOverlays[key]
                 : state.originalDomain[row.key]?[column],
             _context.columnsByTableAndName[row.key.$1]?[column],
           );
+          // An authored unique claim still needs its FK repair when a local
+          // edit makes the parent hidden. Only a released value may replace it.
+          if (foreignKeys.reasons.containsKey(key) &&
+              !authoredOverlays.containsKey(key) &&
+              projectionValuesEqual(localValue, authoredByField[key])) {
+            continue;
+          }
+          if (!projectionValuesEqual(localValue, row.values[column])) {
+            // Retaining a unique release supersedes the FK candidate's reason.
+            foreignKeys.reasons.remove(key);
+          }
+          row.values[column] = localValue;
         }
       }
     }

packages/serverpod_offline_sync/lib/src/database/recorder.dart

@@ -851,6 +851,7 @@ class CrdtMutationRecorder {
     bool projectionUnchanged = false,
     bool authoredColumnValues = false,
     Map<MergeRowKey, Map<String, Object?>> domainBeforeUpsert = const {},
+    List<TableRow> upsertRows = const [],
   }) async {
     await _foreignKeyProjector.assertVisibleTargets(updatedRows, columns, transaction);
 
@@ -865,6 +866,33 @@ class CrdtMutationRecorder {
         'updated',
         transaction,
       );
+      final implicitForeignKeyRepairFields = columns == null
+          ? await _foreignKeyProjector.findImplicitRepairFields(
+              tableName: tableName,
+              rowIds: rowIds,
+              transaction: transaction,
+            )
+          : const <MergeFieldKey>{};
+      final upsertInputs = upsertRows.isEmpty || implicitForeignKeyRepairFields.isEmpty
+          ? const <MergeRowKey, Map<String, Object?>>{}
+          : {
+              for (final row in upsertRows)
+                if (row.id case final UuidValue rowId)
+                  (row.table.tableName, rowId):
+                      row.toJsonForDatabase() as Map<String, dynamic>,
+            };
+      // Insert defaults must not author over an echoed null that is holding
+      // a projected FK claim.
+      bool echoesProjectedNull(UuidValue rowId, String columnName) {
+        if (!implicitForeignKeyRepairFields.contains((tableName, rowId, columnName))) {
+          return false;
+        }
+        final input = upsertInputs[(tableName, rowId)];
+        return input != null &&
+            input[columnName] == null &&
+            domainBeforeUpsert[(tableName, rowId)]?[columnName] == null;
+      }
+
       // Explicit columns author even an unchanged null; full-row passthrough
       // keeps the claim behind an unchanged displayed alternative.
       final authoredOverlays = <MergeFieldKey, Object?>{
@@ -883,20 +911,14 @@ class CrdtMutationRecorder {
                 if ((domainBeforeUpsert[(tableName, row.id)]?.containsKey(columnName) ??
                         false) &&
                     (columns != null ||
-                        !projectionValuesEqual(
-                          domainBeforeUpsert[(tableName, row.id)]![columnName],
-                          value,
-                        )))
+                        (!projectionValuesEqual(
+                              domainBeforeUpsert[(tableName, row.id)]![columnName],
+                              value,
+                            ) &&
+                            !echoesProjectedNull(row.id as UuidValue, columnName))))
                   (tableName, row.id as UuidValue, columnName): value,
       };
       _uniqueResolver.validateAuthoredFields(authoredOverlays);
-      final implicitForeignKeyRepairFields = columns == null
-          ? await _foreignKeyProjector.findImplicitRepairFields(
-              tableName: tableName,
-              rowIds: rowIds,
-              transaction: transaction,
-            )
-          : const <MergeFieldKey>{};
       await _recordUpdatedFields(
         updatedRows,
         crdtDataRows,