fix(model-server): attempt to fix the flaky ReplicatedRepositoryTest

Author: slisson

model-datastructure/src/commonMain/kotlin/org/modelix/model/lazy/CLVersion.kt

@@ -358,9 +358,8 @@ fun IVersion.diff(knownVersions: List<IVersion>, filter: ObjectDeltaFilter = Obj
              *
              * Use the version closest to [this] version as the base because that one should produce the smallest diff.
              */
-            val baseVersion = unknownHistory.mapNotNull { it.baseVersion }
-                .find { allKnownVersions.contains(it.getObjectHash()) }
-                ?: allKnownVersions.values.firstOrNull()
+            val baseVersion = version.baseVersion?.takeIf { allKnownVersions.contains(it.getObjectHash()) }
+                ?: allKnownVersions.values.lastOrNull()
             result += if (baseVersion == null) {
                 IStream.many(version.data.treeRefs.values)
                     .flatMap { it.resolve() }

model-server/src/main/kotlin/org/modelix/model/server/handlers/RepositoriesManager.kt

@@ -36,6 +36,7 @@ import org.modelix.streams.IExecutableStream
 import org.modelix.streams.IStream
 import org.modelix.streams.getBlocking
 import org.modelix.streams.iterateBlocking
+import org.modelix.streams.plus
 import org.slf4j.LoggerFactory
 import java.util.UUID
 
@@ -390,9 +391,16 @@ class RepositoriesManager(val stores: StoreManager) : IRepositoriesManager {
         val store = stores.getAsyncStore(repository?.takeIf { isIsolated(it) ?: false })
         return store.getStreamExecutor().queryManyLater {
             val version = CLVersion.loadFromHash(versionHash, store)
-            IStream.many(filter.knownVersions).flatMap { CLVersion.tryLoadFromHash(it, store) }.toList().flatMap { knownVersions ->
-                version.diff(knownVersions, filter).map { it.getHashString() to it.data.serialize() }
-            }
+
+            val diff = IStream.many(filter.knownVersions).flatMap { CLVersion.tryLoadFromHash(it, store) }.toList()
+                .flatMap { knownVersions ->
+                    version.diff(knownVersions, filter)
+                }
+            val versionHash = version.getObjectHash()
+            // The version itself is always included, because version objects on the client are weakly referenced,
+            // and it may already be garbage collected.
+            (IStream.of(version.asObject()) + diff.filter { it.getHash() != versionHash })
+                .map { it.getHashString() to it.data.serialize() }
         }.let { ObjectDataFlow(it) }
     }