Reject the storage names that start with #, which Chroma reserves

src/ChromaDB.VectorData/ChromaModelBuilder.cs

@@ -44,6 +44,14 @@ protected override void ValidateProperty(PropertyModel propertyModel, VectorStor
     {
         base.ValidateProperty(propertyModel, definition);
 
+        // Chroma reserves the metadata keys that start with #, like #id and #document of the Search API: a filter on #id selects
+        // the record with that id.
+        if (propertyModel is DataPropertyModel && propertyModel.StorageName.StartsWith("#", StringComparison.Ordinal))
+        {
+            throw new NotSupportedException(
+                $"Property '{propertyModel.ModelName}' has the storage name '{propertyModel.StorageName}', but Chroma reserves the metadata keys that start with #.");
+        }
+
         switch (propertyModel)
         {
             case VectorPropertyModel vectorProperty:

test/ChromaDB.VectorData.UnitTests/ChromaCollectionTests.cs

@@ -53,6 +53,68 @@ public ChromaCollectionTests()
     public void RejectsADictionaryRecord()
         => Assert.Throws<NotSupportedException>(() => new ChromaCollection<object, Dictionary<string, object?>>(this._chromaClientMock.Object, TestCollectionName, ownsClient: false));
 
+    [Theory]
+    [InlineData("#id")]
+    [InlineData("#document")]
+    [InlineData("#embedding")]
+    [InlineData("#metadata")]
+    [InlineData("#score")]
+    [InlineData("#other")]
+    public void RejectsADataPropertyWhoseStorageNameStartsWithAHash(string storageName)
+    {
+        // Chroma reserves the metadata keys that start with #: a filter on #id would select the record with that id.
+        var definition = new VectorStoreCollectionDefinition
+        {
+            Properties =
+            [
+                new VectorStoreKeyProperty("Key", typeof(string)),
+                new VectorStoreDataProperty("Tag", typeof(string)) { StorageName = storageName },
+                new VectorStoreVectorProperty("Vector", typeof(ReadOnlyMemory<float>), 4),
+            ]
+        };
+
+        var exception = Assert.Throws<NotSupportedException>(() => new ChromaDynamicCollection(this._chromaClientMock.Object, TestCollectionName, ownsClient: false, new() { Definition = definition }));
+        Assert.Contains($"'{storageName}'", exception.Message);
+    }
+
+    [Fact]
+    public void RejectsAStorageNameThatStartsWithAHashOnARecordType()
+        => Assert.Throws<NotSupportedException>(() => new ChromaCollection<string, HashStorageNameRecord>(this._chromaClientMock.Object, TestCollectionName, ownsClient: false));
+
+    [Fact]
+    public void RejectsAFullTextPropertyWhoseStorageNameStartsWithAHash()
+    {
+        // The full-text property stored as the document is also a metadata key: the client copies the document into it.
+        var definition = new VectorStoreCollectionDefinition
+        {
+            Properties =
+            [
+                new VectorStoreKeyProperty("Key", typeof(string)),
+                new VectorStoreDataProperty("Text", typeof(string)) { StorageName = "#document", IsFullTextIndexed = true },
+                new VectorStoreVectorProperty("Vector", typeof(ReadOnlyMemory<float>), 4),
+            ]
+        };
+
+        Assert.Throws<NotSupportedException>(() => new ChromaDynamicCollection(this._chromaClientMock.Object, TestCollectionName, ownsClient: false, new() { Definition = definition }));
+    }
+
+    [Fact]
+    public void AcceptsAHashInsideAStorageName()
+    {
+        var definition = new VectorStoreCollectionDefinition
+        {
+            Properties =
+            [
+                new VectorStoreKeyProperty("Key", typeof(string)),
+                new VectorStoreDataProperty("Tag", typeof(string)) { StorageName = "tag#1" },
+                new VectorStoreVectorProperty("Vector", typeof(ReadOnlyMemory<float>), 4),
+            ]
+        };
+
+        using var sut = new ChromaDynamicCollection(this._chromaClientMock.Object, TestCollectionName, ownsClient: false, new() { Definition = definition });
+        Assert.Equal(TestCollectionName, sut.Name);
+    }
+
     [Fact]
     public void DynamicCollectionsTakeAClientAndADefinition()
     {
@@ -514,4 +576,16 @@ private static ChromaCollection HybridChromaCollection(params string[] indexes)
     private static string Bm25Index(string key, string sourceKey)
         => "\"" + key + "\":{\"sparse_vector\":{\"sparse_vector_index\":{\"enabled\":true,\"config\":{\"source_key\":\"" + sourceKey + "\",\"bm25\":true,"
             + "\"embedding_function\":{\"type\":\"known\",\"name\":\"chroma_bm25\",\"config\":{\"k\":1.2,\"b\":0.75,\"avg_doc_length\":256,\"token_max_length\":40}}}}}}";
+
+    private sealed class HashStorageNameRecord
+    {
+        [VectorStoreKey]
+        public string Key { get; set; } = "";
+
+        [VectorStoreData(StorageName = "#id")]
+        public string? Tag { get; set; }
+
+        [VectorStoreVector(4)]
+        public ReadOnlyMemory<float> Vector { get; set; }
+    }
 }