Chroma: add the MEVD provider by Laurianti · Pull Request #58 · CommunityToolkit/AI

Laurianti · 2026-10-06T21:39:57Z

Adds CommunityToolkit.VectorData.Chroma, the Chroma provider proposed in #57, with MEVD/test/Chroma.UnitTests and MEVD/test/Chroma.ConformanceTests. It follows the layout of the Qdrant provider, and builds on ChromaDotNet.Client as Qdrant builds on Qdrant.Client. I maintain ChromaDotNet.Client.

The conformance tests start chromadb/chroma:1.5.9 with Testcontainers, so the mevd.yml matrix picks them up. Chroma stores exactly one embedding per record, so there are no multi-vector and no-vector model tests. The hybrid search tests need Chroma Cloud: they run when Chroma:ConnectionString points to it, as the README of the tests says, and are skipped otherwise.

The same code, published as ChromaDotNet.VectorData 0.4.2, runs the Semantic Kernel and Agent Framework samples, and the Semantic Kernel hybrid search sample runs on Chroma Cloud.

The container is written in the tests, as for Weaviate. When Testcontainers.Chroma ships (testcontainers/testcontainers-dotnet#1784), it can replace it.

With the Aspire integration proposed in CommunityToolkit/Aspire#2219, builder.AddChromaClient("chroma") registers the ChromaClient that AddChromaVectorStore() takes from the container.

tryAGI/LangChain.Databases#180 adds Chroma to the tests of LangChain .NET with the same provider, and moves to this package when it ships.

.gitignore gets testsettings.*.json: the conformance tests READMEs, the PgVector one included, describe testsettings.development.json as git-ignored.

Fixes #57

Copilot

Copilot review overview

🟡 Changes recommended

Client reference leaks, non-idempotent disposal, and incorrect nullable-filter negation can cause resource and query failures.

Review effort: Balanced
Findings: 1 · 2 · 1

Open (4)

Make shared wrapper disposal idempotent per owner · New
Handle negated comparisons against nullable metadata correctly · New
Dispose temporary collection to release the owned client reference · New
Fix vector embeddings documentation typo · New

What changed in this PR

Adds the Chroma MEVD provider, including mapping, filtering, vector/hybrid search, dependency injection, and test infrastructure.

Changes:

Implements the Chroma vector store and collection APIs.
Adds unit and container-based conformance tests.
Integrates Chroma into dependencies, solutions, and documentation.

File	Description
`README.md`	Lists the Chroma package.
`MEVD/test/Chroma.UnitTests/FakeEmbeddingGenerator.cs`	Adds a test embedding generator.
`MEVD/test/Chroma.UnitTests/ChromaVectorStoreTests.cs`	Tests vector-store behavior.
`MEVD/test/Chroma.UnitTests/ChromaMapperTests.cs`	Tests record mapping.
`MEVD/test/Chroma.UnitTests/ChromaHotel.cs`	Defines unit-test models.
`MEVD/test/Chroma.UnitTests/ChromaFilterTranslatorTests.cs`	Tests filter translation.
`MEVD/test/Chroma.UnitTests/ChromaCollectionTests.cs`	Tests collection operations.
`MEVD/test/Chroma.UnitTests/ChromaCollectionSearchMappingTests.cs`	Tests score conversion.
`MEVD/test/Chroma.UnitTests/ChromaCollectionCreateMappingTests.cs`	Tests collection definitions.
`MEVD/test/Chroma.UnitTests/Chroma.UnitTests.csproj`	Configures unit tests.
`MEVD/test/Chroma.UnitTests/.editorconfig`	Configures test analyzers.
`MEVD/test/Chroma.ConformanceTests/TypeTests/ChromaKeyTypeTests.cs`	Covers supported keys.
`MEVD/test/Chroma.ConformanceTests/TypeTests/ChromaEmbeddingTypeTests.cs`	Covers embedding types.
`MEVD/test/Chroma.ConformanceTests/TypeTests/ChromaDataTypeTests.cs`	Covers metadata types.
`MEVD/test/Chroma.ConformanceTests/testsettings.json`	Provides test configuration.
`MEVD/test/Chroma.ConformanceTests/Support/ChromaTestStore.cs`	Manages Chroma test instances.
`MEVD/test/Chroma.ConformanceTests/Support/ChromaTestEnvironment.cs`	Loads test settings.
`MEVD/test/Chroma.ConformanceTests/Support/ChromaFixture.cs`	Defines the shared fixture.
`MEVD/test/Chroma.ConformanceTests/README.md`	Documents conformance testing.
`MEVD/test/Chroma.ConformanceTests/ModelTests/ChromaNoDataModelTests.cs`	Tests no-data models.
`MEVD/test/Chroma.ConformanceTests/ModelTests/ChromaDynamicModelTests.cs`	Tests dynamic models.
`MEVD/test/Chroma.ConformanceTests/ModelTests/ChromaBasicModelTests.cs`	Tests basic models.
`MEVD/test/Chroma.ConformanceTests/ChromaTestSuiteImplementationTests.cs`	Verifies suite coverage.
`MEVD/test/Chroma.ConformanceTests/ChromaIndexKindTests.cs`	Tests index support.
`MEVD/test/Chroma.ConformanceTests/ChromaHybridSearchTests.cs`	Tests cloud hybrid search.
`MEVD/test/Chroma.ConformanceTests/ChromaFilterTests.cs`	Tests filtering behavior.
`MEVD/test/Chroma.ConformanceTests/ChromaEmbeddingGenerationTests.cs`	Tests generated embeddings.
`MEVD/test/Chroma.ConformanceTests/ChromaDistanceFunctionTests.cs`	Tests distance functions.
`MEVD/test/Chroma.ConformanceTests/ChromaDependencyInjectionTests.cs`	Tests DI registrations.
`MEVD/test/Chroma.ConformanceTests/ChromaCollectionManagementTests.cs`	Tests collection management.
`MEVD/test/Chroma.ConformanceTests/Chroma.ConformanceTests.csproj`	Configures conformance tests.
`MEVD/src/Chroma/SharedChromaClient.cs`	Adds shared-client ownership.
`MEVD/src/Chroma/README.md`	Documents the provider.
`MEVD/src/Chroma/ChromaVectorStoreOptions.cs`	Defines store options.
`MEVD/src/Chroma/ChromaVectorStore.cs`	Implements the vector store.
`MEVD/src/Chroma/ChromaServiceCollectionExtensions.cs`	Adds DI extensions.
`MEVD/src/Chroma/ChromaModelBuilder.cs`	Validates collection models.
`MEVD/src/Chroma/ChromaMapper.cs`	Maps records and metadata.
`MEVD/src/Chroma/ChromaFilterTranslator.cs`	Translates LINQ filters.
`MEVD/src/Chroma/ChromaFieldMapping.cs`	Maps keys and documents.
`MEVD/src/Chroma/ChromaDynamicCollection.cs`	Adds dynamic collections.
`MEVD/src/Chroma/ChromaConstants.cs`	Defines provider constants.
`MEVD/src/Chroma/ChromaCollectionSearchMapping.cs`	Maps distances and thresholds.
`MEVD/src/Chroma/ChromaCollectionOptions.cs`	Defines collection options.
`MEVD/src/Chroma/ChromaCollectionCreateMapping.cs`	Maps collection schemas.
`MEVD/src/Chroma/ChromaCollection.cs`	Implements CRUD and search.
`MEVD/src/Chroma/Chroma.csproj`	Configures the provider package.
`MEVD/src/Chroma/AssemblyInfo.cs`	Adds assembly licensing.
`MEVD/MEVD.slnf`	Includes Chroma projects.
`Directory.Packages.props`	Adds the Chroma client version.
`CommunityToolkit.AI.slnx`	Includes Chroma projects.
`.gitignore`	Ignores local test settings.

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… does The NativeAOT compiler of .NET 10.0.12 fails on the state machine of the handler when RunOperationAsync returns its task: "VTable ... not computed by the IL scanner".

…omparisons on nullable properties, as CommunityToolkit/AI#58 does

The README says where the provider goes next, CommunityToolkit/AI#58, and what happens to this package then.

…t 300 results, as CommunityToolkit/AI#58 does

Copilot

🟡 Changes recommended

Model validation must reject Chroma’s reserved Search API keys as data-property storage names.

1 open finding

Reject reserved Chroma Search API keys as property names · New

4 resolved since last review

Make shared wrapper disposal idempotent per owner
Dispose temporary collection to release the owned client reference
Handle negated comparisons against nullable metadata correctly
Fix vector embeddings documentation typo

🧠 Review effort: Balanced

+    protected override void ValidateProperty(PropertyModel propertyModel, VectorStoreCollectionDefinition? definition)
+    {
+        base.ValidateProperty(propertyModel, definition);
+
+        switch (propertyModel)


adamsitnik

First of all, big thanks for your contribution @Laurianti

The provider follows established conventions closely enough that I consider this ready to merge. I found two nits myself and used LLM to find one minor bug. As soon as they are addressed, we should be ready to ship.

Again, thank you!

adamsitnik · 2026-10-07T15:50:07Z

+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <Version>1.0.0-preview.1</Version>


nit: for other projects, like Sqlvec, we use X.Y.Z-preview version number:

AI/MEVD/src/SqliteVec/SqliteVec.csproj

Line 4 in c3ed414

<Version>1.0.2-preview</Version>

Suggested change

<Version>1.0.0-preview.1</Version>

<Version>1.0.0-preview</Version>

It allows us to release small patches without bumping preview version number.

Done in 1141099.

adamsitnik · 2026-10-07T16:24:41Z

+        var recordIndex = 0;
+        foreach (var record in records)
+        {
+            if (keyProperty.IsAutoGenerated && keyProperty.GetValue<Guid>(record) == Guid.Empty)


Chroma (unlike Qdrant) supports string keys, and ChromaModelBuilder.ValidateKeyProperty doesn't reject IsAutoGenerated=true on a string key. So we can get InvalidCastException here.

A fix would be to add similar check to ChromaModelBuilder

AI/MEVD/src/InMemory/InMemoryModelBuilder.cs

Lines 24 to 29 in c3ed414

// All .NET types are supported by the InMemory provider, but we support auto-generation of keys only for GUIDs

if (keyProperty.IsAutoGenerated && keyProperty.Type != typeof(Guid))

{

throw new NotSupportedException(

$"Auto-generation is only supported for key properties of type Guid. Property '{keyProperty.ModelName}' has type '{keyProperty.Type.Name}'.");

}

Done in 7791e1c: ChromaModelBuilder now rejects IsAutoGenerated on a string key, as InMemoryModelBuilder does.

adamsitnik · 2026-10-07T16:27:13Z

nit: we could reuse MEVD/test/InMemory.UnitTests/FakeEmbeddingGenerator.cs instead of adding new utility here

Done in e74ad96: the tests use the one in InMemory.UnitTests.

…tyToolkit/AI#58

Laurianti · 2026-10-07T16:46:57Z

Thanks @adamsitnik! The three points are addressed, one commit each.

Copilot AI balanced review requested due to automatic review settings October 6, 2026 21:39

Copilot started reviewing on behalf of Laurianti October 6, 2026 21:40 View session

Copilot AI reviewed Oct 6, 2026

View reviewed changes

Comment thread MEVD/src/Chroma/SharedChromaClient.cs

Comment thread MEVD/src/Chroma/ChromaFilterTranslator.cs Outdated

Comment thread MEVD/src/Chroma/ChromaVectorStore.cs Outdated

Comment thread MEVD/src/Chroma/ChromaVectorStoreOptions.cs Outdated

Laurianti mentioned this pull request Oct 6, 2026

feat: Add Chroma module testcontainers/testcontainers-dotnet#1784

Open

Laurianti added a commit to ChromaDotNet/ChromaDB.VectorData that referenced this pull request Oct 6, 2026

Dispose once, release the temporary collections, and reject negated c…

e971a85

…omparisons on nullable properties, as CommunityToolkit/AI#58 does

This was referenced Oct 6, 2026

Add Chroma hosting and client integrations CommunityToolkit/Aspire#2219

Open

[DOC] List the community SDKs in the reference chroma-core/chroma#7851

Open

Copilot AI mentioned this pull request Oct 6, 2026

Say that the provider is proposed to the AI Community Toolkit ChromaDotNet/ChromaDB.VectorData#6

Merged

Laurianti added a commit to ChromaDotNet/ChromaDB.VectorData that referenced this pull request Oct 6, 2026

Say that the provider is proposed to the AI Community Toolkit

74c027c

The README says where the provider goes next, CommunityToolkit/AI#58, and what happens to this package then.

Laurianti force-pushed the chroma-provider branch from 5df429a to db6101b Compare October 6, 2026 23:57

Laurianti added a commit to ChromaDotNet/ChromaDB.VectorData that referenced this pull request Oct 7, 2026

Say in the README that a vector search on Chroma Cloud returns at mos…

0c4a993

…t 300 results, as CommunityToolkit/AI#58 does

Copilot AI mentioned this pull request Oct 7, 2026

Say in the READMEs that the provider moves to the AI Community Toolkit package ChromaDotNet/ChromaDB.VectorData#7

Merged

This was referenced Oct 7, 2026

feat: add Chroma to the integration tests tryAGI/LangChain.Databases#180

Open

Build on ChromaDotNet.Client 2.11.0 as 0.4.2 ChromaDotNet/ChromaDB.VectorData#14

Merged

Chroma: add the MEVD provider

3085a49

Laurianti force-pushed the chroma-provider branch from 298b46e to 3085a49 Compare October 7, 2026 14:53

adamsitnik requested a balanced review from Copilot October 7, 2026 15:47

Copilot started reviewing on behalf of adamsitnik October 7, 2026 15:47 View session

Copilot AI reviewed Oct 7, 2026

View reviewed changes

Comment thread MEVD/src/Chroma/ChromaModelBuilder.cs

Comment on lines +36 to +40

protected override void ValidateProperty(PropertyModel propertyModel, VectorStoreCollectionDefinition? definition)

{

base.ValidateProperty(propertyModel, definition);

switch (propertyModel)

adamsitnik reviewed Oct 7, 2026

View reviewed changes

Laurianti added a commit to ChromaDotNet/.github that referenced this pull request Oct 7, 2026

Organization profile: add the VectorData provider proposed in Communi…

9f85e27

…tyToolkit/AI#58

Laurianti added 3 commits October 7, 2026 18:39

Chroma: version the package as 1.0.0-preview, as SqliteVec

1141099

Chroma: support auto-generation of keys only for GUIDs, as InMemory does

7791e1c

Chroma: reuse the FakeEmbeddingGenerator of the InMemory unit tests

e74ad96

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Chroma: add the MEVD provider - #58

Chroma: add the MEVD provider#58
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	<Version>1.0.0-preview.1</Version>
	<Version>1.0.0-preview</Version>

	// All .NET types are supported by the InMemory provider, but we support auto-generation of keys only for GUIDs
	if (keyProperty.IsAutoGenerated && keyProperty.Type != typeof(Guid))
	{
	throw new NotSupportedException(
	$"Auto-generation is only supported for key properties of type Guid. Property '{keyProperty.ModelName}' has type '{keyProperty.Type.Name}'.");
	}

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