feat(vectorstores): add Chromia vectorstore integration and examples

[liho00]

Chromia Vector DB for LangChain.js

Chromia integration as a vector store for LangChain.js, built on top of [postchain-client](https://www.npmjs.com/package/postchain-client). This package enables you to use a Chromia blockchain as a persistent and verifiable vector store for document embeddings.

---

Features

• ✅ Add vectors/documents
• ✅ Perform similarity search
• ✅ Delete documents
• 🔜 Filtering support (interface added, not yet implemented)
• ✅ Written in TypeScript with full types and documentation

---

Quickstart

1. Clone and Start a Local Chromia Node

docker run --rm -it -p 7740:7740 registry.gitlab.com/chromaway/example-projects/directory1-example/managed-single:latest
git clone https://github.com/liho00/vector-db-chromia.git
cd vector-db-chromia/chromia/rell
chr build
pmc blockchain add -bc build/vector_example.xml -c dapp -n vector_blockchain

This spins up a local Chromia node using Docker with a default blockchain configuration that supports vector storage.

Note: Ensure Docker is installed and running on your machine.

---

2. Install the Vector Store

npm install @langchain/community
npm install postchain-client

---

3. Usage Example

import { Chromia } from '@langchain/community/vectorstores/chromia';
import { OpenAIEmbeddings } from '@langchain/openai';
import { createPostchainClient } from 'postchain-client'; // Your own wrapper or raw setup

// Setup postchain client
const postchainClient = createPostchainClient({
  blockchainRID: 'your-blockchain-rid',
  nodeUrl: 'http://localhost:7740', // default RPC for Chromia dev node
});

const embeddings = new OpenAIEmbeddings({
  model: 'text-embedding-3-small',
});

const vectorStore = new Chromia(embeddings, {
  client: postchainClient,
  numDimensions: embeddings.dimensions,
});

// Add document
await vectorStore.addDocuments([
  { pageContent: 'sample text', metadata: { source: 'doc1' } },
]);

// Perform a similarity search
const results = await vectorStore.similaritySearch('query', 1);
console.log(results);

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Name	Status	Preview	Comments	Updated (UTC)
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[Prem95]

Hi @jacoblee93 Can you please help to take a look at this PR? Thank you!

[benjamincburns]

@Prem95 this is in draft status - we generally wait until it's no longer a draft to review unless you have specific questions. If you think this is ready, please click the "Ready for review" button and we'll have a look.

Edit: Oh, I see this isn't your PR - @liho00 will need to update the PR status when they're ready for us.

[Prem95]

@Prem95 this is in draft status - we generally wait until it's no longer a draft to review unless you have specific questions. If you think this is ready, please click the "Ready for review" button and we'll have a look.

Edit: Oh, I see this isn't your PR - @liho00 will need to update the PR status when they're ready for us.

Thanks @benjamincburns for the information. It will be updated

[liho00]

Hi @benjamincburns, @jacoblee93 its ready for review now.

[liho00]

Hi @benjamincburns, @jacoblee93 its ready for review now.

[liho00]

Hi @benjamincburns, @jacoblee93 its ready for review now.

[Prem95]

Hi @benjamincburns, please review this, thanks!

[benjamincburns]

Hi @liho00,

The community package has become rather unwieldy, and we recommend against using it in production applications.

Is this something that you want people to be able to use in production? If so, I'd recommend repackaging your changes into a standalone NPM module. You can keep this in your own GitHub repo and publish it to NPM yourself without our involvement, but to make it discoverable you can still create a PR that adds a page about it in our integration docs.

Otherwise if you think that community is the best home for this, we'll leave it open and review it when we're able. Unfortunately adding new features to community isn't a high priority for us right now, so this may take a little while.

[liho00]

Hi @liho00,

The community package has become rather unwieldy, and we recommend against using it in production applications.

Is this something that you want people to be able to use in production? If so, I'd recommend repackaging your changes into a standalone NPM module. You can keep this in your own GitHub repo and publish it to NPM yourself without our involvement, but to make it discoverable you can still create a PR that adds a page about it in our integration docs.

Otherwise if you think that community is the best home for this, we'll leave it open and review it when we're able. Unfortunately adding new features to community isn't a high priority for us right now, so this may take a little while.

https://www.npmjs.com/package/@liholiho/community?activeTab=readme

We have published for our own use, but we still need this to be merged for better endorsement for users.
Thanks!