Add latestVersion field to GraphQL AiCatalogItems

What does this MR do and why?

This MR returns the latest version of an AI item through the latestVersion field.

• #553301 (closed)

How to set up and validate locally

Enable the :global_ai_catalog feature flag:

First, create an agent if you don't have one already:

 mutation {
   aiCatalogAgentCreate(input: {
     name: "Pirate"
     description: "A pirate doing a sum"
     projectId: "gid://gitlab/Project/1000000"
     systemPrompt: "You are a pirate!"
     userPrompt: "What is 2 + 2?"
   }) {
     errors
     item {
       id
     }
   }
 }

Now, create 2 versions for that agent on the Rails console:

item = Ai::Catalog::Item.last

FactoryBot.create(:ai_catalog_item_version, version: '2.0.0', item: item)
FactoryBot.create(:ai_catalog_item_version, version: '2.1.0', item: item)

Now, query for the latestVersion of the agent that you created, the versionName property should be "2.1.0":

Replace <ID> in the query brlow with the id of the item.

{
  aiCatalogItem(id: "gid://gitlab/Ai::Catalog::Item/<ID>") {
    id
    name
    description
    latestVersion {
      id
      versionName
      createdAt
      updatedAt
      publishedAt
      ...on AiCatalogAgentVersion {
        userPrompt
        systemPrompt
      }
    }
  }
}

Example response:

{
  "data": {
    "aiCatalogItem": {
      "id": "gid://gitlab/Ai::Catalog::Item/6",
      "name": "Pirate",
      "description": "A pirate doing a sum",
      "latestVersion": {
        "id": "gid://gitlab/Ai::Catalog::ItemVersion/5",
        "versionName": "2.1.0",
        "createdAt": "2025-07-09T03:08:23Z",
        "updatedAt": "2025-07-09T03:08:23Z",
        "publishedAt": "2025-07-09T03:08:23Z",
        "userPrompt": "What is 2 + 2?",
        "systemPrompt": "You are a pirate!"
      }
    }
  },
  "correlationId": "01JZPN48PQRK2SCPSQXJBMXMQ6"
}

Verify latest_field loads without N+1, by

• Ensuring you have created multiple agents
• And that the agents have multiple versions

Tail the logs tail -f log/development.log, and executing a query to return many items:

{
  aiCatalogItems {
    nodes {
      latestVersion {
        id
      }
    }
  }
}

The logs should show the version records are queried with one request.

MR acceptance checklist

Evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.