Merged GraphQL fragments only use one selection #28133

Describe the Bug

When using multiple GQL fragments in a query that target the same collection, the fields are merged and only the selections of the first query survive the merge.

To Reproduce

• Create a collection pages
• Add a field title: string
• Run a GQL query with merged fragments:

fragment A on Query { page { id } }
fragment B on Query { page { title } }
query { ...A ...B }

• Result only returns id

{
  "data": {
    "page": [
      {
        "id": "1",
        "title": null
      },
      {
        "id": "2",
        "title": null
      }
    ]
  }
}

Directus Version

12.3.0

Hosting Strategy

Self-Hosted (Docker Image)

Database

No response