Add CI for Unity 6.5

[IvanMurzak]

Summary

Add a CI matrix entry for Unity 6.5 so the Unity-MCP plugin is validated against that editor version on every PR/release, alongside the currently covered versions (2022.3.62f3, 2023.2.22f1, 6000.3.1f1).

Status: Blocked

This issue is blocked until game-ci publishes a unityci/editor Docker image for Unity 6.5. Our CI runs Unity inside a container on ubuntu-latest, so without a prebuilt image there is no supported way to execute editor tests headlessly.

Track availability of new tags here:

• Docker Hub tags page: https://hub.docker.com/r/unityci/editor/tags
• Filter by Unity version, e.g. https://hub.docker.com/r/unityci/editor/tags?name=6500
• game-ci docker source: https://github.com/game-ci/docker

Implementation

Once a unityci/editor:ubuntu-6500.<x>.<y>f<z>-base-3 (and -windows-mono-3) tag exists, the change is mechanical and follows the existing pattern in .github/workflows/test_pull_request.yml.

1. Add a Unity-Tests/<unity-6.5-version> project

Create a sibling Unity project to Unity-Tests/6000.3.1f1/ for the new version (the existing ProjectVersion.txt, package manifest, and test assemblies can be copied and version-bumped).

2. Add jobs to test_pull_request.yml

For each test mode (editmode, standalone — and playmode once it is re-enabled), add a job that calls the reusable test_unity_plugin.yml workflow:

test-unity-6500-x-yfz-editmode:
  needs: [build-and-zip-mcp-server]
  uses: ./.github/workflows/test_unity_plugin.yml
  with:
    projectPath: './Unity-Tests/6500.x.yfz'
    unityVersion: '6500.x.yfz'
    testMode: 'editmode'
  secrets: inherit

test-unity-6500-x-yfz-standalone:
  needs: [build-and-zip-mcp-server]
  uses: ./.github/workflows/test_unity_plugin.yml
  with:
    projectPath: './Unity-Tests/6500.x.yfz'
    unityVersion: '6500.x.yfz'
    testMode: 'standalone'
  secrets: inherit

The reusable workflow already builds the custom image name as:

unityci/editor:ubuntu-${{ inputs.unityVersion }}-${{ matrix.platform }}-3

so as long as that tag exists on Docker Hub for the chosen 6.5 patch, no other workflow change is required. Both base and windows-mono platform variants must be available for the matrix to pass.

3. Pre-merge verification

Before merging, manually trigger test_pull_request_manual.yml (or the standard PR run) and confirm:

• The container pulls successfully (no manifest unknown from Docker Hub).
• License activation works for the new version (see .github/actions/unity/activate-license).
• Edit-mode and standalone tests pass.

Acceptance Criteria

• A unityci/editor:ubuntu-6500.x.yfz-base-3 image is available on Docker Hub.
• A unityci/editor:ubuntu-6500.x.yfz-windows-mono-3 image is available on Docker Hub.
• Unity-Tests/6500.x.yfz/ project added.
• Edit-mode + standalone jobs added to test_pull_request.yml.
• Green CI run on a PR exercising the new jobs.

Notes

• Help wanted: anyone who spots a 6.5 tag landing on the unityci/editor Docker Hub page is welcome to pick this up.
• If game-ci does not publish a 6.5 image in a reasonable timeframe, an alternative is to build a custom image from game-ci/docker and push it to a project-controlled registry — but that is out of scope until the upstream path is clearly unavailable.