Welcome tab still opens in Codespaces even when `workbench.startupEditor` is set to `"none"` in Remote settings

[dmalan]

Does this issue occur when all extensions are disabled?: Yes

• VS Code Version: 1.94.0, d78a74bcdfad14d5d3b1b782f87255d802b57511
• OS Version: Codespaces

Steps to Reproduce:

1. Create a new codespace using a .devcontainer.json with "workbench.startupEditor": "none".
2. Welcome tab still appears on first launch.

Notes

Just wanted to re-surface https://github.com/microsoft/vscode/issues/160635, which doesn't seem to have been fixed by https://github.com/microsoft/vscode/pull/169674, at least in Codespaces. Per screenshots below, new codespaces still open for the first time with a Welcome tab, even with a minimalist .devcontainer.json containing only:

{
  "customizations": {
    "vscode": {
      "settings": {
        "workbench.startupEditor": "none"
      }
    }
  }
}

Screenshots

CC @rongxin-liu

[bhavyaus]

This appears to be an issue with configurationDefaults not being applied on the first launch. See the screen recording below:

https://github.com/user-attachments/assets/18f5aadf-83bc-4a1b-8d9f-0bbfe2342ef2

1. Notice that my devcontainer configuration in the project sets "workbench.startupEditor": "none".
2. Next, create a new Codespace for the project.
3. While the environment is being set up, check the workbench.startupEditor setting, and it is set to "readme", coming from Codespaces configuration defaults.
4. After the environment is set up, check the workbench.startupEditor setting again, and it now correctly reflects my devcontainer settings.
5. Subsequent launches of the Codespace follow the startup behavior defined by the workbench.startupEditor setting.

@osortega, is there a way to apply devcontainer.json configuration defaults on the first launch?

[osortega]

I believe the default setting for Codespaces is always readme unless otherwise specified by the devcontainer.json that is sent from the GitHub API to the Codespaces web server.

There might be a regression in GitHub that is causing that info to not be passed correctly and therefore not overriding the default value