unable to add files to the context with @

TL;DR

I am trying to add files to the prompt context using @ like I do in the Gemini CLI, but the result is an error

Error: Exiting due to an error processing the @ command.
See logs for more details
Error: Process completed with exit code 1.

Expected behavior

The files I add with @/path/to/file are added to the context.

Observed behavior

The @ is procesed as a command or something like that

Action YAML

- name: Run Prompt
  uses: google-github-actions/run-gemini-cli@2a77eb258d8d2447292fd5d9df6e7b49533d4f37
  id: analyze-ci-error
  env:
    GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
  with:
    gemini_api_key: ${{ secrets.GEMINI_API_KEY }}
    prompt: |
      ## Context
      @/path/to/a/file
      ## Question
      Answer to the ultimate question of life, the universe, and everything

Log output

Error: Exiting due to an error processing the @ command.
See logs for more details
Error: Process completed with exit code 1.

Additional information

No response

Start by reproducing the workflow from the Action YAML and trace how the prompt is passed to the @ command processing. Confirm the fix by rerunning the workflow with @/path/to/a/file and verifying that the file is added to the prompt context without an error.