Initial plugin design

[simonw]

See:

• llm-echo plugin llm#895

This model plugin will simply echo back the system prompt, regular prompt, any attachments and any previous conversation items. It's a debugging tool that can also be used in automated tests.

[simonw]

Got this working:

% llm -m echo hi                                        
{
  "prompt": "hi",
  "system": "",
  "attachments": [],
  "stream": false,
  "previous": []
}
% llm -m echo hi --async
{
  "prompt": "hi",
  "system": "",
  "attachments": [],
  "stream": false,
  "previous": []
}
% llm -c ok
{
  "prompt": "ok",
  "system": "",
  "attachments": [],
  "stream": false,
  "previous": [
    {
      "prompt": "hi"
    }
  ]
}

[simonw]

And this:

% llm -m echo hi -a https://static.simonwillison.net/static/2025/two-pelicans.jpg
{
  "prompt": "hi",
  "system": "",
  "attachments": [
    {
      "type": "image/jpeg",
      "path": null,
      "url": "https://static.simonwillison.net/static/2025/two-pelicans.jpg",
      "id": "69caf7de384d865612b63cec6663a3cfff56a39197e68da6ffb105d78dce7f6f"
    }
  ],
  "stream": true,
  "previous": []
}