#########
 OneChat
#########

OneChat is a Go program. It prints its name. It is in early development.
Linux is supported.

****************
 Data directory
****************

OneChat keeps its data and its token file in one directory. It uses the
first of these:

#. ``ONECHAT_DIR``, when it is set.
#. ``$XDG_DATA_HOME/onechat``, when ``XDG_DATA_HOME`` is an absolute
   path. A relative value is ignored.
#. ``~/.local/share/onechat``. With no home directory, OneChat exits
   with an error.

OneChat creates the directory with mode 0700.

***************
 Configuration
***************

``config.json`` in the data directory holds the settings. OneChat does
not create it. A missing file or field takes the default, and an unknown
field is an error.

.. code:: json

   {
     "endpoint": "chatgpt",
     "compactor": {"model": "gpt-6-luna", "effort": "high"}
   }

``endpoint``
   ``chatgpt`` (the default) sends model calls to the ChatGPT backend
   with the subscription login. ``api`` sends them to the OpenAI API
   with the key in ``OPENAI_API_KEY``, which must then be set. With
   ``chatgpt``, OneChat ignores ``OPENAI_API_KEY``.

``compactor``
   The model and the reasoning effort of the summaries. The defaults are
   ``gpt-6-luna`` and ``high``.

*************
 Development
*************

Nix supplies the Go toolchain and all tools. Enter the development shell
with direnv:

.. code:: console

   direnv allow

Or enter it directly:

.. code:: console

   nix develop

The shell sets ``ONECHAT_DIR`` to ``.devenv/onechat`` in the checkout,
unless it is already set. Development data goes there, and Git ignores
``.devenv``.

Build and run:

.. code:: console

   nix build
   ./result/bin/onechat

Format and check all files:

.. code:: console

   bin/format
   bin/check
   nix flake check