OneChat
#########
-OneChat is a Go program. It prints its name. It is in early development.
-Linux is supported.
+OneChat is one AI agent in a single chat that never ends. A daemon owns
+the agent and its files, and a terminal client talks to it. 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-6.1-sol", "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-6.1-sol`` and ``high``.
+
+*******
+ Login
+*******
+
+The ``chatgpt`` endpoint needs a login with a ChatGPT account:
+
+.. code:: console
+
+ onechat login
+
+The command shows a link and a code. Open the link on any device, enter
+the code, and approve the login. Device code login must be allowed in
+the ChatGPT security settings. OneChat writes the tokens to
+``auth.json`` in the data directory, with mode 0600, and refreshes them
+before they expire. The file belongs to OneChat only. Do not share it
+with the Codex CLI, because each program rotates the refresh token and
+logs the other out.
+
+*******
+ Agent
+*******
+
+Start the daemon, and then the client in another terminal:
+
+.. code:: console
+
+ onechat daemon
+ onechat chat
+
+The daemon owns the root agent in ``agent/`` in the data directory and
+listens on the Unix socket ``onechat.sock`` there. In the client, each
+line is a message to the agent, the line ``/stop`` interrupts the
+running turn, and Ctrl-D ends the client. The client shows the replies,
+the tool calls, and the first lines of each tool result as they happen.
+The daemon is the only process that uses the token file while it runs,
+so ``onechat login`` and ``onechat probe`` refuse to start until it
+stops.
+
+The agent runs commands with bash as the user in its working directory,
+with no sandbox. It has the rights of the user, also on the token file.
+
+``agent/config.json`` holds the settings of the agent. The first start
+writes it with the defaults and a random ID. Do not change the ID: the
+prompt cache key comes from it.
+
+.. code:: json
+
+ {
+ "name": "OneChat",
+ "id": "0123456789abcdef0123456789abcdef",
+ "model": "gpt-6.1-sol",
+ "effort": "medium",
+ "workdir": "/home/user"
+ }
+
+``workdir`` is an absolute path, and its default is the home directory.
+``agent/instructions.md`` holds the user's instructions: who they are,
+how their files are organized, and how they want work done. The prompt
+ends with them, and a change applies at the next call.
+
+*******
+ Probe
+*******
+
+``onechat probe LOG COUNT [BUILDS]`` measures the compactor on a log. It
+appends the first COUNT messages of LOG, one JSON object ``{"kind",
+"text"}`` on each line, to a new chat in ``probe/`` in the data
+directory, and builds its tree with real model calls. The calls use the
+quota of the account. The run stops at the first failed call, after 660
+calls, or when the used percent of a quota window grows by more than 15
+points. At the end it reports the calls per message, the cached share of
+the input tokens, the retries, the line sizes, and the quota at the
+first and the last call. BUILDS, from 1 to 8, limits the model calls at
+once in the run.
+
+A test writes a generated log of readable made-up messages:
+
+.. code:: console
+
+ ONECHAT_PROBE_LOG=probe.jsonl go test -run TestProbeLogHasTheSyntheticMix
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Development