how their files are organized, and how they want work done. The prompt
ends with them, and a change applies at the next call.
+**************
+ User service
+**************
+
+The Nix package includes ``share/systemd/user/onechat.service``. It runs
+``onechat daemon`` from that package, starts at login when enabled, and
+restarts 5 seconds after a failure. A stop sends SIGTERM to the daemon
+and allows up to 120 seconds for cleanup. Its output goes to the user
+journal. The service has the rights of the user, as the terminal daemon
+does.
+
+Build a package with a separate result link. Keep this link so that Nix
+does not collect the package while the service uses it:
+
+.. code:: console
+
+ nix build --out-link result-service
+ systemctl --user link --force "$(realpath result-service/share/systemd/user/onechat.service)"
+ systemctl --user edit onechat.service
+
+In the editor, set the data directory with this drop-in. Replace
+``DATA_DIR`` with an absolute path to the data directory. Set the same
+``ONECHAT_DIR`` for each terminal client. Without a drop-in, the data
+directory rules above apply to the environment of the user manager, not
+to the development shell.
+
+.. code:: ini
+
+ [Service]
+ Environment="ONECHAT_DIR=DATA_DIR"
+
+The service does not read the environment of an open terminal. If the
+agent needs tools from a shell, set ``Environment="PATH=TOOLS_PATH"`` in
+the same drop-in, with ``TOOLS_PATH`` replaced by the complete search
+path, including bash. For the API endpoint, use
+``EnvironmentFile=ENV_FILE``, with ``ENV_FILE`` replaced by an absolute
+path to a mode 0600 file that sets ``OPENAI_API_KEY``. Keep secrets out
+of the unit and Nix sources.
+
+Use the existing data directory, or copy the development data before the
+first service start. For a copy, first stop the terminal daemon with
+Ctrl-C and wait for it to exit. Replace ``DATA_DIR`` below with a new,
+empty destination. If the development shell uses a custom
+``ONECHAT_DIR``, replace ``.devenv/onechat`` with that source. Copy the
+whole directory so that ``auth.json``, ``telegram.json``,
+``config.json``, ``agent/``, and ``whatsapp/`` stay together, including
+the WhatsApp session and its database files. The copy preserves the file
+modes and the source as a backup. Do not copy or use the same data from
+two running daemons.
+
+.. code:: console
+
+ install -d -m 0700 DATA_DIR
+ cp -a .devenv/onechat/. DATA_DIR/
+
+After the terminal daemon exits and the data is ready, enable and start
+the service:
+
+.. code:: console
+
+ systemctl --user daemon-reload
+ systemctl --user enable --now onechat.service
+ systemctl --user status onechat.service
+ ONECHAT_DIR=DATA_DIR ./result-service/bin/onechat chat
+ journalctl --user -u onechat.service -f
+
+After ``git pull``, build with the same result link, link the unit
+again, reload the user manager, and restart the service:
+
+.. code:: console
+
+ nix build --out-link result-service
+ systemctl --user link --force "$(realpath result-service/share/systemd/user/onechat.service)"
+ systemctl --user daemon-reload
+ systemctl --user restart onechat.service
+
+The service starts with the user manager at login, not at boot without a
+login. To stop it, or also remove its start at login:
+
+.. code:: console
+
+ systemctl --user stop onechat.service
+ systemctl --user disable onechat.service
+
**********
Telegram
**********
clients get a notice at once. When the user removes the device in the
phone, the daemon deletes the session and tells all clients one time.
+***********
+ Schedules
+***********
+
+The agent sets reminders and timed tasks when the user asks for them,
+such as "remind me tomorrow at 9" or "every weekday at 8, tell me what
+my WhatsApp groups talked about". A schedule has a text, the task for
+the agent, and either one time or a cron expression. The agent also
+lists the schedules with their next times, and removes one when the user
+asks. Only the agent has the schedule tools, not its subagents.
+
+A cron expression has five fields: minute, hour, day of month, month,
+and day of week, where 0 and 7 are Sunday. A field is a comma list of
+``*``, ``N``, and ``N-M``, and ``*`` and ``N-M`` can have a step ``/S``,
+as in ``0 8 * * 1-5`` or ``*/15 9-17 * * *``. When both day fields start
+with something other than ``*``, a day matches when either field
+matches. Names such as ``MON``, macros such as ``@daily``, the
+characters ``? L W #``, and ``N/S`` are refused. The runs must be at
+least 5 minutes apart, because each run is a full turn that uses the
+quota, so ``*/5 * * * *`` is the shortest schedule.
+
+The times use the time zone of the machine. A time that the clock skips
+at the start of daylight saving time runs later by the length of the
+skip. A time that the clock repeats at its end runs once, at its first
+occurrence.
+
+At its time, a schedule goes to the chat as a work message that starts
+with ``[Schedule ID]``, with its time and its text, and it starts a
+turn. The message ends with a line that tells the agent to end its turn
+with an empty reply when nothing needs the user. The terminal client
+shows the message, and Telegram shows only the reply. After its run, a
+one-time schedule goes, and a repeating schedule gets its next time.
+
+``agent/schedules.json``, with mode 0600, holds the schedules. Each
+change writes it before the tool answers, so the schedules survive a
+restart. A schedule that came due while the daemon was stopped runs once
+at the next start, with its original time and a line that says that the
+run is late. A repeating schedule that missed several times runs once. A
+crash just after a run goes to the chat can make the run repeat once.
+
*******
Probe
*******