session leaks, remove the linked device in WhatsApp on the phone, and
the session stops working. Without the file, WhatsApp is not linked.
+The daemon reads the text messages of the private chats and the groups,
+from other people and from the user. It does not read media, reactions,
+edits, deletions, view-once and disappearing messages, or the history
+from before the link. The messages of one chat form one batch until the
+chat is quiet for 20 seconds, for 2 minutes or 50 messages at the most.
+Each batch goes to the chat of the agent as one work message that starts
+with ``[WhatsApp]``, with the name and the ID of the chat, and the time,
+the sender, and the text of each message. The messages of the user show
+as ``You``. ``whatsapp/state.json``, with mode 0600, keeps the batches
+that are not in the chat yet, so they survive a restart. A crash just
+after a batch goes to the chat can make the batch repeat once.
+
+A batch of a private chat with a message of another person starts a
+turn, and so does a batch of a group with a message that mentions the
+user or replies to a message of the user. The other batches go to the
+chat with no turn, and the agent sees them at its next turn. A batch
+that starts a turn ends with a line that tells the agent to end its turn
+with an empty reply when nothing in the batch needs the user. No client
+shows an empty reply, so such a batch gives no message in Telegram. The
+terminal client shows each batch, and Telegram shows none.
+
+The phone number of the user never goes to the chat: a mention of the
+user shows as ``@you``, the number shows as ``OWN``, and the chat of the
+user with itself is not read. But the IDs of the other chats go to the
+chat and to the model, because the agent needs them to send. The ID of a
+private chat holds the phone number of the contact, such as
+``15550002222@s.whatsapp.net``, and the ID of a group can hold the
+number of the person who made it.
+
+Each batch of a group goes to the chat, also with no turn, and the
+memory tree summarizes it with model calls, which use the quota.
+
When the session holds a linked device, the daemon connects at its
start, and after a network failure it connects again by itself. When a
disconnection lasts 10 minutes, all clients get one notice, and one more