+A permanent child agent lives in ``agent/children/NAME/`` with the same
+files as the root. The root's ``agent_create(name, responsibility)``
+tool creates and starts it with the root's model, effort, and working
+directory, and a separate random ID. A name describes the area, such as
+``House`` or ``Calendar``. It is one word of 2 to 32 ASCII letters,
+starts with a capital letter, and cannot name the root, an existing
+child, or a subagent. The daemon opens all children at startup. A
+missing or invalid child config stops startup. Only one level of
+children is supported. Remove a child by hand while the daemon is
+stopped. The root's turn state lists each child and its responsibility.
+The root passes area messages from mixed chats with sender, date, and
+words, and asks the user before it sends a child's draft to WhatsApp.
+
+Each child has its own memory, model client, usage file, subagents,
+schedules, and turn loop. Its prompt limits work to its area, asks for
+only reports that need the parent or the user, and permits an empty
+reply. Children have no WhatsApp tools and draft replies instead of
+sending them. Clients address only the root. A child's saved schedules
+and subagents can resume at startup. The ready log line lists the child
+names.
+
+A message from a parent to its own child enters the child's log as
+``user`` and wakes it. A child's final reply reaches the parent as
+``work`` with the prefix ``[NAME] `` and wakes it. An empty reply sends
+nothing. A busy recipient takes the message between tool calls or in its
+next turn. ``agent/messages.json``, with mode 0600, keeps messages until
+their recipient finishes its turn. A daemon stop preserves queued
+messages and reports for the next start without a second log entry. An
+interrupted turn can repeat its model calls and tools after restart.
+Backups lock this queue with the agent files, including children made
+during the daemon run. The root uses ``tell`` for both children and
+subagents. ``zoom("Name")`` gives a child's view or a subagent's whole
+log. ``spawn`` starts short-lived subagents, not permanent children.
+