A folder that carries something, and a way to name one

A folder was a name and nothing else -- and not even that, since PATCH could
rename one and nothing in the interface ever called it. It now carries a
description, a system prompt, and seeds for the model, the kind and the agent
target, with a settings page behind the row.

The prompt is a fourth rung on the ladder, chat > folder > model > instance,
and it goes above the model deliberately: a model's prompt describes the model
wherever it is used, a folder's describes this piece of work whichever model
is pointed at it. It is read when a reply is built rather than copied when a
chat is made, so editing it reaches the chats already there, and the walk up
the parents is bounded and cycle-safe because it runs on the request path.
`api/pages.py` mirrors the ladder for the settings panel and had to gain the
same rung -- a panel naming the wrong source is worse than one naming none,
because it is believed.

The seeds fill in what the request left empty and nothing it filled in: the
folder says what this work usually needs, the screen in front of somebody says
what they want this time. `ssh_profile_id` is a plain string rather than a
foreign key, for the reason `compacted_through_id` is, so it is validated on
read.

Getting *into* a folder needed fixing too. `/api/chats/start` has accepted a
folder_id since folders existed and nothing ever sent one, so the only route in
was to make the chat elsewhere and move it. There is a New chat here on the row
now, and `?folder=` on the new-chat screen.

Naming is a themed dialog, and deliberately not htmx's hx-prompt: htmx calls
the browser's prompt() synchronously and only then fires htmx:prompt with the
answer already in hand, so intercepting the event cannot supply a different one
and the grey box appears anyway. `data-prompt` follows the data-confirm-button
shape instead -- swallow the click, ask, write the answer into hx-vals,
click again behind a guard. JSON.stringify rather than concatenation, or a
folder called `"` produces hx-vals that does not parse and the rename silently
does nothing. Driven under a DOM stub, and there is a test that no template
brings hx-prompt back.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

src/lembas/db/models/chat.py

@@ -49,6 +49,28 @@ class Folder(UUIDPrimaryKey, Timestamps, Base):
     position: Mapped[int] = mapped_column(Integer, default=0, nullable=False)
     collapsed: Mapped[bool] = mapped_column(Boolean, default=False, nullable=False)
 
+    # What chats started in this folder inherit. A folder is where somebody
+    # groups the work on one thing, so it is the natural place to say "chats
+    # about this use this prompt, this model, this machine" -- said once rather
+    # than on every new chat.
+    description: Mapped[str] = mapped_column(String(500), default="")
+    # Read at request time, never copied onto the chat: editing the folder later
+    # has to reach the chats already in it, which is the whole point of putting
+    # it here. It slots into the ladder between the chat and the model.
+    system_prompt: Mapped[str] = mapped_column(Text, default="")
+
+    # Seeds, copied onto a new chat and then that chat's own. Empty means "no
+    # opinion", so a folder can carry a prompt without also dictating a model.
+    model_id: Mapped[str] = mapped_column(String(300), default="")
+    kind: Mapped[str] = mapped_column(String(16), default="")
+    # Deliberately not a ForeignKey. `migrations.py` compiles the column type
+    # only, so a REFERENCES clause would exist on a fresh database and not on an
+    # upgraded one -- the same reason `Chat.compacted_through_id` is a plain id.
+    # The profile may also have been deleted, so it is validated on read.
+    ssh_profile_id: Mapped[str] = mapped_column(String(32), default="")
+    project_dir: Mapped[str] = mapped_column(String(1000), default="")
+    agent_mode: Mapped[str] = mapped_column(String(16), default="")
+
     children: Mapped[list[Folder]] = relationship(
         back_populates="parent",
         cascade="all, delete-orphan",