Prompt suggestions on the new-chat screen

A blank composer is the least helpful thing a chat client can show someone
who has just installed one. Three cards now sit under the empty state, and
an administrator manages them at /admin/suggestions.

Clicking a card fills the composer and stops there. It deliberately does not
send: every default ends mid-sentence, because a card is a starting point
rather than a question somebody already asked, and the caret lands where the
person has to start typing.

Seeding is guarded by a settings flag, not by "is the table empty" --
otherwise an administrator who decided against them would get all three back
on every restart. Capped at twelve, six shown: past a dozen this is a menu,
and a menu on the empty screen is a worse blank page than a blank page.

The cards are gated on there being no chat at all, not on the thread being
empty. An empty chat someone opened on purpose already has a model and a
prompt chosen.

Also fixes a pre-existing bug the position test caught. Both this and
_refresh_models wrote `coalesce(max(position), -1) or -1`, and position 0 is
falsy -- so the second row landed back on 0 on top of the first. The
coalesce was already doing that job; the `or` was undoing it.

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

src/lembas/api/admin.py

@@ -192,7 +192,10 @@ async def _refresh_models(db: DBSession, connection: Connection) -> tuple[int, s
 
     # New models land after everything already ordered, rather than all at
     # position 0 where they would sort by id and shuffle the existing list.
-    next_position = (db.scalar(select(func.coalesce(func.max(Model.position), -1))) or -1) + 1
+    # No `or -1` after the coalesce: position 0 is falsy, so that idiom sent the
+    # second discovered model back to 0 on top of the first.
+    highest = db.scalar(select(func.coalesce(func.max(Model.position), -1)))
+    next_position = int(highest if highest is not None else -1) + 1
 
     for entry in discovered:
         model_id = str(entry["id"])[:300]

src/lembas/api/admin_suggestions.py

@@ -0,0 +1,113 @@
+"""Administration for the cards offered on the new-chat screen."""
+
+from __future__ import annotations
+
+import logging
+
+from fastapi import APIRouter, Form, HTTPException, Request, Response, status
+from fastapi.responses import RedirectResponse
+
+from lembas.api.deps import AdminUser, Db
+from lembas.db.models import Suggestion
+from lembas.services import suggestions as suggestions_service
+from lembas.web.templating import render
+
+log = logging.getLogger(__name__)
+
+router = APIRouter(prefix="/admin/suggestions", tags=["admin-suggestions"])
+
+
+def _suggestion(db: Db, suggestion_id: str) -> Suggestion:
+    suggestion = db.get(Suggestion, suggestion_id)
+    if suggestion is None:
+        raise HTTPException(status.HTTP_404_NOT_FOUND, "That suggestion no longer exists.")
+    return suggestion
+
+
+def _back(message: str = "") -> Response:
+    target = f"/admin/suggestions?saved={message}" if message else "/admin/suggestions"
+    return RedirectResponse(target, status_code=status.HTTP_303_SEE_OTHER)
+
+
+@router.get("")
+async def suggestions_page(request: Request, db: Db, user: AdminUser, saved: str = ""):
+    rows = suggestions_service.all_of_them(db)
+    return render(
+        request,
+        "admin/suggestions.html",
+        {
+            "suggestions": rows,
+            "at_limit": len(rows) >= suggestions_service.MAX_SUGGESTIONS,
+            "max_suggestions": suggestions_service.MAX_SUGGESTIONS,
+            "max_shown": suggestions_service.MAX_SHOWN,
+            "saved": saved,
+        },
+    )
+
+
+@router.post("")
+async def create_suggestion(
+    db: Db,
+    user: AdminUser,
+    name: str = Form(""),
+    description: str = Form(""),
+    prompt: str = Form(""),
+) -> Response:
+    name = name.strip()
+    if not name:
+        return _back("A suggestion needs a name.")
+    if len(suggestions_service.all_of_them(db)) >= suggestions_service.MAX_SUGGESTIONS:
+        return _back(f"That is already {suggestions_service.MAX_SUGGESTIONS}, which is plenty.")
+
+    suggestions_service.create(db, name=name, description=description, prompt=prompt)
+    log.info("%s added suggestion %s", user.email, name)
+    return _back(f"Added {name}.")
+
+
+# Registered before /{suggestion_id}: FastAPI matches in registration order, so
+# with the parameterised route first any literal segment added later would be
+# captured as an id. That has already been a bug once, in /admin/models.
+@router.post("/{suggestion_id}/delete")
+async def delete_suggestion(db: Db, user: AdminUser, suggestion_id: str) -> Response:
+    suggestion = _suggestion(db, suggestion_id)
+    name = suggestion.name
+    db.delete(suggestion)
+    db.commit()
+    log.info("%s deleted suggestion %s", user.email, name)
+    return _back(f"Deleted {name}.")
+
+
+@router.post("/{suggestion_id}")
+async def update_suggestion(
+    request: Request,
+    db: Db,
+    user: AdminUser,
+    suggestion_id: str,
+) -> Response:
+    """Save one row.
+
+    The raw form is read rather than declared parameters because `enabled` is a
+    checkbox: FastAPI cannot tell an unticked box from an absent field, and an
+    absent one is exactly what an unticked box sends.
+    """
+    suggestion = _suggestion(db, suggestion_id)
+    form = await request.form()
+
+    suggestion.name = (
+        str(form.get("name") or "").strip()[: suggestions_service.MAX_NAME] or suggestion.name
+    )
+    suggestion.description = str(form.get("description") or "").strip()[
+        : suggestions_service.MAX_DESCRIPTION
+    ]
+    suggestion.prompt = str(form.get("prompt") or "").replace("\r\n", "\n")[
+        : suggestions_service.MAX_PROMPT
+    ]
+    suggestion.enabled = "enabled" in form
+
+    position = str(form.get("position") or "").strip()
+    if position.isdigit():
+        suggestion.position = min(max(int(position) - 1, 0), 999)
+
+    db.commit()
+    log.info("%s updated suggestion %s", user.email, suggestion.name)
+    return _back(f"Saved {suggestion.name}.")

src/lembas/api/pages.py

@@ -13,6 +13,7 @@ from lembas.security import permissions
 from lembas.services import audio as audio_service
 from lembas.services import chat as chat_service
 from lembas.services import settings_store
+from lembas.services import suggestions as suggestions_service
 from lembas.services.library import documents as documents_service
 from lembas.services.markdown import render_markdown
 from lembas.web.templating import STATIC_DIR, render
@@ -201,6 +202,7 @@ async def chat_index(
             **context,
             "current_model": preselected,
             "starting_temporary": temporary,
+            "suggestions": suggestions_service.visible(db),
             **sidebar_context(db, user),
         },
     )