backend: separate App and server, add websocket endpoint, accept data directory command argument. initialize sqlalchemy database and models in new module. frontend: create backend class for managing ws connection, move ui to chat_screen, create scaffold chat and agent classes.

backend/database.py

@@ -0,0 +1,90 @@
+from typing import Optional
+from sqlalchemy import create_engine, Column, Integer, JSON, ForeignKey
+from sqlalchemy.orm import DeclarativeBase, Mapped, mapped_column
+from sqlalchemy.sql.expression import select
+
+class Base(DeclarativeBase):
+    pass
+
+def create_sql_engine (data_directory):
+    sql_engine = create_engine(f"sqlite:///{data_directory}/horde.db")
+    Base.metadata.create_all(sql_engine)
+    return sql_engine
+
+class User(Base):
+    __modelname__ = "user"
+    __tablename__ = 'users'
+
+    id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
+
+    email: Mapped[str]
+    username: Mapped[str]
+    # Stores the plain password. This must be changed eventually to store a salted hash instead.
+    password: Mapped[str]
+
+class Agent(Base):
+    __modelname__ = "agent"
+    __tablename__ = 'agents'
+
+    id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
+    user_id: Mapped[int] = mapped_column(ForeignKey("users.id"))
+
+    handle: Mapped[Optional[str]]
+    visibility: Mapped[int] = mapped_column(default=0)
+    # Comma separated list of permission symbols
+    permissions: Mapped[str] = mapped_column(default="")
+
+    name: Mapped[str]
+    description: Mapped[Optional[str]]
+    picture: Mapped[Optional[str]]
+    ordering: Mapped[Optional[int]]
+
+    # Agents can be any of a set of agent classes
+    kind: Mapped[str]
+    # Stores the agent data specific to its class
+    data = mapped_column(JSON, default={})
+
+class Chat(Base):
+    __modelname__ = 'chat'
+    __tablename__ = 'chats'
+
+    id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
+    user_id: Mapped[int] = mapped_column(ForeignKey("users.id"))
+
+    name: Mapped[str]
+    description: Mapped[Optional[str]]
+    picture: Mapped[Optional[str]]
+    ordering: Mapped[Optional[int]]
+
+    # For indexing purposes, some information is taken from the last chat message.
+    # Preview is the (possibly cropped) content,
+    # time is the timestamp of the last event.
+    last_message_preview: Mapped[Optional[str]]
+    last_message_time: Mapped[Optional[int]]
+
+# Stores membership of agents in chats. If a record exists linking an agent and a chat,
+# it means the agent participates in that chat.
+class Membership(Base):
+    __modelname__ = 'membership'
+    __tablename__ = 'memberships'
+
+    id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
+    agent_id: Mapped[int] = mapped_column(ForeignKey("agents.id"))
+    chat_id: Mapped[int] = mapped_column(ForeignKey("chats.id"))
+
+class Message(Base):
+    __modelname__ = 'message'
+    __tablename__ = 'messages'
+
+    id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
+    chat_id: Mapped[int] = mapped_column(ForeignKey("chats.id"))
+
+    # Timestamp of this message
+    time: Mapped[int]
+    # Identifier of the sender: user / system / agent-$ID
+    sender: Mapped[str]
+
+    # Predefined set of message types, interpreted as 'text' when empty.
+    kind: Mapped[str]
+    content: Mapped[str]
+