core/memory: add SQLAlchemy schema for user, session, message

src/plyngent/memory/database/schema.py

@@ -0,0 +1,52 @@
+from datetime import datetime  # noqa: TC003
+
+from sqlalchemy import JSON, DateTime, ForeignKey, String, UniqueConstraint, func
+from sqlalchemy.orm import DeclarativeBase, Mapped, mapped_column, relationship
+
+
+class PlyngentBase(DeclarativeBase):
+    pass
+
+
+class User(PlyngentBase):
+    __tablename__: str = "user"
+
+    uid: Mapped[int] = mapped_column(primary_key=True)
+    name: Mapped[str] = mapped_column(String(48), unique=True)
+    email: Mapped[str] = mapped_column(String(255), unique=True)
+    password_hash: Mapped[str] = mapped_column(String(256))
+    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now())
+    # deleted_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
+
+    sessions: Mapped[list["Session"]] = relationship(back_populates="user", cascade="all, delete-orphan")
+
+
+class Session(PlyngentBase):
+    __tablename__: str = "session"
+
+    sid: Mapped[int] = mapped_column(primary_key=True)
+    uid: Mapped[int] = mapped_column(ForeignKey(User.uid, ondelete="CASCADE"), index=True)
+    name: Mapped[str] = mapped_column(String(64))
+    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now())
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), server_default=func.now(), onupdate=func.now()
+    )
+
+    user: Mapped[User] = relationship(back_populates="sessions")
+    messages: Mapped[list["Message"]] = relationship(back_populates="session", cascade="all, delete-orphan")
+
+
+class Message(PlyngentBase):
+    __tablename__: str = "message"
+    __table_args__: tuple[object, ...] = (UniqueConstraint("sid", "seq", name="uq_session_seq"),)
+
+    mid: Mapped[int] = mapped_column(primary_key=True)
+    sid: Mapped[int] = mapped_column(ForeignKey(Session.sid, ondelete="CASCADE"), index=True)
+    seq: Mapped[int] = mapped_column(index=True)
+    data: Mapped[dict[str, object]] = mapped_column(JSON())
+    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now())
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), server_default=func.now(), onupdate=func.now()
+    )
+
+    session: Mapped[Session] = relationship(back_populates="messages")