feat(sprint2): инфраструктура БД — SQLAlchemy 2.0 async + Alembic

Первый кусок Спринта 2: подключаем SQLite через SQLAlchemy 2.0 (async,
ORM-стиль) и Alembic для миграций. Схема выбрана под будущий рост —
в threads сразу заведены nullable user_id и agent_config_id, чтобы
Спринты 3+ не тащили миграции задним числом.

- requirements.txt: sqlalchemy[asyncio]==2.0.36, aiosqlite==0.20.0,
  alembic==1.14.0.
- config: database_url + sqlite_path (./data/sqlite/app.db).
- db/base.py: DeclarativeBase; db/session.py: async engine,
  async_sessionmaker, get_session — FastAPI-dependency.
- db/models/Thread: id, name, user_id?, agent_config_id?, created_at,
  updated_at; relationship messages с cascade all, delete-orphan.
- db/models/Message: id, thread_id FK CASCADE, role, text, sources_json,
  assembled_prompt, created_at.
- Alembic инициализирован через async-шаблон, env.py доработан:
  sys.path, url из settings, target_metadata = Base.metadata.
- Начальная миграция e7199587be4b применена, таблицы threads/messages
  с индексами на FK и nullable-колонки созданы в data/sqlite/app.db.
- .gitignore: исключаем data/sqlite/ (БД — артефакт, не исходник).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.gitignore

@@ -2,6 +2,7 @@ __pycache__/
 *.pyc
 .env
 data/chroma/
+data/sqlite/
 *.egg-info/
 .venv/
 .DS_Store

alembic.ini

@@ -0,0 +1,116 @@
+# A generic, single database configuration.
+
+[alembic]
+# path to migration scripts.
+# Use forward slashes (/) also on windows to provide an os agnostic path
+script_location = migrations
+
+# template used to generate migration file names; The default value is %%(rev)s_%%(slug)s
+# Uncomment the line below if you want the files to be prepended with date and time
+# file_template = %%(year)d_%%(month).2d_%%(day).2d_%%(hour).2d%%(minute).2d-%%(rev)s_%%(slug)s
+
+# sys.path path, will be prepended to sys.path if present.
+# defaults to the current working directory.
+prepend_sys_path = .
+
+# timezone to use when rendering the date within the migration file
+# as well as the filename.
+# If specified, requires the python>=3.9 or backports.zoneinfo library.
+# Any required deps can installed by adding `alembic[tz]` to the pip requirements
+# string value is passed to ZoneInfo()
+# leave blank for localtime
+# timezone =
+
+# max length of characters to apply to the "slug" field
+# truncate_slug_length = 40
+
+# set to 'true' to run the environment during
+# the 'revision' command, regardless of autogenerate
+# revision_environment = false
+
+# set to 'true' to allow .pyc and .pyo files without
+# a source .py file to be detected as revisions in the
+# versions/ directory
+# sourceless = false
+
+# version location specification; This defaults
+# to migrations/versions.  When using multiple version
+# directories, initial revisions must be specified with --version-path.
+# The path separator used here should be the separator specified by "version_path_separator" below.
+# version_locations = %(here)s/bar:%(here)s/bat:migrations/versions
+
+# version path separator; As mentioned above, this is the character used to split
+# version_locations. The default within new alembic.ini files is "os", which uses os.pathsep.
+# If this key is omitted entirely, it falls back to the legacy behavior of splitting on spaces and/or commas.
+# Valid values for version_path_separator are:
+#
+# version_path_separator = :
+# version_path_separator = ;
+# version_path_separator = space
+# version_path_separator = newline
+version_path_separator = os  # Use os.pathsep. Default configuration used for new projects.
+
+# set to 'true' to search source files recursively
+# in each "version_locations" directory
+# new in Alembic version 1.10
+# recursive_version_locations = false
+
+# the output encoding used when revision files
+# are written from script.py.mako
+# output_encoding = utf-8
+
+# URL подставляется из config.settings.database_url в migrations/env.py.
+sqlalchemy.url = sqlite+aiosqlite:///./data/sqlite/app.db
+
+
+[post_write_hooks]
+# post_write_hooks defines scripts or Python functions that are run
+# on newly generated revision scripts.  See the documentation for further
+# detail and examples
+
+# format using "black" - use the console_scripts runner, against the "black" entrypoint
+# hooks = black
+# black.type = console_scripts
+# black.entrypoint = black
+# black.options = -l 79 REVISION_SCRIPT_FILENAME
+
+# lint with attempts to fix using "ruff" - use the exec runner, execute a binary
+# hooks = ruff
+# ruff.type = exec
+# ruff.executable = %(here)s/.venv/bin/ruff
+# ruff.options = --fix REVISION_SCRIPT_FILENAME
+
+# Logging configuration
+[loggers]
+keys = root,sqlalchemy,alembic
+
+[handlers]
+keys = console
+
+[formatters]
+keys = generic
+
+[logger_root]
+level = WARNING
+handlers = console
+qualname =
+
+[logger_sqlalchemy]
+level = WARNING
+handlers =
+qualname = sqlalchemy.engine
+
+[logger_alembic]
+level = INFO
+handlers =
+qualname = alembic
+
+[handler_console]
+class = StreamHandler
+args = (sys.stderr,)
+level = NOTSET
+formatter = generic
+
+[formatter_generic]
+format = %(levelname)-5.5s [%(name)s] %(message)s
+datefmt = %H:%M:%S

config.py

@@ -3,6 +3,8 @@ from pydantic_settings import BaseSettings
 
 class Settings(BaseSettings):
     chroma_persist_dir: str = "./data/chroma"
+    sqlite_path: str = "./data/sqlite/app.db"
+    database_url: str = "sqlite+aiosqlite:///./data/sqlite/app.db"
     embedding_model: str = "intfloat/multilingual-e5-large"
     deepseek_api_key: str = ""
     deepseek_model: str = "deepseek-chat"

db/base.py

@@ -0,0 +1,5 @@
+from sqlalchemy.orm import DeclarativeBase
+
+
+class Base(DeclarativeBase):
+    pass

db/models/__init__.py

@@ -0,0 +1,4 @@
+from db.models.message import Message
+from db.models.thread import Thread
+
+__all__ = ["Thread", "Message"]

db/models/message.py

@@ -0,0 +1,30 @@
+from datetime import datetime, timezone
+from typing import TYPE_CHECKING
+
+from sqlalchemy import DateTime, ForeignKey, Integer, String, Text
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from db.base import Base
+
+if TYPE_CHECKING:
+    from db.models.thread import Thread
+
+
+def _utcnow() -> datetime:
+    return datetime.now(timezone.utc)
+
+
+class Message(Base):
+    __tablename__ = "messages"
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
+    thread_id: Mapped[int] = mapped_column(
+        ForeignKey("threads.id", ondelete="CASCADE"), nullable=False, index=True
+    )
+    role: Mapped[str] = mapped_column(String(20), nullable=False)  # "user" | "assistant"
+    text: Mapped[str] = mapped_column(Text, nullable=False)
+    sources_json: Mapped[str | None] = mapped_column(Text, nullable=True)
+    assembled_prompt: Mapped[str | None] = mapped_column(Text, nullable=True)
+    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), default=_utcnow, nullable=False)
+
+    thread: Mapped["Thread"] = relationship(back_populates="messages")

db/models/thread.py

@@ -0,0 +1,36 @@
+from datetime import datetime, timezone
+from typing import TYPE_CHECKING
+
+from sqlalchemy import DateTime, Integer, String
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from db.base import Base
+
+if TYPE_CHECKING:
+    from db.models.message import Message
+
+
+def _utcnow() -> datetime:
+    return datetime.now(timezone.utc)
+
+
+class Thread(Base):
+    __tablename__ = "threads"
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
+    name: Mapped[str] = mapped_column(String(200), nullable=False)
+
+    # Зарезервировано под Спринты 3+: мульти-пользователи и мульти-промпты.
+    user_id: Mapped[int | None] = mapped_column(Integer, nullable=True, index=True)
+    agent_config_id: Mapped[int | None] = mapped_column(Integer, nullable=True, index=True)
+
+    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), default=_utcnow, nullable=False)
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), default=_utcnow, onupdate=_utcnow, nullable=False
+    )
+
+    messages: Mapped[list["Message"]] = relationship(
+        back_populates="thread",
+        cascade="all, delete-orphan",
+        order_by="Message.created_at",
+    )

db/session.py

@@ -0,0 +1,14 @@
+from collections.abc import AsyncIterator
+
+from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
+
+from config import settings
+
+engine = create_async_engine(settings.database_url, echo=False, future=True)
+
+SessionLocal = async_sessionmaker(engine, expire_on_commit=False, class_=AsyncSession)
+
+
+async def get_session() -> AsyncIterator[AsyncSession]:
+    async with SessionLocal() as session:
+        yield session

migrations/README

@@ -0,0 +1 @@
+Generic single-database configuration with an async dbapi.

migrations/env.py

@@ -0,0 +1,90 @@
+import asyncio
+import os
+import sys
+from logging.config import fileConfig
+
+from sqlalchemy import pool
+from sqlalchemy.engine import Connection
+from sqlalchemy.ext.asyncio import async_engine_from_config
+
+from alembic import context
+
+sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+
+from config import settings  # noqa: E402
+from db.base import Base  # noqa: E402
+from db import models  # noqa: F401, E402 — регистрация моделей в Base.metadata
+
+config = context.config
+config.set_main_option("sqlalchemy.url", settings.database_url)
+
+if config.config_file_name is not None:
+    fileConfig(config.config_file_name)
+
+target_metadata = Base.metadata
+
+# other values from the config, defined by the needs of env.py,
+# can be acquired:
+# my_important_option = config.get_main_option("my_important_option")
+# ... etc.
+
+
+def run_migrations_offline() -> None:
+    """Run migrations in 'offline' mode.
+
+    This configures the context with just a URL
+    and not an Engine, though an Engine is acceptable
+    here as well.  By skipping the Engine creation
+    we don't even need a DBAPI to be available.
+
+    Calls to context.execute() here emit the given string to the
+    script output.
+
+    """
+    url = config.get_main_option("sqlalchemy.url")
+    context.configure(
+        url=url,
+        target_metadata=target_metadata,
+        literal_binds=True,
+        dialect_opts={"paramstyle": "named"},
+    )
+
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+def do_run_migrations(connection: Connection) -> None:
+    context.configure(connection=connection, target_metadata=target_metadata)
+
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+async def run_async_migrations() -> None:
+    """In this scenario we need to create an Engine
+    and associate a connection with the context.
+
+    """
+
+    connectable = async_engine_from_config(
+        config.get_section(config.config_ini_section, {}),
+        prefix="sqlalchemy.",
+        poolclass=pool.NullPool,
+    )
+
+    async with connectable.connect() as connection:
+        await connection.run_sync(do_run_migrations)
+
+    await connectable.dispose()
+
+
+def run_migrations_online() -> None:
+    """Run migrations in 'online' mode."""
+
+    asyncio.run(run_async_migrations())
+
+
+if context.is_offline_mode():
+    run_migrations_offline()
+else:
+    run_migrations_online()

migrations/script.py.mako

@@ -0,0 +1,26 @@
+"""${message}
+
+Revision ID: ${up_revision}
+Revises: ${down_revision | comma,n}
+Create Date: ${create_date}
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+${imports if imports else ""}
+
+# revision identifiers, used by Alembic.
+revision: str = ${repr(up_revision)}
+down_revision: Union[str, None] = ${repr(down_revision)}
+branch_labels: Union[str, Sequence[str], None] = ${repr(branch_labels)}
+depends_on: Union[str, Sequence[str], None] = ${repr(depends_on)}
+
+
+def upgrade() -> None:
+    ${upgrades if upgrades else "pass"}
+
+
+def downgrade() -> None:
+    ${downgrades if downgrades else "pass"}

migrations/versions/e7199587be4b_initial_threads_and_messages.py

@@ -0,0 +1,56 @@
+"""initial: threads and messages
+
+Revision ID: e7199587be4b
+Revises: 
+Create Date: 2026-04-23 10:03:23.691401
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision: str = 'e7199587be4b'
+down_revision: Union[str, None] = None
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.create_table('threads',
+    sa.Column('id', sa.Integer(), autoincrement=True, nullable=False),
+    sa.Column('name', sa.String(length=200), nullable=False),
+    sa.Column('user_id', sa.Integer(), nullable=True),
+    sa.Column('agent_config_id', sa.Integer(), nullable=True),
+    sa.Column('created_at', sa.DateTime(timezone=True), nullable=False),
+    sa.Column('updated_at', sa.DateTime(timezone=True), nullable=False),
+    sa.PrimaryKeyConstraint('id')
+    )
+    op.create_index(op.f('ix_threads_agent_config_id'), 'threads', ['agent_config_id'], unique=False)
+    op.create_index(op.f('ix_threads_user_id'), 'threads', ['user_id'], unique=False)
+    op.create_table('messages',
+    sa.Column('id', sa.Integer(), autoincrement=True, nullable=False),
+    sa.Column('thread_id', sa.Integer(), nullable=False),
+    sa.Column('role', sa.String(length=20), nullable=False),
+    sa.Column('text', sa.Text(), nullable=False),
+    sa.Column('sources_json', sa.Text(), nullable=True),
+    sa.Column('assembled_prompt', sa.Text(), nullable=True),
+    sa.Column('created_at', sa.DateTime(timezone=True), nullable=False),
+    sa.ForeignKeyConstraint(['thread_id'], ['threads.id'], ondelete='CASCADE'),
+    sa.PrimaryKeyConstraint('id')
+    )
+    op.create_index(op.f('ix_messages_thread_id'), 'messages', ['thread_id'], unique=False)
+    # ### end Alembic commands ###
+
+
+def downgrade() -> None:
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.drop_index(op.f('ix_messages_thread_id'), table_name='messages')
+    op.drop_table('messages')
+    op.drop_index(op.f('ix_threads_user_id'), table_name='threads')
+    op.drop_index(op.f('ix_threads_agent_config_id'), table_name='threads')
+    op.drop_table('threads')
+    # ### end Alembic commands ###

requirements.txt

@@ -7,3 +7,6 @@ pymupdf==1.25.1
 python-docx==1.1.2
 httpx==0.28.1
 pydantic-settings==2.7.1
+sqlalchemy[asyncio]==2.0.36
+aiosqlite==0.20.0
+alembic==1.14.0