Add database schema with SQLAlchemy async + Alembic migrations

Set up PostgreSQL database layer with async SQLAlchemy 2.0 and asyncpg driver.
Implements 6 core tables (games, routes, pokemon, route_encounters, nuzlocke_runs,
encounters) with foreign keys, indexes, and an initial Alembic migration.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/alembic.ini

@@ -0,0 +1,150 @@
+# A generic, single database configuration.
+
+[alembic]
+# path to migration scripts.
+# this is typically a path given in POSIX (e.g. forward slashes)
+# format, relative to the token %(here)s which refers to the location of this
+# ini file
+script_location = %(here)s/src/app/alembic
+
+# 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
+# see https://alembic.sqlalchemy.org/en/latest/tutorial.html#editing-the-ini-file
+# for all available tokens
+# file_template = %%(year)d_%%(month).2d_%%(day).2d_%%(hour).2d%%(minute).2d-%%(rev)s_%%(slug)s
+# Or organize into date-based subdirectories (requires recursive_version_locations = true)
+# file_template = %%(year)d/%%(month).2d/%%(day).2d_%%(hour).2d%%(minute).2d_%%(second).2d_%%(rev)s_%%(slug)s
+
+# sys.path path, will be prepended to sys.path if present.
+# defaults to the current working directory.  for multiple paths, the path separator
+# is defined by "path_separator" below.
+prepend_sys_path = src
+
+
+# timezone to use when rendering the date within the migration file
+# as well as the filename.
+# If specified, requires the tzdata library which can be 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 <script_location>/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 "path_separator"
+# below.
+# version_locations = %(here)s/bar:%(here)s/bat:%(here)s/alembic/versions
+
+# path_separator; This indicates what character is used to split lists of file
+# paths, including version_locations and prepend_sys_path within configparser
+# files such as alembic.ini.
+# The default rendered in new alembic.ini files is "os", which uses os.pathsep
+# to provide os-dependent path splitting.
+#
+# Note that in order to support legacy alembic.ini files, this default does NOT
+# take place if path_separator is not present in alembic.ini.  If this
+# option is omitted entirely, fallback logic is as follows:
+#
+# 1. Parsing of the version_locations option falls back to using the legacy
+#    "version_path_separator" key, which if absent then falls back to the legacy
+#    behavior of splitting on spaces and/or commas.
+# 2. Parsing of the prepend_sys_path option falls back to the legacy
+#    behavior of splitting on spaces, commas, or colons.
+#
+# Valid values for path_separator are:
+#
+# path_separator = :
+# path_separator = ;
+# path_separator = space
+# path_separator = newline
+#
+# Use os.pathsep. Default configuration used for new projects.
+path_separator = os
+
+# 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
+
+# database URL.  This is consumed by the user-maintained env.py script only.
+# other means of configuring database URLs may be customized within the env.py
+# file.
+# URL is set programmatically in env.py from app settings
+# sqlalchemy.url =
+
+
+[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 module runner, against the "ruff" module
+# hooks = ruff
+# ruff.type = module
+# ruff.module = ruff
+# ruff.options = check --fix REVISION_SCRIPT_FILENAME
+
+# Alternatively, use the exec runner to execute a binary found on your PATH
+# hooks = ruff
+# ruff.type = exec
+# ruff.executable = ruff
+# ruff.options = check --fix REVISION_SCRIPT_FILENAME
+
+# Logging configuration.  This is also consumed by the user-maintained
+# env.py script only.
+[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

backend/pyproject.toml

@@ -10,6 +10,9 @@ dependencies = [
     "pydantic>=2.10.0",
     "pydantic-settings>=2.7.0",
     "python-dotenv>=1.0.0",
+    "sqlalchemy[asyncio]>=2.0.0",
+    "asyncpg>=0.30.0",
+    "alembic>=1.14.0",
 ]
 
 [project.optional-dependencies]

backend/src/app/alembic/README

@@ -0,0 +1 @@
+Generic single-database configuration.

backend/src/app/alembic/env.py

@@ -0,0 +1,61 @@
+import asyncio
+from logging.config import fileConfig
+
+from sqlalchemy import pool
+from sqlalchemy.ext.asyncio import async_engine_from_config
+
+from alembic import context
+
+from app.core.config import settings
+from app.core.database import Base, _get_async_url
+
+# Import all models so Base.metadata is populated
+import app.models  # noqa: F401
+
+config = context.config
+
+if config.config_file_name is not None:
+    fileConfig(config.config_file_name)
+
+config.set_main_option("sqlalchemy.url", _get_async_url(settings.database_url))
+
+target_metadata = Base.metadata
+
+
+def run_migrations_offline() -> None:
+    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):
+    context.configure(connection=connection, target_metadata=target_metadata)
+
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+async def run_migrations_online() -> None:
+    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()
+
+
+if context.is_offline_mode():
+    run_migrations_offline()
+else:
+    asyncio.run(run_migrations_online())

backend/src/app/alembic/script.py.mako

@@ -0,0 +1,28 @@
+"""${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, Sequence[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:
+    """Upgrade schema."""
+    ${upgrades if upgrades else "pass"}
+
+
+def downgrade() -> None:
+    """Downgrade schema."""
+    ${downgrades if downgrades else "pass"}

backend/src/app/alembic/versions/03e5f186a9d5_initial_schema.py

@@ -0,0 +1,155 @@
+"""initial schema
+
+Revision ID: 03e5f186a9d5
+Revises:
+Create Date: 2026-02-05 13:27:47.649534
+
+"""
+
+from typing import Sequence, Union
+
+import sqlalchemy as sa
+from sqlalchemy.dialects import postgresql
+
+from alembic import op
+
+# revision identifiers, used by Alembic.
+revision: str = "03e5f186a9d5"
+down_revision: Union[str, Sequence[str], None] = None
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.create_table(
+        "games",
+        sa.Column("id", sa.Integer(), primary_key=True),
+        sa.Column("name", sa.String(100), nullable=False),
+        sa.Column("slug", sa.String(100), nullable=False, unique=True),
+        sa.Column("generation", sa.SmallInteger(), nullable=False),
+        sa.Column("region", sa.String(50), nullable=False),
+        sa.Column("box_art_url", sa.String(500), nullable=True),
+        sa.Column("release_year", sa.SmallInteger(), nullable=True),
+    )
+
+    op.create_table(
+        "routes",
+        sa.Column("id", sa.Integer(), primary_key=True),
+        sa.Column("name", sa.String(100), nullable=False),
+        sa.Column(
+            "game_id", sa.Integer(), sa.ForeignKey("games.id"), nullable=False
+        ),
+        sa.Column("order", sa.SmallInteger(), nullable=False),
+    )
+    op.create_index("ix_routes_game_id", "routes", ["game_id"])
+
+    op.create_table(
+        "pokemon",
+        sa.Column("id", sa.Integer(), primary_key=True),
+        sa.Column(
+            "national_dex", sa.SmallInteger(), nullable=False, unique=True
+        ),
+        sa.Column("name", sa.String(50), nullable=False),
+        sa.Column(
+            "types", postgresql.ARRAY(sa.String(20)), nullable=False
+        ),
+        sa.Column("sprite_url", sa.String(500), nullable=True),
+    )
+
+    op.create_table(
+        "route_encounters",
+        sa.Column("id", sa.Integer(), primary_key=True),
+        sa.Column(
+            "route_id", sa.Integer(), sa.ForeignKey("routes.id"), nullable=False
+        ),
+        sa.Column(
+            "pokemon_id",
+            sa.Integer(),
+            sa.ForeignKey("pokemon.id"),
+            nullable=False,
+        ),
+        sa.Column("encounter_method", sa.String(30), nullable=False),
+        sa.Column("encounter_rate", sa.SmallInteger(), nullable=False),
+        sa.UniqueConstraint(
+            "route_id",
+            "pokemon_id",
+            "encounter_method",
+            name="uq_route_pokemon_method",
+        ),
+    )
+    op.create_index(
+        "ix_route_encounters_route_id", "route_encounters", ["route_id"]
+    )
+    op.create_index(
+        "ix_route_encounters_pokemon_id", "route_encounters", ["pokemon_id"]
+    )
+
+    op.create_table(
+        "nuzlocke_runs",
+        sa.Column("id", sa.Integer(), primary_key=True),
+        sa.Column(
+            "game_id", sa.Integer(), sa.ForeignKey("games.id"), nullable=False
+        ),
+        sa.Column("name", sa.String(100), nullable=False),
+        sa.Column("status", sa.String(20), nullable=False),
+        sa.Column(
+            "rules", postgresql.JSONB(), nullable=False, server_default="{}"
+        ),
+        sa.Column(
+            "started_at",
+            sa.DateTime(timezone=True),
+            nullable=False,
+            server_default=sa.func.now(),
+        ),
+        sa.Column(
+            "completed_at", sa.DateTime(timezone=True), nullable=True
+        ),
+    )
+    op.create_index(
+        "ix_nuzlocke_runs_game_id", "nuzlocke_runs", ["game_id"]
+    )
+    op.create_index(
+        "ix_nuzlocke_runs_status", "nuzlocke_runs", ["status"]
+    )
+
+    op.create_table(
+        "encounters",
+        sa.Column("id", sa.Integer(), primary_key=True),
+        sa.Column(
+            "run_id",
+            sa.Integer(),
+            sa.ForeignKey("nuzlocke_runs.id"),
+            nullable=False,
+        ),
+        sa.Column(
+            "route_id", sa.Integer(), sa.ForeignKey("routes.id"), nullable=False
+        ),
+        sa.Column(
+            "pokemon_id",
+            sa.Integer(),
+            sa.ForeignKey("pokemon.id"),
+            nullable=False,
+        ),
+        sa.Column("nickname", sa.String(50), nullable=True),
+        sa.Column("status", sa.String(20), nullable=False),
+        sa.Column("catch_level", sa.SmallInteger(), nullable=True),
+        sa.Column("faint_level", sa.SmallInteger(), nullable=True),
+        sa.Column(
+            "caught_at",
+            sa.DateTime(timezone=True),
+            nullable=False,
+            server_default=sa.func.now(),
+        ),
+    )
+    op.create_index("ix_encounters_run_id", "encounters", ["run_id"])
+    op.create_index("ix_encounters_route_id", "encounters", ["route_id"])
+    op.create_index("ix_encounters_pokemon_id", "encounters", ["pokemon_id"])
+
+
+def downgrade() -> None:
+    op.drop_table("encounters")
+    op.drop_table("nuzlocke_runs")
+    op.drop_table("route_encounters")
+    op.drop_table("pokemon")
+    op.drop_table("routes")
+    op.drop_table("games")

backend/src/app/api/health.py

@@ -1,12 +1,22 @@
 from fastapi import APIRouter
+from sqlalchemy import text
+
+from app.core.database import async_session
 
 router = APIRouter(tags=["health"])
 
 
 @router.get("/health")
 async def health_check():
-    """Health check endpoint."""
-    return {"status": "healthy"}
+    """Health check endpoint with database connectivity verification."""
+    try:
+        async with async_session() as session:
+            await session.execute(text("SELECT 1"))
+        db_status = "connected"
+    except Exception:
+        db_status = "disconnected"
+
+    return {"status": "healthy", "database": db_status}
 
 
 @router.get("/")

backend/src/app/core/config.py

@@ -14,8 +14,8 @@ class Settings(BaseSettings):
     # API settings
     api_v1_prefix: str = "/api/v1"
 
-    # Database settings (for future use)
-    database_url: str = "sqlite:///./nuzlocke.db"
+    # Database settings
+    database_url: str = "postgresql+asyncpg://postgres:postgres@localhost:5432/nuzlocke"
 
 
 settings = Settings()

backend/src/app/core/database.py

@@ -0,0 +1,31 @@
+from collections.abc import AsyncGenerator
+
+from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
+from sqlalchemy.orm import DeclarativeBase
+
+from app.core.config import settings
+
+
+def _get_async_url(url: str) -> str:
+    """Ensure the database URL uses the asyncpg driver."""
+    if url.startswith("postgresql://"):
+        return url.replace("postgresql://", "postgresql+asyncpg://", 1)
+    return url
+
+
+engine = create_async_engine(
+    _get_async_url(settings.database_url),
+    echo=settings.debug,
+    pool_pre_ping=True,
+)
+
+async_session = async_sessionmaker(engine, expire_on_commit=False)
+
+
+class Base(DeclarativeBase):
+    pass
+
+
+async def get_session() -> AsyncGenerator[AsyncSession]:
+    async with async_session() as session:
+        yield session

backend/src/app/main.py

@@ -1,14 +1,25 @@
+from contextlib import asynccontextmanager
+
 from fastapi import FastAPI
 from fastapi.middleware.cors import CORSMiddleware
 
 from app.api.routes import api_router
 from app.core.config import settings
+from app.core.database import engine
+
+
+@asynccontextmanager
+async def lifespan(app: FastAPI):
+    yield
+    await engine.dispose()
+
 
 app = FastAPI(
     title=settings.app_name,
     openapi_url=f"{settings.api_v1_prefix}/openapi.json",
     docs_url="/docs",
     redoc_url="/redoc",
+    lifespan=lifespan,
 )
 
 # Configure CORS

backend/src/app/models/__init__.py

@@ -0,0 +1,15 @@
+from app.models.encounter import Encounter
+from app.models.game import Game
+from app.models.nuzlocke_run import NuzlockeRun
+from app.models.pokemon import Pokemon
+from app.models.route import Route
+from app.models.route_encounter import RouteEncounter
+
+__all__ = [
+    "Encounter",
+    "Game",
+    "NuzlockeRun",
+    "Pokemon",
+    "Route",
+    "RouteEncounter",
+]

backend/src/app/models/encounter.py

@@ -0,0 +1,29 @@
+from datetime import datetime
+
+from sqlalchemy import DateTime, ForeignKey, SmallInteger, String, func
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from app.core.database import Base
+
+
+class Encounter(Base):
+    __tablename__ = "encounters"
+
+    id: Mapped[int] = mapped_column(primary_key=True)
+    run_id: Mapped[int] = mapped_column(ForeignKey("nuzlocke_runs.id"), index=True)
+    route_id: Mapped[int] = mapped_column(ForeignKey("routes.id"), index=True)
+    pokemon_id: Mapped[int] = mapped_column(ForeignKey("pokemon.id"), index=True)
+    nickname: Mapped[str | None] = mapped_column(String(50))
+    status: Mapped[str] = mapped_column(String(20))  # caught, fainted, missed
+    catch_level: Mapped[int | None] = mapped_column(SmallInteger)
+    faint_level: Mapped[int | None] = mapped_column(SmallInteger)
+    caught_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), server_default=func.now()
+    )
+
+    run: Mapped["NuzlockeRun"] = relationship(back_populates="encounters")
+    route: Mapped["Route"] = relationship(back_populates="encounters")
+    pokemon: Mapped["Pokemon"] = relationship(back_populates="encounters")
+
+    def __repr__(self) -> str:
+        return f"<Encounter(id={self.id}, pokemon_id={self.pokemon_id}, status='{self.status}')>"

backend/src/app/models/game.py

@@ -0,0 +1,22 @@
+from sqlalchemy import SmallInteger, String
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from app.core.database import Base
+
+
+class Game(Base):
+    __tablename__ = "games"
+
+    id: Mapped[int] = mapped_column(primary_key=True)
+    name: Mapped[str] = mapped_column(String(100))
+    slug: Mapped[str] = mapped_column(String(100), unique=True)
+    generation: Mapped[int] = mapped_column(SmallInteger)
+    region: Mapped[str] = mapped_column(String(50))
+    box_art_url: Mapped[str | None] = mapped_column(String(500))
+    release_year: Mapped[int | None] = mapped_column(SmallInteger)
+
+    routes: Mapped[list["Route"]] = relationship(back_populates="game")
+    runs: Mapped[list["NuzlockeRun"]] = relationship(back_populates="game")
+
+    def __repr__(self) -> str:
+        return f"<Game(id={self.id}, name='{self.name}')>"

backend/src/app/models/nuzlocke_run.py

@@ -0,0 +1,27 @@
+from datetime import datetime
+
+from sqlalchemy import DateTime, ForeignKey, String, func
+from sqlalchemy.dialects.postgresql import JSONB
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from app.core.database import Base
+
+
+class NuzlockeRun(Base):
+    __tablename__ = "nuzlocke_runs"
+
+    id: Mapped[int] = mapped_column(primary_key=True)
+    game_id: Mapped[int] = mapped_column(ForeignKey("games.id"), index=True)
+    name: Mapped[str] = mapped_column(String(100))
+    status: Mapped[str] = mapped_column(String(20), index=True)  # active, completed, failed
+    rules: Mapped[dict] = mapped_column(JSONB, default=dict)
+    started_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), server_default=func.now()
+    )
+    completed_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))
+
+    game: Mapped["Game"] = relationship(back_populates="runs")
+    encounters: Mapped[list["Encounter"]] = relationship(back_populates="run")
+
+    def __repr__(self) -> str:
+        return f"<NuzlockeRun(id={self.id}, name='{self.name}', status='{self.status}')>"

backend/src/app/models/pokemon.py

@@ -0,0 +1,23 @@
+from sqlalchemy import SmallInteger, String
+from sqlalchemy.dialects.postgresql import ARRAY
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from app.core.database import Base
+
+
+class Pokemon(Base):
+    __tablename__ = "pokemon"
+
+    id: Mapped[int] = mapped_column(primary_key=True)
+    national_dex: Mapped[int] = mapped_column(SmallInteger, unique=True)
+    name: Mapped[str] = mapped_column(String(50))
+    types: Mapped[list[str]] = mapped_column(ARRAY(String(20)))
+    sprite_url: Mapped[str | None] = mapped_column(String(500))
+
+    route_encounters: Mapped[list["RouteEncounter"]] = relationship(
+        back_populates="pokemon"
+    )
+    encounters: Mapped[list["Encounter"]] = relationship(back_populates="pokemon")
+
+    def __repr__(self) -> str:
+        return f"<Pokemon(id={self.id}, name='{self.name}', dex={self.national_dex})>"

backend/src/app/models/route.py

@@ -0,0 +1,22 @@
+from sqlalchemy import ForeignKey, SmallInteger, String
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from app.core.database import Base
+
+
+class Route(Base):
+    __tablename__ = "routes"
+
+    id: Mapped[int] = mapped_column(primary_key=True)
+    name: Mapped[str] = mapped_column(String(100))
+    game_id: Mapped[int] = mapped_column(ForeignKey("games.id"), index=True)
+    order: Mapped[int] = mapped_column(SmallInteger)
+
+    game: Mapped["Game"] = relationship(back_populates="routes")
+    route_encounters: Mapped[list["RouteEncounter"]] = relationship(
+        back_populates="route"
+    )
+    encounters: Mapped[list["Encounter"]] = relationship(back_populates="route")
+
+    def __repr__(self) -> str:
+        return f"<Route(id={self.id}, name='{self.name}')>"

backend/src/app/models/route_encounter.py

@@ -0,0 +1,25 @@
+from sqlalchemy import ForeignKey, SmallInteger, String, UniqueConstraint
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from app.core.database import Base
+
+
+class RouteEncounter(Base):
+    __tablename__ = "route_encounters"
+    __table_args__ = (
+        UniqueConstraint(
+            "route_id", "pokemon_id", "encounter_method", name="uq_route_pokemon_method"
+        ),
+    )
+
+    id: Mapped[int] = mapped_column(primary_key=True)
+    route_id: Mapped[int] = mapped_column(ForeignKey("routes.id"), index=True)
+    pokemon_id: Mapped[int] = mapped_column(ForeignKey("pokemon.id"), index=True)
+    encounter_method: Mapped[str] = mapped_column(String(30))
+    encounter_rate: Mapped[int] = mapped_column(SmallInteger)
+
+    route: Mapped["Route"] = relationship(back_populates="route_encounters")
+    pokemon: Mapped["Pokemon"] = relationship(back_populates="route_encounters")
+
+    def __repr__(self) -> str:
+        return f"<RouteEncounter(route_id={self.route_id}, pokemon_id={self.pokemon_id}, method='{self.encounter_method}')>"