Initial FastAPI + SQLite + Alembic

.gitignore

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+# venv / python cache
+.venv/
+__pycache__/
+*.pyc
+.pytest_cache/
+.ruff_cache/
+
+# env / secrets
+.env
+
+# local data / sqlite
+data/
+*.db
+
+# editor
+.vscode/
+
+# OS
+.DS_Store
+Thumbs.db

alembic.ini

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+# 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/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 = .
+
+
+# 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.
+sqlalchemy.url = driver://user:pass@localhost/dbname
+
+
+[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

alembic/README

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+Generic single-database configuration.

alembic/env.py

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+import os
+import sys
+from logging.config import fileConfig
+
+from sqlalchemy import engine_from_config
+from sqlalchemy import pool
+
+from alembic import context
+
+# Damit "fastapi_demo...." Imports funktionieren:
+sys.path.append(os.path.abspath(os.getcwd()))
+
+from fastapi_demo.app.core.config import settings
+from fastapi_demo.app.db.base import Base
+
+# this is the Alembic Config object, which provides
+# access to the values within the .ini file in use.
+config = context.config
+
+# Interpret the config file for Python logging.
+# This line sets up loggers basically.
+if config.config_file_name is not None:
+    fileConfig(config.config_file_name)
+
+# DB-URL aus .env/settings
+config.set_main_option("sqlalchemy.url", settings.DATABASE_URL)
+# add your model's MetaData object here
+# for 'autogenerate' support
+# from myapp import mymodel
+# target_metadata = mymodel.Base.metadata
+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 run_migrations_online() -> None:
+    """Run migrations in 'online' mode.
+
+    In this scenario we need to create an Engine
+    and associate a connection with the context.
+
+    """
+    connectable = engine_from_config(
+        config.get_section(config.config_ini_section, {}),
+        prefix="sqlalchemy.",
+        poolclass=pool.NullPool,
+    )
+
+    with connectable.connect() as connection:
+        context.configure(connection=connection, target_metadata=target_metadata)
+
+        with context.begin_transaction():
+            context.run_migrations()
+
+
+if context.is_offline_mode():
+    run_migrations_offline()
+else:
+    run_migrations_online()

alembic/script.py.mako

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+"""${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"}

alembic/versions/54567ad268e8_init.py

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+"""init
+
+Revision ID: 54567ad268e8
+Revises: 
+Create Date: 2026-02-06 16:22:40.309011
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision: str = '54567ad268e8'
+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:
+    """Upgrade schema."""
+    # ### commands auto generated by Alembic - please adjust! ###
+    pass
+    # ### end Alembic commands ###
+
+
+def downgrade() -> None:
+    """Downgrade schema."""
+    # ### commands auto generated by Alembic - please adjust! ###
+    pass
+    # ### end Alembic commands ###

alembic/versions/ffb0393ff471_add_revision_to_assets.py

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+"""add revision to assets
+
+Revision ID: ffb0393ff471
+Revises: 54567ad268e8
+Create Date: 2026-02-06 17:02:28.538265
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision: str = 'ffb0393ff471'
+down_revision: Union[str, Sequence[str], None] = '54567ad268e8'
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    """Upgrade schema."""
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.add_column('assets', sa.Column('revision', sa.Integer(), server_default=sa.text('0'), nullable=False))
+    # ### end Alembic commands ###
+
+
+def downgrade() -> None:
+    """Downgrade schema."""
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.drop_column('assets', 'revision')
+    # ### end Alembic commands ###

fastapi_demo/app/api/routes/assets.py

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+from fastapi import APIRouter, Depends
+from uuid import UUID
+from sqlalchemy.orm import Session
+
+from fastapi_demo.app.db.deps import get_db
+from fastapi_demo.app.repositories.sql_assets_repo import SqlAssetsRepo
+from fastapi_demo.app.services.assets_service import AssetsService
+from fastapi_demo.app.schemas.asset import (
+    AssetCreate,
+    AssetOut,
+    AssetTransitionIn,
+    AssetEventOut,
+)
+
+router = APIRouter(prefix="/assets", tags=["assets"])
+
+
+def get_service(db: Session = Depends(get_db)) -> AssetsService:
+    repo = SqlAssetsRepo(db)
+    return AssetsService(repo)
+
+
+@router.post("", response_model=AssetOut, status_code=201)
+def create_asset(payload: AssetCreate, svc: AssetsService = Depends(get_service)):
+    return svc.create_asset(payload)
+
+
+@router.get("/{asset_id}", response_model=AssetOut)
+def get_asset(asset_id: UUID, svc: AssetsService = Depends(get_service)):
+    return svc.get_asset(asset_id)
+
+
+@router.post("/{asset_id}/transition", response_model=AssetOut)
+def transition_asset(
+    asset_id: UUID,
+    payload: AssetTransitionIn,
+    svc: AssetsService = Depends(get_service),
+):
+    asset, _event = svc.transition(asset_id, payload)
+    return asset
+
+
+@router.get("/{asset_id}/events", response_model=list[AssetEventOut])
+def list_events(asset_id: UUID, svc: AssetsService = Depends(get_service)):
+    return svc.list_events(asset_id)

fastapi_demo/app/api/routes/health.py

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+from fastapi import APIRouter
+
+router = APIRouter(tags=["health"])
+
+
+@router.get("/health")
+def health():
+    return {"status": "ok"}

fastapi_demo/app/core/config.py

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+from pydantic_settings import BaseSettings, SettingsConfigDict
+
+
+class Settings(BaseSettings):
+    APP_NAME: str = "FASTAPI_DEMO"
+    ENV: str = "dev"
+    DATABASE_URL: str = "sqlite:///./data/app.db"
+
+    model_config = SettingsConfigDict(env_file=".env", extra="ignore")
+
+
+settings = Settings()

fastapi_demo/app/db/base.py

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+from fastapi_demo.app.db.session import Base  # noqa: F401
+from fastapi_demo.app.db import models  # noqa: F401

fastapi_demo/app/db/deps.py

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+from __future__ import annotations
+
+from typing import Generator
+from fastapi_demo.app.db.session import SessionLocal
+from sqlalchemy.orm import Session
+
+
+def get_db() -> Generator[Session, None, None]:
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()

fastapi_demo/app/db/models.py

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+from __future__ import annotations
+
+from sqlalchemy import String, DateTime, Text, ForeignKey, Integer, text
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+from datetime import datetime
+
+from fastapi_demo.app.db.session import Base
+
+
+class Asset(Base):
+    __tablename__ = "assets"
+
+    id: Mapped[str] = mapped_column(String, primary_key=True, index=True)
+    name: Mapped[str] = mapped_column(String, nullable=False)
+    serial: Mapped[str | None] = mapped_column(String, nullable=True)
+
+    status: Mapped[str] = mapped_column(String, nullable=False)
+
+    revision: Mapped[int] = mapped_column(
+        Integer,
+        nullable=False,
+        server_default=text("0"),
+    )
+
+    created_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), nullable=False
+    )
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), nullable=False
+    )
+
+    events: Mapped[list["AssetEvent"]] = relationship(
+        "AssetEvent",
+        back_populates="asset",
+        cascade="all, delete-orphan",
+        passive_deletes=True,
+    )
+
+
+class AssetEvent(Base):
+    __tablename__ = "asset_events"
+
+    id: Mapped[str] = mapped_column(String, primary_key=True, index=True)
+    asset_id: Mapped[str] = mapped_column(
+        String, ForeignKey("assets.id", ondelete="CASCADE"), index=True
+    )
+
+    from_status: Mapped[str] = mapped_column(String, nullable=False)
+    to_status: Mapped[str] = mapped_column(String, nullable=False)
+    at: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False)
+    note: Mapped[str | None] = mapped_column(Text, nullable=True)
+
+    asset: Mapped["Asset"] = relationship("Asset", back_populates="events")

fastapi_demo/app/db/session.py

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+from __future__ import annotations
+
+from pathlib import Path
+from sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker, declarative_base
+
+from fastapi_demo.app.core.config import settings
+
+# sorgt dafür, dass ./data existiert (für sqlite datei)
+Path("data").mkdir(exist_ok=True)
+
+engine = create_engine(
+    settings.DATABASE_URL,
+    connect_args={"check_same_thread": False}
+    if settings.DATABASE_URL.startswith("sqlite")
+    else {},
+)
+
+SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
+Base = declarative_base()
+
+
+def dispose_engine() -> None:
+    engine.dispose()

fastapi_demo/app/domain/status.py

@@ -0,0 +1,10 @@
+from enum import Enum
+
+
+class AssetStatus(str, Enum):
+    WARENEINGANG = "WARENEINGANG"
+    SICHTPRUEFUNG = "SICHTPRUEFUNG"
+    WARTESCHLANGE = "WARTESCHLANGE"
+    IN_BEARBEITUNG = "IN_BEARBEITUNG"
+    QUALITAETSKONTROLLE = "QUALITAETSKONTROLLE"
+    WARENAUSGANG = "WARENAUSGANG"

fastapi_demo/app/domain/transitions.py

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+from fastapi import HTTPException
+from fastapi_demo.app.domain.status import AssetStatus
+
+# Erlaubte Übergänge (Transition Matrix)
+ALLOWED_TRANSITIONS: dict[AssetStatus, set[AssetStatus]] = {
+    AssetStatus.WARENEINGANG: {AssetStatus.SICHTPRUEFUNG},
+    AssetStatus.SICHTPRUEFUNG: {AssetStatus.WARTESCHLANGE},
+    AssetStatus.WARTESCHLANGE: {AssetStatus.IN_BEARBEITUNG},
+    AssetStatus.IN_BEARBEITUNG: {AssetStatus.QUALITAETSKONTROLLE},
+    AssetStatus.QUALITAETSKONTROLLE: {
+        AssetStatus.WARENAUSGANG,
+        AssetStatus.IN_BEARBEITUNG,
+    },  # z.B. Nacharbeit
+    AssetStatus.WARENAUSGANG: set(),
+}
+
+
+def ensure_transition_allowed(from_status: AssetStatus, to_status: AssetStatus) -> None:
+    allowed = ALLOWED_TRANSITIONS.get(from_status, set())
+    if to_status not in allowed:
+        raise HTTPException(
+            status_code=409,
+            detail=f"Transition nicht erlaubt: {from_status} -> {to_status}",
+        )

fastapi_demo/app/main.py

@@ -0,0 +1,24 @@
+from contextlib import asynccontextmanager
+from fastapi import FastAPI
+
+from fastapi_demo.app.db.session import dispose_engine
+from fastapi_demo.app.api.routes.health import router as health_router
+from fastapi_demo.app.api.routes.assets import router as assets_router
+
+
+@asynccontextmanager
+async def lifespan(app: FastAPI):
+    # Startup
+    yield
+    # Shutdown
+    dispose_engine()
+
+
+app = FastAPI(
+    title="FASTAPI_DEMO",
+    version="0.1.0",
+    lifespan=lifespan,
+)
+
+app.include_router(health_router)
+app.include_router(assets_router)

fastapi_demo/app/repositories/assets_repo.py

@@ -0,0 +1,11 @@
+from typing import Protocol
+from uuid import UUID
+from fastapi_demo.app.schemas.asset import AssetOut, AssetEventOut
+
+
+class AssetsRepo(Protocol):
+    def create(self, asset: AssetOut) -> None: ...
+    def get(self, asset_id: UUID) -> AssetOut | None: ...
+    def update(self, asset: AssetOut) -> None: ...
+    def add_event(self, event: AssetEventOut) -> None: ...
+    def list_events(self, asset_id: UUID) -> list[AssetEventOut]: ...

fastapi_demo/app/repositories/memory_assets_repo.py

@@ -0,0 +1,25 @@
+from uuid import UUID
+from fastapi_demo.app.repositories.assets_repo import AssetsRepo
+from fastapi_demo.app.schemas.asset import AssetOut, AssetEventOut
+
+
+class MemoryAssetsRepo(AssetsRepo):
+    def __init__(self) -> None:
+        self.assets: dict[UUID, AssetOut] = {}
+        self.events: dict[UUID, list[AssetEventOut]] = {}
+
+    def create(self, asset: AssetOut) -> None:
+        self.assets[asset.id] = asset
+        self.events.setdefault(asset.id, [])
+
+    def get(self, asset_id: UUID) -> AssetOut | None:
+        return self.assets.get(asset_id)
+
+    def update(self, asset: AssetOut) -> None:
+        self.assets[asset.id] = asset
+
+    def add_event(self, event: AssetEventOut) -> None:
+        self.events.setdefault(event.asset_id, []).append(event)
+
+    def list_events(self, asset_id: UUID) -> list[AssetEventOut]:
+        return list(self.events.get(asset_id, []))

fastapi_demo/app/repositories/sql_assets_repo.py

@@ -0,0 +1,134 @@
+from __future__ import annotations
+
+from datetime import datetime
+from uuid import UUID, uuid4
+
+from fastapi import HTTPException
+from sqlalchemy import select, update
+from sqlalchemy.orm import Session
+
+from fastapi_demo.app.db.models import Asset as AssetORM, AssetEvent as AssetEventORM
+from fastapi_demo.app.domain.status import AssetStatus
+from fastapi_demo.app.schemas.asset import AssetOut, AssetEventOut
+
+
+class SqlAssetsRepo:
+    def __init__(self, db: Session) -> None:
+        self.db = db
+
+    def create(self, asset: AssetOut) -> None:
+        row = AssetORM(
+            id=str(asset.id),
+            name=asset.name,
+            serial=asset.serial,
+            status=str(asset.status),
+            revision=asset.revision,  # <-- wichtig
+            created_at=asset.updated_at,  # MVP: created_at == updated_at
+            updated_at=asset.updated_at,
+        )
+        self.db.add(row)
+        self.db.commit()
+
+    def get(self, asset_id: UUID) -> AssetOut | None:
+        row = self.db.get(AssetORM, str(asset_id))
+        if not row:
+            return None
+        return AssetOut(
+            id=UUID(row.id),
+            name=row.name,
+            serial=row.serial,
+            status=AssetStatus(row.status),
+            revision=row.revision,  # <-- wichtig
+            updated_at=row.updated_at,
+        )
+
+    def transition_with_revision(
+        self,
+        asset_id: UUID,
+        expected_revision: int,
+        to_status: AssetStatus,
+        at: datetime,
+        note: str | None,
+    ) -> tuple[AssetOut, AssetEventOut]:
+
+        with self.db.begin():  # <-- begin ganz nach oben
+            current = self.db.get(AssetORM, str(asset_id))
+            if not current:
+                raise HTTPException(status_code=404, detail="Asset nicht gefunden")
+
+            from_status = AssetStatus(current.status)
+
+            stmt = (
+                update(AssetORM)
+                .where(
+                    AssetORM.id == str(asset_id),
+                    AssetORM.revision == expected_revision,
+                )
+                .values(
+                    status=str(to_status),
+                    updated_at=at,
+                    revision=expected_revision + 1,
+                )
+            )
+
+            res = self.db.execute(stmt)
+            if res.rowcount != 1:
+                # aktuelle Revision für saubere Fehlermeldung neu lesen
+                latest = self.db.get(AssetORM, str(asset_id))
+                raise HTTPException(
+                    status_code=409,
+                    detail={
+                        "message": "Revision-Konflikt",
+                        "expected_revision": expected_revision,
+                        "current_revision": latest.revision if latest else None,
+                    },
+                )
+
+            event_row = AssetEventORM(
+                id=str(uuid4()),
+                asset_id=str(asset_id),
+                from_status=str(from_status),
+                to_status=str(to_status),
+                at=at,
+                note=note,
+            )
+            self.db.add(event_row)
+
+        # nach Commit: updated Asset laden
+        updated = self.db.get(AssetORM, str(asset_id))
+        assert updated is not None
+
+        asset_out = AssetOut(
+            id=UUID(updated.id),
+            name=updated.name,
+            serial=updated.serial,
+            status=AssetStatus(updated.status),
+            revision=updated.revision,
+            updated_at=updated.updated_at,
+        )
+        event_out = AssetEventOut(
+            asset_id=asset_out.id,
+            from_status=from_status,
+            to_status=to_status,
+            at=at,
+            note=note,
+        )
+        return asset_out, event_out
+
+    def list_events(self, asset_id: UUID) -> list[AssetEventOut]:
+        stmt = (
+            select(AssetEventORM)
+            .where(AssetEventORM.asset_id == str(asset_id))
+            .order_by(AssetEventORM.at.asc())
+        )
+        rows = self.db.execute(stmt).scalars().all()
+        return [
+            AssetEventOut(
+                asset_id=UUID(r.asset_id),
+                from_status=AssetStatus(r.from_status),
+                to_status=AssetStatus(r.to_status),
+                at=r.at,
+                note=r.note,
+            )
+            for r in rows
+        ]

fastapi_demo/app/schemas/asset.py

@@ -0,0 +1,32 @@
+from pydantic import BaseModel, Field
+from uuid import UUID
+from datetime import datetime
+from fastapi_demo.app.domain.status import AssetStatus
+
+
+class AssetCreate(BaseModel):
+    name: str = Field(min_length=1)
+    serial: str | None = None
+
+
+class AssetOut(BaseModel):
+    id: UUID
+    name: str
+    serial: str | None
+    status: AssetStatus
+    revision: int
+    updated_at: datetime
+
+
+class AssetTransitionIn(BaseModel):
+    to_status: AssetStatus
+    expected_revision: int
+    note: str | None = None
+
+
+class AssetEventOut(BaseModel):
+    asset_id: UUID
+    from_status: AssetStatus
+    to_status: AssetStatus
+    at: datetime
+    note: str | None = None

fastapi_demo/app/services/assets_service.py

@@ -0,0 +1,61 @@
+from datetime import datetime, timezone
+from uuid import uuid4, UUID
+from fastapi import HTTPException
+
+from fastapi_demo.app.domain.status import AssetStatus
+from fastapi_demo.app.domain.transitions import ensure_transition_allowed
+from fastapi_demo.app.repositories.assets_repo import AssetsRepo
+from fastapi_demo.app.schemas.asset import (
+    AssetCreate,
+    AssetOut,
+    AssetTransitionIn,
+    AssetEventOut,
+)
+
+
+class AssetsService:
+    def __init__(self, repo: AssetsRepo) -> None:
+        self.repo = repo
+
+    def create_asset(self, data: AssetCreate) -> AssetOut:
+        now = datetime.now(timezone.utc)
+        asset = AssetOut(
+            id=uuid4(),
+            name=data.name,
+            serial=data.serial,
+            status=AssetStatus.WARENEINGANG,
+            revision=0,  # <-- neu
+            updated_at=now,
+        )
+        self.repo.create(asset)
+        return asset
+
+    def get_asset(self, asset_id: UUID) -> AssetOut:
+        asset = self.repo.get(asset_id)
+        if not asset:
+            raise HTTPException(status_code=404, detail="Asset nicht gefunden")
+        return asset
+
+    def transition(
+        self, asset_id: UUID, data: AssetTransitionIn
+    ) -> tuple[AssetOut, AssetEventOut]:
+        asset = self.get_asset(asset_id)
+
+        # Domain-Regel: Transition erlaubt?
+        ensure_transition_allowed(asset.status, data.to_status)
+
+        now = datetime.now(timezone.utc)
+
+        # Repo macht atomar: revision check + status update + event insert
+        updated_asset, event = self.repo.transition_with_revision(
+            asset_id=asset_id,
+            expected_revision=data.expected_revision,
+            to_status=data.to_status,
+            at=now,
+            note=data.note,
+        )
+        return updated_asset, event
+
+    def list_events(self, asset_id: UUID) -> list[AssetEventOut]:
+        self.get_asset(asset_id)  # 404 falls nicht existiert
+        return self.repo.list_events(asset_id)