Verwaltbare Einheiten mit Umrechnung + Chargen bearbeiten + gezieltes Auslagern

Einheiten (neu):
- Tabelle units (name, kind=count|weight|volume, factor, is_builtin); eingebaut
  Stueck/Gramm/Kilogramm/Milliliter/Liter, Admin kann eigene anlegen (z.B. Pfund=500g).
- Bestaende bleiben intern in kanonischer Basis (Stueck/Gramm/Milliliter);
  Product.display_unit_id und Group.min_stock_unit_id als nullable FKs.
- Neuer Umrechnungs-Service (services/conversion.py) ersetzt die feste Einheitenlogik;
  Ein-/Auslagern und Gruppen-Mindestbestand rechnen ueber den Faktor.
- Gruppen-Mindestbestand mit Einheit; Gruppenbestand summiert nur Produkte
  passender Art. Neue Verwaltungsseite "Einheiten" (Admin).
- Schonende Migration beim Start: ADD COLUMN IF NOT EXISTS (Postgres), damit
  bestehende Installationen ihre Daten behalten.

Chargen:
- PATCH /lots/{id} und DELETE /lots/{id}: Menge/MHD korrigieren, Charge loeschen
  (wird als Korrektur-Bewegung protokolliert). Bearbeitung im Produktdetail.

Auslagern:
- Optionales lot_id: gezielt aus einer bestimmten Charge/MHD abbuchen statt FEFO;
  Auswahl-Dropdown in der Auslagern-Seite.

Sonstiges: Roadmap aktualisiert, Tests fuer die Umrechnung.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/app/crud.py

@@ -9,6 +9,7 @@ from sqlalchemy.orm import Session
 
 from .models import Lot, Product
 from .schemas import ProductOut
+from .services.conversion import KIND_OF_BASE, display_unit_info
 from .services.stock import current_stock
 
 
@@ -25,6 +26,10 @@ def product_to_out(db: Session, product: Product) -> ProductOut:
         )
         .count()
     )
+    out.kind = KIND_OF_BASE[product.base_unit].value
+    name, factor = display_unit_info(product)
+    out.unit_name = name
+    out.unit_factor = factor
     return out
 
 

backend/app/main.py

@@ -2,6 +2,7 @@ from contextlib import asynccontextmanager
 
 from fastapi import FastAPI
 from fastapi.middleware.cors import CORSMiddleware
+from sqlalchemy import text
 
 from .config import get_settings
 from .database import Base, SessionLocal, engine
@@ -12,20 +13,44 @@ from .routers import (
     products,
     settings as settings_router,
     stock,
+    units,
     users,
     views,
 )
-from .seed import ensure_first_admin
+from .seed import ensure_builtin_units, ensure_first_admin
 
 settings = get_settings()
 
 
+def _ensure_schema() -> None:
+    """Schonende Migration: fehlende Spalten auf bestehenden Tabellen nachziehen.
+
+    create_all() legt nur fehlende Tabellen an, ändert aber keine bestehenden.
+    Auf Postgres holen wir neue nullable-Spalten per ADD COLUMN IF NOT EXISTS nach,
+    damit vorhandene Installationen ihre Daten behalten. Auf SQLite (Tests) sind
+    die Spalten bereits durch create_all vorhanden.
+    """
+    if engine.dialect.name != "postgresql":
+        return
+    stmts = [
+        "ALTER TABLE products ADD COLUMN IF NOT EXISTS display_unit_id INTEGER "
+        "REFERENCES units(id) ON DELETE SET NULL",
+        "ALTER TABLE groups ADD COLUMN IF NOT EXISTS min_stock_unit_id INTEGER "
+        "REFERENCES units(id) ON DELETE SET NULL",
+    ]
+    with engine.begin() as conn:
+        for stmt in stmts:
+            conn.execute(text(stmt))
+
+
 @asynccontextmanager
 async def lifespan(app: FastAPI):
     # Tabellen anlegen (MVP: create_all statt Alembic-Migrationen).
     Base.metadata.create_all(bind=engine)
+    _ensure_schema()
     db = SessionLocal()
     try:
+        ensure_builtin_units(db)
         ensure_first_admin(db)
     finally:
         db.close()
@@ -57,5 +82,6 @@ app.include_router(products.router)
 app.include_router(stock.router)
 app.include_router(locations.router)
 app.include_router(groups.router)
+app.include_router(units.router)
 app.include_router(views.router)
 app.include_router(settings_router.router)

backend/app/models.py

@@ -4,6 +4,7 @@ import enum
 from datetime import date, datetime, timezone
 
 from sqlalchemy import (
+    Boolean,
     Date,
     DateTime,
     Enum,
@@ -40,6 +41,28 @@ class MovementType(str, enum.Enum):
     adjust = "adjust"
 
 
+class UnitKind(str, enum.Enum):
+    """Art einer Einheit. Bestimmt die kanonische Basiseinheit für die Speicherung."""
+    count = "count"      # Basis: Stück
+    weight = "weight"    # Basis: Gramm
+    volume = "volume"    # Basis: Milliliter
+
+
+class Unit(Base):
+    """Vom Admin verwaltbare Einheit mit Umrechnungsfaktor zur kanonischen Basis.
+
+    factor = wie viele Basiseinheiten 1 dieser Einheit entsprechen
+    (z.B. Kilogramm: kind=weight, factor=1000; Liter: kind=volume, factor=1000).
+    """
+    __tablename__ = "units"
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True)
+    name: Mapped[str] = mapped_column(String(64), unique=True, nullable=False)
+    kind: Mapped[UnitKind] = mapped_column(Enum(UnitKind), nullable=False)
+    factor: Mapped[float] = mapped_column(Float, nullable=False, default=1.0)
+    is_builtin: Mapped[bool] = mapped_column(Boolean, nullable=False, default=False)
+
+
 class User(Base):
     __tablename__ = "users"
 
@@ -55,10 +78,14 @@ class Group(Base):
 
     id: Mapped[int] = mapped_column(Integer, primary_key=True)
     name: Mapped[str] = mapped_column(String(120), unique=True, nullable=False)
-    # Group-level minimum stock is a Schritt-3 feature; column kept for forward-compat.
     min_stock: Mapped[float | None] = mapped_column(Float, nullable=True)
+    # Einheit des Gruppen-Mindestbestands (z.B. Kilogramm). NULL = zählt in Basiseinheiten.
+    min_stock_unit_id: Mapped[int | None] = mapped_column(
+        ForeignKey("units.id", ondelete="SET NULL"), nullable=True
+    )
 
     products: Mapped[list[Product]] = relationship(back_populates="group")
+    min_stock_unit: Mapped[Unit | None] = relationship()
 
 
 class Location(Base):
@@ -82,9 +109,14 @@ class Product(Base):
     brand: Mapped[str | None] = mapped_column(String(255), nullable=True)
     image_url: Mapped[str | None] = mapped_column(String(1024), nullable=True)
 
+    # Kanonische Basiseinheit (piece/gram/milliliter): bestimmt Speicherung + Art (kind).
     base_unit: Mapped[BaseUnit] = mapped_column(
         Enum(BaseUnit), nullable=False, default=BaseUnit.piece
     )
+    # Bevorzugte Anzeige-/Eingabeeinheit (z.B. Kilogramm). NULL = Basiseinheit selbst.
+    display_unit_id: Mapped[int | None] = mapped_column(
+        ForeignKey("units.id", ondelete="SET NULL"), nullable=True
+    )
     # Number of base units contained in one package (e.g. 500 g per package).
     package_size: Mapped[float | None] = mapped_column(Float, nullable=True)
 
@@ -98,6 +130,7 @@ class Product(Base):
     created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), default=_now)
 
     group: Mapped[Group | None] = relationship(back_populates="products")
+    display_unit: Mapped[Unit | None] = relationship()
     lots: Mapped[list[Lot]] = relationship(
         back_populates="product", cascade="all, delete-orphan"
     )

backend/app/routers/groups.py

@@ -5,6 +5,7 @@ from ..database import get_db
 from ..deps import get_current_user, require_admin
 from ..models import Group, Product, User
 from ..schemas import GroupCreate, GroupOut, GroupUpdate
+from ..services.conversion import BASE_OF_KIND
 from ..services.stock import current_stock
 
 router = APIRouter(prefix="/groups", tags=["groups"])
@@ -14,7 +15,17 @@ def _group_to_out(db: Session, group: Group) -> GroupOut:
     out = GroupOut.model_validate(group)
     products = db.query(Product).filter(Product.group_id == group.id).all()
     out.product_count = len(products)
-    out.stock = float(sum(current_stock(db, p.id) for p in products))
+    unit = group.min_stock_unit
+    if unit is not None:
+        # Bestand nur über Produkte gleicher Art, in der Gruppen-Einheit ausgedrückt.
+        base = BASE_OF_KIND[unit.kind]
+        matching = [p for p in products if p.base_unit == base]
+        stock_base = float(sum(current_stock(db, p.id) for p in matching))
+        out.stock = stock_base / unit.factor
+        out.min_stock_unit_name = unit.name
+        out.kind = unit.kind.value
+    else:
+        out.stock = float(sum(current_stock(db, p.id) for p in products))
     return out
 
 
@@ -34,7 +45,11 @@ def create_group(
 ) -> GroupOut:
     if db.query(Group).filter(Group.name == payload.name).first():
         raise HTTPException(status.HTTP_409_CONFLICT, "Gruppe existiert bereits")
-    group = Group(name=payload.name, min_stock=payload.min_stock)
+    group = Group(
+        name=payload.name,
+        min_stock=payload.min_stock,
+        min_stock_unit_id=payload.min_stock_unit_id,
+    )
     db.add(group)
     db.commit()
     db.refresh(group)

backend/app/routers/products.py

@@ -7,6 +7,7 @@ from ..deps import get_current_user, require_admin
 from ..models import BaseUnit, Product, User
 from ..off import lookup_barcode
 from ..schemas import LookupResult, ProductCreate, ProductOut, ProductUpdate
+from ..services.conversion import ConversionError, resolve_product_unit
 
 router = APIRouter(prefix="/products", tags=["products"])
 
@@ -66,12 +67,20 @@ def create_product(
             raise HTTPException(
                 status.HTTP_409_CONFLICT, "Ein Produkt mit diesem Barcode existiert bereits"
             )
+    base_unit = payload.base_unit
+    display_unit_id = None
+    if payload.unit_id is not None:
+        try:
+            base_unit, display_unit_id = resolve_product_unit(db, payload.unit_id)
+        except ConversionError as exc:
+            raise HTTPException(status.HTTP_400_BAD_REQUEST, str(exc)) from exc
     product = Product(
         barcode=payload.barcode or None,
         name=payload.name,
         brand=payload.brand,
         image_url=payload.image_url,
-        base_unit=payload.base_unit,
+        base_unit=base_unit,
+        display_unit_id=display_unit_id,
         package_size=payload.package_size,
         group_id=payload.group_id,
         min_stock=payload.min_stock,
@@ -105,6 +114,17 @@ def update_product(
             raise HTTPException(
                 status.HTTP_409_CONFLICT, "Ein anderes Produkt hat diesen Barcode bereits"
             )
+    # Einheit: unit_id (falls gesetzt) bestimmt base_unit + Anzeigeeinheit.
+    if "unit_id" in data:
+        unit_id = data.pop("unit_id")
+        data.pop("base_unit", None)  # unit_id hat Vorrang
+        if unit_id is None:
+            product.display_unit_id = None
+        else:
+            try:
+                product.base_unit, product.display_unit_id = resolve_product_unit(db, unit_id)
+            except ConversionError as exc:
+                raise HTTPException(status.HTTP_400_BAD_REQUEST, str(exc)) from exc
     for field, value in data.items():
         setattr(product, field, value)
     db.commit()

backend/app/routers/stock.py

@@ -4,7 +4,7 @@ from sqlalchemy.orm import Session
 from ..crud import resolve_product
 from ..database import get_db
 from ..deps import get_current_user
-from ..models import Lot, User
+from ..models import Lot, Movement, MovementType, User
 from ..schemas import (
     BatchCheckInRequest,
     BatchCheckInResponse,
@@ -13,9 +13,16 @@ from ..schemas import (
     CheckOutRequest,
     CheckOutResponse,
     LotOut,
+    LotUpdate,
+)
+from ..services.conversion import ConversionError
+from ..services.stock import (
+    StockError,
+    check_in,
+    check_out,
+    check_out_lot,
+    current_stock,
 )
-from ..services.stock import StockError, check_in, check_out, current_stock
-from ..services.units import UnitError
 
 router = APIRouter(tags=["stock"])
 
@@ -38,7 +45,7 @@ def stock_checkin(
             user=user,
             note=payload.note,
         )
-    except UnitError as exc:
+    except ConversionError as exc:
         raise HTTPException(status.HTTP_400_BAD_REQUEST, str(exc)) from exc
     db.commit()
     db.refresh(lot)
@@ -74,7 +81,7 @@ def stock_checkin_batch(
                     note=payload.note,
                 )
             )
-    except UnitError as exc:
+    except ConversionError as exc:
         db.rollback()
         raise HTTPException(status.HTTP_400_BAD_REQUEST, str(exc)) from exc
     db.commit()
@@ -94,15 +101,31 @@ def stock_checkout(
 ) -> CheckOutResponse:
     product = resolve_product(db, payload.product_id, payload.barcode)
     try:
-        affected = check_out(
-            db,
-            product=product,
-            quantity=payload.quantity,
-            unit=payload.unit,
-            user=user,
-            note=payload.note,
-        )
-    except UnitError as exc:
+        if payload.lot_id is not None:
+            lot = db.get(Lot, payload.lot_id)
+            if lot is None or lot.product_id != product.id:
+                raise HTTPException(
+                    status.HTTP_404_NOT_FOUND, "Charge gehört nicht zu diesem Produkt"
+                )
+            affected = check_out_lot(
+                db,
+                product=product,
+                lot=lot,
+                quantity=payload.quantity,
+                unit=payload.unit,
+                user=user,
+                note=payload.note,
+            )
+        else:
+            affected = check_out(
+                db,
+                product=product,
+                quantity=payload.quantity,
+                unit=payload.unit,
+                user=user,
+                note=payload.note,
+            )
+    except ConversionError as exc:
         raise HTTPException(status.HTTP_400_BAD_REQUEST, str(exc)) from exc
     except StockError as exc:
         raise HTTPException(status.HTTP_409_CONFLICT, str(exc)) from exc
@@ -122,3 +145,63 @@ def list_lots(
     if product_id is not None:
         query = query.filter(Lot.product_id == product_id)
     return query.order_by(Lot.best_before.is_(None), Lot.best_before).all()
+
+
+@router.patch("/lots/{lot_id}", response_model=LotOut)
+def update_lot(
+    lot_id: int,
+    payload: LotUpdate,
+    db: Session = Depends(get_db),
+    user: User = Depends(get_current_user),
+) -> Lot:
+    """Korrigiert eine Charge (Menge in Basiseinheiten, MHD, Lagerort)."""
+    lot = db.get(Lot, lot_id)
+    if lot is None:
+        raise HTTPException(status.HTTP_404_NOT_FOUND, "Charge nicht gefunden")
+
+    data = payload.model_dump(exclude_unset=True)
+    old_quantity = lot.quantity
+    for field, value in data.items():
+        setattr(lot, field, value)
+
+    delta = lot.quantity - old_quantity
+    if abs(delta) > 1e-9:
+        db.add(
+            Movement(
+                product_id=lot.product_id,
+                lot_id=lot.id,
+                user_id=user.id,
+                type=MovementType.adjust,
+                quantity=delta,
+                unit_used="base",
+                note="Charge korrigiert",
+            )
+        )
+    db.commit()
+    db.refresh(lot)
+    return lot
+
+
+@router.delete("/lots/{lot_id}", status_code=status.HTTP_204_NO_CONTENT)
+def delete_lot(
+    lot_id: int,
+    db: Session = Depends(get_db),
+    user: User = Depends(get_current_user),
+) -> None:
+    """Entfernt eine Charge komplett aus dem Bestand."""
+    lot = db.get(Lot, lot_id)
+    if lot is None:
+        raise HTTPException(status.HTTP_404_NOT_FOUND, "Charge nicht gefunden")
+    db.add(
+        Movement(
+            product_id=lot.product_id,
+            lot_id=None,
+            user_id=user.id,
+            type=MovementType.adjust,
+            quantity=-lot.quantity,
+            unit_used="base",
+            note="Charge gelöscht",
+        )
+    )
+    db.delete(lot)
+    db.commit()

backend/app/routers/units.py

@@ -0,0 +1,56 @@
+from fastapi import APIRouter, Depends, HTTPException, status
+from sqlalchemy import func
+from sqlalchemy.orm import Session
+
+from ..database import get_db
+from ..deps import get_current_user, require_admin
+from ..models import Group, Product, Unit, User
+from ..schemas import UnitCreate, UnitOut
+
+router = APIRouter(prefix="/units", tags=["units"])
+
+
+@router.get("", response_model=list[UnitOut])
+def list_units(
+    db: Session = Depends(get_db), _: User = Depends(get_current_user)
+) -> list[Unit]:
+    return db.query(Unit).order_by(Unit.kind, Unit.factor).all()
+
+
+@router.post("", response_model=UnitOut, status_code=status.HTTP_201_CREATED)
+def create_unit(
+    payload: UnitCreate,
+    db: Session = Depends(get_db),
+    _: User = Depends(require_admin),
+) -> Unit:
+    exists = db.query(Unit).filter(func.lower(Unit.name) == payload.name.lower()).first()
+    if exists:
+        raise HTTPException(status.HTTP_409_CONFLICT, "Einheit existiert bereits")
+    unit = Unit(name=payload.name, kind=payload.kind, factor=payload.factor, is_builtin=False)
+    db.add(unit)
+    db.commit()
+    db.refresh(unit)
+    return unit
+
+
+@router.delete("/{unit_id}", status_code=status.HTTP_204_NO_CONTENT)
+def delete_unit(
+    unit_id: int,
+    db: Session = Depends(get_db),
+    _: User = Depends(require_admin),
+) -> None:
+    unit = db.get(Unit, unit_id)
+    if unit is None:
+        raise HTTPException(status.HTTP_404_NOT_FOUND, "Einheit nicht gefunden")
+    if unit.is_builtin:
+        raise HTTPException(status.HTTP_400_BAD_REQUEST, "Eingebaute Einheiten können nicht gelöscht werden")
+    in_use = (
+        db.query(Product).filter(Product.display_unit_id == unit_id).first()
+        or db.query(Group).filter(Group.min_stock_unit_id == unit_id).first()
+    )
+    if in_use:
+        raise HTTPException(
+            status.HTTP_409_CONFLICT, "Einheit wird noch von Produkten/Gruppen verwendet"
+        )
+    db.delete(unit)
+    db.commit()

backend/app/routers/views.py

@@ -7,6 +7,7 @@ from ..database import get_db
 from ..deps import get_current_user
 from ..models import Group, Lot, Movement, Product, User
 from ..schemas import ExpiringItem, GroupShoppingItem, MovementOut, ShoppingItem
+from ..services.conversion import BASE_OF_KIND
 from ..services.stock import current_stock
 from .settings import get_expiry_warning_days
 
@@ -56,8 +57,16 @@ def group_shopping_list(
         db.query(Group).filter(Group.min_stock.isnot(None), Group.min_stock > 0).all()
     )
     for group in groups:
-        products = db.query(Product).filter(Product.group_id == group.id).all()
-        stock = float(sum(current_stock(db, p.id) for p in products))
+        unit = group.min_stock_unit
+        if unit is not None:
+            base = BASE_OF_KIND[unit.kind]
+            products = [p for p in group.products if p.base_unit == base]
+            stock = float(sum(current_stock(db, p.id) for p in products)) / unit.factor
+            unit_name = unit.name
+        else:
+            products = list(group.products)
+            stock = float(sum(current_stock(db, p.id) for p in products))
+            unit_name = ""
         if stock < group.min_stock:
             items.append(
                 GroupShoppingItem(
@@ -66,6 +75,7 @@ def group_shopping_list(
                     stock=stock,
                     min_stock=group.min_stock,
                     deficit=group.min_stock - stock,
+                    unit_name=unit_name,
                     product_count=len(products),
                 )
             )

backend/app/schemas.py

@@ -4,7 +4,23 @@ from datetime import date, datetime
 
 from pydantic import BaseModel, ConfigDict, Field
 
-from .models import BaseUnit, Role
+from .models import BaseUnit, Role, UnitKind
+
+
+# ---- Units ----
+class UnitOut(BaseModel):
+    model_config = ConfigDict(from_attributes=True)
+    id: int
+    name: str
+    kind: UnitKind
+    factor: float
+    is_builtin: bool
+
+
+class UnitCreate(BaseModel):
+    name: str = Field(min_length=1, max_length=64)
+    kind: UnitKind
+    factor: float = Field(gt=0)
 
 
 # ---- Auth / Users ----
@@ -40,19 +56,24 @@ class GroupOut(BaseModel):
     id: int
     name: str
     min_stock: float | None = None
+    min_stock_unit_id: int | None = None
     # angereichert:
     product_count: int = 0
-    stock: float = 0.0
+    stock: float = 0.0            # Bestand in Basiseinheiten
+    min_stock_unit_name: str | None = None
+    kind: str | None = None       # Art der Mindestbestand-Einheit
 
 
 class GroupCreate(BaseModel):
     name: str = Field(min_length=1, max_length=120)
     min_stock: float | None = Field(default=None, ge=0)
+    min_stock_unit_id: int | None = None
 
 
 class GroupUpdate(BaseModel):
     name: str | None = Field(default=None, min_length=1, max_length=120)
     min_stock: float | None = Field(default=None, ge=0)
+    min_stock_unit_id: int | None = None
 
 
 # ---- Locations ----
@@ -75,6 +96,8 @@ class ProductBase(BaseModel):
     brand: str | None = None
     image_url: str | None = None
     base_unit: BaseUnit = BaseUnit.piece
+    # Optionale verwaltete Einheit; setzt base_unit anhand ihrer Art und die Anzeigeeinheit.
+    unit_id: int | None = None
     package_size: float | None = Field(default=None, gt=0)
     group_id: int | None = None
     min_stock: float | None = Field(default=None, ge=0)
@@ -90,6 +113,7 @@ class ProductUpdate(BaseModel):
     brand: str | None = None
     image_url: str | None = None
     base_unit: BaseUnit | None = None
+    unit_id: int | None = None
     package_size: float | None = Field(default=None, gt=0)
     group_id: int | None = None
     min_stock: float | None = Field(default=None, ge=0)
@@ -103,6 +127,7 @@ class ProductOut(BaseModel):
     brand: str | None
     image_url: str | None
     base_unit: BaseUnit
+    display_unit_id: int | None = None
     package_size: float | None
     group_id: int | None
     min_stock: float | None
@@ -111,6 +136,9 @@ class ProductOut(BaseModel):
     # angereichert:
     stock: float = 0.0
     expired_count: int = 0
+    kind: str = ""
+    unit_name: str = ""
+    unit_factor: float = 1.0
 
 
 class LookupResult(BaseModel):
@@ -135,6 +163,8 @@ class CheckOutRequest(BaseModel):
     barcode: str | None = None
     quantity: float = Field(gt=0)
     unit: str
+    # Optional: gezielt aus dieser Charge abbuchen (sonst automatisch FEFO).
+    lot_id: int | None = None
     note: str | None = None
 
 
@@ -148,6 +178,13 @@ class LotOut(BaseModel):
     created_at: datetime
 
 
+class LotUpdate(BaseModel):
+    """Korrektur einer Charge (Vertipper beim Einlagern o.ä.)."""
+    quantity: float | None = Field(default=None, gt=0)
+    best_before: date | None = None
+    location_id: int | None = None
+
+
 class CheckInResponse(BaseModel):
     lot: LotOut
     product_stock: float
@@ -205,6 +242,7 @@ class GroupShoppingItem(BaseModel):
     stock: float
     min_stock: float
     deficit: float
+    unit_name: str = ""
     product_count: int
 
 

backend/app/seed.py

@@ -1,11 +1,30 @@
-"""Erstellt beim ersten Start einen Admin-Benutzer, falls noch keiner existiert."""
+"""Startup-Seeds: erster Admin-Benutzer und die eingebauten Einheiten."""
 
 from sqlalchemy.orm import Session
 
 from .config import get_settings
-from .models import Role, User
+from .models import Role, Unit, UnitKind, User
 from .security import hash_password
 
+# (Name, Art, Faktor zur kanonischen Basiseinheit)
+BUILTIN_UNITS: list[tuple[str, UnitKind, float]] = [
+    ("Stück", UnitKind.count, 1.0),
+    ("Gramm", UnitKind.weight, 1.0),
+    ("Kilogramm", UnitKind.weight, 1000.0),
+    ("Milliliter", UnitKind.volume, 1.0),
+    ("Liter", UnitKind.volume, 1000.0),
+]
+
+
+def ensure_builtin_units(db: Session) -> None:
+    changed = False
+    for name, kind, factor in BUILTIN_UNITS:
+        if not db.query(Unit).filter(Unit.name == name).first():
+            db.add(Unit(name=name, kind=kind, factor=factor, is_builtin=True))
+            changed = True
+    if changed:
+        db.commit()
+
 
 def ensure_first_admin(db: Session) -> None:
     settings = get_settings()

backend/app/services/conversion.py

@@ -0,0 +1,90 @@
+"""Einheiten-Umrechnung auf Basis der verwaltbaren Unit-Tabelle.
+
+Bestände werden immer in der kanonischen Basiseinheit der jeweiligen Art
+gespeichert: Stück (count), Gramm (weight), Milliliter (volume). Verwaltete
+Einheiten (z.B. Kilogramm, Liter, Pfund) rechnen über ihren Faktor dorthin um.
+"""
+
+from __future__ import annotations
+
+from sqlalchemy import func
+from sqlalchemy.orm import Session
+
+from ..models import BaseUnit, Product, Unit, UnitKind
+
+BASE_OF_KIND: dict[UnitKind, BaseUnit] = {
+    UnitKind.count: BaseUnit.piece,
+    UnitKind.weight: BaseUnit.gram,
+    UnitKind.volume: BaseUnit.milliliter,
+}
+KIND_OF_BASE: dict[BaseUnit, UnitKind] = {v: k for k, v in BASE_OF_KIND.items()}
+
+BASE_LABEL: dict[BaseUnit, str] = {
+    BaseUnit.piece: "Stück",
+    BaseUnit.gram: "Gramm",
+    BaseUnit.milliliter: "Milliliter",
+}
+
+PACKAGE_TOKENS = {"package", "packung", "pkg", "pack"}
+
+# Kürzel/Aliase, die direkt auf eingebaute Einheitennamen zeigen.
+_ALIAS = {
+    "g": "gramm", "gram": "gramm", "gramm": "gramm",
+    "kg": "kilogramm", "kilogramm": "kilogramm",
+    "ml": "milliliter", "milliliter": "milliliter",
+    "l": "liter", "liter": "liter",
+    "stück": "stück", "stueck": "stück", "st": "stück", "stk": "stück", "piece": "stück",
+}
+
+
+class ConversionError(ValueError):
+    """Fachlicher Fehler bei der Einheiten-Umrechnung."""
+
+
+def kind_of_product(product: Product) -> UnitKind:
+    return KIND_OF_BASE[product.base_unit]
+
+
+def find_unit(db: Session, token: str) -> Unit | None:
+    t = token.strip().lower()
+    t = _ALIAS.get(t, t)
+    return db.query(Unit).filter(func.lower(Unit.name) == t).first()
+
+
+def to_base(db: Session, product: Product, quantity: float, unit_token: str) -> float:
+    """Rechnet eine Menge (in unit_token) in die Basiseinheit des Produkts um."""
+    if quantity <= 0:
+        raise ConversionError("Menge muss größer als 0 sein")
+
+    t = (unit_token or "").strip().lower()
+    if t in PACKAGE_TOKENS:
+        if not product.package_size or product.package_size <= 0:
+            raise ConversionError(
+                "Für dieses Produkt ist keine Packungsgröße hinterlegt."
+            )
+        return quantity * product.package_size
+
+    unit = find_unit(db, t)
+    if unit is None:
+        raise ConversionError(f"Unbekannte Einheit: {unit_token}")
+    if unit.kind != kind_of_product(product):
+        raise ConversionError(
+            f"Einheit '{unit.name}' passt nicht zur Art des Produkts "
+            f"({BASE_LABEL[product.base_unit]})."
+        )
+    return quantity * unit.factor
+
+
+def resolve_product_unit(db: Session, unit_id: int) -> tuple[BaseUnit, int]:
+    """Ermittelt zu einer gewählten Einheit die kanonische Basiseinheit + Anzeige-ID."""
+    unit = db.get(Unit, unit_id)
+    if unit is None:
+        raise ConversionError("Einheit nicht gefunden")
+    return BASE_OF_KIND[unit.kind], unit.id
+
+
+def display_unit_info(product: Product) -> tuple[str, float]:
+    """Name und Faktor der Anzeigeeinheit des Produkts (Fallback: Basiseinheit)."""
+    if product.display_unit is not None:
+        return product.display_unit.name, product.display_unit.factor
+    return BASE_LABEL[product.base_unit], 1.0

backend/app/services/stock.py

@@ -8,7 +8,7 @@ from sqlalchemy import asc
 from sqlalchemy.orm import Session
 
 from ..models import Lot, Movement, MovementType, Product, User
-from .units import to_base_quantity
+from .conversion import to_base
 
 
 class StockError(ValueError):
@@ -34,7 +34,7 @@ def check_in(
     note: str | None = None,
 ) -> Lot:
     """Legt eine neue Charge an und protokolliert die Bewegung."""
-    quantity_base = to_base_quantity(product, quantity, unit)
+    quantity_base = to_base(db, product, quantity, unit)
 
     lot = Lot(
         product_id=product.id,
@@ -59,6 +59,41 @@ def check_in(
     return lot
 
 
+def check_out_lot(
+    db: Session,
+    product: Product,
+    lot: Lot,
+    quantity: float,
+    unit: str,
+    user: User | None,
+    note: str | None = None,
+) -> list[dict]:
+    """Bucht gezielt von EINER Charge ab (manuelle Auswahl statt FEFO)."""
+    needed = to_base(db, product, quantity, unit)
+    if needed > lot.quantity + 1e-9:
+        raise StockError(
+            f"Diese Charge hat nur {lot.quantity:g} {product.base_unit.value} "
+            f"(benötigt {needed:g})."
+        )
+
+    lot.quantity -= needed
+    db.add(
+        Movement(
+            product_id=product.id,
+            lot_id=lot.id,
+            user_id=user.id if user else None,
+            type=MovementType.out,
+            quantity=needed,
+            unit_used=unit,
+            note=note,
+        )
+    )
+    affected = [{"lot_id": lot.id, "quantity": needed}]
+    if lot.quantity <= 1e-9:
+        db.delete(lot)
+    return affected
+
+
 def _fefo_lots(db: Session, product_id: int) -> list[Lot]:
     """Lots eines Produkts, sortiert nach Ablaufdatum (NULL zuletzt), dann Alter."""
     lots = (
@@ -88,7 +123,7 @@ def check_out(
     Gibt die Liste der betroffenen Chargen mit abgebuchter Menge zurück.
     Wirft StockError, wenn der Gesamtbestand nicht ausreicht.
     """
-    needed = to_base_quantity(product, quantity, unit)
+    needed = to_base(db, product, quantity, unit)
     available = current_stock(db, product.id)
     if needed > available + 1e-9:
         raise StockError(

backend/tests/conftest.py

@@ -5,6 +5,7 @@ from sqlalchemy.pool import StaticPool
 
 from app.database import Base
 from app.models import BaseUnit, Product
+from app.seed import ensure_builtin_units
 
 
 @pytest.fixture()
@@ -17,6 +18,7 @@ def db():
     Base.metadata.create_all(bind=engine)
     TestingSession = sessionmaker(bind=engine, autoflush=False, autocommit=False)
     session = TestingSession()
+    ensure_builtin_units(session)  # Einheiten (Gramm, Kilogramm, …) für Umrechnung
     try:
         yield session
     finally:

backend/tests/test_conversion.py

@@ -0,0 +1,43 @@
+import pytest
+
+from app.models import BaseUnit, Product
+from app.services.conversion import ConversionError, to_base
+
+
+def test_base_unit(db, rice):
+    assert to_base(db, rice, 200, "Gramm") == 200
+    assert to_base(db, rice, 200, "g") == 200  # Kürzel-Alias
+
+
+def test_kilogram_converts_to_grams(db, rice):
+    assert to_base(db, rice, 1, "Kilogramm") == 1000
+    assert to_base(db, rice, 2.5, "kg") == 2500
+
+
+def test_package_uses_package_size(db, rice):
+    # rice: package_size = 500 g
+    assert to_base(db, rice, 3, "package") == 1500
+
+
+def test_wrong_kind_rejected(db, rice):
+    # rice ist ein Gewichts-Produkt -> Volumeneinheit passt nicht
+    with pytest.raises(ConversionError):
+        to_base(db, rice, 1, "Liter")
+
+
+def test_unknown_unit_rejected(db, rice):
+    with pytest.raises(ConversionError):
+        to_base(db, rice, 1, "Eimer")
+
+
+def test_volume_product(db):
+    milk = Product(name="Milch", base_unit=BaseUnit.milliliter, package_size=1000)
+    db.add(milk)
+    db.commit()
+    assert to_base(db, milk, 1, "Liter") == 1000
+    assert to_base(db, milk, 500, "ml") == 500
+
+
+def test_non_positive_quantity_rejected(db, rice):
+    with pytest.raises(ConversionError):
+        to_base(db, rice, 0, "Gramm")

docs/ROADMAP.md

@@ -2,31 +2,52 @@
 
 Selfhostbare Lebensmittel-Lagerverwaltung. Aufbau in mehreren Schritten.
 
-## Schritt 1 – Fundament ✅ (dieser Stand)
-- Backend (FastAPI + PostgreSQL): Datenmodell, Auth mit Rollen, FEFO-Auslagern,
-  Einheiten-Umrechnung, Open-Food-Facts-Lookup mit lokalem Fallback.
+## Schritt 1 – Fundament ✅
+- Backend (FastAPI + PostgreSQL): Datenmodell, Auth mit Rollen (Admin/Benutzer),
+  Chargen mit MHD, FEFO-Auslagern, Open-Food-Facts-Lookup (v0-API) mit lokalem Fallback.
 - Web-UI (React/Vite): Login, Dashboard, Ein-/Auslagern, Produkte, Lagerorte,
-  Benutzerverwaltung, Einkaufsliste – rollenabhängig.
-- Deployment: Docker Compose + `install.sh`, erster Admin beim Setup.
-- Tests: pytest für FEFO-Abbuchung und Einheiten-Umrechnung.
+  Benutzerverwaltung, Einkaufsliste.
+- Deployment: Docker Compose + `install.sh` (Docker-/curl-Autoinstall, Secrets,
+  erster Admin, Health-Check), README.
+- Tests: pytest für FEFO, Einheiten-Umrechnung und OFF-Mengenerkennung.
 
-## Schritt 2 – Native iOS-App (SwiftUI)
+## Schritt 1b – Ausbau Web-UI ✅
+- **Design:** professionelles Layout mit Seitenleiste, eigenes SVG-Icon-Set
+  (bewusst keine Emojis), Light-/Dark-Mode, konsistente Farbcodierung
+  (gelb = Warnfrist, rot = abgelaufen).
+- **Gruppen:** Verwaltung, Zuordnung im Produkt, Gruppen-Mindestbestand **mit Einheit**,
+  Auto-Zuordnungsvorschlag aus der OFF-Kategorie.
+- **Einheiten (verwaltbar):** eigene Tabelle mit Art (Anzahl/Gewicht/Volumen) und
+  Umrechnungsfaktor. Eingebaut: Stück, Gramm, Kilogramm, Milliliter, Liter.
+  Admins können weitere anlegen (z.B. Pfund = 500 g). Gilt für Produkte **und**
+  Gruppen-Mindestbestände; Bestände werden intern in der kanonischen Basiseinheit
+  (Stück/Gramm/Milliliter) gespeichert.
+- **Einlagern:** Drei-Wege-Barcode-Erkennung (bekannt / bei OFF gefunden → inline
+  anlegen / unbekannt), mehrere Chargen je Vorgang mit eigenem MHD,
+  Warnung bei bereits abgelaufenem MHD.
+- **Auslagern:** automatisch per FEFO **oder** gezielte Auswahl einer Charge/MHD,
+  auch Teilmengen.
+- **Chargen bearbeiten:** Menge/MHD korrigieren und Chargen löschen (mit
+  Protokollierung als Korrektur-Bewegung).
+- **Lagerorte:** beliebig tief verschachtelbar (Schrank → Fach → Kiste → …).
+- **Mindestbestände:** je Produkt wahlweise in der Produkteinheit oder in Packungen.
+- **Verlauf:** Bewegungsprotokoll (wer/was/wann), **Einstellungen:** Ablauf-Warnfrist.
+- **Migration:** schonendes Nachziehen neuer Spalten beim Start
+  (`ADD COLUMN IF NOT EXISTS`), damit bestehende Installationen ihre Daten behalten.
+
+## Schritt 2 – Native iOS-App (SwiftUI) – offen
 - Login (Server-URL + Passwort, Token im Keychain).
 - Barcode-Scan (VisionKit / AVFoundation).
-- Einlagern-Flow: scannen → Lookup/Vorbefüllung → Menge + Einheit + MHD → speichern.
-- Auslagern-Flow: scannen → Menge/Einheit (ganz oder Teilmenge g/l) → FEFO.
+- Einlagern-Flow: scannen → Lookup/Vorbefüllung → Menge + Einheit + MHD (mehrere Chargen).
+- Auslagern-Flow: scannen → Menge/Einheit, FEFO oder Chargenauswahl.
 - Einkaufsliste- und „bald ablaufend“-Ansicht.
-- Optional: unbekannte Produkte direkt in der App anlegen.
+- Produkte bei Bedarf direkt in der App anlegen.
 
-## Schritt 3 – Fortgeschrittene Features
-- **Gruppen-Intelligenz:** Produkt beim Einlagern automatisch einer Gruppe zuordnen
-  (Ableitung aus OFF-Kategorie), manuell korrigierbar.
-- **Mindestbestände auf Gruppen** (z. B. „Nudeln“ gesamt), nicht nur einzelne Produkte.
-  (DB-Spalte `groups.min_stock` ist bereits vorbereitet.)
-- **Unterlagerorte** (Regal xy / Fach xy). (DB-Spalte `locations.parent_id` vorbereitet.)
-- **Einheiten-Umwandlung nachträglich** (Packung ↔ g/l) komfortabel in Web + App.
-- **Ablauf-Push-Benachrichtigungen** via APNs.
-- **Produktbilder** aus OFF anzeigen (Web + App) + lokaler Bild-Cache.
-- **Einkaufsliste verfeinern:** Mengenvorschläge, manuelle Ergänzungen, Abhaken/Erledigen.
-- **Bewegungsverlauf/Statistik** (wer/was wann ein-/ausgelagert) – Tabelle `movements`
-  wird bereits befüllt, es fehlt nur die Ansicht.
+## Schritt 3 – Weitere Ideen – offen
+- **Ablauf-Push-Benachrichtigungen** via APNs (setzt die App voraus).
+- **Einkaufsliste verfeinern:** Abhaken dauerhaft speichern, manuelle Einträge,
+  Mengenvorschläge in Packungen.
+- **Statistik/Auswertung** über den Bewegungsverlauf (Verbrauch pro Zeitraum).
+- **Lagerort beim Auslagern** berücksichtigen bzw. pro Charge wählbar beim Einlagern.
+- **Produktbilder lokal cachen** (aktuell direkt von Open Food Facts geladen).
+- **Alembic-Migrationen** statt `create_all` + Startup-ALTER, sobald das Schema stabil ist.

web/src/App.jsx

@@ -9,6 +9,7 @@ import CheckIn from "./pages/CheckIn";
 import CheckOut from "./pages/CheckOut";
 import Groups from "./pages/Groups";
 import Locations from "./pages/Locations";
+import Units from "./pages/Units";
 import Users from "./pages/Users";
 import ShoppingList from "./pages/ShoppingList";
 import History from "./pages/History";
@@ -52,6 +53,7 @@ function Sidebar() {
           <>
             <div className="nav-section">Verwaltung</div>
             <NavItem to="/locations" icon="location" label="Lagerorte" />
+            <NavItem to="/units" icon="box" label="Einheiten" />
             <NavItem to="/users" icon="users" label="Benutzer" />
             <NavItem to="/settings" icon="settings" label="Einstellungen" />
           </>
@@ -104,6 +106,7 @@ export default function App() {
       <Route path="/shopping" element={<Protected><ShoppingList /></Protected>} />
       <Route path="/history" element={<Protected><History /></Protected>} />
       <Route path="/locations" element={<Protected adminOnly><Locations /></Protected>} />
+      <Route path="/units" element={<Protected adminOnly><Units /></Protected>} />
       <Route path="/users" element={<Protected adminOnly><Users /></Protected>} />
       <Route path="/settings" element={<Protected adminOnly><Settings /></Protected>} />
       <Route path="*" element={<Navigate to="/" replace />} />

web/src/api.js

@@ -88,6 +88,8 @@ export const api = {
   checkOut: (body) => request("/stock/checkout", { method: "POST", body }),
   listLots: (productId) =>
     request(`/lots${productId ? `?product_id=${productId}` : ""}`),
+  updateLot: (id, body) => request(`/lots/${id}`, { method: "PATCH", body }),
+  deleteLot: (id) => request(`/lots/${id}`, { method: "DELETE" }),
 
   // Views
   shoppingList: () => request("/shopping-list"),
@@ -105,6 +107,10 @@ export const api = {
   updateGroup: (id, body) => request(`/groups/${id}`, { method: "PATCH", body }),
   deleteGroup: (id) => request(`/groups/${id}`, { method: "DELETE" }),
 
+  listUnits: () => request("/units"),
+  createUnit: (body) => request("/units", { method: "POST", body }),
+  deleteUnit: (id) => request(`/units/${id}`, { method: "DELETE" }),
+
   // Benutzer
   listUsers: () => request("/users"),
   createUser: (body) => request("/users", { method: "POST", body }),

web/src/pages/CheckIn.jsx

@@ -4,7 +4,7 @@ import { api } from "../api";
 import { useAuth } from "../auth";
 import Icon from "../components/Icon";
 import { guessGroup, suggestionToProduct } from "../offUtils";
-import { fmt, isExpired, unitOptions, unitShort } from "../units";
+import { buildUnitOptions, fmt, isExpired } from "../units";
 
 const emptyLine = () => ({ quantity: "", best_before: "" });
 
@@ -18,6 +18,7 @@ export default function CheckIn() {
   const [search, setSearch] = useState("");
   const [locations, setLocations] = useState([]);
   const [groups, setGroups] = useState([]);
+  const [units, setUnits] = useState([]);
 
   const [unit, setUnit] = useState("");
   const [locationId, setLocationId] = useState("");
@@ -30,6 +31,7 @@ export default function CheckIn() {
   useEffect(() => {
     api.listLocations().then(setLocations).catch(() => {});
     api.listGroups().then(setGroups).catch(() => {});
+    api.listUnits().then(setUnits).catch(() => {});
   }, []);
 
   function resetLookup() {
@@ -41,7 +43,8 @@ export default function CheckIn() {
     setProduct(p);
     setResults([]);
     resetLookup();
-    setUnit(unitOptions(p)[0].value);
+    const opts = buildUnitOptions(p, units);
+    setUnit(p.unit_name || (opts[0] && opts[0].value) || "");
     setLines([emptyLine()]);
     setLocationId("");
   }
@@ -118,7 +121,7 @@ export default function CheckIn() {
       const res = await api.checkInBatch({ product_id: product.id, unit, lines: payloadLines });
       setInfo(
         `${payloadLines.length} Charge(n) eingelagert. Neuer Bestand: ` +
-          `${fmt(res.product_stock)} ${unitShort(product.base_unit)}`
+          `${fmt(res.product_stock / (product.unit_factor || 1))} ${product.unit_name}`
       );
       setLines([emptyLine()]);
       setProduct(await api.getProduct(product.id));
@@ -197,7 +200,7 @@ export default function CheckIn() {
               {results.map((p) => (
                 <li key={p.id}>
                   <button className="link-btn" onClick={() => selectProduct(p)}>
-                    {p.name} <span className="muted">({fmt(p.stock)} {unitShort(p.base_unit)})</span>
+                    {p.name} <span className="muted">({fmt(p.stock / (p.unit_factor || 1))} {p.unit_name})</span>
                   </button>
                 </li>
               ))}
@@ -214,7 +217,7 @@ export default function CheckIn() {
               : <span className="thumb thumb-fallback"><Icon name="box" size={16} /></span>}
             <div className="info">
               <div className="title">{product.name}</div>
-              <div className="muted small">Bestand: {fmt(product.stock)} {unitShort(product.base_unit)}</div>
+              <div className="muted small">Bestand: {fmt(product.stock / (product.unit_factor || 1))} {product.unit_name}</div>
             </div>
             <button type="button" className="btn ghost" onClick={() => setProduct(null)}>Ändern</button>
           </div>
@@ -223,7 +226,7 @@ export default function CheckIn() {
             <label className="grow">
               Einheit
               <select value={unit} onChange={(e) => setUnit(e.target.value)}>
-                {unitOptions(product).map((o) => <option key={o.value} value={o.value}>{o.label}</option>)}
+                {buildUnitOptions(product, units).map((o) => <option key={o.value} value={o.value}>{o.label}</option>)}
               </select>
             </label>
             <label className="grow">
@@ -274,7 +277,7 @@ export default function CheckIn() {
             </button>
             {totalQty > 0 && (
               <span className="muted small">Summe: {fmt(totalQty)} {
-                unitOptions(product).find((o) => o.value === unit)?.label || ""
+                buildUnitOptions(product, units).find((o) => o.value === unit)?.label || ""
               }</span>
             )}
           </div>

web/src/pages/CheckOut.jsx

@@ -1,25 +1,38 @@
-import { useState } from "react";
+import { useEffect, useState } from "react";
 import { api } from "../api";
 import Icon from "../components/Icon";
-import { fmt, unitOptions, unitShort } from "../units";
+import { buildUnitOptions, fmt, isExpired, unitShort } from "../units";
 
 export default function CheckOut() {
   const [barcode, setBarcode] = useState("");
   const [search, setSearch] = useState("");
   const [results, setResults] = useState([]);
   const [product, setProduct] = useState(null);
+  const [units, setUnits] = useState([]);
+  const [lots, setLots] = useState([]);
 
   const [quantity, setQuantity] = useState("");
   const [unit, setUnit] = useState("");
+  const [lotId, setLotId] = useState(""); // "" = automatisch (FEFO)
 
   const [error, setError] = useState(null);
   const [info, setInfo] = useState(null);
   const [busy, setBusy] = useState(false);
 
-  function selectProduct(p) {
+  useEffect(() => {
+    api.listUnits().then(setUnits).catch(() => {});
+  }, []);
+
+  async function selectProduct(p) {
     setProduct(p);
     setResults([]);
-    setUnit(unitOptions(p)[0].value);
+    setLotId("");
+    setQuantity("");
+    const opts = buildUnitOptions(p, units);
+    setUnit(p.unit_name || (opts[0] && opts[0].value) || "");
+    try {
+      setLots(await api.listLots(p.id));
+    } catch { setLots([]); }
   }
 
   async function doLookup() {
@@ -28,7 +41,7 @@ export default function CheckOut() {
     try {
       const res = await api.lookup(barcode.trim());
       if (res.found && res.existing_product) {
-        selectProduct(res.existing_product);
+        await selectProduct(res.existing_product);
       } else {
         setError("Kein bekanntes Produkt zu diesem Barcode im Lager.");
       }
@@ -54,10 +67,17 @@ export default function CheckOut() {
         product_id: product.id,
         quantity: Number(quantity),
         unit,
+        lot_id: lotId === "" ? null : Number(lotId),
       });
-      setInfo(`Ausgelagert (${res.affected_lots.length} Charge(n)). Neuer Bestand: ${fmt(res.product_stock)} ${unitShort(product.base_unit)}`);
+      setInfo(
+        `Ausgelagert (${res.affected_lots.length} Charge(n)). Neuer Bestand: ` +
+          `${fmt(res.product_stock / (product.unit_factor || 1))} ${product.unit_name}`
+      );
       setQuantity("");
-      setProduct(await api.getProduct(product.id));
+      const fresh = await api.getProduct(product.id);
+      setProduct(fresh);
+      setLots(await api.listLots(fresh.id));
+      setLotId("");
     } catch (err) {
       setError(err.message);
     } finally {
@@ -65,6 +85,10 @@ export default function CheckOut() {
     }
   }
 
+  const unitOpts = product ? buildUnitOptions(product, units) : [];
+  const selectedLot = lots.find((l) => String(l.id) === String(lotId)) || null;
+  const baseShort = product ? unitShort(product.base_unit) : "";
+
   return (
     <div>
       <div className="page-head"><h1>Auslagern</h1></div>
@@ -96,7 +120,7 @@ export default function CheckOut() {
               {results.map((p) => (
                 <li key={p.id}>
                   <button className="link-btn" onClick={() => selectProduct(p)}>
-                    {p.name} <span className="muted">({fmt(p.stock)} {unitShort(p.base_unit)})</span>
+                    {p.name} <span className="muted">({fmt(p.stock / (p.unit_factor || 1))} {p.unit_name})</span>
                   </button>
                 </li>
               ))}
@@ -113,11 +137,35 @@ export default function CheckOut() {
               : <span className="thumb thumb-fallback"><Icon name="box" size={16} /></span>}
             <div className="info">
               <div className="title">{product.name}</div>
-              <div className="muted small">Verfügbar: {fmt(product.stock)} {unitShort(product.base_unit)}</div>
+              <div className="muted small">
+                Verfügbar: {fmt(product.stock / (product.unit_factor || 1))} {product.unit_name}
+              </div>
             </div>
             <button type="button" className="btn ghost" onClick={() => setProduct(null)}>Ändern</button>
           </div>
 
+          <label>
+            Charge
+            <select value={lotId} onChange={(e) => setLotId(e.target.value)}>
+              <option value="">Automatisch – zuerst ablaufende zuerst (FEFO)</option>
+              {lots.map((l) => (
+                <option key={l.id} value={l.id}>
+                  {l.best_before ? `MHD ${l.best_before}` : "ohne MHD"} · {fmt(l.quantity)} {baseShort}
+                  {isExpired(l.best_before) ? " · abgelaufen" : ""}
+                </option>
+              ))}
+            </select>
+          </label>
+
+          {selectedLot && (
+            <div className={`alert ${isExpired(selectedLot.best_before) ? "error" : "info"}`}>
+              <Icon name="alert" size={16} />
+              Gewählte Charge: {fmt(selectedLot.quantity)} {baseShort}
+              {selectedLot.best_before ? ` · MHD ${selectedLot.best_before}` : " · ohne MHD"}
+              {isExpired(selectedLot.best_before) ? " (abgelaufen)" : ""}
+            </div>
+          )}
+
           <div className="row">
             <label className="grow">
               Menge
@@ -127,14 +175,19 @@ export default function CheckOut() {
             <label className="grow">
               Einheit
               <select value={unit} onChange={(e) => setUnit(e.target.value)}>
-                {unitOptions(product).map((o) => <option key={o.value} value={o.value}>{o.label}</option>)}
+                {unitOpts.map((o) => <option key={o.value} value={o.value}>{o.label}</option>)}
               </select>
             </label>
           </div>
-          <p className="muted small mt-0">
-            Es wird automatisch die zuerst ablaufende Charge zuerst entnommen (FEFO).
-          </p>
-          <button className="btn primary" disabled={busy}><Icon name="checkout" size={16} />{busy ? "…" : "Auslagern"}</button>
+
+          {!selectedLot && (
+            <p className="muted small mt-0">
+              Ohne Auswahl wird automatisch die zuerst ablaufende Charge zuerst entnommen (FEFO).
+            </p>
+          )}
+          <button className="btn primary" disabled={busy}>
+            <Icon name="checkout" size={16} />{busy ? "…" : "Auslagern"}
+          </button>
         </form>
       )}
     </div>

web/src/pages/Dashboard.jsx

@@ -114,8 +114,8 @@ export default function Dashboard() {
                   {groupShopping.map((it) => (
                     <tr key={`g${it.group_id}`}>
                       <td><span className="badge accent">Gruppe</span> {it.name}</td>
-                      <td className="num">{fmt(it.stock)}</td>
-                      <td className="num strong">{fmt(it.deficit)}</td>
+                      <td className="num">{fmt(it.stock)} {it.unit_name}</td>
+                      <td className="num strong">{fmt(it.deficit)} {it.unit_name}</td>
                     </tr>
                   ))}
                   {shopping.map((it) => (

web/src/pages/Groups.jsx

@@ -7,13 +7,15 @@ import { fmt } from "../units";
 export default function Groups() {
   const { isAdmin } = useAuth();
   const [groups, setGroups] = useState([]);
-  const [name, setName] = useState("");
-  const [minStock, setMinStock] = useState("");
+  const [units, setUnits] = useState([]);
+  const [form, setForm] = useState({ name: "", min_stock: "", min_stock_unit_id: "" });
   const [error, setError] = useState(null);
 
   async function load() {
     try {
-      setGroups(await api.listGroups());
+      const [gs, us] = await Promise.all([api.listGroups(), api.listUnits()]);
+      setGroups(gs);
+      setUnits(us);
     } catch (err) {
       setError(err.message);
     }
@@ -25,18 +27,21 @@ export default function Groups() {
     e.preventDefault();
     setError(null);
     try {
-      await api.createGroup({ name, min_stock: minStock === "" ? null : Number(minStock) });
-      setName("");
-      setMinStock("");
+      await api.createGroup({
+        name: form.name,
+        min_stock: form.min_stock === "" ? null : Number(form.min_stock),
+        min_stock_unit_id: form.min_stock_unit_id === "" ? null : Number(form.min_stock_unit_id),
+      });
+      setForm({ name: "", min_stock: "", min_stock_unit_id: form.min_stock_unit_id });
       load();
     } catch (err) {
       setError(err.message);
     }
   }
 
-  async function saveMin(group, value) {
+  async function patch(group, body) {
     try {
-      await api.updateGroup(group.id, { min_stock: value === "" ? null : Number(value) });
+      await api.updateGroup(group.id, body);
       load();
     } catch (err) {
       setError(err.message);
@@ -58,7 +63,7 @@ export default function Groups() {
       <div className="page-head">
         <div>
           <h1>Gruppen</h1>
-          <div className="sub">Fasse Produkte zusammen (z.B. Nudeln, Mehl) und setze einen Gruppen-Mindestbestand</div>
+          <div className="sub">Produkte zusammenfassen (z.B. Nudeln) und einen Gruppen-Mindestbestand mit Einheit setzen</div>
         </div>
       </div>
       {error && <div className="alert error"><Icon name="alert" size={16} />{error}</div>}
@@ -68,7 +73,14 @@ export default function Groups() {
           <div className="table-wrap">
             <table className="table">
               <thead>
-                <tr><th>Gruppe</th><th className="num">Produkte</th><th className="num">Bestand</th><th>Mindestbestand</th><th></th></tr>
+                <tr>
+                  <th>Gruppe</th>
+                  <th className="num">Produkte</th>
+                  <th className="num">Bestand</th>
+                  <th>Mindestbestand</th>
+                  <th>Einheit</th>
+                  <th></th>
+                </tr>
               </thead>
               <tbody>
                 {groups.map((g) => {
@@ -80,17 +92,30 @@ export default function Groups() {
                         {low && <span className="badge warn" style={{ marginLeft: 6 }}>niedrig</span>}
                       </td>
                       <td className="num muted">{g.product_count}</td>
-                      <td className="num">{fmt(g.stock)}</td>
+                      <td className="num">{fmt(g.stock)} {g.min_stock_unit_name || ""}</td>
                       <td>
                         {isAdmin ? (
                           <input type="number" step="any" defaultValue={g.min_stock ?? ""}
-                            style={{ maxWidth: 110, marginTop: 0 }}
+                            style={{ maxWidth: 100, marginTop: 0 }}
                             onBlur={(e) => {
                               const v = e.target.value;
-                              if (v !== String(g.min_stock ?? "")) saveMin(g, v);
+                              if (v !== String(g.min_stock ?? "")) {
+                                patch(g, { min_stock: v === "" ? null : Number(v) });
+                              }
                             }} />
                         ) : (g.min_stock != null ? fmt(g.min_stock) : "–")}
                       </td>
+                      <td>
+                        {isAdmin ? (
+                          <select value={g.min_stock_unit_id ?? ""} style={{ maxWidth: 140, marginTop: 0 }}
+                            onChange={(e) => patch(g, {
+                              min_stock_unit_id: e.target.value === "" ? null : Number(e.target.value),
+                            })}>
+                            <option value="">– Basiseinheit –</option>
+                            {units.map((u) => <option key={u.id} value={u.id}>{u.name}</option>)}
+                          </select>
+                        ) : (g.min_stock_unit_name || "–")}
+                      </td>
                       <td className="num">
                         {isAdmin && (
                           <button className="btn-icon danger" onClick={() => remove(g)} title="Löschen">
@@ -101,7 +126,7 @@ export default function Groups() {
                     </tr>
                   );
                 })}
-                {groups.length === 0 && <tr><td colSpan={5} className="empty">Noch keine Gruppen.</td></tr>}
+                {groups.length === 0 && <tr><td colSpan={6} className="empty">Noch keine Gruppen.</td></tr>}
               </tbody>
             </table>
           </div>
@@ -112,18 +137,27 @@ export default function Groups() {
             <div className="card-head"><Icon name="tag" /><h2>Neue Gruppe</h2></div>
             <label>
               Name
-              <input placeholder="z.B. Nudeln" value={name} onChange={(e) => setName(e.target.value)} required />
-            </label>
-            <label>
-              Mindestbestand (optional)
-              <input type="number" step="any" value={minStock} onChange={(e) => setMinStock(e.target.value)}
-                placeholder="Gesamtmenge über alle Produkte der Gruppe" />
+              <input placeholder="z.B. Nudeln" value={form.name} onChange={(e) => setForm({ ...form, name: e.target.value })} required />
             </label>
+            <div className="row">
+              <label className="grow">
+                Mindestbestand (optional)
+                <input type="number" step="any" value={form.min_stock}
+                  onChange={(e) => setForm({ ...form, min_stock: e.target.value })} placeholder="z.B. 2" />
+              </label>
+              <label className="grow">
+                Einheit
+                <select value={form.min_stock_unit_id}
+                  onChange={(e) => setForm({ ...form, min_stock_unit_id: e.target.value })}>
+                  <option value="">– Basiseinheit –</option>
+                  {units.map((u) => <option key={u.id} value={u.id}>{u.name}</option>)}
+                </select>
+              </label>
+            </div>
             <button className="btn primary"><Icon name="plus" size={16} />Anlegen</button>
             <p className="muted small">
-              Produkte ordnest du einer Gruppe im jeweiligen Produkt-Formular zu.
-              Der Gruppen-Bestand ist die Summe der Produktbestände – sinnvoll, wenn
-              die Produkte dieselbe Basiseinheit haben.
+              Der Gruppen-Bestand summiert nur Produkte, die zur gewählten Einheit passen
+              (Gewicht/Volumen/Stück). Produkte ordnest du im Produkt-Formular einer Gruppe zu.
             </p>
           </form>
         )}

web/src/pages/ProductForm.jsx

@@ -4,13 +4,16 @@ import { api } from "../api";
 import { useAuth } from "../auth";
 import Icon from "../components/Icon";
 import { guessGroup } from "../offUtils";
-import { BASE_UNITS, daysUntil, expiryRowClass, fmt, isExpired, unitShort } from "../units";
+import { daysUntil, expiryRowClass, fmt, isExpired, unitShort } from "../units";
 
 const EMPTY = {
   barcode: "", name: "", brand: "", image_url: "",
-  base_unit: "piece", package_size: "", min_stock: "", group_id: "",
+  unit_id: "", package_size: "", min_stock: "", group_id: "",
 };
 
+// Kanonische Einheit je Basiseinheit (für OFF-Vorschläge und Altbestand).
+const CANONICAL_NAME = { piece: "Stück", gram: "Gramm", milliliter: "Milliliter" };
+
 export default function ProductForm() {
   const { id } = useParams();
   const isNew = !id;
@@ -22,28 +25,45 @@ export default function ProductForm() {
   const [product, setProduct] = useState(null);
   const [lots, setLots] = useState([]);
   const [groups, setGroups] = useState([]);
+  const [units, setUnits] = useState([]);
   const [error, setError] = useState(null);
   const [info, setInfo] = useState(null);
   const [busy, setBusy] = useState(false);
-  // Einheit, in der der Mindestbestand eingegeben wird: "base" oder "package".
-  const [minUnit, setMinUnit] = useState("base");
+  // Einheit für die Mindestbestand-Eingabe: "unit" (gewählte Einheit) oder "package".
+  const [minUnit, setMinUnit] = useState("unit");
   const [warnDays, setWarnDays] = useState(7);
 
+  const selectedUnit = units.find((u) => String(u.id) === String(form.unit_id)) || null;
+  const unitFactor = selectedUnit ? selectedUnit.factor : 1;
+  const unitName = selectedUnit ? selectedUnit.name : "";
+
   function set(k, v) {
     setForm((f) => ({ ...f, [k]: v }));
   }
 
-  // Wechselt die Mindestbestand-Einheit und rechnet den angezeigten Wert um.
+  function canonicalUnitId(unitList, baseUnit) {
+    const name = CANONICAL_NAME[baseUnit];
+    const hit = unitList.find((u) => u.name === name);
+    return hit ? String(hit.id) : "";
+  }
+
+  // Faktor, mit dem der angezeigte Mindestbestand in Basiseinheiten umgerechnet wird.
+  function minFactor(mode, pkgSize, uFactor) {
+    if (mode === "package") return Number(pkgSize) > 0 ? Number(pkgSize) : 1;
+    return uFactor || 1;
+  }
+
   function changeMinUnit(newUnit) {
-    const ps = Number(form.package_size);
-    if (form.min_stock !== "" && ps > 0 && newUnit !== minUnit) {
-      const v = Number(form.min_stock);
-      set("min_stock", String(newUnit === "package" ? v / ps : v * ps));
+    if (form.min_stock !== "" && newUnit !== minUnit) {
+      const oldF = minFactor(minUnit, form.package_size, unitFactor);
+      const newF = minFactor(newUnit, form.package_size, unitFactor);
+      const base = Number(form.min_stock) * oldF;
+      set("min_stock", String(base / newF));
     }
     setMinUnit(newUnit);
   }
 
-  function applySuggestion(s, groupsList) {
+  function applySuggestion(s, groupsList, unitList) {
     const groupGuess = guessGroup(groupsList, s);
     setForm((f) => ({
       ...f,
@@ -51,7 +71,7 @@ export default function ProductForm() {
       name: s.name || f.name,
       brand: s.brand || f.brand,
       image_url: s.image_url || f.image_url,
-      base_unit: s.base_unit || f.base_unit,
+      unit_id: f.unit_id || canonicalUnitId(unitList, s.base_unit || "piece"),
       package_size: s.package_size != null ? String(s.package_size) : f.package_size,
       group_id: f.group_id || groupGuess,
     }));
@@ -63,7 +83,7 @@ export default function ProductForm() {
     );
   }
 
-  async function runLookup(code, groupsList) {
+  async function runLookup(code, groupsList, unitList) {
     if (!code) return;
     setError(null);
     setInfo(null);
@@ -73,7 +93,7 @@ export default function ProductForm() {
         setInfo("Dieses Produkt existiert bereits.");
         navigate(`/products/${res.existing_product.id}`);
       } else if (res.found && res.suggestion) {
-        applySuggestion(res.suggestion, groupsList);
+        applySuggestion(res.suggestion, groupsList, unitList);
       } else {
         setInfo("Barcode unbekannt – bitte Daten selbst eingeben.");
       }
@@ -85,29 +105,30 @@ export default function ProductForm() {
   useEffect(() => {
     async function load() {
       try {
-        const gs = await api.listGroups();
+        const [gs, us] = await Promise.all([api.listGroups(), api.listUnits()]);
         setGroups(gs);
+        setUnits(us);
         try {
           const s = await api.listSettings();
           const row = s.find((x) => x.key === "expiry_warning_days");
           if (row) setWarnDays(parseInt(row.value, 10) || 7);
-        } catch { /* Einstellungen optional */ }
+        } catch { /* optional */ }
+
         if (!isNew) {
           const p = await api.getProduct(id);
           setProduct(p);
-          // Mindestbestand ist in Basiseinheiten gespeichert; bei Packungsprodukten
-          // zeigen wir ihn zur besseren Verständlichkeit in Packungen an.
-          let minDisplay = p.min_stock ?? "";
-          if (p.min_stock != null && p.package_size && p.package_size > 0) {
-            minDisplay = p.min_stock / p.package_size;
-            setMinUnit("package");
-          } else {
-            setMinUnit("base");
-          }
+          const uid = p.display_unit_id
+            ? String(p.display_unit_id)
+            : canonicalUnitId(us, p.base_unit);
+          const uf = us.find((u) => String(u.id) === uid)?.factor || 1;
+          const mode = p.package_size && p.package_size > 0 ? "package" : "unit";
+          const f = mode === "package" ? p.package_size : uf;
+          setMinUnit(mode);
           setForm({
             barcode: p.barcode || "", name: p.name, brand: p.brand || "",
-            image_url: p.image_url || "", base_unit: p.base_unit,
-            package_size: p.package_size ?? "", min_stock: minDisplay,
+            image_url: p.image_url || "", unit_id: uid,
+            package_size: p.package_size ?? "",
+            min_stock: p.min_stock != null ? p.min_stock / f : "",
             group_id: p.group_id ?? "",
           });
           setLots(await api.listLots(id));
@@ -115,7 +136,7 @@ export default function ProductForm() {
           const bc = searchParams.get("barcode");
           if (bc) {
             set("barcode", bc);
-            await runLookup(bc, gs);
+            await runLookup(bc, gs, us);
           }
         }
       } catch (err) {
@@ -127,18 +148,16 @@ export default function ProductForm() {
   }, [id]);
 
   function buildPayload() {
-    const ps = Number(form.package_size);
     let minBase = null;
     if (form.min_stock !== "") {
-      const v = Number(form.min_stock);
-      minBase = minUnit === "package" && ps > 0 ? v * ps : v;
+      minBase = Number(form.min_stock) * minFactor(minUnit, form.package_size, unitFactor);
     }
     return {
       barcode: form.barcode || null,
       name: form.name,
       brand: form.brand || null,
       image_url: form.image_url || null,
-      base_unit: form.base_unit,
+      unit_id: form.unit_id === "" ? null : Number(form.unit_id),
       package_size: form.package_size === "" ? null : Number(form.package_size),
       min_stock: minBase,
       group_id: form.group_id === "" ? null : Number(form.group_id),
@@ -157,6 +176,7 @@ export default function ProductForm() {
         await api.updateProduct(id, buildPayload());
         setInfo("Gespeichert.");
         setProduct(await api.getProduct(id));
+        setLots(await api.listLots(id));
       }
     } catch (err) {
       setError(err.message);
@@ -176,14 +196,18 @@ export default function ProductForm() {
   }
 
   const readOnly = !isAdmin;
-  const unitLabel = unitShort(form.base_unit);
+  const baseShort = product ? unitShort(product.base_unit) : "";
 
   return (
     <div>
       <div className="page-head">
         <div>
           <h1>{isNew ? "Neues Produkt" : form.name || "Produkt"}</h1>
-          {!isNew && <div className="sub">Bestand: {fmt(product?.stock)} {unitLabel}</div>}
+          {!isNew && product && (
+            <div className="sub">
+              Bestand: {fmt(product.stock / (product.unit_factor || 1))} {product.unit_name}
+            </div>
+          )}
         </div>
         <button className="btn ghost" onClick={() => navigate(-1)}>Zurück</button>
       </div>
@@ -199,7 +223,7 @@ export default function ProductForm() {
               <input value={form.barcode} onChange={(e) => set("barcode", e.target.value)} disabled={readOnly} />
             </label>
             {isAdmin && (
-              <button type="button" className="btn" onClick={() => runLookup(form.barcode, groups)}>
+              <button type="button" className="btn" onClick={() => runLookup(form.barcode, groups, units)}>
                 <Icon name="search" size={16} />Nachschlagen
               </button>
             )}
@@ -214,16 +238,16 @@ export default function ProductForm() {
           </label>
           <div className="row">
             <label className="grow">
-              Basiseinheit
-              <select value={form.base_unit} onChange={(e) => set("base_unit", e.target.value)} disabled={readOnly}>
-                {BASE_UNITS.map((u) => <option key={u.value} value={u.value}>{u.label}</option>)}
+              Einheit
+              <select value={form.unit_id} onChange={(e) => set("unit_id", e.target.value)} disabled={readOnly} required>
+                <option value="">– wählen –</option>
+                {units.map((u) => <option key={u.id} value={u.id}>{u.name}</option>)}
               </select>
             </label>
             <label className="grow">
-              Packungsgröße{unitLabel !== "Stk" ? ` (in ${unitLabel})` : ""}
+              Packungsgröße{baseShort ? ` (in ${baseShort})` : ""}
               <input type="number" step="any" value={form.package_size}
-                onChange={(e) => set("package_size", e.target.value)} disabled={readOnly}
-                placeholder="z.B. 500" />
+                onChange={(e) => set("package_size", e.target.value)} disabled={readOnly} placeholder="z.B. 500" />
             </label>
           </div>
           <div className="row">
@@ -231,11 +255,10 @@ export default function ProductForm() {
               Mindestbestand
               <div className="field-inline">
                 <input type="number" step="any" value={form.min_stock}
-                  onChange={(e) => set("min_stock", e.target.value)} disabled={readOnly}
-                  placeholder="z.B. 2" />
+                  onChange={(e) => set("min_stock", e.target.value)} disabled={readOnly} placeholder="z.B. 2" />
                 <select value={minUnit} onChange={(e) => changeMinUnit(e.target.value)}
-                  disabled={readOnly} style={{ maxWidth: 140, marginTop: 0 }}>
-                  <option value="base">{unitShort(form.base_unit)}</option>
+                  disabled={readOnly} style={{ maxWidth: 150, marginTop: 0 }}>
+                  <option value="unit">{unitName || "Einheit"}</option>
                   {form.package_size && <option value="package">Packung(en)</option>}
                 </select>
               </div>
@@ -263,40 +286,127 @@ export default function ProductForm() {
         </form>
 
         {!isNew && (
-          <section className="card">
-            <div className="card-head"><Icon name="box" /><h2>Chargen im Bestand</h2></div>
-            {lots.some((l) => isExpired(l.best_before)) && (
-              <div className="alert error"><Icon name="alert" size={16} />
-                Dieses Produkt hat abgelaufene Chargen im Bestand.
-              </div>
-            )}
-            {form.image_url && <img className="product-img" src={form.image_url} alt="" />}
-            <div className="table-wrap">
-              <table className="table">
-                <thead><tr><th className="num">Menge</th><th>MHD</th><th>Eingelagert</th></tr></thead>
-                <tbody>
-                  {lots.map((l) => {
-                    const cls = expiryRowClass(l.best_before, warnDays);
-                    const dLeft = daysUntil(l.best_before);
-                    return (
-                      <tr key={l.id} className={cls}>
-                        <td className="num">{fmt(l.quantity)} {unitLabel}</td>
-                        <td>
-                          {l.best_before || "–"}
-                          {cls === "row-danger" && <span className="badge danger" style={{ marginLeft: 6 }}>abgelaufen</span>}
-                          {cls === "row-warn" && <span className="badge warn" style={{ marginLeft: 6 }}>{dLeft}d</span>}
-                        </td>
-                        <td className="muted">{new Date(l.created_at).toLocaleDateString("de-DE")}</td>
-                      </tr>
-                    );
-                  })}
-                  {lots.length === 0 && <tr><td colSpan={3} className="empty">Keine Chargen im Bestand.</td></tr>}
-                </tbody>
-              </table>
-            </div>
-          </section>
+          <LotsCard
+            productId={id}
+            lots={lots}
+            baseShort={baseShort}
+            warnDays={warnDays}
+            isAdmin={isAdmin}
+            imageUrl={form.image_url}
+            onChanged={async () => {
+              setLots(await api.listLots(id));
+              setProduct(await api.getProduct(id));
+            }}
+            onError={setError}
+          />
         )}
       </div>
     </div>
   );
 }
+
+/** Chargen-Karte mit Bearbeiten/Löschen. */
+function LotsCard({ productId, lots, baseShort, warnDays, isAdmin, imageUrl, onChanged, onError }) {
+  const [editId, setEditId] = useState(null);
+  const [draft, setDraft] = useState({ quantity: "", best_before: "" });
+
+  function startEdit(l) {
+    setEditId(l.id);
+    setDraft({ quantity: l.quantity, best_before: l.best_before || "" });
+  }
+
+  async function saveEdit(l) {
+    try {
+      await api.updateLot(l.id, {
+        quantity: Number(draft.quantity),
+        best_before: draft.best_before || null,
+      });
+      setEditId(null);
+      await onChanged();
+    } catch (err) {
+      onError(err.message);
+    }
+  }
+
+  async function removeLot(l) {
+    if (!confirm("Charge wirklich löschen?")) return;
+    try {
+      await api.deleteLot(l.id);
+      await onChanged();
+    } catch (err) {
+      onError(err.message);
+    }
+  }
+
+  return (
+    <section className="card">
+      <div className="card-head"><Icon name="box" /><h2>Chargen im Bestand</h2></div>
+      {lots.some((l) => isExpired(l.best_before)) && (
+        <div className="alert error"><Icon name="alert" size={16} />
+          Dieses Produkt hat abgelaufene Chargen im Bestand.
+        </div>
+      )}
+      {imageUrl && <img className="product-img" src={imageUrl} alt="" />}
+      <div className="table-wrap">
+        <table className="table">
+          <thead>
+            <tr><th className="num">Menge</th><th>MHD</th><th>Eingelagert</th><th></th></tr>
+          </thead>
+          <tbody>
+            {lots.map((l) => {
+              const cls = expiryRowClass(l.best_before, warnDays);
+              const dLeft = daysUntil(l.best_before);
+              const editing = editId === l.id;
+              return (
+                <tr key={l.id} className={cls}>
+                  <td className="num">
+                    {editing ? (
+                      <input type="number" step="any" min="0" value={draft.quantity}
+                        onChange={(e) => setDraft({ ...draft, quantity: e.target.value })}
+                        style={{ maxWidth: 100, marginTop: 0 }} />
+                    ) : (
+                      <>{fmt(l.quantity)} {baseShort}</>
+                    )}
+                  </td>
+                  <td>
+                    {editing ? (
+                      <input type="date" value={draft.best_before}
+                        onChange={(e) => setDraft({ ...draft, best_before: e.target.value })}
+                        style={{ maxWidth: 150, marginTop: 0 }} />
+                    ) : (
+                      <>
+                        {l.best_before || "–"}
+                        {cls === "row-danger" && <span className="badge danger" style={{ marginLeft: 6 }}>abgelaufen</span>}
+                        {cls === "row-warn" && <span className="badge warn" style={{ marginLeft: 6 }}>{dLeft}d</span>}
+                      </>
+                    )}
+                  </td>
+                  <td className="muted">{new Date(l.created_at).toLocaleDateString("de-DE")}</td>
+                  <td className="num">
+                    {isAdmin && (editing ? (
+                      <div className="field-inline" style={{ justifyContent: "flex-end" }}>
+                        <button className="btn sm primary" onClick={() => saveEdit(l)}>Speichern</button>
+                        <button className="btn sm" onClick={() => setEditId(null)}>Abbrechen</button>
+                      </div>
+                    ) : (
+                      <div className="field-inline" style={{ justifyContent: "flex-end" }}>
+                        <button className="btn-icon" onClick={() => startEdit(l)} title="Charge bearbeiten">
+                          <Icon name="edit" size={16} />
+                        </button>
+                        <button className="btn-icon danger" onClick={() => removeLot(l)} title="Charge löschen">
+                          <Icon name="trash" size={16} />
+                        </button>
+                      </div>
+                    ))}
+                  </td>
+                </tr>
+              );
+            })}
+            {lots.length === 0 && <tr><td colSpan={4} className="empty">Keine Chargen im Bestand.</td></tr>}
+          </tbody>
+        </table>
+      </div>
+      <p className="muted small">Mengen sind in der Basiseinheit ({baseShort}) angegeben.</p>
+    </section>
+  );
+}

web/src/pages/Products.jsx

@@ -84,17 +84,22 @@ export default function Products() {
                       )}
                     </td>
                     <td className="muted">{p.brand || "–"}</td>
-                    <td>{unitShort(p.base_unit)}{p.package_size ? ` · Pkg ${fmt(p.package_size)}` : ""}</td>
+                    <td>
+                      {p.unit_name || unitShort(p.base_unit)}
+                      {p.package_size ? ` · Pkg ${fmt(p.package_size)} ${unitShort(p.base_unit)}` : ""}
+                    </td>
                     <td className="num">
-                      {fmt(p.stock)} {unitShort(p.base_unit)}
+                      {fmt(p.stock / (p.unit_factor || 1))} {p.unit_name || unitShort(p.base_unit)}
                       {low && <span className="badge warn" style={{ marginLeft: 6 }}>niedrig</span>}
                     </td>
                     <td className="num">
                       {p.package_size
                         ? `${fmt(p.stock / p.package_size)} Pkg`
-                        : `${fmt(p.stock)} ${unitShort(p.base_unit)}`}
+                        : `${fmt(p.stock / (p.unit_factor || 1))} ${p.unit_name || unitShort(p.base_unit)}`}
+                    </td>
+                    <td className="num muted">
+                      {p.min_stock != null ? `${fmt(p.min_stock / (p.unit_factor || 1))}` : "–"}
                     </td>
-                    <td className="num muted">{p.min_stock != null ? fmt(p.min_stock) : "–"}</td>
                     <td className="num"><Link to={`/products/${p.id}`}>Details</Link></td>
                   </tr>
                 );

web/src/pages/ShoppingList.jsx

@@ -46,7 +46,8 @@ export default function ShoppingList() {
                     <span className="item-name">{it.name}</span>
                   </label>
                   <span className="muted small">
-                    fehlt <strong>{fmt(it.deficit)}</strong> (Bestand {fmt(it.stock)} / min {fmt(it.min_stock)})
+                    fehlt <strong>{fmt(it.deficit)} {it.unit_name}</strong>{" "}
+                    (Bestand {fmt(it.stock)} / min {fmt(it.min_stock)} {it.unit_name})
                   </span>
                 </li>
               );

web/src/pages/Units.jsx

@@ -0,0 +1,107 @@
+import { useEffect, useState } from "react";
+import { api } from "../api";
+import Icon from "../components/Icon";
+import { fmt } from "../units";
+
+const KIND_LABEL = { count: "Anzahl (Stück)", weight: "Gewicht (Basis: Gramm)", volume: "Volumen (Basis: Milliliter)" };
+
+export default function Units() {
+  const [units, setUnits] = useState([]);
+  const [form, setForm] = useState({ name: "", kind: "weight", factor: "" });
+  const [error, setError] = useState(null);
+
+  async function load() {
+    try {
+      setUnits(await api.listUnits());
+    } catch (err) {
+      setError(err.message);
+    }
+  }
+
+  useEffect(() => { load(); }, []);
+
+  async function add(e) {
+    e.preventDefault();
+    setError(null);
+    try {
+      await api.createUnit({ name: form.name, kind: form.kind, factor: Number(form.factor) });
+      setForm({ name: "", kind: form.kind, factor: "" });
+      load();
+    } catch (err) {
+      setError(err.message);
+    }
+  }
+
+  async function remove(u) {
+    if (!confirm(`Einheit "${u.name}" löschen?`)) return;
+    try {
+      await api.deleteUnit(u.id);
+      load();
+    } catch (err) {
+      setError(err.message);
+    }
+  }
+
+  const baseUnitOfKind = { count: "Stück", weight: "Gramm", volume: "Milliliter" };
+
+  return (
+    <div>
+      <div className="page-head">
+        <div>
+          <h1>Einheiten</h1>
+          <div className="sub">Faktor = wie viele Basiseinheiten 1 dieser Einheit entsprechen</div>
+        </div>
+      </div>
+      {error && <div className="alert error"><Icon name="alert" size={16} />{error}</div>}
+
+      <div className="grid-2">
+        <div className="card" style={{ padding: 0 }}>
+          <div className="table-wrap">
+            <table className="table">
+              <thead><tr><th>Name</th><th>Art</th><th className="num">Faktor</th><th></th></tr></thead>
+              <tbody>
+                {units.map((u) => (
+                  <tr key={u.id}>
+                    <td className="strong">{u.name}{u.is_builtin && <span className="badge" style={{ marginLeft: 6 }}>eingebaut</span>}</td>
+                    <td className="muted">{KIND_LABEL[u.kind] || u.kind}</td>
+                    <td className="num">{fmt(u.factor)} {baseUnitOfKind[u.kind]}</td>
+                    <td className="num">
+                      {!u.is_builtin && (
+                        <button className="btn-icon danger" onClick={() => remove(u)} title="Löschen">
+                          <Icon name="trash" size={16} />
+                        </button>
+                      )}
+                    </td>
+                  </tr>
+                ))}
+              </tbody>
+            </table>
+          </div>
+        </div>
+
+        <form className="card" onSubmit={add}>
+          <div className="card-head"><Icon name="settings" /><h2>Neue Einheit</h2></div>
+          <label>
+            Name
+            <input placeholder="z.B. Pfund" value={form.name} onChange={(e) => setForm({ ...form, name: e.target.value })} required />
+          </label>
+          <label>
+            Art
+            <select value={form.kind} onChange={(e) => setForm({ ...form, kind: e.target.value })}>
+              <option value="count">Anzahl (Stück)</option>
+              <option value="weight">Gewicht (Basis: Gramm)</option>
+              <option value="volume">Volumen (Basis: Milliliter)</option>
+            </select>
+          </label>
+          <label>
+            Faktor zur Basiseinheit
+            <input type="number" step="any" min="0" value={form.factor}
+              onChange={(e) => setForm({ ...form, factor: e.target.value })} required
+              placeholder={`z.B. 500 (= 500 ${baseUnitOfKind[form.kind]})`} />
+          </label>
+          <button className="btn primary"><Icon name="plus" size={16} />Anlegen</button>
+        </form>
+      </div>
+    </div>
+  );
+}

web/src/units.js

@@ -69,3 +69,23 @@ export function amountText(qty, packageSize, baseUnit) {
   }
   return `${fmt(qty)} ${unitShort(baseUnit)}`;
 }
+
+// Einheiten-Optionen fürs Ein-/Auslagern: verwaltete Einheiten der Produkt-Art + Packung.
+export function buildUnitOptions(product, units) {
+  const opts = (units || [])
+    .filter((u) => u.kind === product.kind)
+    .map((u) => ({ value: u.name, label: u.name }));
+  if (product.package_size) {
+    opts.push({
+      value: "package",
+      label: `Packung (${fmt(product.package_size)} ${unitShort(product.base_unit)})`,
+    });
+  }
+  return opts;
+}
+
+// Bestand eines Produkts in seiner Anzeigeeinheit, z.B. "1,5 Kilogramm".
+export function stockLabel(product) {
+  const factor = product.unit_factor || 1;
+  return `${fmt((product.stock || 0) / factor)} ${product.unit_name || unitShort(product.base_unit)}`;
+}