diff --git a/backend/innercontext/api/health.py b/backend/innercontext/api/health.py
index 5f04434..b0da062 100644
--- a/backend/innercontext/api/health.py
+++ b/backend/innercontext/api/health.py
@@ -3,7 +3,7 @@ from datetime import datetime
 from typing import Optional
 from uuid import UUID, uuid4
 
-from fastapi import APIRouter, Depends, HTTPException
+from fastapi import APIRouter, Depends
 from pydantic import field_validator
 from sqlmodel import Session, SQLModel, col, select
 
@@ -72,8 +72,11 @@ class LabResultCreate(SQLModel):
     @classmethod
     def check_test_code_format(cls, v: str) -> str:
         if not re.fullmatch(r"\d+-\d", v):
-            raise ValueError("test_code must match LOINC format: digits-digit (e.g. 718-7)")
+            raise ValueError(
+                "test_code must match LOINC format: digits-digit (e.g. 718-7)"
+            )
         return v
+
     test_name_original: Optional[str] = None
     test_name_loinc: Optional[str] = None
 
@@ -142,9 +145,7 @@ def list_medications(
 
 
 @router.post("/medications", response_model=MedicationEntry, status_code=201)
-def create_medication(
-    data: MedicationCreate, session: Session = Depends(get_session)
-):
+def create_medication(data: MedicationCreate, session: Session = Depends(get_session)):
     entry = MedicationEntry(record_id=uuid4(), **data.model_dump())
     session.add(entry)
     session.commit()
@@ -274,9 +275,7 @@ def list_lab_results(
 
 
 @router.post("/lab-results", response_model=LabResult, status_code=201)
-def create_lab_result(
-    data: LabResultCreate, session: Session = Depends(get_session)
-):
+def create_lab_result(data: LabResultCreate, session: Session = Depends(get_session)):
     result = LabResult(record_id=uuid4(), **data.model_dump())
     session.add(result)
     session.commit()
diff --git a/backend/innercontext/api/inventory.py b/backend/innercontext/api/inventory.py
index 85fdce3..9d50034 100644
--- a/backend/innercontext/api/inventory.py
+++ b/backend/innercontext/api/inventory.py
@@ -1,12 +1,12 @@
 from uuid import UUID
 
-from fastapi import APIRouter, Depends, HTTPException
+from fastapi import APIRouter, Depends
 from sqlmodel import Session
 
 from db import get_session
+from innercontext.api.products import InventoryUpdate
 from innercontext.api.utils import get_or_404
 from innercontext.models import ProductInventory
-from innercontext.api.products import InventoryUpdate
 
 router = APIRouter()
 
diff --git a/backend/innercontext/api/products.py b/backend/innercontext/api/products.py
index d7fc443..86b5979 100644
--- a/backend/innercontext/api/products.py
+++ b/backend/innercontext/api/products.py
@@ -2,30 +2,33 @@ from datetime import date
 from typing import Optional
 from uuid import UUID, uuid4
 
-from fastapi import APIRouter, Depends, HTTPException, Query
+from fastapi import APIRouter, Depends, Query
 from sqlmodel import Session, SQLModel, select
 
 from db import get_session
 from innercontext.api.utils import get_or_404
 from innercontext.models import (
     Product,
+    ProductBase,
     ProductCategory,
     ProductInventory,
+    ProductPublic,
+    ProductWithInventory,
     SkinConcern,
 )
+from innercontext.models.enums import (
+    AbsorptionSpeed,
+    DayTime,
+    PriceTier,
+    SkinType,
+    TextureType,
+)
 from innercontext.models.product import (
     ActiveIngredient,
     ProductContext,
     ProductEffectProfile,
     ProductInteraction,
 )
-from innercontext.models.enums import (
-    AbsorptionSpeed,
-    DayTime,
-    PriceTier,
-    TextureType,
-    SkinType,
-)
 
 router = APIRouter()
 
@@ -35,57 +38,8 @@ router = APIRouter()
 # ---------------------------------------------------------------------------
 
 
-class ProductCreate(SQLModel):
-    name: str
-    brand: str
-    line_name: Optional[str] = None
-    sku: Optional[str] = None
-    url: Optional[str] = None
-    barcode: Optional[str] = None
-
-    category: ProductCategory
-    recommended_time: DayTime
-
-    texture: Optional[TextureType] = None
-    absorption_speed: Optional[AbsorptionSpeed] = None
-    leave_on: bool
-
-    price_tier: Optional[PriceTier] = None
-    size_ml: Optional[float] = None
-    pao_months: Optional[int] = None
-
-    inci: list[str] = []
-    actives: Optional[list[ActiveIngredient]] = None
-
-    recommended_for: list[SkinType] = []
-
-    targets: list[SkinConcern] = []
-    contraindications: list[str] = []
-    usage_notes: Optional[str] = None
-
-    fragrance_free: Optional[bool] = None
-    essential_oils_free: Optional[bool] = None
-    alcohol_denat_free: Optional[bool] = None
-    pregnancy_safe: Optional[bool] = None
-
-    product_effect_profile: ProductEffectProfile = ProductEffectProfile()
-
-    ph_min: Optional[float] = None
-    ph_max: Optional[float] = None
-
-    incompatible_with: Optional[list[ProductInteraction]] = None
-    synergizes_with: Optional[list[str]] = None
-    context_rules: Optional[ProductContext] = None
-
-    min_interval_hours: Optional[int] = None
-    max_frequency_per_week: Optional[int] = None
-
-    is_medication: bool = False
-    is_tool: bool = False
-    needle_length_mm: Optional[float] = None
-
-    personal_tolerance_notes: Optional[str] = None
-    personal_repurchase_intent: Optional[bool] = None
+class ProductCreate(ProductBase):
+    pass
 
 
 class ProductUpdate(SQLModel):
@@ -159,17 +113,12 @@ class InventoryUpdate(SQLModel):
     notes: Optional[str] = None
 
 
-# ---------------------------------------------------------------------------
-# Helper
-# ---------------------------------------------------------------------------
-
-
 # ---------------------------------------------------------------------------
 # Product routes
 # ---------------------------------------------------------------------------
 
 
-@router.get("", response_model=list[Product])
+@router.get("", response_model=list[ProductPublic])
 def list_products(
     category: Optional[ProductCategory] = None,
     brand: Optional[str] = None,
@@ -205,7 +154,7 @@ def list_products(
     return products
 
 
-@router.post("", response_model=Product, status_code=201)
+@router.post("", response_model=ProductPublic, status_code=201)
 def create_product(data: ProductCreate, session: Session = Depends(get_session)):
     product = Product(
         id=uuid4(),
@@ -217,16 +166,18 @@ def create_product(data: ProductCreate, session: Session = Depends(get_session))
     return product
 
 
-@router.get("/{product_id}")
+@router.get("/{product_id}", response_model=ProductWithInventory)
 def get_product(product_id: UUID, session: Session = Depends(get_session)):
     product = get_or_404(session, Product, product_id)
-    inventory = session.exec(select(ProductInventory).where(ProductInventory.product_id == product_id)).all()
-    data = product.model_dump(mode="json")
-    data["inventory"] = [item.model_dump(mode="json") for item in inventory]
-    return data
+    inventory = session.exec(
+        select(ProductInventory).where(ProductInventory.product_id == product_id)
+    ).all()
+    result = ProductWithInventory.model_validate(product, from_attributes=True)
+    result.inventory = list(inventory)
+    return result
 
 
-@router.patch("/{product_id}", response_model=Product)
+@router.patch("/{product_id}", response_model=ProductPublic)
 def update_product(
     product_id: UUID, data: ProductUpdate, session: Session = Depends(get_session)
 ):
@@ -252,9 +203,7 @@ def delete_product(product_id: UUID, session: Session = Depends(get_session)):
 
 
 @router.get("/{product_id}/inventory", response_model=list[ProductInventory])
-def list_product_inventory(
-    product_id: UUID, session: Session = Depends(get_session)
-):
+def list_product_inventory(product_id: UUID, session: Session = Depends(get_session)):
     get_or_404(session, Product, product_id)
     stmt = select(ProductInventory).where(ProductInventory.product_id == product_id)
     return session.exec(stmt).all()
diff --git a/backend/innercontext/api/routines.py b/backend/innercontext/api/routines.py
index ad8b25c..e20156b 100644
--- a/backend/innercontext/api/routines.py
+++ b/backend/innercontext/api/routines.py
@@ -2,7 +2,7 @@ from datetime import date
 from typing import Optional
 from uuid import UUID, uuid4
 
-from fastapi import APIRouter, Depends, HTTPException
+from fastapi import APIRouter, Depends
 from sqlmodel import Session, SQLModel, select
 
 from db import get_session
@@ -105,7 +105,9 @@ def list_grooming_schedule(session: Session = Depends(get_session)):
 @router.get("/{routine_id}")
 def get_routine(routine_id: UUID, session: Session = Depends(get_session)):
     routine = get_or_404(session, Routine, routine_id)
-    steps = session.exec(select(RoutineStep).where(RoutineStep.routine_id == routine_id)).all()
+    steps = session.exec(
+        select(RoutineStep).where(RoutineStep.routine_id == routine_id)
+    ).all()
     data = routine.model_dump(mode="json")
     data["steps"] = [step.model_dump(mode="json") for step in steps]
     return data
@@ -206,9 +208,7 @@ def update_grooming_schedule(
 
 
 @router.delete("/grooming-schedule/{entry_id}", status_code=204)
-def delete_grooming_schedule(
-    entry_id: UUID, session: Session = Depends(get_session)
-):
+def delete_grooming_schedule(entry_id: UUID, session: Session = Depends(get_session)):
     entry = get_or_404(session, GroomingSchedule, entry_id)
     session.delete(entry)
     session.commit()
diff --git a/backend/innercontext/api/skincare.py b/backend/innercontext/api/skincare.py
index 19979bc..0bed948 100644
--- a/backend/innercontext/api/skincare.py
+++ b/backend/innercontext/api/skincare.py
@@ -2,12 +2,16 @@ from datetime import date
 from typing import Optional
 from uuid import UUID, uuid4
 
-from fastapi import APIRouter, Depends, HTTPException
+from fastapi import APIRouter, Depends
 from sqlmodel import Session, SQLModel, select
 
 from db import get_session
 from innercontext.api.utils import get_or_404
-from innercontext.models import SkinConditionSnapshot
+from innercontext.models import (
+    SkinConditionSnapshot,
+    SkinConditionSnapshotBase,
+    SkinConditionSnapshotPublic,
+)
 from innercontext.models.enums import (
     BarrierState,
     OverallSkinState,
@@ -24,23 +28,8 @@ router = APIRouter()
 # ---------------------------------------------------------------------------
 
 
-class SnapshotCreate(SQLModel):
-    snapshot_date: date
-    overall_state: Optional[OverallSkinState] = None
-    trend: Optional[SkinTrend] = None
-    skin_type: Optional[SkinType] = None
-
-    hydration_level: Optional[int] = None
-    sebum_tzone: Optional[int] = None
-    sebum_cheeks: Optional[int] = None
-    sensitivity_level: Optional[int] = None
-
-    barrier_state: Optional[BarrierState] = None
-
-    active_concerns: list[SkinConcern] = []
-    risks: list[str] = []
-    priorities: list[str] = []
-    notes: Optional[str] = None
+class SnapshotCreate(SkinConditionSnapshotBase):
+    pass
 
 
 class SnapshotUpdate(SQLModel):
@@ -62,17 +51,12 @@ class SnapshotUpdate(SQLModel):
     notes: Optional[str] = None
 
 
-# ---------------------------------------------------------------------------
-# Helper
-# ---------------------------------------------------------------------------
-
-
 # ---------------------------------------------------------------------------
 # Routes
 # ---------------------------------------------------------------------------
 
 
-@router.get("", response_model=list[SkinConditionSnapshot])
+@router.get("", response_model=list[SkinConditionSnapshotPublic])
 def list_snapshots(
     from_date: Optional[date] = None,
     to_date: Optional[date] = None,
@@ -89,10 +73,8 @@ def list_snapshots(
     return session.exec(stmt).all()
 
 
-@router.post("", response_model=SkinConditionSnapshot, status_code=201)
-def create_snapshot(
-    data: SnapshotCreate, session: Session = Depends(get_session)
-):
+@router.post("", response_model=SkinConditionSnapshotPublic, status_code=201)
+def create_snapshot(data: SnapshotCreate, session: Session = Depends(get_session)):
     snapshot = SkinConditionSnapshot(id=uuid4(), **data.model_dump())
     session.add(snapshot)
     session.commit()
@@ -100,12 +82,12 @@ def create_snapshot(
     return snapshot
 
 
-@router.get("/{snapshot_id}", response_model=SkinConditionSnapshot)
+@router.get("/{snapshot_id}", response_model=SkinConditionSnapshotPublic)
 def get_snapshot(snapshot_id: UUID, session: Session = Depends(get_session)):
     return get_or_404(session, SkinConditionSnapshot, snapshot_id)
 
 
-@router.patch("/{snapshot_id}", response_model=SkinConditionSnapshot)
+@router.patch("/{snapshot_id}", response_model=SkinConditionSnapshotPublic)
 def update_snapshot(
     snapshot_id: UUID,
     data: SnapshotUpdate,
diff --git a/backend/innercontext/models/__init__.py b/backend/innercontext/models/__init__.py
index 07355e7..50b164a 100644
--- a/backend/innercontext/models/__init__.py
+++ b/backend/innercontext/models/__init__.py
@@ -25,13 +25,20 @@ from .health import LabResult, MedicationEntry, MedicationUsage
 from .product import (
     ActiveIngredient,
     Product,
+    ProductBase,
     ProductContext,
     ProductEffectProfile,
     ProductInteraction,
     ProductInventory,
+    ProductPublic,
+    ProductWithInventory,
 )
 from .routine import GroomingSchedule, Routine, RoutineStep
-from .skincare import SkinConditionSnapshot
+from .skincare import (
+    SkinConditionSnapshot,
+    SkinConditionSnapshotBase,
+    SkinConditionSnapshotPublic,
+)
 
 __all__ = [
     # domain
@@ -64,14 +71,19 @@ __all__ = [
     # product
     "ActiveIngredient",
     "Product",
+    "ProductBase",
     "ProductContext",
     "ProductEffectProfile",
     "ProductInteraction",
     "ProductInventory",
+    "ProductPublic",
+    "ProductWithInventory",
     # routine
     "GroomingSchedule",
     "Routine",
     "RoutineStep",
     # skincare
     "SkinConditionSnapshot",
+    "SkinConditionSnapshotBase",
+    "SkinConditionSnapshotPublic",
 ]
diff --git a/backend/innercontext/models/enums.py b/backend/innercontext/models/enums.py
index 53ddaa5..1441bf5 100644
--- a/backend/innercontext/models/enums.py
+++ b/backend/innercontext/models/enums.py
@@ -1,6 +1,5 @@
 from enum import Enum
 
-
 # ---------------------------------------------------------------------------
 # Shared / Product
 # ---------------------------------------------------------------------------
diff --git a/backend/innercontext/models/product.py b/backend/innercontext/models/product.py
index 88d9cf1..42a1755 100644
--- a/backend/innercontext/models/product.py
+++ b/backend/innercontext/models/product.py
@@ -21,7 +21,6 @@ from .enums import (
     TextureType,
 )
 
-
 # ---------------------------------------------------------------------------
 # Value objects
 # ---------------------------------------------------------------------------
@@ -83,16 +82,11 @@ def _ev(v: object) -> str:
 
 
 # ---------------------------------------------------------------------------
-# Table models
+# Base model (pure Python types, no sa_column, no id/timestamps)
 # ---------------------------------------------------------------------------
 
 
-class Product(SQLModel, table=True):
-    __tablename__ = "products"
-    __domains__: ClassVar[frozenset[Domain]] = frozenset({Domain.SKINCARE})
-
-    id: UUID = Field(default_factory=uuid4, primary_key=True)
-
+class ProductBase(SQLModel):
     name: str
     brand: str
     line_name: str | None = Field(default=None, max_length=128)
@@ -107,10 +101,61 @@ class Product(SQLModel, table=True):
     absorption_speed: AbsorptionSpeed | None = None
     leave_on: bool
 
-    price_tier: PriceTier | None = Field(default=None, index=True)
+    price_tier: PriceTier | None = None
     size_ml: float | None = Field(default=None, gt=0)
     pao_months: int | None = Field(default=None, ge=1, le=60)
 
+    inci: list[str] = Field(default_factory=list)
+    actives: list[ActiveIngredient] | None = None
+
+    recommended_for: list[SkinType] = Field(default_factory=list)
+
+    targets: list[SkinConcern] = Field(default_factory=list)
+    contraindications: list[str] = Field(default_factory=list)
+    usage_notes: str | None = None
+
+    fragrance_free: bool | None = None
+    essential_oils_free: bool | None = None
+    alcohol_denat_free: bool | None = None
+    pregnancy_safe: bool | None = None
+
+    product_effect_profile: ProductEffectProfile = Field(
+        default_factory=ProductEffectProfile
+    )
+
+    ph_min: float | None = Field(default=None, ge=0, le=14)
+    ph_max: float | None = Field(default=None, ge=0, le=14)
+
+    incompatible_with: list[ProductInteraction] | None = None
+    synergizes_with: list[str] | None = None
+    context_rules: ProductContext | None = None
+
+    min_interval_hours: int | None = Field(default=None, ge=0)
+    max_frequency_per_week: int | None = Field(default=None, ge=1, le=14)
+
+    is_medication: bool = Field(default=False)
+    is_tool: bool = Field(default=False)
+    needle_length_mm: float | None = Field(default=None, gt=0)
+
+    personal_tolerance_notes: str | None = None
+    personal_repurchase_intent: bool | None = None
+
+
+# ---------------------------------------------------------------------------
+# Table models
+# ---------------------------------------------------------------------------
+
+
+class Product(ProductBase, table=True):
+    __tablename__ = "products"
+    __domains__: ClassVar[frozenset[Domain]] = frozenset({Domain.SKINCARE})
+
+    id: UUID = Field(default_factory=uuid4, primary_key=True)
+
+    # Override: add index for table context
+    price_tier: PriceTier | None = Field(default=None, index=True)
+
+    # Override 9 JSON fields with sa_column (only in table model)
     inci: list[str] = Field(
         default_factory=list, sa_column=Column(JSON, nullable=False)
     )
@@ -128,21 +173,12 @@ class Product(SQLModel, table=True):
     contraindications: list[str] = Field(
         default_factory=list, sa_column=Column(JSON, nullable=False)
     )
-    usage_notes: str | None = None
-
-    fragrance_free: bool | None = None
-    essential_oils_free: bool | None = None
-    alcohol_denat_free: bool | None = None
-    pregnancy_safe: bool | None = None
 
     product_effect_profile: ProductEffectProfile = Field(
         default_factory=ProductEffectProfile,
         sa_column=Column(JSON, nullable=False),
     )
 
-    ph_min: float | None = Field(default=None, ge=0, le=14)
-    ph_max: float | None = Field(default=None, ge=0, le=14)
-
     incompatible_with: list[ProductInteraction] | None = Field(
         default=None, sa_column=Column(JSON, nullable=True)
     )
@@ -153,16 +189,6 @@ class Product(SQLModel, table=True):
         default=None, sa_column=Column(JSON, nullable=True)
     )
 
-    min_interval_hours: int | None = Field(default=None, ge=0)
-    max_frequency_per_week: int | None = Field(default=None, ge=1, le=14)
-
-    is_medication: bool = Field(default=False)
-    is_tool: bool = Field(default=False)
-    needle_length_mm: float | None = Field(default=None, gt=0)
-
-    personal_tolerance_notes: str | None = None
-    personal_repurchase_intent: bool | None = None
-
     created_at: datetime = Field(default_factory=utc_now, nullable=False)
     updated_at: datetime = Field(
         default_factory=utc_now,
@@ -264,13 +290,12 @@ class Product(SQLModel, table=True):
                 ctx["ph_max"] = self.ph_max
 
         ep = self.product_effect_profile
-        if ep is not None:
-            if isinstance(ep, dict):
-                nonzero = {k: v for k, v in ep.items() if v >= 2}
-            else:
-                nonzero = {k: v for k, v in ep.model_dump().items() if v >= 2}
-            if nonzero:
-                ctx["effect_profile"] = nonzero
+        if isinstance(ep, dict):
+            nonzero = {k: v for k, v in ep.items() if v >= 2}
+        else:
+            nonzero = {k: v for k, v in ep.model_dump().items() if v >= 2}
+        if nonzero:
+            ctx["effect_profile"] = nonzero
 
         if self.incompatible_with:
             parts = []
@@ -307,7 +332,12 @@ class Product(SQLModel, table=True):
             ctx["max_frequency_per_week"] = self.max_frequency_per_week
 
         safety = {}
-        for flag in ("fragrance_free", "essential_oils_free", "alcohol_denat_free", "pregnancy_safe"):
+        for flag in (
+            "fragrance_free",
+            "essential_oils_free",
+            "alcohol_denat_free",
+            "pregnancy_safe",
+        ):
             val = getattr(self, flag)
             if val is not None:
                 safety[flag] = val
@@ -358,3 +388,18 @@ class ProductInventory(SQLModel, table=True):
     created_at: datetime = Field(default_factory=utc_now, nullable=False)
 
     product: Optional["Product"] = Relationship(back_populates="inventory")
+
+
+# ---------------------------------------------------------------------------
+# Public response models
+# ---------------------------------------------------------------------------
+
+
+class ProductPublic(ProductBase):
+    id: UUID
+    created_at: datetime
+    updated_at: datetime
+
+
+class ProductWithInventory(ProductPublic):
+    inventory: list[ProductInventory] = []
diff --git a/backend/innercontext/models/skincare.py b/backend/innercontext/models/skincare.py
index 8a90609..de5eebf 100644
--- a/backend/innercontext/models/skincare.py
+++ b/backend/innercontext/models/skincare.py
@@ -11,19 +11,13 @@ from .base import utc_now
 from .domain import Domain
 from .enums import BarrierState, OverallSkinState, SkinConcern, SkinTrend, SkinType
 
+# ---------------------------------------------------------------------------
+# Base model (pure Python types, no sa_column, no id/created_at)
+# ---------------------------------------------------------------------------
 
-class SkinConditionSnapshot(SQLModel, table=True):
-    """
-    Tygodniowy snapshot kondycji skóry wypełniany przez LLM na podstawie zdjęć
-    i kontekstu rutyny. Wszystkie metryki numeryczne w skali 1–5.
-    """
 
-    __tablename__ = "skin_condition_snapshots"
-    __domains__: ClassVar[frozenset[Domain]] = frozenset({Domain.SKINCARE})
-    __table_args__ = (UniqueConstraint("snapshot_date", name="uq_skin_snapshot_date"),)
-
-    id: UUID = Field(default_factory=uuid4, primary_key=True)
-    snapshot_date: date = Field(index=True)
+class SkinConditionSnapshotBase(SQLModel):
+    snapshot_date: date
 
     overall_state: OverallSkinState | None = None
     trend: SkinTrend | None = None
@@ -38,17 +32,53 @@ class SkinConditionSnapshot(SQLModel, table=True):
     barrier_state: BarrierState | None = None
 
     # Aktywne troski — podzbiór SkinConcern widoczny na zdjęciach lub wynikający z rutyny
+    active_concerns: list[SkinConcern] = Field(default_factory=list)
+
+    # Wolny tekst — LLM wypełnia na podstawie analizy
+    risks: list[str] = Field(default_factory=list)
+    priorities: list[str] = Field(default_factory=list)
+    notes: str | None = None
+
+
+# ---------------------------------------------------------------------------
+# Table model
+# ---------------------------------------------------------------------------
+
+
+class SkinConditionSnapshot(SkinConditionSnapshotBase, table=True):
+    """
+    Tygodniowy snapshot kondycji skóry wypełniany przez LLM na podstawie zdjęć
+    i kontekstu rutyny. Wszystkie metryki numeryczne w skali 1–5.
+    """
+
+    __tablename__ = "skin_condition_snapshots"
+    __domains__: ClassVar[frozenset[Domain]] = frozenset({Domain.SKINCARE})
+    __table_args__ = (UniqueConstraint("snapshot_date", name="uq_skin_snapshot_date"),)
+
+    id: UUID = Field(default_factory=uuid4, primary_key=True)
+
+    # Override: add index for table context
+    snapshot_date: date = Field(index=True)
+
+    # Override 3 JSON fields with sa_column (only in table model)
     active_concerns: list[SkinConcern] = Field(
         default_factory=list, sa_column=Column(JSON, nullable=False)
     )
-
-    # Wolny tekst — LLM wypełnia na podstawie analizy
     risks: list[str] = Field(
         default_factory=list, sa_column=Column(JSON, nullable=False)
     )
     priorities: list[str] = Field(
         default_factory=list, sa_column=Column(JSON, nullable=False)
     )
-    notes: str | None = None
 
     created_at: datetime = Field(default_factory=utc_now, nullable=False)
+
+
+# ---------------------------------------------------------------------------
+# Public response model
+# ---------------------------------------------------------------------------
+
+
+class SkinConditionSnapshotPublic(SkinConditionSnapshotBase):
+    id: UUID
+    created_at: datetime
diff --git a/backend/main.py b/backend/main.py
index 993ca93..d996bd7 100644
--- a/backend/main.py
+++ b/backend/main.py
@@ -4,11 +4,11 @@ from dotenv import load_dotenv
 
 load_dotenv()  # load .env before db.py reads DATABASE_URL
 
-from fastapi import FastAPI
-from fastapi.middleware.cors import CORSMiddleware
+from fastapi import FastAPI  # noqa: E402
+from fastapi.middleware.cors import CORSMiddleware  # noqa: E402
 
-from db import create_db_and_tables
-from innercontext.api import health, inventory, products, routines, skincare
+from db import create_db_and_tables  # noqa: E402
+from innercontext.api import health, inventory, products, routines, skincare  # noqa: E402
 
 
 @asynccontextmanager
diff --git a/backend/tests/test_health.py b/backend/tests/test_health.py
index 8c98b1a..29a5331 100644
--- a/backend/tests/test_health.py
+++ b/backend/tests/test_health.py
@@ -1,6 +1,5 @@
 import uuid
 
-
 # ---------------------------------------------------------------------------
 # Medications
 # ---------------------------------------------------------------------------
@@ -32,9 +31,7 @@ def test_list_filter_kind(client):
     client.post(
         "/health/medications", json={"kind": "prescription", "product_name": "A"}
     )
-    client.post(
-        "/health/medications", json={"kind": "supplement", "product_name": "B"}
-    )
+    client.post("/health/medications", json={"kind": "supplement", "product_name": "B"})
     r = client.get("/health/medications?kind=supplement")
     assert r.status_code == 200
     data = r.json()
@@ -46,9 +43,7 @@ def test_list_filter_product_name(client):
     client.post(
         "/health/medications", json={"kind": "otc", "product_name": "Epiduo Forte"}
     )
-    client.post(
-        "/health/medications", json={"kind": "otc", "product_name": "Panoxyl"}
-    )
+    client.post("/health/medications", json={"kind": "otc", "product_name": "Panoxyl"})
     r = client.get("/health/medications?product_name=epid")
     assert r.status_code == 200
     data = r.json()
@@ -113,7 +108,11 @@ def test_create_usage(client, created_medication):
     mid = created_medication["record_id"]
     r = client.post(
         f"/health/medications/{mid}/usages",
-        json={"valid_from": "2026-01-01T08:00:00", "dose_value": 1.0, "dose_unit": "pea"},
+        json={
+            "valid_from": "2026-01-01T08:00:00",
+            "dose_value": 1.0,
+            "dose_unit": "pea",
+        },
     )
     assert r.status_code == 201
     data = r.json()
@@ -156,7 +155,9 @@ def test_update_usage(client, created_medication):
     )
     uid = r.json()["record_id"]
 
-    r2 = client.patch(f"/health/usages/{uid}", json={"dose_value": 2.5, "dose_unit": "mg"})
+    r2 = client.patch(
+        f"/health/usages/{uid}", json={"dose_value": 2.5, "dose_unit": "mg"}
+    )
     assert r2.status_code == 200
     assert r2.json()["dose_value"] == 2.5
     assert r2.json()["dose_unit"] == "mg"
@@ -247,8 +248,14 @@ def test_list_filter_flag(client):
 
 
 def test_list_filter_date_range(client):
-    client.post("/health/lab-results", json={**LAB_RESULT_DATA, "collected_at": "2026-01-01T00:00:00"})
-    client.post("/health/lab-results", json={**LAB_RESULT_DATA, "collected_at": "2026-06-01T00:00:00"})
+    client.post(
+        "/health/lab-results",
+        json={**LAB_RESULT_DATA, "collected_at": "2026-01-01T00:00:00"},
+    )
+    client.post(
+        "/health/lab-results",
+        json={**LAB_RESULT_DATA, "collected_at": "2026-06-01T00:00:00"},
+    )
     r = client.get("/health/lab-results?from_date=2026-05-01T00:00:00")
     assert r.status_code == 200
     data = r.json()
@@ -271,7 +278,9 @@ def test_get_lab_result_not_found(client):
 def test_update_lab_result(client):
     r = client.post("/health/lab-results", json=LAB_RESULT_DATA)
     rid = r.json()["record_id"]
-    r2 = client.patch(f"/health/lab-results/{rid}", json={"notes": "Recheck in 3 months"})
+    r2 = client.patch(
+        f"/health/lab-results/{rid}", json={"notes": "Recheck in 3 months"}
+    )
     assert r2.status_code == 200
     assert r2.json()["notes"] == "Recheck in 3 months"
 
diff --git a/backend/tests/test_product_model.py b/backend/tests/test_product_model.py
index 735b1a7..f2076b3 100644
--- a/backend/tests/test_product_model.py
+++ b/backend/tests/test_product_model.py
@@ -1,9 +1,7 @@
 """Unit tests for Product.to_llm_context() — no database required."""
-from uuid import uuid4
 
 from typing import Any
-
-import pytest
+from uuid import uuid4
 
 from innercontext.models import Product
 from innercontext.models.enums import (
diff --git a/backend/tests/test_products.py b/backend/tests/test_products.py
index f550a69..1fae538 100644
--- a/backend/tests/test_products.py
+++ b/backend/tests/test_products.py
@@ -55,7 +55,9 @@ def test_list_filter_category(client, client_and_data=None):
         "recommended_time": "both",
         "leave_on": True,
     }
-    r1 = client.post("/products", json={**base, "name": "Moist", "category": "moisturizer"})
+    r1 = client.post(
+        "/products", json={**base, "name": "Moist", "category": "moisturizer"}
+    )
     r2 = client.post("/products", json={**base, "name": "Ser", "category": "serum"})
     assert r1.status_code == 201
     assert r2.status_code == 201
@@ -96,7 +98,12 @@ def test_list_filter_is_medication(client):
     # is_medication=True requires usage_notes (model validator)
     client.post(
         "/products",
-        json={**base, "name": "Med", "is_medication": True, "usage_notes": "Apply pea-sized amount"},
+        json={
+            **base,
+            "name": "Med",
+            "is_medication": True,
+            "usage_notes": "Apply pea-sized amount",
+        },
     )
 
     r = client.get("/products?is_medication=true")
diff --git a/backend/tests/test_routines.py b/backend/tests/test_routines.py
index 0df2565..b240079 100644
--- a/backend/tests/test_routines.py
+++ b/backend/tests/test_routines.py
@@ -1,6 +1,5 @@
 import uuid
 
-
 # ---------------------------------------------------------------------------
 # Routines
 # ---------------------------------------------------------------------------
diff --git a/backend/tests/test_skincare.py b/backend/tests/test_skincare.py
index 2d922b9..db5f63a 100644
--- a/backend/tests/test_skincare.py
+++ b/backend/tests/test_skincare.py
@@ -112,9 +112,7 @@ def test_update_snapshot_concerns(client):
 
 
 def test_update_snapshot_not_found(client):
-    r = client.patch(
-        f"/skincare/{uuid.uuid4()}", json={"overall_state": "good"}
-    )
+    r = client.patch(f"/skincare/{uuid.uuid4()}", json={"overall_state": "good"})
     assert r.status_code == 404