diff --git a/src/app/__init__.py b/src/app/__init__.py
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diff --git a/src/app/core/__init__.py b/src/app/core/__init__.py
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diff --git a/src/app/core/__pycache__/config.cpython-313.pyc b/src/app/core/__pycache__/config.cpython-313.pyc
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diff --git a/src/app/core/__pycache__/exceptions.cpython-313.pyc b/src/app/core/__pycache__/exceptions.cpython-313.pyc
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diff --git a/src/app/core/config.py b/src/app/core/config.py
new file mode 100644
index 0000000..146e283
--- /dev/null
+++ b/src/app/core/config.py
@@ -0,0 +1,15 @@
+from typing import List
+from pydantic import AnyHttpUrl
+from pydantic_settings import BaseSettings, SettingsConfigDict
+
+class Settings(BaseSettings):
+    model_config = SettingsConfigDict(
+        env_file=".env",
+        env_file_encoding="utf-8",
+        case_sensitive=True
+    )
+
+    PROJECT_NAME: str = "Recipe Book GraphQL API"
+    BACKEND_CORS_ORIGINS: List[AnyHttpUrl] = []
+
+settings = Settings()
\ No newline at end of file
diff --git a/src/app/core/exceptions.py b/src/app/core/exceptions.py
new file mode 100644
index 0000000..0db2f2e
--- /dev/null
+++ b/src/app/core/exceptions.py
@@ -0,0 +1,24 @@
+class BaseAppException(Exception):
+    """Exception de base pour l'application."""
+    pass
+
+class DALException(BaseAppException):
+    """Exception levée pour les erreurs de la couche d'accès aux données (DAL)."""
+    def __init__(self, message: str, original_exception: Exception = None):
+        self.message = message
+        self.original_exception = original_exception
+        super().__init__(self.message)
+
+class BLLException(BaseAppException):
+    """Exception de base pour les erreurs de la couche métier (BLL)."""
+    pass
+
+class NotFoundBLLException(BLLException):
+    """Levée lorsqu'une ressource n'est pas trouvée."""
+    def __init__(self, resource_name: str, resource_id: int | str):
+        message = f"{resource_name} avec l'ID '{resource_id}' non trouvé."
+        super().__init__(message)
+
+class ValidationBLLException(BLLException):
+    """Levée pour les erreurs de validation des règles métier."""
+    pass
\ No newline at end of file
diff --git a/src/app/graphql/__init__.py b/src/app/graphql/__init__.py
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diff --git a/src/app/graphql/extensions.py b/src/app/graphql/extensions.py
new file mode 100644
index 0000000..648c282
--- /dev/null
+++ b/src/app/graphql/extensions.py
@@ -0,0 +1,12 @@
+from strawberry.extensions import Extension
+from app.core.exceptions import BLLException
+
+class BusinessLogicErrorExtension(Extension):
+    def on_request_end(self):
+        for error in self.execution_context.errors:
+            original_error = error.original_error
+            if isinstance(original_error, BLLException):
+                error.message = f"[Business Error] {original_error}"
+                if not error.extensions:
+                    error.extensions = {}
+                error.extensions['code'] = original_error.__class__.__name__
\ No newline at end of file
diff --git a/src/app/graphql/inputs/__init__.py b/src/app/graphql/inputs/__init__.py
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diff --git a/src/app/graphql/inputs/__pycache__/recipe_input.cpython-313.pyc b/src/app/graphql/inputs/__pycache__/recipe_input.cpython-313.pyc
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diff --git a/src/app/graphql/inputs/ingredient_input.py b/src/app/graphql/inputs/ingredient_input.py
new file mode 100644
index 0000000..a6a2b95
--- /dev/null
+++ b/src/app/graphql/inputs/ingredient_input.py
@@ -0,0 +1,6 @@
+import strawberry
+
+@strawberry.input
+class IngredientInput:
+    name: str
+    quantity: str
\ No newline at end of file
diff --git a/src/app/graphql/inputs/recipe_input.py b/src/app/graphql/inputs/recipe_input.py
new file mode 100644
index 0000000..75f4636
--- /dev/null
+++ b/src/app/graphql/inputs/recipe_input.py
@@ -0,0 +1,9 @@
+import strawberry
+from typing import List
+from .ingredient_input import IngredientInput
+
+@strawberry.input
+class AddRecipeInput:
+    title: str
+    description: str
+    ingredients: List[IngredientInput]
\ No newline at end of file
diff --git a/src/app/graphql/mutations.py b/src/app/graphql/mutations.py
new file mode 100644
index 0000000..fdc5b4b
--- /dev/null
+++ b/src/app/graphql/mutations.py
@@ -0,0 +1,16 @@
+import strawberry
+from app.graphql.types.recipe import Recipe
+from app.graphql.inputs.recipe_input import AddRecipeInput
+from app.graphql.resolvers.recipe_resolvers import resolve_add_recipe
+
+
+@strawberry.type
+class Mutation:
+    """
+    Point d'entrée pour toutes les requêtes d'écriture.
+    """
+
+    addRecipe: Recipe = strawberry.field(
+        resolver=resolve_add_recipe,
+        description="Ajoute une nouvelle recette au livre de cuisine."
+    )
\ No newline at end of file
diff --git a/src/app/graphql/queries.py b/src/app/graphql/queries.py
new file mode 100644
index 0000000..51b040c
--- /dev/null
+++ b/src/app/graphql/queries.py
@@ -0,0 +1,21 @@
+import strawberry
+from typing import List, Optional
+from app.graphql.types.recipe import Recipe
+from app.graphql.resolvers.recipe_resolvers import resolve_recipes, resolve_recipe_by_id
+
+
+@strawberry.type
+class Query:
+    """
+    Point d'entrée pour toutes les requêtes de lecture.
+    """
+
+    recipes: List[Recipe] = strawberry.field(
+        resolver=resolve_recipes,
+        description="Récupère la liste de toutes les recettes de cuisine."
+    )
+
+    recipe: Optional[Recipe] = strawberry.field(
+        resolver=resolve_recipe_by_id,
+        description="Récupère une recette par son ID."
+    )
\ No newline at end of file
diff --git a/src/app/graphql/resolvers/__init__.py b/src/app/graphql/resolvers/__init__.py
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diff --git a/src/app/graphql/resolvers/recipe_resolvers.py b/src/app/graphql/resolvers/recipe_resolvers.py
new file mode 100644
index 0000000..8ba0bdd
--- /dev/null
+++ b/src/app/graphql/resolvers/recipe_resolvers.py
@@ -0,0 +1,30 @@
+import strawberry
+from typing import List, Optional
+from app.graphql.types.recipe import Recipe
+from app.graphql.inputs.recipe_input import AddRecipeInput
+import app.services.recipe_service as recipe_service
+
+def resolve_recipes() -> List[Recipe]:
+    """Resolver pour obtenir la liste de toutes les recettes."""
+    return recipe_service.get_all_recipes()
+
+
+def resolve_recipe_by_id(id: strawberry.ID) -> Optional[Recipe]:
+    """Resolver pour obtenir une recette par son ID."""
+    # Strawberry.ID est une chaîne, il faut la convertir en entier
+    return recipe_service.get_recipe_by_id(recipe_id=int(id))
+
+
+def resolve_add_recipe(input: AddRecipeInput) -> Recipe:
+    """Resolver pour ajouter une nouvelle recette."""
+    # Conversion des inputs strawberry en dictionnaires simples
+    ingredients_data = [
+        {"name": ing.name, "quantity": ing.quantity}
+        for ing in input.ingredients
+    ]
+
+    return recipe_service.add_new_recipe(
+        title=input.title,
+        description=input.description,
+        ingredients=ingredients_data
+    )
\ No newline at end of file
diff --git a/src/app/graphql/types/__init__.py b/src/app/graphql/types/__init__.py
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diff --git a/src/app/graphql/types/ingredient.py b/src/app/graphql/types/ingredient.py
new file mode 100644
index 0000000..793401e
--- /dev/null
+++ b/src/app/graphql/types/ingredient.py
@@ -0,0 +1,6 @@
+import strawberry
+
+@strawberry.type
+class Ingredient:
+    name: str
+    quantity: str
\ No newline at end of file
diff --git a/src/app/graphql/types/recipe.py b/src/app/graphql/types/recipe.py
new file mode 100644
index 0000000..69c796e
--- /dev/null
+++ b/src/app/graphql/types/recipe.py
@@ -0,0 +1,10 @@
+import strawberry
+from typing import List
+from .ingredient import Ingredient
+
+@strawberry.type
+class Recipe:
+    id: strawberry.ID
+    title: str
+    description: str
+    ingredients: List[Ingredient]
\ No newline at end of file
diff --git a/src/app/main.py b/src/app/main.py
new file mode 100644
index 0000000..60e72f0
--- /dev/null
+++ b/src/app/main.py
@@ -0,0 +1,43 @@
+from fastapi import FastAPI
+from app.core.config import settings
+from strawberry.fastapi import GraphQLRouter
+import strawberry
+import uvicorn
+from fastapi.middleware.cors import CORSMiddleware
+from app.graphql.extensions import BusinessLogicErrorExtension
+from app.graphql.mutations import Mutation
+from app.graphql.queries import Query
+
+# Crée l'application FastAPI
+app = FastAPI(
+    title="Recipe Book GraphQL API",
+    description="API GraphQL pour un livre de recettes de cuisine.",
+    version="1.0.0"
+)
+
+# CORS middleware
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=[str(origin).rstrip('/') for origin in settings.BACKEND_CORS_ORIGINS] if settings.BACKEND_CORS_ORIGINS else ["*"],
+    allow_credentials=True,
+    allow_methods=["*"],
+    allow_headers=["*"],
+)
+
+# Crée le schéma GraphQL
+schema = strawberry.Schema(
+    query=Query,
+    mutation=Mutation,
+    extensions=[BusinessLogicErrorExtension]
+)
+
+# Crée le routeur GraphQL
+graphql_app = GraphQLRouter(schema)
+app.include_router(graphql_app, prefix="/graphql")
+
+@app.get("/", tags=["Root"])
+def read_root():
+    return {"message": "Bienvenue sur l'API du livre de recettes. Rendez-vous sur /graphql"}
+
+if __name__ == "__main__":
+    uvicorn.run(app, host="0.0.0.0", port=8004)
\ No newline at end of file
diff --git a/src/app/models/__init__.py b/src/app/models/__init__.py
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diff --git a/src/app/models/ingredient.py b/src/app/models/ingredient.py
new file mode 100644
index 0000000..07ca891
--- /dev/null
+++ b/src/app/models/ingredient.py
@@ -0,0 +1,5 @@
+from pydantic import BaseModel
+
+class Ingredient(BaseModel):
+    name: str
+    quantity: str
\ No newline at end of file
diff --git a/src/app/models/recipe.py b/src/app/models/recipe.py
new file mode 100644
index 0000000..8648ab1
--- /dev/null
+++ b/src/app/models/recipe.py
@@ -0,0 +1,9 @@
+from pydantic import BaseModel
+from typing import List
+from .ingredient import Ingredient
+
+class Recipe(BaseModel):
+    id: int
+    title: str
+    description: str
+    ingredients: List[Ingredient]
\ No newline at end of file
diff --git a/src/app/repositories/__init__.py b/src/app/repositories/__init__.py
new file mode 100644
index 0000000..e69de29
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diff --git a/src/app/repositories/__pycache__/recipe_repository.cpython-313.pyc b/src/app/repositories/__pycache__/recipe_repository.cpython-313.pyc
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diff --git a/src/app/repositories/recipe_repository.py b/src/app/repositories/recipe_repository.py
new file mode 100644
index 0000000..b28e9f6
--- /dev/null
+++ b/src/app/repositories/recipe_repository.py
@@ -0,0 +1,61 @@
+from typing import List, Optional, Dict, Any
+from app.models.recipe import Recipe
+
+# --- Base de données en mémoire ---
+_RECIPES_DB = [
+    {
+        "id": 1,
+        "title": "Crêpes simples",
+        "description": "Une recette facile pour des crêpes délicieuses.",
+        "ingredients": [
+            {"name": "Farine", "quantity": "250g"},
+            {"name": "Oeufs", "quantity": "4"},
+            {"name": "Lait", "quantity": "500ml"},
+            {"name": "Sucre", "quantity": "2 cuillères à soupe"}
+        ],
+    },
+    {
+        "id": 2,
+        "title": "Gâteau au chocolat",
+        "description": "Un classique qui plaît à tout le monde.",
+        "ingredients": [
+            {"name": "Chocolat noir", "quantity": "200g"},
+            {"name": "Beurre", "quantity": "150g"},
+            {"name": "Sucre", "quantity": "100g"},
+            {"name": "Oeufs", "quantity": "3"},
+            {"name": "Farine", "quantity": "50g"}
+        ],
+    },
+]
+# Compteur pour simuler l'auto-incrémentation des IDs
+_next_id = 3
+# ---
+
+class RecipeRepository:
+    """
+    Simule l'accès à une base de données de recettes.
+    """
+    def list(self) -> List[Recipe]:
+        """Retourne toutes les recettes."""
+        return [Recipe.model_validate(r) for r in _RECIPES_DB]
+
+    def find_by_id(self, recipe_id: int) -> Optional[Recipe]:
+        """Trouve une recette par son ID."""
+        for recipe_data in _RECIPES_DB:
+            if recipe_data["id"] == recipe_id:
+                return Recipe.model_validate(recipe_data)
+        return None
+
+    def create(self, recipe_data: Dict[str, Any]) -> Recipe:
+        """Crée une nouvelle recette et l'ajoute à la DB."""
+        global _next_id
+        new_recipe = {
+            "id": _next_id,
+            **recipe_data
+        }
+        _RECIPES_DB.append(new_recipe)
+        _next_id += 1
+        return Recipe.model_validate(new_recipe)
+
+# Instance unique du repository
+recipe_repository = RecipeRepository()
diff --git a/src/app/services/__init__.py b/src/app/services/__init__.py
new file mode 100644
index 0000000..e69de29
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diff --git a/src/app/services/__pycache__/recipe_service.cpython-313.pyc b/src/app/services/__pycache__/recipe_service.cpython-313.pyc
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diff --git a/src/app/services/recipe_service.py b/src/app/services/recipe_service.py
new file mode 100644
index 0000000..87036b2
--- /dev/null
+++ b/src/app/services/recipe_service.py
@@ -0,0 +1,40 @@
+from typing import List, Dict, Any
+from app.models.recipe import Recipe
+from app.repositories.recipe_repository import recipe_repository
+from app.core.exceptions import NotFoundBLLException, ValidationBLLException
+
+def get_all_recipes() -> List[Recipe]:
+    """Récupère toutes les recettes."""
+    return recipe_repository.list()
+
+
+def get_recipe_by_id(recipe_id: int) -> Recipe:
+    """
+    Récupère une recette par son ID.
+    Lève une exception si la recette n'est pas trouvée.
+    """
+    recipe = recipe_repository.find_by_id(recipe_id)
+    if not recipe:
+        raise NotFoundBLLException(resource_name="Recipe", resource_id=recipe_id)
+    return recipe
+
+
+def add_new_recipe(title: str, description: str, ingredients: List[Dict[str, Any]]) -> Recipe:
+    """
+    Ajoute une nouvelle recette après validation.
+    """
+    # Règle métier simple : le titre ne doit pas être vide
+    if not title or not title.strip():
+        raise ValidationBLLException("Le titre de la recette ne peut pas être vide.")
+
+    # Règle métier simple : il faut au moins un ingrédient
+    if not ingredients:
+        raise ValidationBLLException("Une recette doit contenir au moins un ingrédient.")
+
+    recipe_data = {
+        "title": title,
+        "description": description,
+        "ingredients": ingredients
+    }
+
+    return recipe_repository.create(recipe_data)
\ No newline at end of file