diff --git a/alembic/versions/8756e344268a_optional_constraints_fixed_price_.py b/alembic/versions/8756e344268a_optional_constraints_fixed_price_.py
new file mode 100644
index 0000000..b831a24
--- /dev/null
+++ b/alembic/versions/8756e344268a_optional_constraints_fixed_price_.py
@@ -0,0 +1,36 @@
+"""Optional constraints fixed, price argument added for product
+
+Revision ID: 8756e344268a
+Revises: af58496e0468
+Create Date: 2026-02-04 17:23:47.783119
+
+"""
+
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+# revision identifiers, used by Alembic.
+revision: str = "8756e344268a"
+down_revision: Union[str, Sequence[str], None] = "af58496e0468"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    """Upgrade schema."""
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.alter_column("categories", "name", existing_type=sa.TEXT(), nullable=False)
+    op.add_column("products", sa.Column("price", sa.Integer(), nullable=False))
+    op.alter_column("products", "name", existing_type=sa.TEXT(), nullable=False)
+    # ### end Alembic commands ###
+
+
+def downgrade() -> None:
+    """Downgrade schema."""
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.alter_column("products", "name", existing_type=sa.TEXT(), nullable=True)
+    op.drop_column("products", "price")
+    op.alter_column("categories", "name", existing_type=sa.TEXT(), nullable=True)
+    # ### end Alembic commands ###
diff --git a/config.py b/config.py
index 4dc1b70..4e23dca 100644
--- a/config.py
+++ b/config.py
@@ -8,5 +8,6 @@ logger = logging.getLogger(__name__)
 BOT_TOKEN = os.getenv("BOT_TOKEN", "")
 
 POSTGRES_URL = os.getenv(
-    "POSTGRES_URL", "postgresql+asyncpg://postgres:postgres@localhost:5432/postgres"
+    "POSTGRES_URL",
+    "postgresql+asyncpg://postgres:HEXDEVFUCKINGSUCKS!@localhost:5432/postgres",
 )
diff --git a/db/models/products.py b/db/models/products.py
index aa188d2..7b3d9a2 100644
--- a/db/models/products.py
+++ b/db/models/products.py
@@ -9,7 +9,7 @@ class Category(Base):
     __tablename__ = "categories"
 
     id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
-    name: Mapped[Optional[str]] = mapped_column(Text)
+    name: Mapped[str] = mapped_column(Text, nullable=False)
     parent_id: Mapped[Optional[int]] = mapped_column(ForeignKey("categories.id"))
 
     parent: Mapped["Category"] = relationship("Category", remote_side=[id])
@@ -20,8 +20,9 @@ class Product(Base):
 
     id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
     category_id: Mapped[Optional[int]] = mapped_column(ForeignKey("categories.id"))
-    name: Mapped[Optional[str]] = mapped_column(Text)
+    name: Mapped[str] = mapped_column(Text, nullable=False)
     description: Mapped[Optional[str]] = mapped_column(Text)
+    price: Mapped[int] = mapped_column()
 
     search_vector: Mapped[str] = mapped_column(TSVECTOR)
 
diff --git a/dto/__init__.py b/dto/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/dto/categories.py b/dto/categories.py
new file mode 100644
index 0000000..5189f6a
--- /dev/null
+++ b/dto/categories.py
@@ -0,0 +1,7 @@
+from dataclasses import dataclass
+
+
+@dataclass(slots=True)
+class CategoryDTO:
+    id: int
+    name: str
diff --git a/handlers/client.py b/handlers/client.py
index a59e22a..92073c5 100644
--- a/handlers/client.py
+++ b/handlers/client.py
@@ -1,10 +1,12 @@
-from aiogram import Router
-from aiogram.types import Message
+from aiogram import Router, F
+from aiogram.types import CallbackQuery, Message
 from aiogram.filters import Command
 from aiogram.fsm.context import FSMContext
 from sqlalchemy.ext.asyncio import AsyncSession
 
-from misc.kb import main_menu_kb
+from misc.kb import main_menu_kb, render_category
+from repositories.categories import CategoriesRepository
+from services.categories import CategoryService
 from services.orders import OrderService
 
 router = Router()
@@ -19,6 +21,15 @@ async def main_menu(msg: Message, state: FSMContext):
     )  # TODO: Write a welcome message
 
 
+@router.callback_query(F.data.startswith("menu:"))
+async def main_menu_cb(cb: CallbackQuery, state: FSMContext):
+    await state.clear()
+
+    await cb.message.edit_text(
+        "hii!", reply_markup=await main_menu_kb(cb.from_user.id)
+    )  # TODO: Write a welcome message
+
+
 @router.message(Command("orders"))
 async def get_orders(
     msg: Message,
@@ -30,3 +41,33 @@ async def get_orders(
 
     count = await order_service.get_order_count(session, msg.from_user.id)
     await msg.answer(f"you have {count} orders.")
+
+
+@router.callback_query(F.data.startswith("cat:"))
+async def subcatalogue(
+    cb: CallbackQuery,
+    state: FSMContext,
+    category_service: CategoryService,
+    session: AsyncSession,
+    categories_repo: CategoriesRepository,
+):
+    await state.clear()
+
+    cat_id = cb.data.split(":")[1]
+
+    if cat_id == "root":
+        children = await category_service.get_children(session)
+        kb = await render_category(children, show_menu=True)
+
+    else:
+        cat_id = int(cat_id)
+
+        children = await category_service.get_children(session, cat_id)
+        category = await categories_repo.get_category_by_id(session, cat_id)
+        parent_id = category.parent_id or "root"
+        kb = await render_category(children, parent_id)
+
+    await cb.message.edit_text(
+        "category selection",
+        reply_markup=kb,
+    )
diff --git a/main.py b/main.py
index fa88832..eef6048 100644
--- a/main.py
+++ b/main.py
@@ -8,9 +8,11 @@ from handlers import init_handlers
 from middlewares.di import DIMiddleware
 from middlewares.repository import RepositoryMiddleware
 from middlewares.session import DBSessionMiddleware
+from repositories.categories import CategoriesRepository
 from repositories.orders import OrderRepository
 from services import OrderService
 from db.base import async_session
+from services.categories import CategoryService
 
 logging.basicConfig(level=logging.DEBUG)
 
@@ -26,11 +28,18 @@ async def main():
     order_repository = OrderRepository()
     order_service = OrderService(order_repository)
 
+    category_repository = CategoriesRepository()
+    category_service = CategoryService(category_repository)
+
     # DI Middleware Init
-    dp.message.middleware(DIMiddleware(order_service))
+    dp.message.middleware(DIMiddleware(order_service, category_service))
     dp.message.middleware(DBSessionMiddleware(async_session))
     dp.message.middleware(RepositoryMiddleware())
 
+    dp.callback_query.middleware(DIMiddleware(order_service, category_service))
+    dp.callback_query.middleware(DBSessionMiddleware(async_session))
+    dp.callback_query.middleware(RepositoryMiddleware())
+
     init_handlers(dp)
 
     await dp.start_polling(bot)
diff --git a/middlewares/di.py b/middlewares/di.py
index d3acb6a..4c3e26a 100644
--- a/middlewares/di.py
+++ b/middlewares/di.py
@@ -1,12 +1,14 @@
 from aiogram import BaseMiddleware
 from typing import Any, Callable
 
+from services.categories import CategoryService
 from services.orders import OrderService
 
 
 class DIMiddleware(BaseMiddleware):
-    def __init__(self, order_service: OrderService):
+    def __init__(self, order_service: OrderService, category_service: CategoryService):
         self._order_service = order_service
+        self._category_service = category_service
 
     async def __call__(
         self,
@@ -15,5 +17,6 @@ class DIMiddleware(BaseMiddleware):
         data: dict[str, Any],
     ) -> Any:
         data["order_service"] = self._order_service
+        data["category_service"] = self._category_service
 
         return await handler(event, data)
diff --git a/middlewares/repository.py b/middlewares/repository.py
index bf99883..7b50694 100644
--- a/middlewares/repository.py
+++ b/middlewares/repository.py
@@ -1,9 +1,10 @@
 from aiogram import BaseMiddleware
 
-from repositories.orders import OrderRepository
+from repositories import OrderRepository, CategoriesRepository
 
 
 class RepositoryMiddleware(BaseMiddleware):
     async def __call__(self, handler, event, data):
         data["order_repo"] = OrderRepository()
+        data["categories_repo"] = CategoriesRepository()
         return await handler(event, data)
diff --git a/misc/kb/client.py b/misc/kb/client.py
index 131e4d2..ecdbcb3 100644
--- a/misc/kb/client.py
+++ b/misc/kb/client.py
@@ -1,20 +1,58 @@
+from typing import Optional
+
 from aiogram.types import InlineKeyboardButton, InlineKeyboardMarkup
 from aiogram.utils.keyboard import InlineKeyboardBuilder
 
+from dto.categories import CategoryDTO
 
-async def cart_btn(user_id: int) -> InlineKeyboardButton:
+
+def cart_btn(user_id: int) -> InlineKeyboardButton:
     return InlineKeyboardButton(
         text="🛒 Корзина ()", callback_data="cart"
     )  # TODO: Database integration, get cart items count
 
 
+def get_back_btn(
+    data: str = "menu:main", text: Optional[str] = "⬅️ Назад"
+) -> InlineKeyboardButton:
+    return InlineKeyboardButton(text=text, callback_data=data)
+
+
 async def main_menu_kb(user_id: int) -> InlineKeyboardMarkup:
     return InlineKeyboardBuilder(
         [
             [
-                InlineKeyboardButton(text="📦 Каталог", callback_data="catalogue"),
+                InlineKeyboardButton(text="📦 Каталог", callback_data="cat:root"),
                 InlineKeyboardButton(text="🔍", callback_data="find"),
             ],
-            [await cart_btn(user_id)],
+            [cart_btn(user_id)],
         ]
     ).as_markup()
+
+
+async def render_category(
+    children: list[CategoryDTO],
+    parent_id: Optional[int] = None,
+    show_menu: bool = False,
+) -> InlineKeyboardMarkup:
+    btns = [
+        InlineKeyboardButton(
+            text=category.name,
+            callback_data=f"cat:{category.id}",
+        )
+        for category in children
+    ]
+
+    nav = []
+
+    if parent_id is not None:
+        nav.append(
+            InlineKeyboardButton(text="⬅️ Назад", callback_data=f"cat:{parent_id}")
+        )
+
+    if show_menu:
+        nav.append(InlineKeyboardButton(text="⬅️ Назад", callback_data="menu:main"))
+
+    return InlineKeyboardBuilder(
+        [btns[i : i + 2] for i in range(0, len(children), 2)] + [nav],
+    ).as_markup()
diff --git a/postgresql.fish b/postgresql.fish
index 7c61324..55f0c03 100755
--- a/postgresql.fish
+++ b/postgresql.fish
@@ -1 +1,2 @@
-docker run --name test-postgres -e POSTGRES_PASSWORD=HEXDEVFUCKINGSUCKS! -p 5432:5432 -d postgres
\ No newline at end of file
+docker start test-postgres
+pg_isready -h localhost -p 5432
\ No newline at end of file
diff --git a/repositories/__init__.py b/repositories/__init__.py
index e69de29..78afc50 100644
--- a/repositories/__init__.py
+++ b/repositories/__init__.py
@@ -0,0 +1,4 @@
+from .orders import OrderRepository
+from .categories import CategoriesRepository
+
+__all__ = ["OrderRepository", "CategoriesRepository"]
diff --git a/repositories/categories.py b/repositories/categories.py
new file mode 100644
index 0000000..f9c6830
--- /dev/null
+++ b/repositories/categories.py
@@ -0,0 +1,21 @@
+from sqlalchemy.ext.asyncio import AsyncSession
+from sqlalchemy import select
+from typing import Optional
+
+from db.models import Category
+
+
+class CategoriesRepository:
+    async def get_category_by_id(
+        self, session: AsyncSession, category_id: int
+    ) -> Optional[Category]:
+        stmt = select(Category).where(Category.id == category_id)
+        return await session.scalar(stmt)
+
+    async def get_category_by_parent_id(
+        self, session: AsyncSession, parent_id: Optional[int] = None
+    ) -> list[Category]:
+        stmt = select(Category).where(Category.parent_id == parent_id)
+        result = await session.scalars(stmt)
+
+        return list(result)
diff --git a/repositories/orders.py b/repositories/orders.py
index 1618d70..b8bde11 100644
--- a/repositories/orders.py
+++ b/repositories/orders.py
@@ -1,8 +1,8 @@
 from sqlalchemy.ext.asyncio import AsyncSession
 from sqlalchemy import select
-from typing import Optional, Union, List
+from typing import Optional
 
-from db.models import Order, OrderItem, OrderStatus
+from db.models import Order
 
 
 class OrderRepository:
diff --git a/services/categories.py b/services/categories.py
new file mode 100644
index 0000000..0a36ff8
--- /dev/null
+++ b/services/categories.py
@@ -0,0 +1,18 @@
+from typing import Optional
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from dto.categories import CategoryDTO
+from repositories import CategoriesRepository
+
+
+class CategoryService:
+    def __init__(self, category_repo: CategoriesRepository):
+        self.category_repo = category_repo
+
+    async def get_children(
+        self, session: AsyncSession, parent_id: Optional[int] = None
+    ) -> list[CategoryDTO]:
+        result = await self.category_repo.get_category_by_parent_id(session, parent_id)
+        return [
+            CategoryDTO(x.id, x.name) for x in result
+        ]  # FIXME: Optimization may be required here - O(n)
diff --git a/startup.sh b/startup.sh
new file mode 100644
index 0000000..8b3ad8f
--- /dev/null
+++ b/startup.sh
@@ -0,0 +1,19 @@
+#!/bin/bash
+
+set -e
+
+echo "formatting..."
+black .
+
+echo "checking psql..."
+if ! pg_isready -h localhost -p 5432; then
+    echo "psql is down, try again" >&2
+    exit 1
+fi
+echo "psql is up and is recieving connections."
+
+echo "running migrations..."
+alembic upgrade head
+
+echo "starting the bot..."
+exec python main.py
\ No newline at end of file