From fb8c221ee9fe40cea1ba20b7e0ff76bdc6939016 Mon Sep 17 00:00:00 2001
From: Paul de Raaij <paul@paulderaaij.nl>
Date: Sun, 26 Jul 2026 07:09:37 -0400
Subject: [PATCH] feat: add UserId value object and update ClassifiedAd to use
 it

---
 .agent/current-plan.md              | 32 +++++++++++------------------
 domain/__init__.py                  |  2 +-
 domain/marketplace/__init__.py      |  3 ++-
 domain/marketplace/classified_ad.py |  6 ++++--
 domain/marketplace/user_id.py       |  7 +++++++
 tests/test_classified_ad.py         | 11 +++++-----
 tests/test_user_id.py               | 25 ++++++++++++++++++++++
 7 files changed, 57 insertions(+), 29 deletions(-)
 create mode 100644 domain/marketplace/user_id.py
 create mode 100644 tests/test_user_id.py

diff --git a/.agent/current-plan.md b/.agent/current-plan.md
index ef75c1b..52fdc05 100644
--- a/.agent/current-plan.md
+++ b/.agent/current-plan.md
@@ -1,35 +1,27 @@
-# Plan: ClassifiedAd Domain Entity
+# Plan: UserId Value Object
 
 ## Status: COMPLETED
 
 ## Objective
-Create the first Domain Entity representing a ClassifiedAd with the specified attributes.
+Create a UserId value object in the marketplace domain with an immutable UUID value.
 
 ## Decisions Made
-- **Location**: `domain/marketplace/classified_ad.py`
+- **Location**: `domain/marketplace/user_id.py`
 - **Class style**: `@dataclass(frozen=True)` for immutability
-- **Validation**: No validation, just hold data
-- **Tests**: Yes, create unit tests
+- **Tests**: Yes
 
-## Entity Structure
+## Value Object Structure
 ```python
 @dataclass(frozen=True)
-class ClassifiedAd:
-    id: UUID
-    _ownerId: UUID
-    title: str
-    text: str
-    _price: Decimal
+class UserId:
+    value: UUID
 ```
 
 ## Files Created
-- `domain/__init__.py`
-- `domain/marketplace/__init__.py`
-- `domain/marketplace/classified_ad.py`
-- `tests/test_classified_ad.py`
-- `pyproject.toml`
+- `domain/marketplace/user_id.py`
+- `tests/test_user_id.py`
 
 ## Test Results
-- `test_classified_ad_creation` - PASSED
-- `test_classified_ad_is_immutable` - PASSED
-- `test_classified_ad_equality` - PASSED
\ No newline at end of file
+- `test_user_id_creation` - PASSED
+- `test_user_id_is_immutable` - PASSED
+- `test_user_id_equality` - PASSED
\ No newline at end of file
diff --git a/domain/__init__.py b/domain/__init__.py
index 2dc0adf..d27fd9a 100644
--- a/domain/__init__.py
+++ b/domain/__init__.py
@@ -1 +1 @@
-from .marketplace import classified_ad
\ No newline at end of file
+from .marketplace import classified_ad as classified_ad
\ No newline at end of file
diff --git a/domain/marketplace/__init__.py b/domain/marketplace/__init__.py
index b39d335..daa252c 100644
--- a/domain/marketplace/__init__.py
+++ b/domain/marketplace/__init__.py
@@ -1 +1,2 @@
-from .classified_ad import ClassifiedAd
\ No newline at end of file
+from .classified_ad import ClassifiedAd as ClassifiedAd
+from .user_id import UserId as UserId
\ No newline at end of file
diff --git a/domain/marketplace/classified_ad.py b/domain/marketplace/classified_ad.py
index 663d3d6..22ab7ec 100644
--- a/domain/marketplace/classified_ad.py
+++ b/domain/marketplace/classified_ad.py
@@ -2,11 +2,13 @@ from dataclasses import dataclass
 from decimal import Decimal
 from uuid import UUID
 
+from domain.marketplace.user_id import UserId
+
 
 @dataclass(frozen=True)
 class ClassifiedAd:
     id: UUID
-    _ownerId: UUID
+    _ownerId: UserId
     title: str
     text: str
-    _price: Decimal
\ No newline at end of file
+    _price: Decimal
diff --git a/domain/marketplace/user_id.py b/domain/marketplace/user_id.py
new file mode 100644
index 0000000..f708208
--- /dev/null
+++ b/domain/marketplace/user_id.py
@@ -0,0 +1,7 @@
+from dataclasses import dataclass
+from uuid import UUID
+
+
+@dataclass(frozen=True)
+class UserId:
+    value: UUID
diff --git a/tests/test_classified_ad.py b/tests/test_classified_ad.py
index 6433bfc..0d3b884 100644
--- a/tests/test_classified_ad.py
+++ b/tests/test_classified_ad.py
@@ -1,12 +1,13 @@
 from decimal import Decimal
-from uuid import UUID, uuid4
+from uuid import uuid4
 
 from domain.marketplace.classified_ad import ClassifiedAd
+from domain.marketplace.user_id import UserId
 
 
 def test_classified_ad_creation():
     ad_id = uuid4()
-    owner_id = uuid4()
+    owner_id = UserId(value=uuid4())
 
     ad = ClassifiedAd(
         id=ad_id,
@@ -26,7 +27,7 @@ def test_classified_ad_creation():
 def test_classified_ad_is_immutable():
     ad = ClassifiedAd(
         id=uuid4(),
-        _ownerId=uuid4(),
+        _ownerId=UserId(value=uuid4()),
         title="Title",
         text="Text",
         _price=Decimal("10.00"),
@@ -41,7 +42,7 @@ def test_classified_ad_is_immutable():
 
 def test_classified_ad_equality():
     ad_id = uuid4()
-    owner_id = uuid4()
+    owner_id = UserId(value=uuid4())
 
     ad1 = ClassifiedAd(
         id=ad_id,
@@ -58,4 +59,4 @@ def test_classified_ad_equality():
         _price=Decimal("10.00"),
     )
 
-    assert ad1 == ad2
\ No newline at end of file
+    assert ad1 == ad2
diff --git a/tests/test_user_id.py b/tests/test_user_id.py
new file mode 100644
index 0000000..3d9f6e9
--- /dev/null
+++ b/tests/test_user_id.py
@@ -0,0 +1,25 @@
+from uuid import UUID, uuid4
+
+from domain.marketplace.user_id import UserId
+
+
+def test_user_id_creation():
+    user_id = UserId(value=uuid4())
+    assert isinstance(user_id.value, UUID)
+
+
+def test_user_id_is_immutable():
+    user_id = UserId(value=uuid4())
+
+    try:
+        user_id.value = uuid4()  # type: ignore
+        assert False, "Should have raised FrozenInstanceError"
+    except AttributeError:
+        pass
+
+
+def test_user_id_equality():
+    uid = uuid4()
+    user_id1 = UserId(value=uid)
+    user_id2 = UserId(value=uid)
+    assert user_id1 == user_id2