diff --git a/src/example/note/sqlite_repository.py b/src/example/note/sqlite_repository.py
new file mode 100644
index 0000000..b178b62
--- /dev/null
+++ b/src/example/note/sqlite_repository.py
@@ -0,0 +1,52 @@
+"""SQLite-backed Note repository using SQLAlchemy Core."""
+
+from nene2.database import DatabaseQueryExecutorInterface
+
+from .entity import Note
+from .repository import NoteRepositoryInterface
+
+
+class SqliteNoteRepository(NoteRepositoryInterface):
+    """Persistent Note repository backed by a SQL database via SQLAlchemy Core."""
+
+    def __init__(self, executor: DatabaseQueryExecutorInterface) -> None:
+        self._executor = executor
+
+    def find_all(self, limit: int, offset: int) -> list[Note]:
+        rows = self._executor.fetch_all(
+            "SELECT id, title, body FROM notes ORDER BY id LIMIT :limit OFFSET :offset",
+            {"limit": limit, "offset": offset},
+        )
+        return [Note(id=row["id"], title=row["title"], body=row["body"]) for row in rows]
+
+    def find_by_id(self, note_id: int) -> Note | None:
+        row = self._executor.fetch_one(
+            "SELECT id, title, body FROM notes WHERE id = :id",
+            {"id": note_id},
+        )
+        return Note(id=row["id"], title=row["title"], body=row["body"]) if row else None
+
+    def save(self, title: str, body: str) -> Note:
+        new_id = self._executor.write(
+            "INSERT INTO notes (title, body) VALUES (:title, :body)",
+            {"title": title, "body": body},
+        )
+        return Note(id=new_id, title=title, body=body)
+
+    def update(self, note_id: int, title: str, body: str) -> Note | None:
+        affected = self._executor.write(
+            "UPDATE notes SET title = :title, body = :body WHERE id = :id",
+            {"title": title, "body": body, "id": note_id},
+        )
+        return Note(id=note_id, title=title, body=body) if affected > 0 else None
+
+    def delete(self, note_id: int) -> bool:
+        affected = self._executor.write(
+            "DELETE FROM notes WHERE id = :id",
+            {"id": note_id},
+        )
+        return affected > 0
+
+    def count(self) -> int:
+        row = self._executor.fetch_one("SELECT COUNT(*) AS cnt FROM notes")
+        return int(row["cnt"]) if row else 0
diff --git a/src/example/tag/sqlite_repository.py b/src/example/tag/sqlite_repository.py
new file mode 100644
index 0000000..5aaf8df
--- /dev/null
+++ b/src/example/tag/sqlite_repository.py
@@ -0,0 +1,52 @@
+"""SQLite-backed Tag repository using SQLAlchemy Core."""
+
+from nene2.database import DatabaseQueryExecutorInterface
+
+from .entity import Tag
+from .repository import TagRepositoryInterface
+
+
+class SqliteTagRepository(TagRepositoryInterface):
+    """Persistent Tag repository backed by a SQL database via SQLAlchemy Core."""
+
+    def __init__(self, executor: DatabaseQueryExecutorInterface) -> None:
+        self._executor = executor
+
+    def find_all(self, limit: int, offset: int) -> list[Tag]:
+        rows = self._executor.fetch_all(
+            "SELECT id, name FROM tags ORDER BY id LIMIT :limit OFFSET :offset",
+            {"limit": limit, "offset": offset},
+        )
+        return [Tag(id=row["id"], name=row["name"]) for row in rows]
+
+    def find_by_id(self, tag_id: int) -> Tag | None:
+        row = self._executor.fetch_one(
+            "SELECT id, name FROM tags WHERE id = :id",
+            {"id": tag_id},
+        )
+        return Tag(id=row["id"], name=row["name"]) if row else None
+
+    def save(self, name: str) -> Tag:
+        new_id = self._executor.write(
+            "INSERT INTO tags (name) VALUES (:name)",
+            {"name": name},
+        )
+        return Tag(id=new_id, name=name)
+
+    def update(self, tag_id: int, name: str) -> Tag | None:
+        affected = self._executor.write(
+            "UPDATE tags SET name = :name WHERE id = :id",
+            {"name": name, "id": tag_id},
+        )
+        return Tag(id=tag_id, name=name) if affected > 0 else None
+
+    def delete(self, tag_id: int) -> bool:
+        affected = self._executor.write(
+            "DELETE FROM tags WHERE id = :id",
+            {"id": tag_id},
+        )
+        return affected > 0
+
+    def count(self) -> int:
+        row = self._executor.fetch_one("SELECT COUNT(*) AS cnt FROM tags")
+        return int(row["cnt"]) if row else 0
diff --git a/tests/example/note/test_note_repository.py b/tests/example/note/test_note_repository.py
new file mode 100644
index 0000000..a1da2a2
--- /dev/null
+++ b/tests/example/note/test_note_repository.py
@@ -0,0 +1,89 @@
+"""Repository contract tests — run against both InMemory and SQLite implementations."""
+
+import pytest
+from sqlalchemy import create_engine
+
+from nene2.database import SqlAlchemyQueryExecutor
+from src.example.note.entity import Note
+from src.example.note.repository import InMemoryNoteRepository, NoteRepositoryInterface
+from src.example.note.sqlite_repository import SqliteNoteRepository
+
+
+def _create_schema(executor: SqlAlchemyQueryExecutor) -> None:
+    executor.write(
+        "CREATE TABLE IF NOT EXISTS notes ("
+        "id INTEGER PRIMARY KEY AUTOINCREMENT,"
+        "title TEXT NOT NULL,"
+        "body TEXT NOT NULL,"
+        "created_at DATETIME DEFAULT CURRENT_TIMESTAMP,"
+        "updated_at DATETIME DEFAULT CURRENT_TIMESTAMP"
+        ")"
+    )
+
+
+def _sqlite_repo() -> SqliteNoteRepository:
+    engine = create_engine("sqlite:///:memory:")
+    executor = SqlAlchemyQueryExecutor(engine)
+    _create_schema(executor)
+    return SqliteNoteRepository(executor)
+
+
+@pytest.fixture(params=["inmemory", "sqlite"])
+def repo(request: pytest.FixtureRequest) -> NoteRepositoryInterface:
+    if request.param == "inmemory":
+        return InMemoryNoteRepository()
+    return _sqlite_repo()
+
+
+def test_save_and_find_by_id(repo: NoteRepositoryInterface) -> None:
+    note = repo.save("Hello", "World")
+    found = repo.find_by_id(note.id)
+    assert found == note
+
+
+def test_find_by_id_returns_none_when_missing(repo: NoteRepositoryInterface) -> None:
+    assert repo.find_by_id(9999) is None
+
+
+def test_find_all_returns_saved_notes(repo: NoteRepositoryInterface) -> None:
+    repo.save("A", "a")
+    repo.save("B", "b")
+    items = repo.find_all(limit=10, offset=0)
+    assert len(items) == 2
+    assert items[0].title == "A"
+    assert items[1].title == "B"
+
+
+def test_find_all_respects_limit_and_offset(repo: NoteRepositoryInterface) -> None:
+    for i in range(5):
+        repo.save(f"Note {i}", "body")
+    page = repo.find_all(limit=2, offset=2)
+    assert len(page) == 2
+    assert page[0].title == "Note 2"
+
+
+def test_count_reflects_saved_notes(repo: NoteRepositoryInterface) -> None:
+    assert repo.count() == 0
+    repo.save("T", "B")
+    repo.save("T2", "B2")
+    assert repo.count() == 2
+
+
+def test_update_changes_title_and_body(repo: NoteRepositoryInterface) -> None:
+    note = repo.save("Old", "old body")
+    updated = repo.update(note.id, "New", "new body")
+    assert updated == Note(id=note.id, title="New", body="new body")
+
+
+def test_update_returns_none_for_missing_id(repo: NoteRepositoryInterface) -> None:
+    assert repo.update(9999, "T", "B") is None
+
+
+def test_delete_removes_note(repo: NoteRepositoryInterface) -> None:
+    note = repo.save("T", "B")
+    assert repo.delete(note.id) is True
+    assert repo.find_by_id(note.id) is None
+
+
+def test_delete_returns_false_for_missing_id(repo: NoteRepositoryInterface) -> None:
+    assert repo.delete(9999) is False
diff --git a/tests/example/tag/test_tag_repository.py b/tests/example/tag/test_tag_repository.py
new file mode 100644
index 0000000..a823f30
--- /dev/null
+++ b/tests/example/tag/test_tag_repository.py
@@ -0,0 +1,84 @@
+"""Repository contract tests — run against both InMemory and SQLite implementations."""
+
+import pytest
+from sqlalchemy import create_engine
+
+from nene2.database import SqlAlchemyQueryExecutor
+from src.example.tag.entity import Tag
+from src.example.tag.repository import InMemoryTagRepository, TagRepositoryInterface
+from src.example.tag.sqlite_repository import SqliteTagRepository
+
+
+def _create_schema(executor: SqlAlchemyQueryExecutor) -> None:
+    executor.write(
+        "CREATE TABLE IF NOT EXISTS tags ("
+        "id INTEGER PRIMARY KEY AUTOINCREMENT,"
+        "name TEXT NOT NULL UNIQUE,"
+        "created_at DATETIME DEFAULT CURRENT_TIMESTAMP"
+        ")"
+    )
+
+
+def _sqlite_repo() -> SqliteTagRepository:
+    engine = create_engine("sqlite:///:memory:")
+    executor = SqlAlchemyQueryExecutor(engine)
+    _create_schema(executor)
+    return SqliteTagRepository(executor)
+
+
+@pytest.fixture(params=["inmemory", "sqlite"])
+def repo(request: pytest.FixtureRequest) -> TagRepositoryInterface:
+    if request.param == "inmemory":
+        return InMemoryTagRepository()
+    return _sqlite_repo()
+
+
+def test_save_and_find_by_id(repo: TagRepositoryInterface) -> None:
+    tag = repo.save("python")
+    found = repo.find_by_id(tag.id)
+    assert found == tag
+
+
+def test_find_by_id_returns_none_when_missing(repo: TagRepositoryInterface) -> None:
+    assert repo.find_by_id(9999) is None
+
+
+def test_find_all_returns_saved_tags(repo: TagRepositoryInterface) -> None:
+    repo.save("python")
+    repo.save("fastapi")
+    items = repo.find_all(limit=10, offset=0)
+    assert len(items) == 2
+
+
+def test_find_all_respects_limit_and_offset(repo: TagRepositoryInterface) -> None:
+    for name in ["a", "b", "c", "d", "e"]:
+        repo.save(name)
+    page = repo.find_all(limit=2, offset=2)
+    assert len(page) == 2
+
+
+def test_count_reflects_saved_tags(repo: TagRepositoryInterface) -> None:
+    assert repo.count() == 0
+    repo.save("x")
+    repo.save("y")
+    assert repo.count() == 2
+
+
+def test_update_changes_name(repo: TagRepositoryInterface) -> None:
+    tag = repo.save("old")
+    updated = repo.update(tag.id, "new")
+    assert updated == Tag(id=tag.id, name="new")
+
+
+def test_update_returns_none_for_missing_id(repo: TagRepositoryInterface) -> None:
+    assert repo.update(9999, "x") is None
+
+
+def test_delete_removes_tag(repo: TagRepositoryInterface) -> None:
+    tag = repo.save("temp")
+    assert repo.delete(tag.id) is True
+    assert repo.find_by_id(tag.id) is None
+
+
+def test_delete_returns_false_for_missing_id(repo: TagRepositoryInterface) -> None:
+    assert repo.delete(9999) is False