Add pytest test suite (92 tests, all passing)

Covers every module in src/ with unit tests:

- tests/conftest.py        shared fixtures (complete_registration, fresh_state, …)
- tests/test_models.py     RegistrationData.is_complete(), to_dict/from_dict round-trips
- tests/test_storage.py    normalize_email, _diff_registrations, ConversationStore CRUD,
                           registration versioning
- tests/test_llm.py        litellm wrapper — message construction, model passthrough,
                           error propagation
- tests/test_agent.py      EmailAgent — new/existing conversations, registration
                           completion, admin notification, fallback on LLM error,
                           JSON parsing, _apply_updates
- tests/test_notifier.py   AdminNotifier routing, fee calculation, SMTP dispatch
- tests/test_knowledge_base.py  KnowledgeBase loading and reload

All external I/O (litellm, SMTP, filesystem) is mocked. Tests run fast (~6s)
with no network access required.

https://claude.ai/code/session_01HaUFs7SaLD5SoiuGCY27Tw

tests/test_storage.py

@@ -0,0 +1,159 @@
+"""Tests for ConversationStore and storage helpers."""
+
+import json
+from pathlib import Path
+
+import pytest
+
+from src.storage.json_store import (
+    ConversationStore,
+    normalize_email,
+    _diff_registrations,
+)
+from src.models.conversation import ConversationState
+
+
+# ---------------------------------------------------------------------------
+# normalize_email
+# ---------------------------------------------------------------------------
+
+
+class TestNormalizeEmail:
+    def test_lowercases(self):
+        assert normalize_email("Anna.Muster@Example.COM") == "anna.muster@example.com"
+
+    def test_strips_whitespace(self):
+        assert normalize_email("  user@example.com  ") == "user@example.com"
+
+    def test_already_normalized(self):
+        assert normalize_email("user@example.com") == "user@example.com"
+
+
+# ---------------------------------------------------------------------------
+# _diff_registrations
+# ---------------------------------------------------------------------------
+
+
+class TestDiffRegistrations:
+    def test_detects_changed_field(self):
+        old = {"child": {"fullName": "Lena"}}
+        new = {"child": {"fullName": "Lena Muster"}}
+        diff = _diff_registrations(old, new)
+        assert "child.fullName" in diff
+        assert diff["child.fullName"] == ("Lena", "Lena Muster")
+
+    def test_unchanged_fields_not_included(self):
+        old = {"child": {"fullName": "Lena", "dateOfBirth": "2022-01-01"}}
+        new = {"child": {"fullName": "Lena", "dateOfBirth": "2022-01-01"}}
+        assert _diff_registrations(old, new) == {}
+
+    def test_nested_change_detected(self):
+        old = {"parentGuardian": {"email": "old@example.com"}}
+        new = {"parentGuardian": {"email": "new@example.com"}}
+        diff = _diff_registrations(old, new)
+        assert "parentGuardian.email" in diff
+
+
+# ---------------------------------------------------------------------------
+# ConversationStore — CRUD
+# ---------------------------------------------------------------------------
+
+
+@pytest.fixture
+def store(tmp_path) -> ConversationStore:
+    return ConversationStore(tmp_path)
+
+
+class TestConversationStoreCRUD:
+    def test_load_returns_none_for_unknown_email(self, store):
+        assert store.load("nobody@example.com") is None
+
+    def test_save_and_load_round_trip(self, store, fresh_state):
+        store.save(fresh_state)
+        loaded = store.load(fresh_state.parent_email)
+        assert loaded is not None
+        assert loaded.conversation_id == fresh_state.conversation_id
+
+    def test_save_overwrites_existing(self, store, fresh_state):
+        store.save(fresh_state)
+        fresh_state.language = "en"
+        store.save(fresh_state)
+        loaded = store.load(fresh_state.parent_email)
+        assert loaded.language == "en"
+
+    def test_delete_removes_conversation(self, store, fresh_state):
+        store.save(fresh_state)
+        store.delete(fresh_state.parent_email)
+        assert store.load(fresh_state.parent_email) is None
+
+    def test_delete_nonexistent_is_silent(self, store):
+        store.delete("ghost@example.com")  # should not raise
+
+    def test_list_incomplete_returns_non_completed(self, store, fresh_state):
+        store.save(fresh_state)
+        incomplete = store.list_incomplete()
+        assert any(s.conversation_id == fresh_state.conversation_id for s in incomplete)
+
+    def test_list_incomplete_excludes_completed(self, store, fresh_state):
+        fresh_state.completed = True
+        store.save(fresh_state)
+        incomplete = store.list_incomplete()
+        assert all(not s.completed for s in incomplete)
+
+    def test_find_by_email_is_alias_for_load(self, store, fresh_state):
+        store.save(fresh_state)
+        assert store.find_by_email(fresh_state.parent_email) is not None
+
+
+# ---------------------------------------------------------------------------
+# ConversationStore — registration versioning
+# ---------------------------------------------------------------------------
+
+
+class TestRegistrationVersioning:
+    def test_save_registration_creates_version_1(self, store, fresh_state, complete_registration):
+        fresh_state.registration = complete_registration
+        fresh_state.completed = True
+        email_key, version = store.save_registration(fresh_state)
+        assert version == 1
+        # email_key is the filesystem-safe form (@ → _at_)
+        assert email_key == "anna.muster_at_example.com"
+
+    def test_save_registration_writes_current_json(self, store, fresh_state, complete_registration, tmp_path):
+        fresh_state.registration = complete_registration
+        fresh_state.completed = True
+        email_key, _ = store.save_registration(fresh_state)
+        current = tmp_path / "registrations" / email_key / "current.json"
+        assert current.exists()
+
+    def test_save_registration_version_increments(self, store, fresh_state, complete_registration):
+        fresh_state.registration = complete_registration
+        fresh_state.completed = True
+        store.save_registration(fresh_state)
+        _, v2 = store.save_registration_version(
+            fresh_state, {"child.fullName": ("Old", "New")}
+        )
+        assert v2 == 2
+
+    def test_get_current_registration_returns_latest(self, store, fresh_state, complete_registration):
+        fresh_state.registration = complete_registration
+        fresh_state.completed = True
+        store.save_registration(fresh_state)
+        current = store.get_current_registration(fresh_state.parent_email)
+        assert current is not None
+        assert current["metadata"]["version"] == 1
+
+    def test_get_registration_history_returns_all_versions(self, store, fresh_state, complete_registration):
+        fresh_state.registration = complete_registration
+        fresh_state.completed = True
+        store.save_registration(fresh_state)
+        store.save_registration_version(fresh_state, {"child.fullName": ("A", "B")})
+        history = store.get_registration_history(fresh_state.parent_email)
+        assert len(history) == 2
+
+    def test_list_registrations_includes_saved(self, store, fresh_state, complete_registration):
+        fresh_state.registration = complete_registration
+        fresh_state.completed = True
+        store.save_registration(fresh_state)
+        registrations = store.list_registrations()
+        assert len(registrations) == 1