diff --git a/backend/app/middleware/security.py b/backend/app/middleware/security.py
index b58d2f6..aba4c3a 100644
--- a/backend/app/middleware/security.py
+++ b/backend/app/middleware/security.py
@@ -52,29 +52,29 @@ class SecurityHeadersMiddleware(BaseHTTPMiddleware):
 
         # Content Security Policy (CSP)
         # Restricts sources of content that can be loaded
-        # 
+        #
         # SECURITY TODO: Current CSP includes 'unsafe-inline' and 'unsafe-eval' which
         # weaken XSS protection. To remove these:
-        # 
+        #
         # For script-src 'unsafe-inline':
         # 1. Move all inline <script> tags from templates to external .js files
         # 2. OR implement CSP nonces for inline scripts (requires template changes)
         # 3. Convert any inline event handlers (onclick, etc.) to addEventListener
-        # 
+        #
         # For script-src 'unsafe-eval':
         # 1. Verify no code uses eval(), Function(), setTimeout/setInterval with strings
         # 2. If using libraries that require eval, consider alternatives
         # 3. Current scan shows no eval usage - can likely remove this directive
-        # 
+        #
         # For style-src 'unsafe-inline':
         # 1. Move inline styles to CSS files or use style tags with nonces
         # 2. Replace style="" attributes with CSS classes
         # 3. OR implement CSP nonces for inline styles
-        # 
+        #
         # Target secure CSP (no inline):
         # "script-src 'self'"
         # "style-src 'self' https://fonts.googleapis.com"
-        # 
+        #
         # See: https://developer.mozilla.org/en-US/docs/Web/HTTP/CSP
         csp_directives = [
             "default-src 'self'",
diff --git a/backend/app/models/report.py b/backend/app/models/report.py
index e982468..f9102b5 100644
--- a/backend/app/models/report.py
+++ b/backend/app/models/report.py
@@ -21,7 +21,7 @@ class DMARCReport(Base):
     source_email = Column(String, nullable=True)
 
     # Policy information
-    policy = Column(String, nullable=True, index=True)  # none, quarantine, reject
+    policy = Column(String, nullable=True)  # none, quarantine, reject (indexed via __table_args__)
     subdomain_policy = Column(String, nullable=True)
     adkim = Column(String(1), nullable=True)  # r (relaxed) or s (strict)
     aspf = Column(String(1), nullable=True)  # r (relaxed) or s (strict)
@@ -62,7 +62,7 @@ class ReportRecord(Base):
     count = Column(Integer, nullable=False, default=0)
 
     # Policy evaluation
-    disposition = Column(String, nullable=False, index=True)  # none, quarantine, reject
+    disposition = Column(String, nullable=False)  # none, quarantine, reject (indexed via __table_args__)
     dkim = Column(String, nullable=True, index=True)  # pass, fail
     spf = Column(String, nullable=True, index=True)  # pass, fail
 
diff --git a/backend/app/tests/conftest.py b/backend/app/tests/conftest.py
index f98b060..31035cc 100644
--- a/backend/app/tests/conftest.py
+++ b/backend/app/tests/conftest.py
@@ -1,60 +1,46 @@
-import asyncio
-
 import pytest
-import pytest_asyncio
 from app.core.database import Base, get_db
-from app.core.security import get_password_hash
-from app.models.user import User
+
+# Import all models so Base.metadata knows every table
+import app.models.domain  # noqa: F401
+import app.models.report  # noqa: F401
+import app.models.user  # noqa: F401
+
+from app.services.report_store import ReportStore
 from fastapi import FastAPI
 from fastapi.testclient import TestClient
-from httpx import AsyncClient
 from sqlalchemy import create_engine
 from sqlalchemy.orm import sessionmaker
 
-# Use in-memory SQLite database for tests
-TEST_DATABASE_URL = "sqlite:///./test.db"
 
-
-@pytest.fixture(scope="session")
-def event_loop():
-    """Create an instance of the default event loop for each test case."""
-    loop = asyncio.get_event_loop_policy().new_event_loop()
-    yield loop
-    loop.close()
-
-
-@pytest.fixture(scope="session")
+@pytest.fixture()
 def test_app() -> FastAPI:
-    # Avoid circular import
+    """Create a fresh FastAPI application instance for testing."""
     from app.main import create_app
 
     app = create_app()
     return app
 
 
-@pytest.fixture(scope="function")
+@pytest.fixture()
 def db_session():
-    # Create the SQLite database engine
-    engine = create_engine(TEST_DATABASE_URL)
-
-    # Create all tables
+    """Create a fresh in-memory SQLite database session per test."""
+    engine = create_engine("sqlite://", connect_args={"check_same_thread": False})
     Base.metadata.create_all(engine)
-
-    # Create a new session
     TestingSessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
     db = TestingSessionLocal()
-
     try:
         yield db
     finally:
         db.close()
-        # Drop all tables after the test
         Base.metadata.drop_all(engine)
+        engine.dispose()
 
 
-@pytest.fixture(scope="function")
+@pytest.fixture()
 def client(test_app: FastAPI, db_session):
-    # Override the get_db dependency to use the test database
+    """Create a TestClient with a DB override for the test app."""
+
     def override_get_db():
         try:
             yield db_session
@@ -62,38 +48,15 @@ def client(test_app: FastAPI, db_session):
             pass
 
     test_app.dependency_overrides[get_db] = override_get_db
-
-    # Use the FastAPI TestClient
     with TestClient(test_app) as test_client:
         yield test_client
+    test_app.dependency_overrides.clear()
 
 
-@pytest_asyncio.fixture(scope="function")
-async def async_client(test_app: FastAPI, db_session):
-    # Override the get_db dependency to use the test database
-    def override_get_db():
-        try:
-            yield db_session
-        finally:
-            pass
-
-    test_app.dependency_overrides[get_db] = override_get_db
-
-    async with AsyncClient(app=test_app, base_url="http://testserver") as ac:
-        yield ac
-
-
-@pytest.fixture(scope="function")
-def test_user(db_session):
-    """Create a test user in the database."""
-    user = User(
-        email="test@example.com",
-        hashed_password=get_password_hash("password"),
-        is_active=True,
-        is_superuser=False,
-        is_verified=True,
-    )
-    db_session.add(user)
-    db_session.commit()
-    db_session.refresh(user)
-    return user
+@pytest.fixture(autouse=True)
+def _reset_report_store():
+    """Reset the ReportStore singleton between tests to avoid state leakage."""
+    store = ReportStore.get_instance()
+    store.clear()
+    yield
+    store.clear()
diff --git a/backend/app/tests/test_api.py b/backend/app/tests/test_api.py
index ed77aba..0b6cef1 100644
--- a/backend/app/tests/test_api.py
+++ b/backend/app/tests/test_api.py
@@ -1,10 +1,8 @@
-from app.models.domain import Domain
 from fastapi.testclient import TestClient
-from sqlalchemy.orm import Session
 
 
-def test_read_health(client: TestClient):
-    """Test health check endpoint"""
+def test_health_check(client: TestClient):
+    """Test the health check endpoint returns status ok."""
     response = client.get("/api/v1/health")
     assert response.status_code == 200
     data = response.json()
@@ -12,47 +10,29 @@ def test_read_health(client: TestClient):
     assert "version" in data
 
 
-def test_read_domains_empty(client: TestClient):
-    """Test reading domains when none exist"""
-    response = client.get("/api/v1/domains")
+def test_domains_empty(client: TestClient):
+    """Test that GET /api/v1/domains/domains returns empty list when no reports uploaded."""
+    response = client.get("/api/v1/domains/domains")
     assert response.status_code == 200
     data = response.json()
     assert data == []
 
 
-def test_read_domains(client: TestClient, db_session: Session):
-    """Test reading domains"""
-    # Create some test domains
-    domain1 = Domain(name="example.com", description="Example Domain", active=True)
-    domain2 = Domain(name="test.com", description="Test Domain", active=True)
-    db_session.add_all([domain1, domain2])
-    db_session.commit()
-
-    response = client.get("/api/v1/domains")
-    assert response.status_code == 200
-    data = response.json()
-
-    assert len(data) == 2
-    assert {"name": "example.com", "description": "Example Domain"}.items() <= data[0].items()
-    assert {"name": "test.com", "description": "Test Domain"}.items() <= data[1].items()
-
-
-def test_create_domain(client: TestClient):
-    """Test creating a new domain"""
+def test_reports_upload_invalid_extension(client: TestClient):
+    """Test that uploading a file with an unsupported extension returns 400."""
     response = client.post(
-        "/api/v1/domains",
-        json={"name": "newdomain.com", "description": "New Domain", "active": True},
+        "/api/v1/reports/upload",
+        files={"file": ("report.txt", b"not a report", "text/plain")},
     )
+    assert response.status_code == 400
+    assert "Invalid file type" in response.json()["detail"]
 
-    assert response.status_code == 201
-    data = response.json()
-    assert data["name"] == "newdomain.com"
-    assert data["description"] == "New Domain"
-    assert data["active"] is True
-    assert "id" in data
 
-    # Check that the domain was actually created
-    response = client.get("/api/v1/domains")
-    assert response.status_code == 200
-    domains = response.json()
-    assert any(d["name"] == "newdomain.com" for d in domains)
+def test_reports_upload_empty_file(client: TestClient):
+    """Test that uploading an empty file returns 400."""
+    response = client.post(
+        "/api/v1/reports/upload",
+        files={"file": ("report.xml", b"", "application/xml")},
+    )
+    assert response.status_code == 400
+    assert "empty" in response.json()["detail"].lower()
diff --git a/backend/app/tests/test_dmarc_parser.py b/backend/app/tests/test_dmarc_parser.py
index 54d9a19..9a8adc7 100644
--- a/backend/app/tests/test_dmarc_parser.py
+++ b/backend/app/tests/test_dmarc_parser.py
@@ -1,112 +1,119 @@
-from unittest.mock import MagicMock, patch
+import io
+import zipfile
 
-import defusedxml.ElementTree as ET
+import pytest
 from app.services.dmarc_parser import DMARCParser
 
+SAMPLE_XML = """\
+<?xml version="1.0" encoding="UTF-8" ?>
+<feedback>
+    <report_metadata>
+        <org_name>google.com</org_name>
+        <email>noreply-dmarc-support@google.com</email>
+        <report_id>123456789</report_id>
+        <date_range>
+            <begin>1597449600</begin>
+            <end>1597535999</end>
+        </date_range>
+    </report_metadata>
+    <policy_published>
+        <domain>example.com</domain>
+        <adkim>r</adkim>
+        <aspf>r</aspf>
+        <p>none</p>
+        <sp>none</sp>
+        <pct>100</pct>
+    </policy_published>
+    <record>
+        <row>
+            <source_ip>203.0.113.1</source_ip>
+            <count>2</count>
+            <policy_evaluated>
+                <disposition>none</disposition>
+                <dkim>pass</dkim>
+                <spf>fail</spf>
+            </policy_evaluated>
+        </row>
+        <identifiers>
+            <header_from>example.com</header_from>
+        </identifiers>
+        <auth_results>
+            <dkim>
+                <domain>example.com</domain>
+                <result>pass</result>
+                <selector>default</selector>
+            </dkim>
+            <spf>
+                <domain>example.com</domain>
+                <result>fail</result>
+            </spf>
+        </auth_results>
+    </record>
+</feedback>
+"""
+
 
 class TestDMARCParser:
+    """Tests for the DMARC XML parser."""
 
-    def setup_method(self):
-        """Set up test fixtures"""
-        self.parser = DMARCParser()
+    def test_parse_xml_report(self):
+        """Test parsing a plain XML DMARC report."""
+        xml_bytes = SAMPLE_XML.encode("utf-8")
+        result = DMARCParser.parse_file(xml_bytes, "report.xml")
 
-        # Sample XML string for testing
-        self.sample_xml = """<?xml version="1.0" encoding="UTF-8" ?>
-        <feedback>
-            <report_metadata>
-                <org_name>google.com</org_name>
-                <email>noreply-dmarc-support@google.com</email>
-                <report_id>123456789</report_id>
-                <date_range>
-                    <begin>1597449600</begin>
-                    <end>1597535999</end>
-                </date_range>
-            </report_metadata>
-            <policy_published>
-                <domain>example.com</domain>
-                <adkim>r</adkim>
-                <aspf>r</aspf>
-                <p>none</p>
-                <sp>none</sp>
-                <pct>100</pct>
-            </policy_published>
-            <record>
-                <row>
-                    <source_ip>203.0.113.1</source_ip>
-                    <count>2</count>
-                    <policy_evaluated>
-                        <disposition>none</disposition>
-                        <dkim>pass</dkim>
-                        <spf>fail</spf>
-                    </policy_evaluated>
-                </row>
-                <identifiers>
-                    <header_from>example.com</header_from>
-                </identifiers>
-                <auth_results>
-                    <dkim>
-                        <domain>example.com</domain>
-                        <result>pass</result>
-                        <selector>default</selector>
-                    </dkim>
-                    <spf>
-                        <domain>example.com</domain>
-                        <result>fail</result>
-                    </spf>
-                </auth_results>
-            </record>
-        </feedback>
-        """
+        # Report metadata (flat keys from _parse_xml)
+        assert result["report_id"] == "123456789"
+        assert result["org_name"] == "google.com"
+        assert result["email"] == "noreply-dmarc-support@google.com"
+        assert result["begin_timestamp"] == 1597449600
+        assert result["end_timestamp"] == 1597535999
 
-    def test_parse_aggregate_report_xml(self):
-        """Test parsing an XML aggregate report"""
-        # Use DMARCParser.parse_file with file_content (bytes) and filename
-        xml_bytes = self.sample_xml.encode("utf-8")
-        result = DMARCParser.parse_file(xml_bytes, "test_report.xml")
+        # Policy published
+        assert result["domain"] == "example.com"
+        assert result["policy"]["p"] == "none"
 
-        # Verify report metadata
-        assert result["report_metadata"]["org_name"] == "google.com"
-        assert result["report_metadata"]["email"] == "noreply-dmarc-support@google.com"
-        assert result["report_metadata"]["report_id"] == "123456789"
-        assert result["report_metadata"]["begin_date"] == 1597449600
-        assert result["report_metadata"]["end_date"] == 1597535999
-
-        # Verify policy published
-        assert result["policy_published"]["domain"] == "example.com"
-        assert result["policy_published"]["policy"] == "none"
-
-        # Verify record data
+        # Records
         assert len(result["records"]) == 1
         record = result["records"][0]
         assert record["source_ip"] == "203.0.113.1"
         assert record["count"] == 2
-        assert record["policy_evaluated"]["disposition"] == "none"
-        assert record["policy_evaluated"]["dkim"] == "pass"
-        assert record["policy_evaluated"]["spf"] == "fail"
-        assert record["identifiers"]["header_from"] == "example.com"
+        assert record["disposition"] == "none"
+        assert record["dkim_result"] == "pass"
+        assert record["spf_result"] == "fail"
+        assert record["header_from"] == "example.com"
 
-    @patch("app.services.dmarc_parser.zipfile.ZipFile")
-    def test_parse_aggregate_report_zip(self, mock_zipfile):
-        """Test parsing a zipped aggregate report"""
-        # Setup mock zipfile extraction
-        mock_zip_instance = MagicMock()
-        mock_zipfile.return_value.__enter__.return_value = mock_zip_instance
-        mock_zip_instance.namelist.return_value = ["report.xml"]
-        mock_zip_instance.read.return_value = self.sample_xml.encode("utf-8")
+        # Summary
+        assert result["summary"]["total_count"] == 2
+        assert result["summary"]["passed_count"] == 2  # dkim passed
+        assert result["summary"]["failed_count"] == 0
 
-        # Create fake zip file content
-        zip_content = b"fake_zip_content"
-        result = DMARCParser.parse_file(zip_content, "test_report.zip")
+    def test_parse_zip_report(self):
+        """Test parsing a DMARC report inside a ZIP archive."""
+        xml_bytes = SAMPLE_XML.encode("utf-8")
 
-        # Assertions similar to test_parse_aggregate_report_xml
-        assert result["report_metadata"]["org_name"] == "google.com"
+        zip_buffer = io.BytesIO()
+        with zipfile.ZipFile(zip_buffer, "w") as zf:
+            zf.writestr("report.xml", xml_bytes)
+        zip_content = zip_buffer.getvalue()
+
+        result = DMARCParser.parse_file(zip_content, "report.zip")
+
+        assert result["report_id"] == "123456789"
+        assert result["domain"] == "example.com"
         assert len(result["records"]) == 1
 
-    def test_extract_authentication_results(self):
-        """Test extracting authentication results from report"""
-        # This test was for an internal method that may have changed
-        # The functionality is tested through test_parse_aggregate_report_xml
-        # which validates the full parsing including authentication results
-        import pytest
+    def test_file_too_large(self):
+        """Test that files exceeding the size limit are rejected."""
+        large_content = b"x" * (11 * 1024 * 1024)  # 11 MB
+        with pytest.raises(ValueError, match="too large"):
+            DMARCParser.parse_file(large_content, "report.xml")
 
-        pytest.skip("Internal method test - functionality covered by integration tests")
+    def test_invalid_xml(self):
+        """Test that invalid XML raises a ValueError."""
+        with pytest.raises(ValueError):
+            DMARCParser.parse_file(b"not xml at all", "report.xml")
+
+    def test_unsupported_extension_returns_none(self):
+        """Test that an unsupported file extension raises ValueError."""
+        with pytest.raises(ValueError, match="Could not extract XML"):
+            DMARCParser.parse_file(b"some content", "report.pdf")
diff --git a/backend/app/tests/test_models.py b/backend/app/tests/test_models.py
index 204eb4e..43703b4 100644
--- a/backend/app/tests/test_models.py
+++ b/backend/app/tests/test_models.py
@@ -4,14 +4,15 @@ from sqlalchemy.orm import Session
 
 
 class TestDomainModel:
-    """Tests for the Domain model"""
+    """Tests for the Domain ORM model."""
 
     def test_create_domain(self, db_session: Session):
-        """Test creating a domain in the database"""
         domain = Domain(
-            name="example.com", description="Test domain", active=True, dmarc_policy="quarantine"
+            name="example.com",
+            description="Test domain",
+            active=True,
+            dmarc_policy="quarantine",
         )
-
         db_session.add(domain)
         db_session.commit()
         db_session.refresh(domain)
@@ -23,66 +24,44 @@ class TestDomainModel:
         assert domain.dmarc_policy == "quarantine"
 
     def test_domain_reports_relationship(self, db_session: Session):
-        """Test the relationship between domains and DMARC reports"""
-        # Create a domain
         domain = Domain(name="example.com", active=True)
         db_session.add(domain)
         db_session.commit()
 
-        # Create reports for the domain
-        report1 = DMARCReport(
+        report = DMARCReport(
             domain_id=domain.id,
             report_id="report1",
             org_name="Google",
             begin_date=1597449600,
             end_date=1597535999,
-            source_email="noreply-dmarc-support@google.com",
+            source_email="noreply@google.com",
         )
-
-        report2 = DMARCReport(
-            domain_id=domain.id,
-            report_id="report2",
-            org_name="Microsoft",
-            begin_date=1597536000,
-            end_date=1597622399,
-            source_email="dmarc@microsoft.com",
-        )
-
-        db_session.add_all([report1, report2])
+        db_session.add(report)
         db_session.commit()
 
-        # Query the domain and check its reports
-        domain = db_session.query(Domain).filter_by(name="example.com").first()
-        assert domain is not None
-        assert len(domain.reports) == 2
-        assert domain.reports[0].report_id in ["report1", "report2"]
-        assert domain.reports[1].report_id in ["report1", "report2"]
+        fetched = db_session.query(Domain).filter_by(name="example.com").first()
+        assert fetched is not None
+        assert len(fetched.reports) == 1
+        assert fetched.reports[0].report_id == "report1"
 
 
 class TestDMARCReportModel:
-    """Tests for the DMARCReport model"""
+    """Tests for the DMARCReport ORM model."""
 
     def test_create_report(self, db_session: Session):
-        """Test creating a DMARC report in the database"""
-        # Create a domain first
         domain = Domain(name="example.com", active=True)
         db_session.add(domain)
         db_session.commit()
 
-        # Create a report
         report = DMARCReport(
             domain_id=domain.id,
             report_id="123456789",
             org_name="Google",
             begin_date=1597449600,
             end_date=1597535999,
-            source_email="noreply-dmarc-support@google.com",
+            source_email="noreply@google.com",
             policy="none",
-            adkim="r",
-            aspf="r",
-            percentage=100,
         )
-
         db_session.add(report)
         db_session.commit()
         db_session.refresh(report)
@@ -91,12 +70,9 @@ class TestDMARCReportModel:
         assert report.domain_id == domain.id
         assert report.report_id == "123456789"
         assert report.org_name == "Google"
-        assert report.begin_date == 1597449600
         assert report.policy == "none"
 
     def test_report_records_relationship(self, db_session: Session):
-        """Test the relationship between reports and records"""
-        # Create domain and report
         domain = Domain(name="example.com", active=True)
         db_session.add(domain)
         db_session.commit()
@@ -107,13 +83,12 @@ class TestDMARCReportModel:
             org_name="Google",
             begin_date=1597449600,
             end_date=1597535999,
-            source_email="noreply-dmarc-support@google.com",
+            source_email="noreply@google.com",
         )
         db_session.add(report)
         db_session.commit()
 
-        # Create records for the report
-        record1 = ReportRecord(
+        record = ReportRecord(
             report_id=report.id,
             source_ip="203.0.113.1",
             count=2,
@@ -121,26 +96,11 @@ class TestDMARCReportModel:
             dkim="pass",
             spf="fail",
             header_from="example.com",
-            envelope_from=None,
         )
-
-        record2 = ReportRecord(
-            report_id=report.id,
-            source_ip="203.0.113.2",
-            count=5,
-            disposition="none",
-            dkim="pass",
-            spf="pass",
-            header_from="example.com",
-            envelope_from=None,
-        )
-
-        db_session.add_all([record1, record2])
+        db_session.add(record)
         db_session.commit()
 
-        # Query the report and check its records
-        report = db_session.query(DMARCReport).filter_by(report_id="123456789").first()
-        assert report is not None
-        assert len(report.records) == 2
-        assert report.records[0].source_ip in ["203.0.113.1", "203.0.113.2"]
-        assert report.records[1].source_ip in ["203.0.113.1", "203.0.113.2"]
+        fetched = db_session.query(DMARCReport).filter_by(report_id="123456789").first()
+        assert fetched is not None
+        assert len(fetched.records) == 1
+        assert fetched.records[0].source_ip == "203.0.113.1"
diff --git a/backend/app/tests/test_report_store.py b/backend/app/tests/test_report_store.py
new file mode 100644
index 0000000..ce9f254
--- /dev/null
+++ b/backend/app/tests/test_report_store.py
@@ -0,0 +1,79 @@
+from app.services.report_store import ReportStore
+
+
+def _sample_report(domain: str = "example.com") -> dict:
+    """Return a minimal parsed report dict for testing."""
+    return {
+        "domain": domain,
+        "report_id": "rpt-001",
+        "org_name": "google.com",
+        "begin_date": "2020-08-15T00:00:00",
+        "end_date": "2020-08-15T23:59:59",
+        "begin_timestamp": 1597449600,
+        "end_timestamp": 1597535999,
+        "policy": {"p": "none", "sp": "none", "pct": "100"},
+        "records": [
+            {
+                "source_ip": "203.0.113.1",
+                "count": 5,
+                "disposition": "none",
+                "dkim_result": "pass",
+                "spf_result": "fail",
+                "header_from": domain,
+            }
+        ],
+        "summary": {
+            "total_count": 5,
+            "passed_count": 5,
+            "failed_count": 0,
+            "pass_rate": 100.0,
+        },
+    }
+
+
+class TestReportStore:
+    """Tests for the in-memory ReportStore."""
+
+    def test_add_report_creates_domain(self):
+        store = ReportStore.get_instance()
+        store.add_report(_sample_report("test.com"))
+
+        domains = store.get_domains()
+        assert "test.com" in domains
+
+    def test_domain_summary_after_add(self):
+        store = ReportStore.get_instance()
+        store.add_report(_sample_report("test.com"))
+
+        summary = store.get_domain_summary("test.com")
+        assert summary["total_count"] == 5
+        assert summary["passed_count"] == 5
+        assert summary["reports_processed"] == 1
+
+    def test_get_domain_reports(self):
+        store = ReportStore.get_instance()
+        store.add_report(_sample_report("test.com"))
+
+        reports = store.get_domain_reports("test.com")
+        assert len(reports) == 1
+        assert reports[0]["report_id"] == "rpt-001"
+
+    def test_clear(self):
+        store = ReportStore.get_instance()
+        store.add_report(_sample_report("test.com"))
+        store.clear()
+
+        assert store.get_domains() == []
+
+    def test_delete_domain(self):
+        store = ReportStore.get_instance()
+        store.add_report(_sample_report("test.com"))
+        store.add_report(_sample_report("other.com"))
+
+        assert store.delete_domain_with_cleanup("test.com") is True
+        assert "test.com" not in store.get_domains()
+        assert "other.com" in store.get_domains()
+
+    def test_delete_nonexistent_domain(self):
+        store = ReportStore.get_instance()
+        assert store.delete_domain_with_cleanup("nope.com") is False
diff --git a/backend/app/tests/test_reports_api.py b/backend/app/tests/test_reports_api.py
index fdcf929..e14fe77 100644
--- a/backend/app/tests/test_reports_api.py
+++ b/backend/app/tests/test_reports_api.py
@@ -1,162 +1,117 @@
 import io
 import zipfile
 
-from app.models.domain import Domain
 from fastapi.testclient import TestClient
-from sqlalchemy.orm import Session
+
+SAMPLE_XML = """\
+<?xml version="1.0" encoding="UTF-8" ?>
+<feedback>
+    <report_metadata>
+        <org_name>google.com</org_name>
+        <email>noreply-dmarc-support@google.com</email>
+        <report_id>123456789</report_id>
+        <date_range>
+            <begin>1597449600</begin>
+            <end>1597535999</end>
+        </date_range>
+    </report_metadata>
+    <policy_published>
+        <domain>example.com</domain>
+        <adkim>r</adkim>
+        <aspf>r</aspf>
+        <p>none</p>
+        <sp>none</sp>
+        <pct>100</pct>
+    </policy_published>
+    <record>
+        <row>
+            <source_ip>203.0.113.1</source_ip>
+            <count>2</count>
+            <policy_evaluated>
+                <disposition>none</disposition>
+                <dkim>pass</dkim>
+                <spf>fail</spf>
+            </policy_evaluated>
+        </row>
+        <identifiers>
+            <header_from>example.com</header_from>
+        </identifiers>
+        <auth_results>
+            <dkim>
+                <domain>example.com</domain>
+                <result>pass</result>
+                <selector>default</selector>
+            </dkim>
+            <spf>
+                <domain>example.com</domain>
+                <result>fail</result>
+            </spf>
+        </auth_results>
+    </record>
+</feedback>
+"""
 
 
-def test_read_reports_empty(client: TestClient):
-    """Test reading reports when none exist"""
-    response = client.get("/api/v1/reports")
+def _make_zip(xml_content: str) -> bytes:
+    """Create a ZIP file containing the given XML content."""
+    buf = io.BytesIO()
+    with zipfile.ZipFile(buf, "w") as zf:
+        zf.writestr("report.xml", xml_content)
+    return buf.getvalue()
+
+
+def test_upload_report_success(client: TestClient):
+    """Uploading a valid zipped DMARC report succeeds."""
+    zip_bytes = _make_zip(SAMPLE_XML)
+    response = client.post(
+        "/api/v1/reports/upload",
+        files={"file": ("report.zip", zip_bytes, "application/zip")},
+    )
     assert response.status_code == 200
     data = response.json()
-    assert data == []
-
-
-def test_upload_report_no_domain(client: TestClient):
-    """Test uploading a report when domain doesn't exist"""
-    # Create a simple XML report
-    xml_content = """<?xml version="1.0" encoding="UTF-8" ?>
-    <feedback>
-        <report_metadata>
-            <org_name>google.com</org_name>
-            <email>noreply-dmarc-support@google.com</email>
-            <report_id>123456789</report_id>
-            <date_range>
-                <begin>1597449600</begin>
-                <end>1597535999</end>
-            </date_range>
-        </report_metadata>
-        <policy_published>
-            <domain>nonexistentdomain.com</domain>
-            <adkim>r</adkim>
-            <aspf>r</aspf>
-            <p>none</p>
-            <sp>none</sp>
-            <pct>100</pct>
-        </policy_published>
-        <record>
-            <row>
-                <source_ip>203.0.113.1</source_ip>
-                <count>2</count>
-                <policy_evaluated>
-                    <disposition>none</disposition>
-                    <dkim>pass</dkim>
-                    <spf>fail</spf>
-                </policy_evaluated>
-            </row>
-            <identifiers>
-                <header_from>nonexistentdomain.com</header_from>
-            </identifiers>
-            <auth_results>
-                <dkim>
-                    <domain>nonexistentdomain.com</domain>
-                    <result>pass</result>
-                    <selector>default</selector>
-                </dkim>
-                <spf>
-                    <domain>nonexistentdomain.com</domain>
-                    <result>fail</result>
-                </spf>
-            </auth_results>
-        </record>
-    </feedback>
-    """
-
-    # Create an in-memory zip file
-    zip_buffer = io.BytesIO()
-    with zipfile.ZipFile(zip_buffer, "w") as zip_file:
-        zip_file.writestr("report.xml", xml_content)
-    zip_buffer.seek(0)
-
-    # Upload the zip file
-    response = client.post(
-        "/api/v1/reports/upload", files={"file": ("report.zip", zip_buffer, "application/zip")}
-    )
-
-    # Should return an error since domain doesn't exist
-    assert response.status_code == 404
-    data = response.json()
-    assert "domain not found" in data["detail"].lower()
-
-
-def test_upload_report_success(client: TestClient, db_session: Session):
-    """Test successfully uploading a report"""
-    # Create a domain first
-    domain = Domain(name="example.com", active=True)
-    db_session.add(domain)
-    db_session.commit()
-
-    # Create a simple XML report
-    xml_content = """<?xml version="1.0" encoding="UTF-8" ?>
-    <feedback>
-        <report_metadata>
-            <org_name>google.com</org_name>
-            <email>noreply-dmarc-support@google.com</email>
-            <report_id>123456789</report_id>
-            <date_range>
-                <begin>1597449600</begin>
-                <end>1597535999</end>
-            </date_range>
-        </report_metadata>
-        <policy_published>
-            <domain>example.com</domain>
-            <adkim>r</adkim>
-            <aspf>r</aspf>
-            <p>none</p>
-            <sp>none</sp>
-            <pct>100</pct>
-        </policy_published>
-        <record>
-            <row>
-                <source_ip>203.0.113.1</source_ip>
-                <count>2</count>
-                <policy_evaluated>
-                    <disposition>none</disposition>
-                    <dkim>pass</dkim>
-                    <spf>fail</spf>
-                </policy_evaluated>
-            </row>
-            <identifiers>
-                <header_from>example.com</header_from>
-            </identifiers>
-            <auth_results>
-                <dkim>
-                    <domain>example.com</domain>
-                    <result>pass</result>
-                    <selector>default</selector>
-                </dkim>
-                <spf>
-                    <domain>example.com</domain>
-                    <result>fail</result>
-                </spf>
-            </auth_results>
-        </record>
-    </feedback>
-    """
-
-    # Create an in-memory zip file
-    zip_buffer = io.BytesIO()
-    with zipfile.ZipFile(zip_buffer, "w") as zip_file:
-        zip_file.writestr("report.xml", xml_content)
-    zip_buffer.seek(0)
-
-    # Upload the zip file
-    response = client.post(
-        "/api/v1/reports/upload", files={"file": ("report.zip", zip_buffer, "application/zip")}
-    )
-
-    # Should be successful
-    assert response.status_code == 201
-    data = response.json()
     assert data["success"] is True
-    assert "report_id" in data
+    assert data["domain"] == "example.com"
 
-    # Check that the report was actually created
-    response = client.get("/api/v1/reports")
+
+def test_upload_populates_domains_list(client: TestClient):
+    """After uploading a report, the domain appears in the reports/domains endpoint."""
+    zip_bytes = _make_zip(SAMPLE_XML)
+    client.post(
+        "/api/v1/reports/upload",
+        files={"file": ("report.zip", zip_bytes, "application/zip")},
+    )
+
+    response = client.get("/api/v1/reports/domains")
     assert response.status_code == 200
-    reports = response.json()
-    assert len(reports) == 1
-    assert reports[0]["report_id"] == "123456789"
-    assert reports[0]["org_name"] == "google.com"
+    domains = response.json()
+    assert "example.com" in domains
+
+
+def test_reports_domains_empty(client: TestClient):
+    """GET /api/v1/reports/domains returns empty list when no reports uploaded."""
+    response = client.get("/api/v1/reports/domains")
+    assert response.status_code == 200
+    assert response.json() == []
+
+
+def test_reports_summary_empty(client: TestClient):
+    """GET /api/v1/reports/summary returns empty list when no reports uploaded."""
+    response = client.get("/api/v1/reports/summary")
+    assert response.status_code == 200
+    assert response.json() == []
+
+
+def test_upload_and_get_domain_summary(client: TestClient):
+    """After uploading a report, the domain summary endpoint returns correct data."""
+    zip_bytes = _make_zip(SAMPLE_XML)
+    client.post(
+        "/api/v1/reports/upload",
+        files={"file": ("report.zip", zip_bytes, "application/zip")},
+    )
+
+    response = client.get("/api/v1/reports/domain/example.com/summary")
+    assert response.status_code == 200
+    data = response.json()
+    assert data["domain"] == "example.com"
+    assert data["total_count"] == 2
+    assert data["reports_processed"] == 1
diff --git a/backend/app/tests/test_security.py b/backend/app/tests/test_security.py
index c6c9e5a..395d0d6 100644
--- a/backend/app/tests/test_security.py
+++ b/backend/app/tests/test_security.py
@@ -1,98 +1,78 @@
 """
-Security-focused unit tests for DMARQ application.
+Security-focused tests for DMARQ application.
 
-Tests authentication, input validation, file upload security, and other security features.
+Covers API key management, domain validation, file upload limits, and XML parsing security.
 """
 
 import pytest
-from app.core.security import (
-    add_api_key,
-    generate_api_key,
-    verify_api_key,
-)
+from app.core.security import add_api_key, generate_api_key, verify_api_key
 from app.services.dmarc_parser import DMARCParser
 from app.utils.domain_validator import validate_domain, validate_domain_config
 
 
-class TestAuthentication:
-    """Test authentication and API key functionality."""
+class TestAPIKeySecurity:
+    """Test API key generation and verification."""
 
-    def test_generate_api_key(self):
-        """Test API key generation."""
+    def test_generate_api_key_length_and_uniqueness(self):
+        """Generated keys should be 64 hex characters and unique."""
         key1 = generate_api_key()
         key2 = generate_api_key()
 
-        # Keys should be 64 characters (32 bytes hex encoded)
         assert len(key1) == 64
         assert len(key2) == 64
-
-        # Keys should be unique
         assert key1 != key2
-
-        # Keys should be hexadecimal
         assert all(c in "0123456789abcdef" for c in key1)
 
     def test_add_and_verify_api_key(self):
-        """Test adding and verifying API keys."""
+        """Keys should only be valid after being added."""
         key = generate_api_key()
-
-        # Key should not be valid before adding
         assert not verify_api_key(key)
 
-        # Add key
-        assert add_api_key(key)
+        assert add_api_key(key) is True
+        assert verify_api_key(key) is True
 
-        # Key should now be valid
-        assert verify_api_key(key)
-
-        # Adding same key again should return False
-        assert not add_api_key(key)
-
-    def test_password_hashing(self):
-        """Test password hashing and verification."""
-        # Skip this test if bcrypt has issues
-        pytest.skip("Skipping due to bcrypt compatibility issues in test environment")
+        # Adding the same key again returns False
+        assert add_api_key(key) is False
 
 
 class TestDomainValidation:
-    """Test domain validation security."""
+    """Test domain name validation."""
 
-    def test_valid_domains(self):
-        """Test validation of legitimate domains."""
-        valid_domains = [
+    @pytest.mark.parametrize(
+        "domain",
+        [
             "example.com",
             "subdomain.example.com",
             "my-domain.example.org",
             "test123.example.net",
-        ]
+        ],
+    )
+    def test_valid_domains(self, domain):
+        is_valid, error, _ = validate_domain(domain, check_dns=False)
+        assert is_valid, f"Domain {domain} should be valid: {error}"
 
-        for domain in valid_domains:
-            is_valid, error, error_code = validate_domain(domain, check_dns=False)
-            assert is_valid, f"Domain {domain} should be valid: {error}"
+    @pytest.mark.parametrize(
+        "domain",
+        [
+            "",
+            "   ",
+            "example",
+            "-example.com",
+            "example-.com",
+            "exam ple.com",
+            "example..com",
+            "a" * 64 + ".com",
+            "a" * 254,
+        ],
+    )
+    def test_invalid_domain_format(self, domain):
+        is_valid, error, _ = validate_domain(domain, check_dns=False)
+        assert not is_valid, f"Domain '{domain}' should be invalid"
+        assert error is not None
 
-    def test_invalid_domain_format(self):
-        """Test rejection of invalid domain formats."""
-        invalid_domains = [
-            "",  # Empty
-            "   ",  # Whitespace
-            "example",  # No TLD
-            "-example.com",  # Starts with hyphen
-            "example-.com",  # Ends with hyphen
-            "exam ple.com",  # Contains space
-            "example..com",  # Double dot
-            "example.com.",  # Trailing dot (should fail with current regex)
-            "a" * 64 + ".com",  # Label too long (>63 chars)
-            "a" * 250 + ".com",  # Domain too long (>253 chars)
-        ]
-
-        for domain in invalid_domains:
-            is_valid, error, error_code = validate_domain(domain, check_dns=False)
-            assert not is_valid, f"Domain '{domain}' should be invalid"
-            assert error is not None
-
-    def test_malicious_domain_input(self):
-        """Test rejection of domains with malicious characters."""
-        malicious_domains = [
+    @pytest.mark.parametrize(
+        "domain",
+        [
             "example.com<script>",
             "example.com'; DROP TABLE users--",
             "example.com|whoami",
@@ -101,91 +81,60 @@ class TestDomainValidation:
             "example.com$USER",
             'example.com"test',
             "example.com\\\\test",
-        ]
+        ],
+    )
+    def test_malicious_domain_input(self, domain):
+        is_valid, _, _ = validate_domain(domain, check_dns=False)
+        assert not is_valid, f"Malicious domain '{domain}' should be rejected"
 
-        for domain in malicious_domains:
-            is_valid, error, error_code = validate_domain(domain, check_dns=False)
-            assert not is_valid, f"Malicious domain '{domain}' should be rejected"
-
-    def test_domain_length_limits(self):
-        """Test domain length validation."""
-        # Max label is 63 characters - this should be caught by label length check
-        long_label = "a" * 64 + ".example.com"
-        is_valid, error, error_code = validate_domain(long_label, check_dns=False)
-        assert not is_valid
-        # Could be caught by format check or label length check
-        assert error is not None
-
-        # Max domain is 253 characters
-        long_domain = "a" * 254  # 254 chars, no dot
-        is_valid, error, error_code = validate_domain(long_domain, check_dns=False)
-        assert not is_valid
-        assert "too long" in error.lower() or "invalid" in error.lower()
-
-    def test_domain_config_validation(self):
-        """Test domain configuration validation."""
-        # Valid config
-        valid_config = {"name": "example.com", "description": "Test domain"}
-        result = validate_domain_config(valid_config)
+    def test_domain_config_validation_valid(self):
+        result = validate_domain_config({"name": "example.com", "description": "Test domain"})
         assert result["valid"]
         assert len(result["errors"]) == 0
 
-        # Missing name
-        invalid_config = {"description": "Test"}
-        result = validate_domain_config(invalid_config)
+    def test_domain_config_missing_name(self):
+        result = validate_domain_config({"description": "Test"})
         assert not result["valid"]
         assert "name" in result["errors"]
 
-        # Description too long
-        long_desc_config = {"name": "example.com", "description": "a" * 501}
-        result = validate_domain_config(long_desc_config)
+    def test_domain_config_description_too_long(self):
+        result = validate_domain_config({"name": "example.com", "description": "a" * 501})
         assert not result["valid"]
         assert "description" in result["errors"]
 
-        # Malicious description
-        malicious_config = {"name": "example.com", "description": "<script>alert('xss')</script>"}
-        result = validate_domain_config(malicious_config)
+    def test_domain_config_xss_description(self):
+        result = validate_domain_config(
+            {"name": "example.com", "description": "<script>alert('xss')</script>"}
+        )
         assert not result["valid"]
         assert "description" in result["errors"]
 
 
 class TestFileUploadSecurity:
-    """Test file upload security features."""
+    """Test file upload size limits."""
 
     def test_file_size_limit(self):
-        """Test file size limit enforcement."""
-        parser = DMARCParser()
-
-        # Create a file that's too large (> 10 MB)
         large_content = b"x" * (11 * 1024 * 1024)
-
-        with pytest.raises(ValueError) as exc_info:
-            parser.parse_file(large_content, "test.xml")
-
-        assert "too large" in str(exc_info.value).lower()
+        with pytest.raises(ValueError, match="too large"):
+            DMARCParser.parse_file(large_content, "test.xml")
 
 
 class TestXMLParsingSecurity:
-    """Test XML parsing security features."""
+    """Test XML parsing security (defusedxml, XXE protection)."""
 
-    def test_defusedxml_import(self):
-        """Test that defusedxml is being used."""
+    def test_defusedxml_is_used(self):
         import app.services.dmarc_parser as parser_module
 
-        # Check that the module uses defusedxml
         assert hasattr(parser_module, "ET")
-        # The module name should contain 'defusedxml'
-        assert (
-            "defusedxml" in str(parser_module.ET.__name__).lower()
-            or "defusedxml" in str(parser_module.ET.__module__).lower()
+        module_info = str(getattr(parser_module.ET, "__name__", "")) + str(
+            getattr(parser_module.ET, "__module__", "")
         )
+        assert "defusedxml" in module_info.lower()
 
-    def test_xml_entity_expansion_protection(self):
-        """Test protection against XML entity expansion attacks."""
-        parser = DMARCParser()
-
-        # XXE attack payload
-        xxe_payload = b"""<?xml version="1.0"?>
+    def test_xxe_protection(self):
+        """defusedxml should prevent XXE entity expansion."""
+        xxe_payload = b"""\
+<?xml version="1.0"?>
 <!DOCTYPE foo [
 <!ENTITY xxe SYSTEM "file:///etc/passwd">
 ]>
@@ -195,23 +144,10 @@ class TestXMLParsingSecurity:
     </report_metadata>
 </feedback>
 """
-
-        # Should either fail parsing or not expand the entity
-        # defusedxml should prevent this
+        # defusedxml should raise an error or not expand the entity
         try:
-            result = parser.parse_file(xxe_payload, "test.xml")
-            # If it doesn't raise an error, the entity should not be expanded
+            result = DMARCParser.parse_file(xxe_payload, "test.xml")
             org_name = result.get("org_name", "")
-            assert not org_name.startswith("root:") and "/bin" not in org_name
-        except Exception:
-            # Expected - defusedxml should prevent parsing
-            pass
-
-
-# Note: TestSecurityHeaders and TestErrorHandling tests are not implemented
-# because they require proper async client setup. These will be added in a future PR
-# with proper integration test infrastructure.
-
-
-if __name__ == "__main__":
-    pytest.main([__file__, "-v"])
+            assert "root:" not in org_name and "/bin" not in org_name
+        except (ValueError, Exception):
+            pass  # Expected – defusedxml blocks DTD processing