diff --git a/tests/test_database.py b/tests/test_database.py
index 8310aae8..008b1d7e 100644
--- a/tests/test_database.py
+++ b/tests/test_database.py
@@ -323,3 +323,211 @@ class TestInitDbErrors:
 
         with pytest.raises(exc.SQLAlchemyError):
             init_db()
+
+
+@pytest.mark.unit
+class TestMultiVersionMigrations:
+    """Test migration scenarios from various database versions."""
+
+    def test_migration_from_v1_to_v2_processing_logs(self, tmp_path):
+        """Test migration from v1 (no detail column) to v2 (with detail)."""
+        from sqlalchemy import create_engine, inspect, text
+
+        from app.database import _run_schema_migrations
+
+        # Create v1 database (without detail column)
+        db_path = str(tmp_path / "v1_to_v2.db")
+        engine = create_engine(f"sqlite:///{db_path}")
+        with engine.begin() as conn:
+            conn.execute(
+                text(
+                    "CREATE TABLE processing_logs ("
+                    "id INTEGER PRIMARY KEY, "
+                    "file_id INTEGER, "
+                    "task_id VARCHAR, "
+                    "step_name VARCHAR, "
+                    "status VARCHAR, "
+                    "message VARCHAR, "
+                    "timestamp DATETIME)"
+                )
+            )
+            # Insert test data
+            conn.execute(
+                text(
+                    "INSERT INTO processing_logs (task_id, step_name, status, message) "
+                    "VALUES ('test-1', 'test_step', 'success', 'Test message')"
+                )
+            )
+
+        # Run migration to v2
+        _run_schema_migrations(engine)
+
+        # Verify detail column exists and old data is preserved
+        inspector = inspect(engine)
+        columns = [col["name"] for col in inspector.get_columns("processing_logs")]
+        assert "detail" in columns
+
+        # Verify old data still accessible
+        with engine.connect() as conn:
+            result = conn.execute(text("SELECT task_id, message, detail FROM processing_logs WHERE task_id = 'test-1'"))
+            row = result.fetchone()
+            assert row[0] == "test-1"
+            assert row[1] == "Test message"
+            assert row[2] is None  # detail should be NULL for old records
+
+        engine.dispose()
+
+    def test_migration_from_v1_to_v3_files_table(self, tmp_path):
+        """Test migration from v1 (basic) to v3 (with dedup columns)."""
+        from sqlalchemy import create_engine, inspect, text
+
+        from app.database import _run_schema_migrations
+
+        # Create v1 database (minimal files table)
+        db_path = str(tmp_path / "v1_to_v3.db")
+        engine = create_engine(f"sqlite:///{db_path}")
+        with engine.begin() as conn:
+            conn.execute(
+                text(
+                    "CREATE TABLE files ("
+                    "id INTEGER PRIMARY KEY, "
+                    "filename VARCHAR, "
+                    "filehash VARCHAR, "
+                    "upload_date DATETIME)"
+                )
+            )
+            # Insert test data
+            conn.execute(text("INSERT INTO files (filename, filehash) VALUES ('test.pdf', 'abc123')"))
+
+        # Run migration to v3 (adds path columns and dedup columns)
+        _run_schema_migrations(engine)
+
+        # Verify all new columns exist
+        inspector = inspect(engine)
+        columns = {col["name"] for col in inspector.get_columns("files")}
+        assert "original_file_path" in columns
+        assert "processed_file_path" in columns
+        assert "is_duplicate" in columns
+        assert "duplicate_of_id" in columns
+
+        # Verify old data preserved with default values
+        with engine.connect() as conn:
+            result = conn.execute(text("SELECT filename, is_duplicate FROM files WHERE filename = 'test.pdf'"))
+            row = result.fetchone()
+            assert row[0] == "test.pdf"
+            # is_duplicate should be False (0) by default
+            assert row[1] in (0, False)
+
+        engine.dispose()
+
+    def test_migration_with_unique_index_already_dropped(self, tmp_path):
+        """Test that migration handles case where unique index was already dropped."""
+        from sqlalchemy import create_engine, text
+
+        from app.database import _run_schema_migrations
+
+        # Create database without unique index
+        db_path = str(tmp_path / "no_index.db")
+        engine = create_engine(f"sqlite:///{db_path}")
+        with engine.begin() as conn:
+            conn.execute(
+                text(
+                    "CREATE TABLE files ("
+                    "id INTEGER PRIMARY KEY, "
+                    "filename VARCHAR, "
+                    "filehash VARCHAR, "
+                    "original_file_path VARCHAR, "
+                    "processed_file_path VARCHAR, "
+                    "is_duplicate BOOLEAN DEFAULT FALSE NOT NULL, "
+                    "duplicate_of_id INTEGER)"
+                )
+            )
+
+        # Run migration - should not error even though there's no index to drop
+        _run_schema_migrations(engine)
+
+        # Should complete without error
+        engine.dispose()
+
+    def test_migration_partial_state(self, tmp_path):
+        """Test migration from partial state (some columns added, some missing)."""
+        from sqlalchemy import create_engine, inspect, text
+
+        from app.database import _run_schema_migrations
+
+        # Create database with only some of the new columns
+        db_path = str(tmp_path / "partial.db")
+        engine = create_engine(f"sqlite:///{db_path}")
+        with engine.begin() as conn:
+            # Files table with only original_file_path, missing processed_file_path and dedup columns
+            conn.execute(
+                text(
+                    "CREATE TABLE files ("
+                    "id INTEGER PRIMARY KEY, "
+                    "filename VARCHAR, "
+                    "filehash VARCHAR, "
+                    "original_file_path VARCHAR)"
+                )
+            )
+            # Processing logs with detail column already present
+            conn.execute(
+                text(
+                    "CREATE TABLE processing_logs ("
+                    "id INTEGER PRIMARY KEY, "
+                    "task_id VARCHAR, "
+                    "step_name VARCHAR, "
+                    "status VARCHAR, "
+                    "message VARCHAR, "
+                    "detail TEXT, "
+                    "timestamp DATETIME)"
+                )
+            )
+
+        # Run migration - should add missing columns only
+        _run_schema_migrations(engine)
+
+        # Verify all columns exist now
+        inspector = inspect(engine)
+        files_columns = {col["name"] for col in inspector.get_columns("files")}
+        assert "original_file_path" in files_columns
+        assert "processed_file_path" in files_columns
+        assert "is_duplicate" in files_columns
+        assert "duplicate_of_id" in files_columns
+
+        logs_columns = {col["name"] for col in inspector.get_columns("processing_logs")}
+        assert "detail" in logs_columns
+
+        engine.dispose()
+
+    def test_migration_exception_handling(self, tmp_path):
+        """Test that migration handles exceptions gracefully for index operations."""
+        from sqlalchemy import create_engine, text
+
+        from app.database import _run_schema_migrations
+
+        # Create database with all columns but trigger exception path
+        db_path = str(tmp_path / "exception_test.db")
+        engine = create_engine(f"sqlite:///{db_path}")
+        with engine.begin() as conn:
+            conn.execute(
+                text(
+                    "CREATE TABLE files ("
+                    "id INTEGER PRIMARY KEY, "
+                    "filename VARCHAR, "
+                    "filehash VARCHAR, "
+                    "original_file_path VARCHAR, "
+                    "processed_file_path VARCHAR, "
+                    "is_duplicate BOOLEAN DEFAULT FALSE NOT NULL, "
+                    "duplicate_of_id INTEGER)"
+                )
+            )
+
+        # Run migration - should handle the exception path for index operations
+        # (when get_indexes might have issues)
+        try:
+            _run_schema_migrations(engine)
+            # Should complete without raising
+        except Exception as e:
+            pytest.fail(f"Migration should handle exceptions gracefully: {e}")
+
+        engine.dispose()
diff --git a/tests/test_notification.py b/tests/test_notification.py
index a828b7a9..2fd2edee 100644
--- a/tests/test_notification.py
+++ b/tests/test_notification.py
@@ -232,3 +232,249 @@ class TestAppriseInitialization:
 
         # Should still return instance
         assert result == mock_apprise_instance
+
+
+@pytest.mark.unit
+class TestSendNotification:
+    """Test send_notification function"""
+
+    @patch("app.utils.notification.init_apprise")
+    @patch("app.utils.notification.settings")
+    def test_send_notification_no_urls_configured(self, mock_settings, mock_init_apprise):
+        """Test sending notification when no URLs are configured."""
+        from app.utils.notification import send_notification
+
+        mock_settings.notification_urls = []
+
+        result = send_notification("Test", "Test message")
+
+        assert result is False
+        mock_init_apprise.assert_not_called()
+
+    @patch("app.utils.notification.init_apprise")
+    @patch("app.utils.notification.settings")
+    def test_send_notification_success_type(self, mock_settings, mock_init_apprise):
+        """Test notification with success type."""
+        from app.utils.notification import send_notification
+
+        mock_settings.notification_urls = ["https://example.com/notify"]
+        mock_apprise = MagicMock()
+        mock_server = MagicMock()
+        mock_server.notify.return_value = True
+        mock_apprise.servers = [mock_server]
+        mock_init_apprise.return_value = mock_apprise
+
+        result = send_notification("Test", "Message", notification_type="success")
+
+        assert result is True
+        mock_server.notify.assert_called_once()
+        # Check that SUCCESS type was used
+        call_kwargs = mock_server.notify.call_args[1]
+        assert "notify_type" in call_kwargs
+
+    @patch("app.utils.notification.init_apprise")
+    @patch("app.utils.notification.settings")
+    def test_send_notification_warning_type(self, mock_settings, mock_init_apprise):
+        """Test notification with warning type."""
+        from app.utils.notification import send_notification
+
+        mock_settings.notification_urls = ["https://example.com/notify"]
+        mock_apprise = MagicMock()
+        mock_server = MagicMock()
+        mock_server.notify.return_value = True
+        mock_apprise.servers = [mock_server]
+        mock_init_apprise.return_value = mock_apprise
+
+        result = send_notification("Test", "Message", notification_type="warn")
+
+        assert result is True
+
+    @patch("app.utils.notification.init_apprise")
+    @patch("app.utils.notification.settings")
+    def test_send_notification_failure_type(self, mock_settings, mock_init_apprise):
+        """Test notification with failure type."""
+        from app.utils.notification import send_notification
+
+        mock_settings.notification_urls = ["https://example.com/notify"]
+        mock_apprise = MagicMock()
+        mock_server = MagicMock()
+        mock_server.notify.return_value = True
+        mock_apprise.servers = [mock_server]
+        mock_init_apprise.return_value = mock_apprise
+
+        result = send_notification("Test", "Message", notification_type="failed")
+
+        assert result is True
+
+    @patch("app.utils.notification.init_apprise")
+    @patch("app.utils.notification.settings")
+    def test_send_notification_no_servers(self, mock_settings, mock_init_apprise):
+        """Test notification when no servers are available."""
+        from app.utils.notification import send_notification
+
+        mock_settings.notification_urls = ["https://example.com/notify"]
+        mock_apprise = MagicMock()
+        mock_apprise.servers = []
+        mock_init_apprise.return_value = mock_apprise
+
+        result = send_notification("Test", "Message")
+
+        assert result is False
+
+    @patch("app.utils.notification.init_apprise")
+    @patch("app.utils.notification.settings")
+    def test_send_notification_partial_success(self, mock_settings, mock_init_apprise):
+        """Test notification with multiple servers, some failing."""
+        from app.utils.notification import send_notification
+
+        mock_settings.notification_urls = ["https://example.com/notify"]
+        mock_apprise = MagicMock()
+        mock_server1 = MagicMock()
+        mock_server1.notify.return_value = True
+        mock_server2 = MagicMock()
+        mock_server2.notify.return_value = False
+        mock_apprise.servers = [mock_server1, mock_server2]
+        mock_init_apprise.return_value = mock_apprise
+
+        result = send_notification("Test", "Message")
+
+        assert result is True  # At least one succeeded
+
+    @patch("app.utils.notification.init_apprise")
+    @patch("app.utils.notification.settings")
+    def test_send_notification_with_attachments(self, mock_settings, mock_init_apprise):
+        """Test notification with file attachments."""
+        from app.utils.notification import send_notification
+
+        mock_settings.notification_urls = ["https://example.com/notify"]
+        mock_apprise = MagicMock()
+        mock_server = MagicMock()
+        mock_server.notify.return_value = True
+        mock_apprise.servers = [mock_server]
+        mock_init_apprise.return_value = mock_apprise
+
+        result = send_notification("Test", "Message", attachments=["/path/to/file.pdf"])
+
+        assert result is True
+        call_kwargs = mock_server.notify.call_args[1]
+        assert call_kwargs["attach"] == ["/path/to/file.pdf"]
+
+    @patch("app.utils.notification.init_apprise")
+    @patch("app.utils.notification.settings")
+    def test_send_notification_exception_handling(self, mock_settings, mock_init_apprise):
+        """Test that exceptions are caught and logged."""
+        from app.utils.notification import send_notification
+
+        mock_settings.notification_urls = ["https://example.com/notify"]
+        mock_init_apprise.side_effect = Exception("Connection error")
+
+        result = send_notification("Test", "Message")
+
+        assert result is False
+
+
+@pytest.mark.unit
+class TestNotificationHelpers:
+    """Test notification helper functions."""
+
+    @patch("app.utils.notification.send_notification")
+    @patch("app.utils.notification.settings")
+    def test_notify_celery_failure_disabled(self, mock_settings, mock_send):
+        """Test Celery failure notification when disabled."""
+        from app.utils.notification import notify_celery_failure
+
+        mock_settings.notify_on_task_failure = False
+
+        result = notify_celery_failure("test_task", "task-123", Exception("Error"), [], {})
+
+        assert result is False
+        mock_send.assert_not_called()
+
+    @patch("app.utils.notification.send_notification")
+    @patch("app.utils.notification.settings")
+    def test_notify_celery_failure_enabled(self, mock_settings, mock_send):
+        """Test Celery failure notification when enabled."""
+        from app.utils.notification import notify_celery_failure
+
+        mock_settings.notify_on_task_failure = True
+        mock_send.return_value = True
+
+        result = notify_celery_failure("test_task", "task-123", Exception("Error"), [], {})
+
+        assert result is True
+        mock_send.assert_called_once()
+        call_args = mock_send.call_args[1]
+        assert call_args["notification_type"] == "failure"
+
+    @patch("app.utils.notification.send_notification")
+    @patch("app.utils.notification.settings")
+    def test_notify_credential_failure_disabled(self, mock_settings, mock_send):
+        """Test credential failure notification when disabled."""
+        from app.utils.notification import notify_credential_failure
+
+        mock_settings.notify_on_credential_failure = False
+
+        result = notify_credential_failure("Dropbox", "Invalid token")
+
+        assert result is False
+        mock_send.assert_not_called()
+
+    @patch("app.utils.notification.send_notification")
+    @patch("app.utils.notification.settings")
+    def test_notify_startup_disabled(self, mock_settings, mock_send):
+        """Test startup notification when disabled."""
+        from app.utils.notification import notify_startup
+
+        mock_settings.notify_on_startup = False
+
+        result = notify_startup()
+
+        assert result is False
+        mock_send.assert_not_called()
+
+    @patch("app.utils.notification.send_notification")
+    @patch("app.utils.notification.settings")
+    def test_notify_shutdown_disabled(self, mock_settings, mock_send):
+        """Test shutdown notification when disabled."""
+        from app.utils.notification import notify_shutdown
+
+        mock_settings.notify_on_shutdown = False
+
+        result = notify_shutdown()
+
+        assert result is False
+        mock_send.assert_not_called()
+
+    @patch("app.utils.notification.send_notification")
+    @patch("app.utils.notification.settings")
+    def test_notify_file_processed_disabled(self, mock_settings, mock_send):
+        """Test file processed notification when disabled."""
+        from app.utils.notification import notify_file_processed
+
+        mock_settings.notify_on_file_processed = False
+
+        result = notify_file_processed("test.pdf", 1024000, {}, [])
+
+        assert result is False
+        mock_send.assert_not_called()
+
+    @patch("app.utils.notification.send_notification")
+    @patch("app.utils.notification.settings")
+    def test_notify_file_processed_with_metadata(self, mock_settings, mock_send):
+        """Test file processed notification with metadata."""
+        from app.utils.notification import notify_file_processed
+
+        mock_settings.notify_on_file_processed = True
+        mock_send.return_value = True
+
+        metadata = {"document_type": "invoice", "tags": ["important", "finance"]}
+        result = notify_file_processed("test.pdf", 2048000, metadata, ["dropbox", "s3"])
+
+        assert result is True
+        mock_send.assert_called_once()
+        # Check message contains expected info
+        message = mock_send.call_args[0][1]
+        assert "2.00 MB" in message
+        assert "invoice" in message
+        assert "important, finance" in message
+        assert "dropbox, s3" in message
diff --git a/tests/test_upload_to_s3.py b/tests/test_upload_to_s3.py
new file mode 100644
index 00000000..c20c0c46
--- /dev/null
+++ b/tests/test_upload_to_s3.py
@@ -0,0 +1,224 @@
+"""Tests for app/tasks/upload_to_s3.py module."""
+
+import os
+from unittest.mock import MagicMock, patch
+
+import pytest
+from botocore.exceptions import ClientError
+
+from app.tasks.upload_to_s3 import upload_to_s3
+
+
+@pytest.mark.unit
+class TestUploadToS3:
+    """Tests for S3 upload functionality."""
+
+    @patch("app.tasks.upload_to_s3.boto3.client")
+    @patch("app.tasks.upload_to_s3.settings")
+    def test_upload_success_with_folder_prefix(self, mock_settings, mock_boto_client, tmp_path):
+        """Test successful S3 upload with folder prefix."""
+        # Setup
+        test_file = tmp_path / "test.pdf"
+        test_file.write_text("test content")
+        
+        mock_settings.s3_bucket_name = "my-bucket"
+        mock_settings.aws_access_key_id = "AKIAIOSFODNN7EXAMPLE"
+        mock_settings.aws_secret_access_key = "wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY"
+        mock_settings.aws_region = "us-east-1"
+        mock_settings.s3_folder_prefix = "documents"
+        mock_settings.s3_storage_class = "STANDARD"
+        mock_settings.s3_acl = "private"
+
+        mock_s3 = MagicMock()
+        mock_boto_client.return_value = mock_s3
+
+        # Execute
+        result = upload_to_s3.apply(args=[str(test_file)])
+
+        # Verify
+        assert result.result["status"] == "Completed"
+        assert result.result["s3_bucket"] == "my-bucket"
+        assert result.result["s3_key"] == "documents/test.pdf"
+        
+        mock_s3.upload_file.assert_called_once()
+        call_args = mock_s3.upload_file.call_args
+        assert call_args[0][0] == str(test_file)
+        assert call_args[0][1] == "my-bucket"
+        assert call_args[0][2] == "documents/test.pdf"
+        assert call_args[1]["ExtraArgs"]["StorageClass"] == "STANDARD"
+        assert call_args[1]["ExtraArgs"]["ACL"] == "private"
+
+    @patch("app.tasks.upload_to_s3.boto3.client")
+    @patch("app.tasks.upload_to_s3.settings")
+    def test_upload_without_folder_prefix(self, mock_settings, mock_boto_client, tmp_path):
+        """Test S3 upload without folder prefix."""
+        test_file = tmp_path / "test.pdf"
+        test_file.write_text("test content")
+        
+        mock_settings.s3_bucket_name = "my-bucket"
+        mock_settings.aws_access_key_id = "key"
+        mock_settings.aws_secret_access_key = "secret"
+        mock_settings.aws_region = "us-west-2"
+        mock_settings.s3_folder_prefix = None
+        mock_settings.s3_storage_class = "STANDARD"
+        mock_settings.s3_acl = None
+
+        mock_s3 = MagicMock()
+        mock_boto_client.return_value = mock_s3
+
+        result = upload_to_s3.apply(args=[str(test_file)])
+
+        assert result.result["s3_key"] == "test.pdf"
+        # Verify ACL not included when None
+        extra_args = mock_s3.upload_file.call_args[1]["ExtraArgs"]
+        assert "ACL" not in extra_args
+
+    @patch("app.tasks.upload_to_s3.boto3.client")
+    @patch("app.tasks.upload_to_s3.settings")
+    def test_upload_with_folder_prefix_no_trailing_slash(self, mock_settings, mock_boto_client, tmp_path):
+        """Test that folder prefix gets trailing slash added."""
+        test_file = tmp_path / "test.pdf"
+        test_file.write_text("test content")
+        
+        mock_settings.s3_bucket_name = "my-bucket"
+        mock_settings.aws_access_key_id = "key"
+        mock_settings.aws_secret_access_key = "secret"
+        mock_settings.aws_region = "us-west-2"
+        mock_settings.s3_folder_prefix = "uploads/docs"  # No trailing slash
+        mock_settings.s3_storage_class = "STANDARD"
+        mock_settings.s3_acl = None
+
+        mock_s3 = MagicMock()
+        mock_boto_client.return_value = mock_s3
+
+        result = upload_to_s3.apply(args=[str(test_file)])
+
+        # Should add trailing slash
+        assert result.result["s3_key"] == "uploads/docs/test.pdf"
+
+    @patch("app.tasks.upload_to_s3.settings")
+    def test_upload_file_not_found(self, mock_settings):
+        """Test S3 upload with non-existent file."""
+        mock_settings.s3_bucket_name = "my-bucket"
+        mock_settings.aws_access_key_id = "key"
+        mock_settings.aws_secret_access_key = "secret"
+        
+        with pytest.raises(FileNotFoundError):
+            upload_to_s3.apply(args=["/nonexistent/file.pdf"])
+
+    @patch("app.tasks.upload_to_s3.settings")
+    def test_upload_missing_bucket_name(self, mock_settings, tmp_path):
+        """Test S3 upload with missing bucket name."""
+        test_file = tmp_path / "test.pdf"
+        test_file.write_text("test content")
+        
+        mock_settings.s3_bucket_name = None
+        mock_settings.aws_access_key_id = "key"
+        mock_settings.aws_secret_access_key = "secret"
+
+        with pytest.raises(ValueError, match="bucket name"):
+            upload_to_s3.apply(args=[str(test_file)])
+
+    @patch("app.tasks.upload_to_s3.settings")
+    def test_upload_missing_credentials(self, mock_settings, tmp_path):
+        """Test S3 upload with missing AWS credentials."""
+        test_file = tmp_path / "test.pdf"
+        test_file.write_text("test content")
+        
+        mock_settings.s3_bucket_name = "my-bucket"
+        mock_settings.aws_access_key_id = None
+        mock_settings.aws_secret_access_key = None
+
+        with pytest.raises(ValueError, match="credentials"):
+            upload_to_s3.apply(args=[str(test_file)])
+
+    @patch("app.tasks.upload_to_s3.boto3.client")
+    @patch("app.tasks.upload_to_s3.settings")
+    def test_upload_client_error(self, mock_settings, mock_boto_client, tmp_path):
+        """Test S3 upload with boto3 ClientError."""
+        test_file = tmp_path / "test.pdf"
+        test_file.write_text("test content")
+        
+        mock_settings.s3_bucket_name = "my-bucket"
+        mock_settings.aws_access_key_id = "key"
+        mock_settings.aws_secret_access_key = "secret"
+        mock_settings.aws_region = "us-east-1"
+        mock_settings.s3_folder_prefix = None
+        mock_settings.s3_storage_class = "STANDARD"
+        mock_settings.s3_acl = None
+
+        mock_s3 = MagicMock()
+        error_response = {"Error": {"Code": "NoSuchBucket", "Message": "The specified bucket does not exist"}}
+        mock_s3.upload_file.side_effect = ClientError(error_response, "upload_file")
+        mock_boto_client.return_value = mock_s3
+
+        with pytest.raises(Exception, match="Failed to upload"):
+            upload_to_s3.apply(args=[str(test_file)])
+
+    @patch("app.tasks.upload_to_s3.boto3.client")
+    @patch("app.tasks.upload_to_s3.settings")
+    def test_upload_generic_exception(self, mock_settings, mock_boto_client, tmp_path):
+        """Test S3 upload with generic exception."""
+        test_file = tmp_path / "test.pdf"
+        test_file.write_text("test content")
+        
+        mock_settings.s3_bucket_name = "my-bucket"
+        mock_settings.aws_access_key_id = "key"
+        mock_settings.aws_secret_access_key = "secret"
+        mock_settings.aws_region = "us-east-1"
+        mock_settings.s3_folder_prefix = None
+        mock_settings.s3_storage_class = "STANDARD"
+        mock_settings.s3_acl = None
+
+        mock_s3 = MagicMock()
+        mock_s3.upload_file.side_effect = Exception("Network error")
+        mock_boto_client.return_value = mock_s3
+
+        with pytest.raises(Exception, match="Error uploading"):
+            upload_to_s3.apply(args=[str(test_file)])
+
+    @patch("app.tasks.upload_to_s3.boto3.client")
+    @patch("app.tasks.upload_to_s3.settings")
+    def test_upload_with_different_storage_classes(self, mock_settings, mock_boto_client, tmp_path):
+        """Test S3 upload with different storage classes."""
+        test_file = tmp_path / "test.pdf"
+        test_file.write_text("test content")
+        
+        mock_settings.s3_bucket_name = "my-bucket"
+        mock_settings.aws_access_key_id = "key"
+        mock_settings.aws_secret_access_key = "secret"
+        mock_settings.aws_region = "us-east-1"
+        mock_settings.s3_folder_prefix = None
+        mock_settings.s3_acl = None
+
+        mock_s3 = MagicMock()
+        mock_boto_client.return_value = mock_s3
+
+        # Test INTELLIGENT_TIERING
+        mock_settings.s3_storage_class = "INTELLIGENT_TIERING"
+        result = upload_to_s3.apply(args=[str(test_file)])
+        extra_args = mock_s3.upload_file.call_args[1]["ExtraArgs"]
+        assert extra_args["StorageClass"] == "INTELLIGENT_TIERING"
+
+    @patch("app.tasks.upload_to_s3.boto3.client")
+    @patch("app.tasks.upload_to_s3.settings")
+    def test_upload_url_generation(self, mock_settings, mock_boto_client, tmp_path):
+        """Test that the S3 URL is properly generated."""
+        test_file = tmp_path / "test.pdf"
+        test_file.write_text("test content")
+        
+        mock_settings.s3_bucket_name = "my-bucket"
+        mock_settings.aws_access_key_id = "key"
+        mock_settings.aws_secret_access_key = "secret"
+        mock_settings.aws_region = "eu-west-1"
+        mock_settings.s3_folder_prefix = "docs"
+        mock_settings.s3_storage_class = "STANDARD"
+        mock_settings.s3_acl = None
+
+        mock_s3 = MagicMock()
+        mock_boto_client.return_value = mock_s3
+
+        result = upload_to_s3.apply(args=[str(test_file)])
+
+        expected_url = "https://my-bucket.s3.eu-west-1.amazonaws.com/docs/test.pdf"
+        assert result.result["s3_url"] == expected_url
diff --git a/tests/test_upload_to_sftp.py b/tests/test_upload_to_sftp.py
new file mode 100644
index 00000000..cea5ed56
--- /dev/null
+++ b/tests/test_upload_to_sftp.py
@@ -0,0 +1,225 @@
+"""Tests for app/tasks/upload_to_sftp.py module."""
+
+import os
+from unittest.mock import MagicMock, Mock, patch
+
+import pytest
+
+from app.tasks.upload_to_sftp import upload_to_sftp
+
+
+@pytest.mark.unit
+class TestUploadToSFTP:
+    """Tests for SFTP upload functionality."""
+
+    @patch("app.tasks.upload_to_sftp.paramiko.SSHClient")
+    @patch("app.tasks.upload_to_sftp.settings")
+    def test_upload_with_key_authentication(self, mock_settings, mock_ssh_class, tmp_path):
+        """Test SFTP upload using SSH key authentication."""
+        # Setup
+        test_file = tmp_path / "test.pdf"
+        test_file.write_text("test content")
+        
+        mock_settings.sftp_host = "sftp.example.com"
+        mock_settings.sftp_port = 22
+        mock_settings.sftp_username = "testuser"
+        mock_settings.sftp_password = None
+        mock_settings.sftp_private_key = str(tmp_path / "key.pem")
+        mock_settings.sftp_private_key_passphrase = "passphrase"
+        mock_settings.sftp_folder = "/uploads"
+        mock_settings.workdir = str(tmp_path)
+        mock_settings.sftp_disable_host_key_verification = False
+
+        # Create mock key file
+        key_file = tmp_path / "key.pem"
+        key_file.write_text("fake key")
+
+        # Mock SSH and SFTP
+        mock_ssh = MagicMock()
+        mock_sftp = MagicMock()
+        mock_ssh.open_sftp.return_value = mock_sftp
+        mock_sftp.stat.side_effect = FileNotFoundError
+        mock_ssh_class.return_value = mock_ssh
+
+        # Execute
+        task = upload_to_sftp.apply(args=[str(test_file)])
+
+        # Verify
+        assert task.result["status"] == "Completed"
+        mock_ssh.connect.assert_called_once()
+        connect_kwargs = mock_ssh.connect.call_args[1]
+        assert connect_kwargs["key_filename"] == str(tmp_path / "key.pem")
+        assert connect_kwargs["passphrase"] == "passphrase"
+        mock_sftp.put.assert_called_once()
+
+    @patch("app.tasks.upload_to_sftp.paramiko.SSHClient")
+    @patch("app.tasks.upload_to_sftp.settings")
+    def test_upload_with_password_authentication(self, mock_settings, mock_ssh_class, tmp_path):
+        """Test SFTP upload using password authentication."""
+        # Setup
+        test_file = tmp_path / "test.pdf"
+        test_file.write_text("test content")
+        
+        mock_settings.sftp_host = "sftp.example.com"
+        mock_settings.sftp_port = 22
+        mock_settings.sftp_username = "testuser"
+        mock_settings.sftp_password = "testpass"
+        mock_settings.sftp_private_key = None
+        mock_settings.sftp_folder = "/uploads"
+        mock_settings.workdir = str(tmp_path)
+        mock_settings.sftp_disable_host_key_verification = False
+
+        # Mock SSH and SFTP
+        mock_ssh = MagicMock()
+        mock_sftp = MagicMock()
+        mock_ssh.open_sftp.return_value = mock_sftp
+        mock_sftp.stat.side_effect = FileNotFoundError
+        mock_ssh_class.return_value = mock_ssh
+
+        # Execute
+        task = upload_to_sftp.apply(args=[str(test_file)])
+
+        # Verify
+        assert task.result["status"] == "Completed"
+        connect_kwargs = mock_ssh.connect.call_args[1]
+        assert connect_kwargs["password"] == "testpass"
+        assert "key_filename" not in connect_kwargs
+
+    @patch("app.tasks.upload_to_sftp.paramiko.SSHClient")
+    @patch("app.tasks.upload_to_sftp.settings")
+    def test_upload_with_disabled_host_key_verification(self, mock_settings, mock_ssh_class, tmp_path):
+        """Test SFTP upload with host key verification disabled."""
+        import paramiko
+
+        test_file = tmp_path / "test.pdf"
+        test_file.write_text("test content")
+        
+        mock_settings.sftp_host = "sftp.example.com"
+        mock_settings.sftp_port = 22
+        mock_settings.sftp_username = "testuser"
+        mock_settings.sftp_password = "testpass"
+        mock_settings.sftp_folder = ""
+        mock_settings.workdir = str(tmp_path)
+        mock_settings.sftp_disable_host_key_verification = True
+
+        mock_ssh = MagicMock()
+        mock_sftp = MagicMock()
+        mock_ssh.open_sftp.return_value = mock_sftp
+        mock_sftp.stat.side_effect = FileNotFoundError
+        mock_ssh_class.return_value = mock_ssh
+
+        # Execute
+        task = upload_to_sftp.apply(args=[str(test_file)])
+
+        # Verify AutoAddPolicy was set
+        mock_ssh.set_missing_host_key_policy.assert_called()
+        # Check that it was called with AutoAddPolicy (not RejectPolicy)
+        call_arg = mock_ssh.set_missing_host_key_policy.call_args[0][0]
+        assert isinstance(call_arg, paramiko.AutoAddPolicy)
+
+    @patch("app.tasks.upload_to_sftp.settings")
+    def test_upload_file_not_found(self, mock_settings):
+        """Test SFTP upload with non-existent file."""
+        mock_settings.sftp_host = "sftp.example.com"
+        mock_settings.sftp_port = 22
+        mock_settings.sftp_username = "testuser"
+        
+        with pytest.raises(FileNotFoundError):
+            upload_to_sftp.apply(args=["/nonexistent/file.pdf"])
+
+    @patch("app.tasks.upload_to_sftp.settings")
+    def test_upload_missing_configuration(self, mock_settings, tmp_path):
+        """Test SFTP upload with missing configuration."""
+        test_file = tmp_path / "test.pdf"
+        test_file.write_text("test content")
+        
+        mock_settings.sftp_host = None
+        mock_settings.sftp_port = None
+        mock_settings.sftp_username = None
+
+        result = upload_to_sftp.apply(args=[str(test_file)])
+
+        assert result.result["status"] == "Skipped"
+        assert "not configured" in result.result["reason"]
+
+    @patch("app.tasks.upload_to_sftp.paramiko.SSHClient")
+    @patch("app.tasks.upload_to_sftp.settings")
+    def test_upload_no_authentication_method(self, mock_settings, mock_ssh_class, tmp_path):
+        """Test SFTP upload with no authentication method available."""
+        test_file = tmp_path / "test.pdf"
+        test_file.write_text("test content")
+        
+        mock_settings.sftp_host = "sftp.example.com"
+        mock_settings.sftp_port = 22
+        mock_settings.sftp_username = "testuser"
+        mock_settings.sftp_password = None
+        mock_settings.sftp_private_key = None
+        mock_settings.sftp_folder = ""
+        mock_settings.workdir = str(tmp_path)
+        mock_settings.sftp_disable_host_key_verification = False
+
+        mock_ssh = MagicMock()
+        mock_ssh_class.return_value = mock_ssh
+
+        with pytest.raises(Exception, match="No authentication method"):
+            upload_to_sftp.apply(args=[str(test_file)])
+
+    @patch("app.tasks.upload_to_sftp.paramiko.SSHClient")
+    @patch("app.tasks.upload_to_sftp.settings")
+    def test_upload_creates_remote_directories(self, mock_settings, mock_ssh_class, tmp_path):
+        """Test that remote directories are created as needed."""
+        test_file = tmp_path / "test.pdf"
+        test_file.write_text("test content")
+        
+        mock_settings.sftp_host = "sftp.example.com"
+        mock_settings.sftp_port = 22
+        mock_settings.sftp_username = "testuser"
+        mock_settings.sftp_password = "testpass"
+        mock_settings.sftp_folder = "/remote/nested/path"
+        mock_settings.workdir = str(tmp_path)
+        mock_settings.sftp_disable_host_key_verification = False
+
+        mock_ssh = MagicMock()
+        mock_sftp = MagicMock()
+        mock_ssh.open_sftp.return_value = mock_sftp
+        
+        # Simulate directories not existing
+        mock_sftp.stat.side_effect = FileNotFoundError
+        mock_ssh_class.return_value = mock_ssh
+
+        # Execute
+        task = upload_to_sftp.apply(args=[str(test_file)])
+
+        # Verify mkdir was called for each directory level
+        mkdir_calls = [call[0][0] for call in mock_sftp.mkdir.call_args_list]
+        assert any("/remote" in call for call in mkdir_calls)
+        assert any("/remote/nested" in call for call in mkdir_calls)
+        assert any("/remote/nested/path" in call for call in mkdir_calls)
+
+    @patch("app.tasks.upload_to_sftp.paramiko.SSHClient")
+    @patch("app.tasks.upload_to_sftp.settings")
+    def test_upload_connection_error_cleanup(self, mock_settings, mock_ssh_class, tmp_path):
+        """Test that connections are cleaned up on error."""
+        test_file = tmp_path / "test.pdf"
+        test_file.write_text("test content")
+        
+        mock_settings.sftp_host = "sftp.example.com"
+        mock_settings.sftp_port = 22
+        mock_settings.sftp_username = "testuser"
+        mock_settings.sftp_password = "testpass"
+        mock_settings.sftp_folder = ""
+        mock_settings.workdir = str(tmp_path)
+        mock_settings.sftp_disable_host_key_verification = False
+
+        mock_ssh = MagicMock()
+        mock_sftp = MagicMock()
+        mock_ssh.open_sftp.return_value = mock_sftp
+        mock_sftp.put.side_effect = Exception("Upload failed")
+        mock_ssh_class.return_value = mock_ssh
+
+        with pytest.raises(Exception, match="Upload failed"):
+            upload_to_sftp.apply(args=[str(test_file)])
+
+        # Verify cleanup was attempted
+        mock_sftp.close.assert_called_once()
+        mock_ssh.close.assert_called_once()
diff --git a/tests/test_views_license.py b/tests/test_views_license.py
index c5867ed6..c2b7d571 100644
--- a/tests/test_views_license.py
+++ b/tests/test_views_license.py
@@ -1,5 +1,8 @@
 """Tests for app/views/license_routes.py module."""
 
+from pathlib import Path
+from unittest.mock import mock_open, patch
+
 import pytest
 
 
@@ -11,3 +14,26 @@ class TestLicenseViews:
         """Test license API endpoint."""
         response = client.get("/api/license")
         assert response.status_code in (200, 404)
+
+    def test_get_lgpl_license_success(self, client):
+        """Test successful LGPL license retrieval."""
+        # Create a mock license file
+        license_content = "GNU Lesser General Public License\nVersion 3, 29 June 2007"
+        
+        with patch("pathlib.Path.exists", return_value=True):
+            with patch("builtins.open", mock_open(read_data=license_content)):
+                response = client.get("/licenses/lgpl.txt")
+                assert response.status_code == 200
+                assert "GNU Lesser General Public License" in response.text
+
+    def test_get_lgpl_license_not_found(self, client):
+        """Test LGPL license file not found."""
+        with patch("pathlib.Path.exists", return_value=False):
+            response = client.get("/licenses/lgpl.txt")
+            assert response.status_code == 404
+            assert "not found" in response.json()["detail"].lower()
+
+    def test_serve_attribution_page(self, client):
+        """Test attribution page is served."""
+        response = client.get("/attribution")
+        assert response.status_code in (200, 404, 500)  # Allow for missing template