perf: add indexed notification summaries and widget

src/govoplan_notifications/backend/db/models.py

@@ -19,6 +19,14 @@ class NotificationMessage(Base, TimestampMixin):
     __table_args__ = (
         Index("ix_notification_messages_tenant_status", "tenant_id", "status"),
         Index("ix_notification_messages_tenant_recipient", "tenant_id", "recipient_type", "recipient_id"),
+        Index(
+            "ix_notification_messages_summary",
+            "tenant_id",
+            "recipient_id",
+            "deleted_at",
+            "status",
+            "read_at",
+        ),
         Index("ix_notification_messages_source", "tenant_id", "source_module", "source_resource_type", "source_resource_id"),
         Index("ix_notification_messages_due", "tenant_id", "status", "not_before_at"),
     )

src/govoplan_notifications/backend/manifest.py

@@ -104,6 +104,13 @@ manifest = ModuleManifest(
             ),
         ),
         view_surfaces=(
+            ViewSurface(
+                id="notifications.widget.summary",
+                module_id=MODULE_ID,
+                kind="section",
+                label="Notification summary widget",
+                order=30,
+            ),
             ViewSurface(
                 id="notifications.settings.preferences",
                 module_id=MODULE_ID,

src/govoplan_notifications/backend/migrations/versions/7a8b9c0d1e2f_v020_notification_summary_index.py

@@ -0,0 +1,29 @@
+"""Add notification summary covering index.
+
+Revision ID: 7a8b9c0d1e2f
+Revises: 6f7a8b9c0d1e
+"""
+
+from alembic import op
+
+
+revision = "7a8b9c0d1e2f"
+down_revision = "6f7a8b9c0d1e"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.create_index(
+        "ix_notification_messages_summary",
+        "notification_messages",
+        ["tenant_id", "recipient_id", "deleted_at", "status", "read_at"],
+        unique=False,
+    )
+
+
+def downgrade() -> None:
+    op.drop_index(
+        "ix_notification_messages_summary",
+        table_name="notification_messages",
+    )

src/govoplan_notifications/backend/service.py

@@ -6,7 +6,7 @@ from email.message import EmailMessage
 from pathlib import Path
 from typing import Any
 
-from sqlalchemy import event, or_
+from sqlalchemy import and_, case, event, func, or_
 from sqlalchemy.orm import Session
 
 from govoplan_core.core.notifications import NotificationDispatchRequest
@@ -200,21 +200,75 @@ def notification_summary(
     user_id: str | None = None,
     recipient_ids: tuple[str, ...] | None = None,
 ) -> dict[str, int | bool]:
-    base_query = session.query(NotificationMessage).filter(
+    filters = [
         NotificationMessage.tenant_id == tenant_id,
         NotificationMessage.deleted_at.is_(None),
-    )
+    ]
     if recipient_ids is not None:
-        base_query = base_query.filter(NotificationMessage.recipient_id.in_(recipient_ids))
-    active_query = base_query.filter(NotificationMessage.status.notin_(["cancelled", "skipped"]))
+        filters.append(NotificationMessage.recipient_id.in_(recipient_ids))
+    active = NotificationMessage.status.notin_(["cancelled", "skipped"])
+    total, unread, pending, failed = (
+        session.query(
+            func.count(NotificationMessage.id),
+            func.coalesce(
+                func.sum(
+                    case(
+                        (
+                            and_(
+                                active,
+                                NotificationMessage.read_at.is_(None),
+                            ),
+                            1,
+                        ),
+                        else_=0,
+                    )
+                ),
+                0,
+            ),
+            func.coalesce(
+                func.sum(
+                    case(
+                        (
+                            and_(
+                                active,
+                                NotificationMessage.status.in_(
+                                    sorted(PENDING_STATUSES)
+                                ),
+                            ),
+                            1,
+                        ),
+                        else_=0,
+                    )
+                ),
+                0,
+            ),
+            func.coalesce(
+                func.sum(
+                    case(
+                        (
+                            and_(
+                                active,
+                                NotificationMessage.status == "failed",
+                            ),
+                            1,
+                        ),
+                        else_=0,
+                    )
+                ),
+                0,
+            ),
+        )
+        .filter(*filters)
+        .one()
+    )
     show_unread_badge = True
     if user_id:
         show_unread_badge = get_notification_preferences(session, tenant_id=tenant_id, user_id=user_id).show_unread_badge
     return {
-        "total": base_query.count(),
-        "unread": active_query.filter(NotificationMessage.read_at.is_(None)).count(),
-        "pending": active_query.filter(NotificationMessage.status.in_(sorted(PENDING_STATUSES))).count(),
-        "failed": active_query.filter(NotificationMessage.status == "failed").count(),
+        "total": int(total or 0),
+        "unread": int(unread or 0),
+        "pending": int(pending or 0),
+        "failed": int(failed or 0),
         "show_unread_badge": show_unread_badge,
     }