feat: enhance activity and task APIs with improved payload handling and response models

app/api/v1/tasks/models.py

@@ -1,13 +1,36 @@
-"""Task API schemas."""
+"""Task API schemas and helpers."""
 from __future__ import annotations
 
-from datetime import date
+from datetime import date, datetime, time, timezone
 
 from pydantic import BaseModel
 
+from app.models.task import TaskCreate
+
 
 class TaskCreatePayload(BaseModel):
     deal_id: int
     title: str
     description: str | None = None
-    due_date: date
+    due_date: date | None = None
+
+    def to_domain(self) -> TaskCreate:
+        return TaskCreate(
+            deal_id=self.deal_id,
+            title=self.title,
+            description=self.description,
+            due_date=_date_to_datetime(self.due_date) if self.due_date else None,
+        )
+
+
+def to_range_boundary(value: date | None, *, end_of_day: bool) -> datetime | None:
+    """Convert a date query param to an inclusive datetime boundary."""
+
+    if value is None:
+        return None
+    boundary_time = time(23, 59, 59, 999999) if end_of_day else time(0, 0, 0)
+    return datetime.combine(value, boundary_time, tzinfo=timezone.utc)
+
+
+def _date_to_datetime(value: date) -> datetime:
+    return datetime.combine(value, time(0, 0, 0), tzinfo=timezone.utc)