feat: implement daily-ice-usage endpoint for Profile API

Add custom action to ProfileViewSet that returns aggregated daily ice usage
for a specific profile and date. Endpoint accepts date query parameter in
YYYY-MM-DD format and returns total feet built, total ice cubic yards, and
per-section breakdowns.

Implementation uses get_object_or_404 for proper 404 handling, explicit None
checking for aggregate results (no implicit defaults), and proper type
annotations throughout.

Tests added for success case, no-data case, invalid profile, and missing
date parameter validation.

apps/profiles/views.py

@@ -2,7 +2,15 @@
 
 from __future__ import annotations
 
-from rest_framework import viewsets
+from datetime import datetime
+from decimal import Decimal
+
+from django.db.models import Sum
+from django.shortcuts import get_object_or_404
+from rest_framework import status, viewsets
+from rest_framework.decorators import action
+from rest_framework.request import Request
+from rest_framework.response import Response
 
 from apps.profiles.models import DailyProgress, Profile, WallSection
 from apps.profiles.serializers import (
@@ -18,6 +26,65 @@ class ProfileViewSet(viewsets.ModelViewSet[Profile]):
     queryset = Profile.objects.all()
     serializer_class = ProfileSerializer
 
+    @action(detail=True, methods=["get"], url_path="daily-ice-usage")
+    def daily_ice_usage(self, request: Request, pk: int) -> Response:
+        """Get daily ice usage aggregated by profile for a specific date."""
+        profile = get_object_or_404(Profile, pk=pk)
+        target_date = request.query_params.get("date")
+
+        if not target_date:
+            return Response(
+                {"error": "date parameter is required"},
+                status=status.HTTP_400_BAD_REQUEST,
+            )
+
+        # Validate date format (YYYY-MM-DD)
+        try:
+            datetime.strptime(target_date, "%Y-%m-%d")
+        except ValueError:
+            return Response(
+                {"error": "date must be in YYYY-MM-DD format"},
+                status=status.HTTP_400_BAD_REQUEST,
+            )
+
+        # Get all wall sections for this profile
+        wall_sections = WallSection.objects.filter(profile=profile)
+
+        # Get daily progress for all sections on target date
+        daily_progress = DailyProgress.objects.filter(wall_section__in=wall_sections, date=target_date)
+
+        # Aggregate totals
+        aggregates = daily_progress.aggregate(
+            total_feet=Sum("feet_built"),
+            total_ice=Sum("ice_cubic_yards"),
+        )
+
+        # Explicit None checking with ternary operators
+        total_feet_built = Decimal("0.00") if aggregates["total_feet"] is None else aggregates["total_feet"]
+        total_ice_cubic_yards = Decimal("0.00") if aggregates["total_ice"] is None else aggregates["total_ice"]
+
+        # Build section breakdown
+        sections = []
+        for progress in daily_progress:
+            sections.append(
+                {
+                    "section_name": progress.wall_section.section_name,
+                    "feet_built": str(progress.feet_built),
+                    "ice_cubic_yards": str(progress.ice_cubic_yards),
+                }
+            )
+
+        return Response(
+            {
+                "profile_id": profile.id,
+                "profile_name": profile.name,
+                "date": target_date,
+                "total_feet_built": str(total_feet_built),
+                "total_ice_cubic_yards": str(total_ice_cubic_yards),
+                "sections": sections,
+            }
+        )
+
 
 class WallSectionViewSet(viewsets.ModelViewSet[WallSection]):
     """ViewSet for WallSection CRUD operations."""

tests/integration/test_profile_api.py

@@ -2,11 +2,16 @@
 
 from __future__ import annotations
 
+from datetime import date
+from decimal import Decimal
+
 import pytest
 from django.urls import reverse
 from rest_framework import status
 from rest_framework.test import APIClient
 
+from apps.profiles.models import DailyProgress, Profile, WallSection
+
 
 @pytest.mark.django_db
 @pytest.mark.integration
@@ -192,3 +197,78 @@ class TestProfileAPI:
 
         assert response.status_code == status.HTTP_201_CREATED
         assert response.data["is_active"] is True
+
+    def test_daily_ice_usage_success(self, api_client: APIClient) -> None:
+        """Test daily ice usage endpoint returns aggregated data."""
+        # Create profile
+        profile = Profile.objects.create(name="Northern Watch", team_lead="Jon Snow")
+
+        # Create wall sections
+        section1 = WallSection.objects.create(
+            profile=profile,
+            section_name="Tower 1-2",
+            start_position=Decimal("0.00"),
+            target_length_feet=Decimal("500.00"),
+        )
+        section2 = WallSection.objects.create(
+            profile=profile,
+            section_name="Tower 2-3",
+            start_position=Decimal("500.00"),
+            target_length_feet=Decimal("500.00"),
+        )
+
+        # Create daily progress for same date
+        target_date = date(2025, 10, 15)
+        DailyProgress.objects.create(
+            wall_section=section1,
+            date=target_date,
+            feet_built=Decimal("12.50"),
+            ice_cubic_yards=Decimal("2437.50"),
+            cost_gold_dragons=Decimal("4631250.00"),
+        )
+        DailyProgress.objects.create(
+            wall_section=section2,
+            date=target_date,
+            feet_built=Decimal("16.25"),
+            ice_cubic_yards=Decimal("3168.75"),
+            cost_gold_dragons=Decimal("6020625.00"),
+        )
+
+        url = reverse("profile-daily-ice-usage", kwargs={"pk": profile.id})
+        response = api_client.get(url, {"date": "2025-10-15"})
+
+        assert response.status_code == status.HTTP_200_OK
+        assert response.data["profile_id"] == profile.id
+        assert response.data["profile_name"] == "Northern Watch"
+        assert response.data["date"] == "2025-10-15"
+        assert response.data["total_feet_built"] == "28.75"
+        assert response.data["total_ice_cubic_yards"] == "5606.25"
+        assert len(response.data["sections"]) == 2
+
+    def test_daily_ice_usage_no_data_for_date(self, api_client: APIClient) -> None:
+        """Test daily ice usage when no progress exists for given date."""
+        profile = Profile.objects.create(name="Northern Watch", team_lead="Jon Snow")
+
+        url = reverse("profile-daily-ice-usage", kwargs={"pk": profile.id})
+        response = api_client.get(url, {"date": "2025-10-15"})
+
+        assert response.status_code == status.HTTP_200_OK
+        assert response.data["total_feet_built"] == "0.00"
+        assert response.data["total_ice_cubic_yards"] == "0.00"
+        assert response.data["sections"] == []
+
+    def test_daily_ice_usage_invalid_profile(self, api_client: APIClient) -> None:
+        """Test daily ice usage with non-existent profile returns 404."""
+        url = reverse("profile-daily-ice-usage", kwargs={"pk": 9999})
+        response = api_client.get(url, {"date": "2025-10-15"})
+
+        assert response.status_code == status.HTTP_404_NOT_FOUND
+
+    def test_daily_ice_usage_missing_date_param(self, api_client: APIClient) -> None:
+        """Test daily ice usage without date parameter returns 400."""
+        profile = Profile.objects.create(name="Northern Watch", team_lead="Jon Snow")
+
+        url = reverse("profile-daily-ice-usage", kwargs={"pk": profile.id})
+        response = api_client.get(url)
+
+        assert response.status_code == status.HTTP_400_BAD_REQUEST