施肥計画機能を追加（年度×品種単位のマトリクス管理）

- Backend: apps/fertilizer を新規追加
  - Fertilizer（肥料マスタ）、FertilizationPlan、FertilizationEntry モデル
  - 肥料マスタ・施肥計画 CRUD API
  - 3方式の自動計算API（反当袋数・均等配分・反当チッソ成分量）
  - 作付け計画から圃場候補を取得する API
  - WeasyPrint による PDF 出力（圃場×肥料=袋数 マトリクス表）
- Frontend: app/fertilizer を新規追加
  - 施肥計画一覧（年度セレクタ・PDF出力・編集・削除）
  - 肥料マスタ管理（インライン編集）
  - 施肥計画編集（品種選択→圃場自動取得→肥料追加→自動計算→マトリクス手動調整）
- Navbar に「施肥計画」メニューを追加（Sprout アイコン）
- Cursor ルールファイル・連携ガイドを削除（Claude Code 単独運用へ）

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/apps/fertilizer/admin.py

@@ -0,0 +1,19 @@
+from django.contrib import admin
+from .models import Fertilizer, FertilizationPlan, FertilizationEntry
+
+
+@admin.register(Fertilizer)
+class FertilizerAdmin(admin.ModelAdmin):
+    list_display = ['name', 'maker', 'capacity_kg', 'nitrogen_pct']
+
+
+class FertilizationEntryInline(admin.TabularInline):
+    model = FertilizationEntry
+    extra = 0
+
+
+@admin.register(FertilizationPlan)
+class FertilizationPlanAdmin(admin.ModelAdmin):
+    list_display = ['name', 'year', 'variety']
+    list_filter = ['year']
+    inlines = [FertilizationEntryInline]

backend/apps/fertilizer/apps.py

@@ -0,0 +1,7 @@
+from django.apps import AppConfig
+
+
+class FertilizerConfig(AppConfig):
+    default_auto_field = 'django.db.models.BigAutoField'
+    name = 'apps.fertilizer'
+    verbose_name = '施肥計画'

backend/apps/fertilizer/migrations/0001_initial.py

@@ -0,0 +1,67 @@
+# Generated by Django 5.0 on 2026-03-01 02:50
+
+import django.db.models.deletion
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    initial = True
+
+    dependencies = [
+        ('fields', '0006_e1c_chusankan_17_fields'),
+        ('plans', '0004_crop_base_temp'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='Fertilizer',
+            fields=[
+                ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('name', models.CharField(max_length=100, unique=True, verbose_name='肥料名')),
+                ('maker', models.CharField(blank=True, max_length=100, null=True, verbose_name='メーカー')),
+                ('capacity_kg', models.DecimalField(blank=True, decimal_places=3, max_digits=8, null=True, verbose_name='1袋重量(kg)')),
+                ('nitrogen_pct', models.DecimalField(blank=True, decimal_places=2, max_digits=5, null=True, verbose_name='窒素含有率(%)')),
+                ('phosphorus_pct', models.DecimalField(blank=True, decimal_places=2, max_digits=5, null=True, verbose_name='リン酸含有率(%)')),
+                ('potassium_pct', models.DecimalField(blank=True, decimal_places=2, max_digits=5, null=True, verbose_name='カリ含有率(%)')),
+                ('notes', models.TextField(blank=True, null=True, verbose_name='備考')),
+            ],
+            options={
+                'verbose_name': '肥料マスタ',
+                'verbose_name_plural': '肥料マスタ',
+                'ordering': ['name'],
+            },
+        ),
+        migrations.CreateModel(
+            name='FertilizationPlan',
+            fields=[
+                ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('name', models.CharField(max_length=200, verbose_name='計画名')),
+                ('year', models.IntegerField(verbose_name='年度')),
+                ('created_at', models.DateTimeField(auto_now_add=True)),
+                ('updated_at', models.DateTimeField(auto_now=True)),
+                ('variety', models.ForeignKey(on_delete=django.db.models.deletion.PROTECT, related_name='fertilization_plans', to='plans.variety', verbose_name='品種')),
+            ],
+            options={
+                'verbose_name': '施肥計画',
+                'verbose_name_plural': '施肥計画',
+                'ordering': ['-year', 'variety'],
+            },
+        ),
+        migrations.CreateModel(
+            name='FertilizationEntry',
+            fields=[
+                ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('bags', models.DecimalField(decimal_places=2, max_digits=8, verbose_name='袋数')),
+                ('field', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, to='fields.field', verbose_name='圃場')),
+                ('plan', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='entries', to='fertilizer.fertilizationplan')),
+                ('fertilizer', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, to='fertilizer.fertilizer', verbose_name='肥料')),
+            ],
+            options={
+                'verbose_name': '施肥エントリ',
+                'verbose_name_plural': '施肥エントリ',
+                'ordering': ['field', 'fertilizer'],
+                'unique_together': {('plan', 'field', 'fertilizer')},
+            },
+        ),
+    ]

backend/apps/fertilizer/models.py

@@ -0,0 +1,69 @@
+from django.db import models
+
+
+class Fertilizer(models.Model):
+    name = models.CharField(max_length=100, unique=True, verbose_name='肥料名')
+    maker = models.CharField(max_length=100, blank=True, null=True, verbose_name='メーカー')
+    capacity_kg = models.DecimalField(
+        max_digits=8, decimal_places=3, blank=True, null=True, verbose_name='1袋重量(kg)'
+    )
+    nitrogen_pct = models.DecimalField(
+        max_digits=5, decimal_places=2, blank=True, null=True, verbose_name='窒素含有率(%)'
+    )
+    phosphorus_pct = models.DecimalField(
+        max_digits=5, decimal_places=2, blank=True, null=True, verbose_name='リン酸含有率(%)'
+    )
+    potassium_pct = models.DecimalField(
+        max_digits=5, decimal_places=2, blank=True, null=True, verbose_name='カリ含有率(%)'
+    )
+    notes = models.TextField(blank=True, null=True, verbose_name='備考')
+
+    class Meta:
+        verbose_name = '肥料マスタ'
+        verbose_name_plural = '肥料マスタ'
+        ordering = ['name']
+
+    def __str__(self):
+        return self.name
+
+
+class FertilizationPlan(models.Model):
+    name = models.CharField(max_length=200, verbose_name='計画名')
+    year = models.IntegerField(verbose_name='年度')
+    variety = models.ForeignKey(
+        'plans.Variety', on_delete=models.PROTECT,
+        related_name='fertilization_plans', verbose_name='品種'
+    )
+    created_at = models.DateTimeField(auto_now_add=True)
+    updated_at = models.DateTimeField(auto_now=True)
+
+    class Meta:
+        verbose_name = '施肥計画'
+        verbose_name_plural = '施肥計画'
+        ordering = ['-year', 'variety']
+
+    def __str__(self):
+        return f"{self.year} {self.name}"
+
+
+class FertilizationEntry(models.Model):
+    """圃場 × 肥料 × 袋数 の中間テーブル"""
+    plan = models.ForeignKey(
+        FertilizationPlan, on_delete=models.CASCADE, related_name='entries'
+    )
+    field = models.ForeignKey(
+        'fields.Field', on_delete=models.CASCADE, verbose_name='圃場'
+    )
+    fertilizer = models.ForeignKey(
+        Fertilizer, on_delete=models.CASCADE, verbose_name='肥料'
+    )
+    bags = models.DecimalField(max_digits=8, decimal_places=2, verbose_name='袋数')
+
+    class Meta:
+        verbose_name = '施肥エントリ'
+        verbose_name_plural = '施肥エントリ'
+        unique_together = [['plan', 'field', 'fertilizer']]
+        ordering = ['field', 'fertilizer']
+
+    def __str__(self):
+        return f"{self.plan} / {self.field} / {self.fertilizer}: {self.bags}袋"

backend/apps/fertilizer/serializers.py

@@ -0,0 +1,81 @@
+from rest_framework import serializers
+from .models import Fertilizer, FertilizationPlan, FertilizationEntry
+
+
+class FertilizerSerializer(serializers.ModelSerializer):
+    class Meta:
+        model = Fertilizer
+        fields = '__all__'
+
+
+class FertilizationEntrySerializer(serializers.ModelSerializer):
+    field_name = serializers.CharField(source='field.name', read_only=True)
+    field_area_tan = serializers.DecimalField(
+        source='field.area_tan', max_digits=6, decimal_places=4, read_only=True
+    )
+    fertilizer_name = serializers.CharField(source='fertilizer.name', read_only=True)
+
+    class Meta:
+        model = FertilizationEntry
+        fields = ['id', 'field', 'field_name', 'field_area_tan', 'fertilizer', 'fertilizer_name', 'bags']
+
+
+class FertilizationPlanSerializer(serializers.ModelSerializer):
+    variety_name = serializers.SerializerMethodField()
+    crop_name = serializers.SerializerMethodField()
+    entries = FertilizationEntrySerializer(many=True, read_only=True)
+    field_count = serializers.SerializerMethodField()
+    fertilizer_count = serializers.SerializerMethodField()
+
+    class Meta:
+        model = FertilizationPlan
+        fields = [
+            'id', 'name', 'year', 'variety', 'variety_name', 'crop_name',
+            'entries', 'field_count', 'fertilizer_count', 'created_at', 'updated_at'
+        ]
+
+    def get_variety_name(self, obj):
+        return obj.variety.name
+
+    def get_crop_name(self, obj):
+        return obj.variety.crop.name
+
+    def get_field_count(self, obj):
+        return obj.entries.values('field').distinct().count()
+
+    def get_fertilizer_count(self, obj):
+        return obj.entries.values('fertilizer').distinct().count()
+
+
+class FertilizationPlanWriteSerializer(serializers.ModelSerializer):
+    """保存用（entries を一括で受け取る）"""
+    entries = serializers.ListField(child=serializers.DictField(), write_only=True, required=False)
+
+    class Meta:
+        model = FertilizationPlan
+        fields = ['id', 'name', 'year', 'variety', 'entries']
+
+    def create(self, validated_data):
+        entries_data = validated_data.pop('entries', [])
+        plan = FertilizationPlan.objects.create(**validated_data)
+        self._save_entries(plan, entries_data)
+        return plan
+
+    def update(self, instance, validated_data):
+        entries_data = validated_data.pop('entries', None)
+        for attr, value in validated_data.items():
+            setattr(instance, attr, value)
+        instance.save()
+        if entries_data is not None:
+            instance.entries.all().delete()
+            self._save_entries(instance, entries_data)
+        return instance
+
+    def _save_entries(self, plan, entries_data):
+        for entry in entries_data:
+            FertilizationEntry.objects.create(
+                plan=plan,
+                field_id=entry['field_id'],
+                fertilizer_id=entry['fertilizer_id'],
+                bags=entry['bags'],
+            )

backend/apps/fertilizer/templates/fertilizer/pdf.html

@@ -0,0 +1,58 @@
+<!DOCTYPE html>
+<html lang="ja">
+<head>
+<meta charset="UTF-8">
+<style>
+  @page { size: A4 landscape; margin: 15mm; }
+  body { font-family: "Noto Sans CJK JP", "Hiragino Kaku Gothic Pro", sans-serif; font-size: 10pt; }
+  h1 { font-size: 14pt; text-align: center; margin-bottom: 4px; }
+  .subtitle { text-align: center; font-size: 10pt; color: #555; margin-bottom: 12px; }
+  table { width: 100%; border-collapse: collapse; margin-top: 8px; }
+  th, td { border: 1px solid #888; padding: 4px 6px; text-align: right; }
+  th { background: #e8f5e9; text-align: center; }
+  .col-name { text-align: left; }
+  .col-area { text-align: right; }
+  tr.total-row { font-weight: bold; background: #f5f5f5; }
+  .zero { color: #bbb; }
+</style>
+</head>
+<body>
+<h1>施肥計画書</h1>
+<p class="subtitle">{{ plan.year }}年度　{{ plan.variety.crop.name }} / {{ plan.variety.name }}　「{{ plan.name }}」</p>
+
+<table>
+  <thead>
+    <tr>
+      <th class="col-name">圃場名</th>
+      <th class="col-area">面積(反)</th>
+      {% for fert in fertilizers %}
+      <th>{{ fert.name }}<br><small>（袋）</small></th>
+      {% endfor %}
+      <th>合計袋数</th>
+    </tr>
+  </thead>
+  <tbody>
+    {% for row in rows %}
+    <tr>
+      <td class="col-name">{{ row.field.name }}</td>
+      <td class="col-area">{{ row.field.area_tan }}</td>
+      {% for cell in row.cells %}
+      <td>{% if cell %}{{ cell }}{% else %}<span class="zero">-</span>{% endif %}</td>
+      {% endfor %}
+      <td>{{ row.total }}</td>
+    </tr>
+    {% endfor %}
+  </tbody>
+  <tfoot>
+    <tr class="total-row">
+      <td class="col-name">合計</td>
+      <td></td>
+      {% for total in fert_totals %}
+      <td>{{ total }}</td>
+      {% endfor %}
+      <td>{{ grand_total }}</td>
+    </tr>
+  </tfoot>
+</table>
+</body>
+</html>

backend/apps/fertilizer/urls.py

@@ -0,0 +1,13 @@
+from django.urls import path, include
+from rest_framework.routers import DefaultRouter
+from . import views
+
+router = DefaultRouter()
+router.register(r'fertilizers', views.FertilizerViewSet, basename='fertilizer')
+router.register(r'plans', views.FertilizationPlanViewSet, basename='fertilization-plan')
+
+urlpatterns = [
+    path('', include(router.urls)),
+    path('candidate_fields/', views.CandidateFieldsView.as_view(), name='candidate-fields'),
+    path('calculate/', views.CalculateView.as_view(), name='fertilizer-calculate'),
+]

backend/apps/fertilizer/views.py

@@ -0,0 +1,196 @@
+from decimal import Decimal, InvalidOperation
+
+from django.http import HttpResponse
+from django.template.loader import render_to_string
+from rest_framework import viewsets, status
+from rest_framework.decorators import action
+from rest_framework.permissions import IsAuthenticated
+from rest_framework.response import Response
+from rest_framework.views import APIView
+from weasyprint import HTML
+
+from apps.fields.models import Field
+from apps.plans.models import Plan, Variety
+from .models import Fertilizer, FertilizationPlan
+from .serializers import (
+    FertilizerSerializer,
+    FertilizationPlanSerializer,
+    FertilizationPlanWriteSerializer,
+)
+
+
+class FertilizerViewSet(viewsets.ModelViewSet):
+    permission_classes = [IsAuthenticated]
+    queryset = Fertilizer.objects.all()
+    serializer_class = FertilizerSerializer
+
+
+class FertilizationPlanViewSet(viewsets.ModelViewSet):
+    permission_classes = [IsAuthenticated]
+
+    def get_queryset(self):
+        qs = FertilizationPlan.objects.select_related('variety', 'variety__crop').prefetch_related(
+            'entries', 'entries__field', 'entries__fertilizer'
+        )
+        year = self.request.query_params.get('year')
+        if year:
+            qs = qs.filter(year=year)
+        return qs
+
+    def get_serializer_class(self):
+        if self.action in ['create', 'update', 'partial_update']:
+            return FertilizationPlanWriteSerializer
+        return FertilizationPlanSerializer
+
+    @action(detail=True, methods=['get'])
+    def pdf(self, request, pk=None):
+        plan = self.get_object()
+        entries = plan.entries.select_related('field', 'fertilizer').order_by(
+            'field__display_order', 'field__id', 'fertilizer__name'
+        )
+
+        # 圃場・肥料の一覧を整理
+        fields_map = {}
+        fertilizers_map = {}
+        for entry in entries:
+            fields_map[entry.field_id] = entry.field
+            fertilizers_map[entry.fertilizer_id] = entry.fertilizer
+
+        fields = sorted(fields_map.values(), key=lambda f: (f.display_order, f.id))
+        fertilizers = sorted(fertilizers_map.values(), key=lambda f: f.name)
+
+        # マトリクスデータ生成
+        matrix = {}
+        for entry in entries:
+            matrix[(entry.field_id, entry.fertilizer_id)] = entry.bags
+
+        rows = []
+        for field in fields:
+            cells = [matrix.get((field.id, fert.id), '') for fert in fertilizers]
+            total = sum(v for v in cells if v != '')
+            rows.append({
+                'field': field,
+                'cells': cells,
+                'total': total,
+            })
+
+        # 肥料ごとの合計
+        fert_totals = []
+        for fert in fertilizers:
+            total = sum(
+                matrix.get((field.id, fert.id), Decimal('0'))
+                for field in fields
+            )
+            fert_totals.append(total)
+
+        context = {
+            'plan': plan,
+            'fertilizers': fertilizers,
+            'rows': rows,
+            'fert_totals': fert_totals,
+            'grand_total': sum(fert_totals),
+        }
+        html_string = render_to_string('fertilizer/pdf.html', context)
+        pdf_file = HTML(string=html_string).write_pdf()
+        response = HttpResponse(pdf_file, content_type='application/pdf')
+        response['Content-Disposition'] = f'attachment; filename="fertilization_{plan.year}_{plan.id}.pdf"'
+        return response
+
+
+class CandidateFieldsView(APIView):
+    """作付け計画から圃場候補を返す"""
+    permission_classes = [IsAuthenticated]
+
+    def get(self, request):
+        year = request.query_params.get('year')
+        variety_id = request.query_params.get('variety_id')
+        if not year or not variety_id:
+            return Response({'error': 'year と variety_id が必要です'}, status=status.HTTP_400_BAD_REQUEST)
+
+        field_ids = Plan.objects.filter(
+            year=year, variety_id=variety_id
+        ).values_list('field_id', flat=True)
+
+        fields = Field.objects.filter(id__in=field_ids).order_by('display_order', 'id')
+        data = [
+            {
+                'id': f.id,
+                'name': f.name,
+                'area_tan': str(f.area_tan),
+                'area_m2': f.area_m2,
+                'group_name': f.group_name,
+            }
+            for f in fields
+        ]
+        return Response(data)
+
+
+class CalculateView(APIView):
+    """自動計算（保存しない）"""
+    permission_classes = [IsAuthenticated]
+
+    def post(self, request):
+        method = request.data.get('method')   # 'nitrogen' | 'even' | 'per_tan'
+        param = request.data.get('param')     # 数値パラメータ
+        fertilizer_id = request.data.get('fertilizer_id')
+        field_ids = request.data.get('field_ids', [])
+
+        if not method or param is None or not field_ids:
+            return Response({'error': 'method, param, field_ids が必要です'}, status=status.HTTP_400_BAD_REQUEST)
+
+        try:
+            param = Decimal(str(param))
+        except InvalidOperation:
+            return Response({'error': 'param は数値で指定してください'}, status=status.HTTP_400_BAD_REQUEST)
+
+        fields = Field.objects.filter(id__in=field_ids)
+        if not fields.exists():
+            return Response({'error': '圃場が見つかりません'}, status=status.HTTP_400_BAD_REQUEST)
+
+        results = []
+
+        if method == 'per_tan':
+            # 反当袋数配分: S = Sa × A
+            for field in fields:
+                area = Decimal(str(field.area_tan))
+                bags = (param * area).quantize(Decimal('0.01'))
+                results.append({'field_id': field.id, 'bags': float(bags)})
+
+        elif method == 'even':
+            # 在庫/指定数量均等配分: S = (SS / Sum(A)) × A
+            total_area = sum(Decimal(str(f.area_tan)) for f in fields)
+            if total_area == 0:
+                return Response({'error': '圃場の面積が0です'}, status=status.HTTP_400_BAD_REQUEST)
+            for field in fields:
+                area = Decimal(str(field.area_tan))
+                bags = (param * area / total_area).quantize(Decimal('0.01'))
+                results.append({'field_id': field.id, 'bags': float(bags)})
+
+        elif method == 'nitrogen':
+            # 反当チッソ成分量配分: S = (Nr / (C × Nd/100)) × A
+            if not fertilizer_id:
+                return Response({'error': 'nitrogen 方式には fertilizer_id が必要です'}, status=status.HTTP_400_BAD_REQUEST)
+            try:
+                fertilizer = Fertilizer.objects.get(id=fertilizer_id)
+            except Fertilizer.DoesNotExist:
+                return Response({'error': '肥料が見つかりません'}, status=status.HTTP_404_NOT_FOUND)
+            if not fertilizer.capacity_kg or not fertilizer.nitrogen_pct:
+                return Response(
+                    {'error': 'この肥料には1袋重量(kg)と窒素含有率(%)の登録が必要です'},
+                    status=status.HTTP_400_BAD_REQUEST
+                )
+            c = Decimal(str(fertilizer.capacity_kg))
+            nd = Decimal(str(fertilizer.nitrogen_pct))
+            # 1袋あたりの窒素量 (kg)
+            nc = c * nd / Decimal('100')
+            if nc == 0:
+                return Response({'error': '窒素含有量が0のため計算できません'}, status=status.HTTP_400_BAD_REQUEST)
+            for field in fields:
+                area = Decimal(str(field.area_tan))
+                bags = (param / nc * area).quantize(Decimal('0.01'))
+                results.append({'field_id': field.id, 'bags': float(bags)})
+
+        else:
+            return Response({'error': 'method は nitrogen / even / per_tan のいずれかです'}, status=status.HTTP_400_BAD_REQUEST)
+
+        return Response(results)

backend/keinasystem/settings.py

@@ -43,6 +43,7 @@ INSTALLED_APPS = [
     'apps.reports',
     'apps.mail',
     'apps.weather',
+    'apps.fertilizer',
 ]
 
 MIDDLEWARE = [

backend/keinasystem/urls.py

@@ -57,4 +57,5 @@ urlpatterns = [
     path('api/auth/change-password/', ChangePasswordView.as_view(), name='change-password'),
     path('api/mail/', include('apps.mail.urls')),
     path('api/weather/', include('apps.weather.urls')),
+    path('api/fertilizer/', include('apps.fertilizer.urls')),
 ]