feat(groups): group views with subtotals for budget and month

budget_group_views composes SectionViews into grouped dataclasses
with a combined total and the default open flag. month_group_views
does the same with planned and applied totals. Group order, labels,
and section-to-group mapping all come from the groups module.

Refs #11

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/quartermaster/month_service.py

@@ -9,7 +9,15 @@ from enum import Enum
 from sqlalchemy import select
 from sqlalchemy.orm import Session
 
+from quartermaster.groups import (
+    GROUP_DEFAULT_OPEN,
+    GROUP_LABELS,
+    Group,
+    group_order,
+    sections_in_group,
+)
 from quartermaster.models import (
+    SECTION_LABELS,
     DebtTarget,
     Entry,
     Month,
@@ -48,6 +56,16 @@ class ZeroAmounts:
     applied: Decimal
 
 
+@dataclass(frozen=True)
+class MonthGroupView:
+    group: Group
+    label: str
+    default_open: bool
+    sections: list[MonthSectionView]
+    total_planned: Decimal
+    total_applied: Decimal
+
+
 def valid_year_month(year_month: str) -> bool:
     return bool(YEAR_MONTH_RE.match(year_month))
 
@@ -148,6 +166,28 @@ def month_zero(month: Month) -> ZeroAmounts:
     )
 
 
+def month_group_views(month: Month) -> list[MonthGroupView]:
+    views: list[MonthGroupView] = []
+    for group in group_order():
+        sections = [
+            section_view(month, s, SECTION_LABELS[s])
+            for s in sections_in_group(group)
+        ]
+        planned = sum((sv.total_planned for sv in sections), Decimal("0"))
+        applied = sum((sv.total_applied for sv in sections), Decimal("0"))
+        views.append(
+            MonthGroupView(
+                group=group,
+                label=GROUP_LABELS[group],
+                default_open=GROUP_DEFAULT_OPEN[group],
+                sections=sections,
+                total_planned=planned,
+                total_applied=applied,
+            )
+        )
+    return views
+
+
 def section_view(month: Month, section: Section, label: str) -> MonthSectionView:
     entries = [e for e in month.entries if e.section == section]
     entries.sort(key=lambda e: e.id)

src/quartermaster/service.py

@@ -6,7 +6,14 @@ from decimal import Decimal
 from sqlalchemy import select
 from sqlalchemy.orm import Session
 
-from quartermaster.models import DebtTarget, Entry, Section
+from quartermaster.groups import (
+    GROUP_DEFAULT_OPEN,
+    GROUP_LABELS,
+    Group,
+    group_order,
+    sections_in_group,
+)
+from quartermaster.models import SECTION_LABELS, DebtTarget, Entry, Section
 
 
 def zero_tone(value: Decimal) -> str:
@@ -23,6 +30,15 @@ class SectionView:
     total: Decimal
 
 
+@dataclass(frozen=True)
+class BudgetGroupView:
+    group: Group
+    label: str
+    default_open: bool
+    sections: list[SectionView]
+    total: Decimal
+
+
 def list_entries(db: Session, section: Section) -> list[Entry]:
     stmt = select(Entry).where(Entry.section == section).order_by(Entry.id)
     return list(db.scalars(stmt))
@@ -32,6 +48,33 @@ def section_total(entries: list[Entry]) -> Decimal:
     return sum((e.amount for e in entries), Decimal("0"))
 
 
+def section_view(db: Session, section: Section) -> SectionView:
+    entries = list_entries(db, section)
+    return SectionView(
+        section=section,
+        label=SECTION_LABELS[section],
+        entries=entries,
+        total=section_total(entries),
+    )
+
+
+def budget_group_views(db: Session) -> list[BudgetGroupView]:
+    views: list[BudgetGroupView] = []
+    for group in group_order():
+        sections = [section_view(db, s) for s in sections_in_group(group)]
+        total = sum((sv.total for sv in sections), Decimal("0"))
+        views.append(
+            BudgetGroupView(
+                group=group,
+                label=GROUP_LABELS[group],
+                default_open=GROUP_DEFAULT_OPEN[group],
+                sections=sections,
+                total=total,
+            )
+        )
+    return views
+
+
 def budget_zero(db: Session) -> Decimal:
     stmt = select(Entry)
     total_income = Decimal("0")