Analytics: date-range filter + fix category endpoint Decimal crash

by-category and daily-spending accept start_date/end_date (range wins
over cycle); Analytics gets a two-month calendar range picker beside
the cycle selector. Fixes a latent float/Decimal TypeError that 500'd
spending_by_category whenever it had data — the category donut had
never rendered. Regression + range tests added.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

backend/app/api/v1/endpoints/analytics.py

@@ -43,6 +43,8 @@ class DailySpending(BaseModel):
 def spending_by_category(
     cycle_year: Optional[int] = None,
     cycle_month: Optional[int] = None,
+    start_date: Optional[str] = None,
+    end_date: Optional[str] = None,
     session: Session = Depends(get_session),
     _user: str = Depends(get_current_user),
 ):
@@ -61,13 +63,19 @@ def spending_by_category(
         .group_by(Transaction.category_id)
     )
 
-    if cycle_year and cycle_month:
+    # Arbitrary date range takes precedence over the cycle filter.
+    if start_date and end_date:
+        query = query.where(
+            Transaction.date >= datetime.fromisoformat(start_date),
+            Transaction.date < datetime.fromisoformat(end_date),
+        )
+    elif cycle_year and cycle_month:
         start, end = get_cycle_range(cycle_year, cycle_month)
         query = query.where(Transaction.date >= start, Transaction.date < end)
 
     rows = session.exec(query).all()
 
-    grand_total = sum(r[1] for r in rows) or 1
+    grand_total = float(sum(float(r[1]) for r in rows)) or 1.0
 
     results = []
     for category_id, total, count in rows:
@@ -165,6 +173,8 @@ def monthly_trend(
 def daily_spending(
     cycle_year: Optional[int] = None,
     cycle_month: Optional[int] = None,
+    start_date: Optional[str] = None,
+    end_date: Optional[str] = None,
     session: Session = Depends(get_session),
     _user: str = Depends(get_current_user),
 ):
@@ -187,7 +197,12 @@ def daily_spending(
         .order_by(func.date(Transaction.date))
     )
 
-    if cycle_year and cycle_month:
+    if start_date and end_date:
+        query = query.where(
+            Transaction.date >= datetime.fromisoformat(start_date),
+            Transaction.date < datetime.fromisoformat(end_date),
+        )
+    elif cycle_year and cycle_month:
         start, end = get_cycle_range(cycle_year, cycle_month)
         query = query.where(Transaction.date >= start, Transaction.date < end)
 

backend/tests/test_analytics.py

@@ -0,0 +1,62 @@
+"""Analytics endpoints: category aggregation (Decimal regression) and the
+arbitrary date-range filters added for the Analytics range picker."""
+
+from datetime import datetime
+from decimal import Decimal
+
+from app.api.v1.endpoints.analytics import daily_spending, spending_by_category
+from app.models.models import Category, Transaction
+
+from tests.test_installments import make_cc_tx
+
+
+def seed(session):
+    cat = Category(name="Groceries")
+    session.add(cat)
+    session.commit()
+    make_cc_tx(session, merchant="A", amount="1000.50", reference="a1",
+               date=datetime(2026, 6, 2), category_id=cat.id)
+    make_cc_tx(session, merchant="B", amount="2000.00", reference="b1",
+               date=datetime(2026, 6, 20))
+    return cat
+
+
+class TestSpendingByCategory:
+    def test_decimal_sum_does_not_crash_and_percentages_add_up(self, session):
+        """Regression: Decimal grand total vs float row total raised
+        TypeError, 500ing the endpoint whenever it had data."""
+        seed(session)
+        rows = spending_by_category(session=session, _user="t")
+        assert {r.category_name for r in rows} == {"Groceries", "Uncategorized"}
+        assert sum(r.percentage for r in rows) == 100.0
+
+    def test_date_range_overrides_cycle(self, session):
+        seed(session)
+        rows = spending_by_category(
+            start_date="2026-06-01",
+            end_date="2026-06-10",
+            cycle_year=2026,
+            cycle_month=1,  # would match nothing; range must win
+            session=session,
+            _user="t",
+        )
+        assert len(rows) == 1
+        assert rows[0].category_name == "Groceries"
+        assert rows[0].total == 1000.50
+
+
+class TestDailySpending:
+    def test_date_range_filter(self, session):
+        seed(session)
+        rows = daily_spending(
+            start_date="2026-06-15", end_date="2026-07-01",
+            session=session, _user="t",
+        )
+        assert [r.date for r in rows] == ["2026-06-20"]
+        assert rows[0].total == 2000.00
+
+    def test_future_cuotas_excluded(self, session):
+        make_cc_tx(session, merchant="FUTURE", amount="500.00",
+                   reference="f1", date=datetime(2030, 1, 19))
+        rows = daily_spending(session=session, _user="t")
+        assert rows == []

frontend/src/lib/api-types.gen.ts

@@ -2419,6 +2419,8 @@ export interface operations {
             query?: {
                 cycle_year?: number | null;
                 cycle_month?: number | null;
+                start_date?: string | null;
+                end_date?: string | null;
             };
             header?: {
                 authorization?: string | null;
@@ -2455,6 +2457,8 @@ export interface operations {
             query?: {
                 cycle_year?: number | null;
                 cycle_month?: number | null;
+                start_date?: string | null;
+                end_date?: string | null;
             };
             header?: {
                 authorization?: string | null;

frontend/src/pages/Analytics.tsx

@@ -1,5 +1,6 @@
 import { useState } from 'react';
 import { useQuery } from '@tanstack/react-query';
+import { type DateRange } from 'react-day-picker';
 import {
   PieChart,
   Pie,
@@ -11,7 +12,7 @@ import {
   LineChart,
   Line,
 } from 'recharts';
-import { BarChart3, ChartPie } from 'lucide-react';
+import { BarChart3, CalendarRange, ChartPie, X } from 'lucide-react';
 
 import api, { getRateHistory } from '@/lib/api';
 import { categoricalColor, MAX_SLICES } from '@/lib/charts';
@@ -19,6 +20,13 @@ import ErrorState from '@/components/ErrorState';
 import BillingCycleSelector from '@/components/BillingCycleSelector';
 import { PageHeader } from '@/components/page-header';
 import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card';
+import { Button } from '@/components/ui/button';
+import { Calendar } from '@/components/ui/calendar';
+import {
+  Popover,
+  PopoverContent,
+  PopoverTrigger,
+} from '@/components/ui/popover';
 import {
   Empty,
   EmptyDescription,
@@ -110,15 +118,26 @@ const dailyChartConfig = {
 
 export default function Analytics() {
   const [cycle, setCycle] = useState<{ year: number; month: number } | null>(null);
-  const cycleParams: Record<string, string> = cycle
+  const [range, setRange] = useState<DateRange | undefined>();
+
+  const toISODate = (d: Date) => d.toISOString().slice(0, 10);
+  const nextDay = (d: Date) => new Date(d.getFullYear(), d.getMonth(), d.getDate() + 1);
+  const rangeActive = !!(range?.from && range?.to);
+  // Range takes precedence over the billing-cycle filter (end is exclusive).
+  const periodParams: Record<string, string> = rangeActive
+    ? {
+        start_date: toISODate(range!.from!),
+        end_date: toISODate(nextDay(range!.to!)),
+      }
+    : cycle
       ? { cycle_year: String(cycle.year), cycle_month: String(cycle.month) }
       : {};
 
   const byCategoryQ = useQuery({
-    queryKey: ['analytics', 'by-category', cycle],
+    queryKey: ['analytics', 'by-category', cycle, range],
     queryFn: ({ signal }) =>
       api
-        .get<CategorySpending[]>('/analytics/by-category', { params: cycleParams, signal })
+        .get<CategorySpending[]>('/analytics/by-category', { params: periodParams, signal })
         .then((r) => r.data),
     placeholderData: (prev) => prev,
   });
@@ -130,10 +149,10 @@ export default function Analytics() {
       api.get<MonthlyTrend[]>('/analytics/monthly-trend', { signal }).then((r) => r.data),
   });
   const dailyQ = useQuery({
-    queryKey: ['analytics', 'daily', cycle],
+    queryKey: ['analytics', 'daily', cycle, range],
     queryFn: ({ signal }) =>
       api
-        .get<DailySpending[]>('/analytics/daily-spending', { params: cycleParams, signal })
+        .get<DailySpending[]>('/analytics/daily-spending', { params: periodParams, signal })
         .then((r) => r.data),
     placeholderData: (prev) => prev,
   });
@@ -173,7 +192,55 @@ export default function Analytics() {
         icon={BarChart3}
         title="Analytics"
         subtitle="Desglose y tendencias de gasto"
-        actions={<BillingCycleSelector value={cycle} onChange={setCycle} />}
+        actions={
+          <>
+            <Popover>
+              <PopoverTrigger
+                render={
+                  <Button
+                    variant="outline"
+                    size="sm"
+                    className={rangeActive ? 'text-foreground' : 'text-muted-foreground'}
+                  />
+                }
+              >
+                <CalendarRange className="w-4 h-4 mr-2" aria-hidden />
+                {rangeActive
+                  ? `${range!.from!.toLocaleDateString('es-CR', { day: 'numeric', month: 'short' })} – ${range!.to!.toLocaleDateString('es-CR', { day: 'numeric', month: 'short' })}`
+                  : 'Rango'}
+              </PopoverTrigger>
+              <PopoverContent className="w-auto p-0" align="end">
+                <Calendar
+                  mode="range"
+                  selected={range}
+                  onSelect={(r) => {
+                    setRange(r);
+                    if (r?.from && r?.to) setCycle(null);
+                  }}
+                  numberOfMonths={2}
+                />
+              </PopoverContent>
+            </Popover>
+            {rangeActive && (
+              <Button
+                variant="ghost"
+                size="icon"
+                onClick={() => setRange(undefined)}
+                title="Quitar rango"
+                aria-label="Quitar rango de fechas"
+              >
+                <X className="w-4 h-4" aria-hidden />
+              </Button>
+            )}
+            <BillingCycleSelector
+              value={cycle}
+              onChange={(c) => {
+                setCycle(c);
+                if (c) setRange(undefined);
+              }}
+            />
+          </>
+        }
       />
 
       {anyError && (