Fix current-period % Budget bugs on Rolling 12 Weeks/Months tables

Rolling12Months: current month's budget wasn't prorated at all, so
%Budget compared MTD actual against the FULL monthly budget — always
looked artificially favorable. Now prorates by elapsed PY DOW-matched
sales share (flat day-count fallback), reusing already-fetched data.

Rolling12Weeks: budget was prorated, but the elapsed-day count mixed a
real timestamp with Math.ceil(...)+1, always overstating elapsed days
by one and inflating the budget denominator. Rewrote to sum per-day
budgets by date string (no fractional-time bug), and applied the same
PY DOW-weighting as the Weekly page, sourcing each day from its own
calendar month so weeks spanning a month boundary split correctly.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

frontend/src/pages/Rolling12Months.tsx

@@ -90,8 +90,19 @@ export default function Rolling12Months() {
             if (date >= monthFrom && date <= effectiveTo) { sales += val.sales; pySales += val.py }
           }
 
-          const monKey = `${monthFrom}`
+          // Budget: prorated to elapsed-to-date by each day's share of the month's PY (DOW-matched)
-          const budget = budgetMap[monKey] ?? null
+          // sales — falls back to flat day-count when PY data is missing. For complete past months
+          // effectiveTo === monthTo, so this always resolves to the full budget (fraction = 1).
+          let monthPyTotal = 0
+          for (const [date, val] of Object.entries(salesByDate)) {
+            if (date >= monthFrom && date <= monthTo) monthPyTotal += val.py
+          }
+          const monKey    = `${monthFrom}`
+          const budgetRaw = budgetMap[monKey] ?? null
+          const mtdFrac   = monthPyTotal > 0
+            ? pySales / monthPyTotal
+            : parseInt(effectiveTo.slice(8), 10) / dim
+          const budget = budgetRaw != null ? budgetRaw * mtdFrac : null
           const label  = `${MONTH_LABELS[month - 1]}-${String(year).slice(2)}`
 
           tableRows.push({ label, wages, budget, sales, pySales, partial: isCurrentMonth })

frontend/src/pages/Rolling12Weeks.tsx

@@ -18,7 +18,14 @@ function startOfWeek(d: Date): Date {
   r.setHours(0, 0, 0, 0)
   return r
 }
-function daysInMonth(d: Date): number { return new Date(d.getFullYear(), d.getMonth() + 1, 0).getDate() }
+function monthKeyOf(dateStr: string): string { return dateStr.slice(0, 7) }
+function daysInMonthKey(monthKey: string): number {
+  const [y, m] = monthKey.split('-').map(Number)
+  return new Date(y, m, 0).getDate()
+}
+function monthRangeOf(monthKey: string): { from: string; to: string } {
+  return { from: `${monthKey}-01`, to: `${monthKey}-${String(daysInMonthKey(monthKey)).padStart(2, '0')}` }
+}
 function fmtMoney(n: number): string { return `£${Math.round(n).toLocaleString('en-GB')}` }
 function pctClass(p: number): string { return p <= 100 ? 'pct-green' : p <= 110 ? 'pct-amber' : 'pct-red' }
 function fmtDelta(p: number): string { const d = p - 100; return `${d >= 0 ? '+' : ''}${d.toFixed(1)}%` }
@@ -43,10 +50,24 @@ export default function Rolling12Weeks() {
         const rangeStart = addDays(thisMonday, -12 * 7)
         const rangeEnd   = addDays(thisMonday, 6)  // end of current week
 
-        const [actRes, salesRes, budRes] = await Promise.all([
+        // Budget is monthly, so weighting each week's share needs full-month PY sales as the
+        // denominator — gather every distinct calendar month touched by any of the 13 weeks
+        // (a week can span two months) and fetch each one's full range.
+        const monthKeySet = new Set<string>()
+        for (let w = 0; w < 13; w++) {
+          const wStart = addDays(rangeStart, w * 7)
+          const wEnd   = addDays(wStart, 6)
+          monthKeySet.add(monthKeyOf(fmt(wStart)))
+          monthKeySet.add(monthKeyOf(fmt(wEnd)))
+        }
+        const monthKeys   = Array.from(monthKeySet)
+        const monthRanges = monthKeys.map(monthRangeOf)
+
+        const [actRes, salesRes, budRes, monthSalesResList] = await Promise.all([
           getActuals(fmt(rangeStart), fmt(rangeEnd)),
           getNetSales(fmt(rangeStart), fmt(rangeEnd)),
           getBudgets(),
+          Promise.all(monthRanges.map(r => getNetSales(r.from, r.to))),
         ])
 
         const salesByDate: Record<string, { sales: number; py: number }> = {}
@@ -54,9 +75,30 @@ export default function Rolling12Weeks() {
           salesByDate[d.date] = { sales: d.net_sales, py: d.py_sales }
         }
 
-        const budgetMap: Record<string, number> = {}
+        // Per-day PY sales and per-month PY totals, used to weight each week's budget share
+        const pySalesByDay: Record<string, number> = {}
+        const monthPyTotals: Record<string, number> = {}
+        monthKeys.forEach((key, i) => {
+          let total = 0
+          for (const d of monthSalesResList[i].days) { pySalesByDay[d.date] = d.py_sales; total += d.py_sales }
+          monthPyTotals[key] = total
+        })
+
+        const budgetMap: Record<string, number> = {} // monthKey (YYYY-MM) -> amount
         for (const b of budRes.budgets as WageBudget[]) {
-          budgetMap[b.month] = b.budget_amount
+          budgetMap[b.month.slice(0, 7)] = b.budget_amount
+        }
+
+        // Budget for a single day: sourced from that day's own calendar month, weighted by its
+        // share of that month's PY (DOW-matched) sales — falls back to a flat day-count split
+        // within that month when PY sales data isn't available.
+        const dayBudget = (ds: string): number => {
+          const mKey = monthKeyOf(ds)
+          const monthBudget = budgetMap[mKey]
+          if (monthBudget == null) return 0
+          const monthTotal = monthPyTotals[mKey] ?? 0
+          if (monthTotal > 0) return monthBudget * ((pySalesByDay[ds] ?? 0) / monthTotal)
+          return monthBudget / daysInMonthKey(mKey)
         }
 
         // Dept lookup
@@ -95,20 +137,25 @@ export default function Rolling12Weeks() {
             pySales += salesByDate[ds]?.py    ?? 0
           }
 
-          // Pro-rata budget
+          // Budget: sum of each elapsed day's own-month, PY-weighted share (see dayBudget above)
-          const monStr = `${wStart.getFullYear()}-${String(wStart.getMonth() + 1).padStart(2, '0')}-01`
+          let budget = 0
-          const monthBudget = budgetMap[monStr]
+          let anyBudget = false
-          const budget = monthBudget != null
+          for (let i = 0; i <= 6; i++) {
-            ? monthBudget * (isPartial ? (Math.ceil((today.getTime() - wStart.getTime()) / 86_400_000) + 1) : 7) / daysInMonth(wStart)
+            const d = addDays(wStart, i)
-            : null
+            if (d > effectiveEnd) break
+            const ds = fmt(d)
+            if (budgetMap[monthKeyOf(ds)] != null) anyBudget = true
+            budget += dayBudget(ds)
+          }
+          const budgetVal = anyBudget ? budget : null
 
           const label = `w/e ${wEnd.toLocaleDateString('en-GB', { day: 'numeric', month: 'short' })}`
-          tableRows.push({ label, wages, budget, sales, pySales, partial: isPartial })
+          tableRows.push({ label, wages, budget: budgetVal, sales, pySales, partial: isPartial })
 
           const cdRow: Record<string, number | string> = { label }
           for (const dep of depts) cdRow[dep.department_name] = deptWages[dep.department_id] ?? 0
           cdRow._wages  = wages
-          cdRow._budget = budget ?? 0
+          cdRow._budget = budgetVal ?? 0
           cData.push(cdRow)
         }