Compare: add salaried staff diagnostic (C) using users?show_wages=true

Fetches all active users with salary field set whose report_department_id
is in a No 4 department. Reports raw salary field shape, prorated period
cost, and combined (shifts oncostExLeave + prorated salary) to test whether
salaried staff account for the gap vs WF native report.

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

backend/src/lib/workforce.js

@@ -468,13 +468,42 @@ export async function compareEndpoints(from, to) {
   // A3: Same shifts, no client-side dept filter (trust the API filter entirely)
 
   // B: Per-day timesheets + shift.id dedup, filtered by locationDeptIds
-  const [a, a2, a3, b] = await Promise.all([
+  // C: Salaried staff — users with salary field, report_department_id in location depts
+  const [a, a2, a3, b, allUsers] = await Promise.all([
     fetchShiftsAndSummarise(shiftsReportLoc, locationDeptIds),
     fetchShiftsAndSummarise(shiftsReportLoc, reportLocationDeptIds),
-    fetchShiftsAndSummarise(shiftsReportLoc, null),  // trust API filter entirely
+    fetchShiftsAndSummarise(shiftsReportLoc, null),
     fetchTimesheetsByDay(from, to, locationDeptIds),
+    wfFetchPaged('/api/v2/users?show_wages=true&show_inactive=false'),
   ])
 
+  // Find salaried staff based at this location (report_department_id in a location dept)
+  const salaryUsers = locationDeptIds
+    ? allUsers.filter(u => u.salary != null && locationDeptIds.has(String(u.report_department_id)))
+    : allUsers.filter(u => u.salary != null)
+
+  // Prorate salary for the query period: annual / 365 * days, or monthly / 31 * days
+  const days = Math.max(1, Math.ceil((new Date(to) - new Date(from)) / 86_400_000) + 1)
+  const salaryDetails = salaryUsers.map(u => {
+    const sal = u.salary
+    // salary field structure unknown until we see it — expose the raw value
+    return {
+      user_id:              u.id,
+      name:                 u.name || `${u.legal_first_name || ''} ${u.legal_last_name || ''}`.trim(),
+      report_department_id: u.report_department_id,
+      salary_raw:           sal,
+      // Attempt prorations based on common WF salary field shapes
+      // If salary is a number: assume annual amount
+      annual_if_number: typeof sal === 'number' ? sal : null,
+      monthly_if_number: typeof sal === 'number' ? +(sal / 12).toFixed(2) : null,
+      period_prorated:  typeof sal === 'number' ? +(sal / 365 * days).toFixed(2) : null,
+    }
+  })
+
+  const totalSalaryAnnual   = salaryDetails.reduce((s, u) => s + (u.annual_if_number  ?? 0), 0)
+  const totalSalaryMonthly  = salaryDetails.reduce((s, u) => s + (u.monthly_if_number ?? 0), 0)
+  const totalSalaryProrated = salaryDetails.reduce((s, u) => s + (u.period_prorated   ?? 0), 0)
+
   // Dept breakdown for report_location_id depts — to see which extra depts A2 picks up vs A
   const extraDepts = reportLocationDeptIds && locationDeptIds
     ? allDepts
@@ -492,6 +521,17 @@ export async function compareEndpoints(from, to) {
     A2_shifts_api_filtered_report_dept_filter: { ...a2, note: 'shifts + report_location_id API filter + client dept filter (location_id OR report_location_id match)' },
     A3_shifts_api_filtered_no_client_filter:   { ...a3, note: 'shifts + report_location_id API filter only — no client-side dept filter' },
     B_timesheets_per_day_dept_filter: b,
+    C_salaried_staff: {
+      count:               salaryUsers.length,
+      period_days:         days,
+      total_annual:        +totalSalaryAnnual.toFixed(2),
+      total_monthly:       +totalSalaryMonthly.toFixed(2),
+      total_prorated:      +totalSalaryProrated.toFixed(2),
+      // Combined: A shifts oncostExLeave + prorated salary
+      combined_oncostExLeave_plus_salary_prorated: +(a.oncostExLeave + totalSalaryProrated).toFixed(2),
+      note: 'users with salary field set, report_department_id in location depts. salary_raw shows the actual API field shape.',
+      staff: salaryDetails,
+    },
     wf_report_reference: {
       note: 'Target: WF "Cost by Location and Team" — Timesheet exc. leave inc. allowances',
       timesheet_exc_leave: 51005.72,