Cross-customer cost compute on the Admin side

Per-customer cost over a UTC time range, joining the fleet hierarchy:
hourly_per_device CA × Devices × Sites × Municipalities × active Tariff
× period (in the municipality's local time) → per-bucket kWh × rate.
Per-day rollup + per-device breakdown. VAT applied per bucket so cost
stays correct across mid-window tariff changes.

Backend
- FleetCostService.ComputeAsync(customerId, fromUtc, toUtc):
  - Loads device→site→municipality mapping (small per customer).
  - Loads tariffs (with periods) grouped by municipality, ordered by
    EffectiveFrom desc for active-tariff lookup.
  - Reads hourly buckets in range from fleet.hourly_per_device via
    raw ADO (the CA isn't an EF entity).
  - For each bucket: pick active tariff for the bucket's date, convert
    bucket start to local time via Municipality.TimeZoneId, pick the
    matching period (or default rate), compute base + VAT.
  - Rolls up per UTC date + per device. Tracks BucketsWithoutTariff
    when site has no muni or no tariff covers the bucket date.
- New DTOs: FleetCostDto / FleetCostDayDto / FleetCostDeviceDto.
- Endpoint: GET /api/fleet/customers/{id}/cost?from&to. AdminOnly.
  Validation: to > from, range <= 366 days (BadRequest on violation).
- Period-selection helper duplicated from CostCalculator (5 lines;
  generic abstraction across TariffPeriod / FleetTariffPeriod is
  more code than the duplication).
- Fixed monthly charges deliberately NOT applied (whole-month billing
  concept; FixedMonthlyChargesIncluded=false in the response).

Frontend
- AdminCustomerDetailPage gets a Cost tab:
  - RangePicker with quick ranges (Today, Last 7d, Last 30d, This
    month). Default last 7 days.
  - 4 Statistic cards: total kWh, base cost, VAT, total.
  - Warning alerts: when buckets-without-tariff > 0; always-on info
    that fixed monthly charges aren't included.
  - Per-day table + per-device table.

Verified end-to-end on the running stack
- Patched DEV0001's existing site to LocalMunicipalityId=1
  (Phase 23 test municipality with Domestic TOU tariff).
- Ingested 3 measurements at 10:00 / 10:20 / 10:40 UTC with kWh
  totals 2000 / 2020 / 2050 → hourly CA bucket has delta = 50 kWh.
- Total kWh in window = 56 (50 from new bucket + 6 from earlier
  Phase 14 backfill bucket).
- Tariff resolution: 10:00-12:00 UTC = 12:00-14:00 SAST, which is
  neither Peak (17:00-20:00 weekdays) nor Off-Peak (weekends only)
  → defaults to 2.50/kWh.
- 56 × 2.50 = 140.00 base ✓
- 140 × 0.15 = 21.00 VAT ✓
- Total 161.00 ✓ exactly what the API returned.

Docs: FLEET-DESIGN.md §11 row updated — tariff sync + cost compute
both marked as shipped.

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

portal/docs/FLEET-DESIGN.md

@@ -316,7 +316,7 @@ Database__ConnectionString=Host=timescaledb;...        # central fleet DB (separ
 
 | Seam | Where v2 picks it up |
 |---|---|
-| ~~Tariff sync~~ + cross-customer cost | **Tariff sync shipped.** `fleet.Municipalities` + `fleet.Tariffs` + `fleet.TariffPeriods` mirror the customer-side rate hierarchy scoped by `CustomerId`. New push batch types: `municipalities`, `tariffs` (with periods nested). Per-municipality rates preserved. **Cost compute on Admin side is the natural next step** — a `FleetCostService` joining `fleet.hourly_per_device` × tariffs → per-customer kWh × rate. |
+| ~~Tariff sync + cross-customer cost~~ | **Both shipped.** `fleet.Municipalities` + `fleet.Tariffs` + `fleet.TariffPeriods` mirror the customer-side rate hierarchy scoped by `CustomerId` (per-customer per-municipality rates preserved). `FleetCostService` joins `fleet.hourly_per_device` × Devices × Sites × Municipalities × active Tariff × period (in municipality local time) → per-bucket cost. Endpoint: `GET /api/fleet/customers/{id}/cost?from&to`. Per-day rollup + per-device breakdown. VAT applied per bucket from the active tariff. Fixed monthly charges intentionally excluded (whole-month billing concept). 366-day range cap. UI: **Cost** tab on customer detail with RangePicker, summary cards, daily + per-device tables. |
 | Per-customer Postgres RLS for multi-Admin-user setups | Add `current_setting('app.customer_filter')`-based RLS policies on `fleet.*` tables; Admin role to customer-scope mapping in `IdentityRole.CustomerId`. |
 | Bidirectional Admin → Customer commands | New WebSocket or long-poll channel on customer side; gated by mutual cert or a second token. |
 | Branding sync (for the "Admin sees customer's brand when drilling in" niceness) | Push branding row from customer; Admin renders the customer's brand on Customer-detail pages. |

portal/frontend/src/api/fleet.ts

@@ -112,3 +112,46 @@ export async function fetchFleetCustomerDetail(id: string): Promise<FleetCustome
   const { data } = await api.get<FleetCustomerDetail>(`/fleet/customers/${id}/detail`);
   return data;
 }
+
+export interface FleetCostDay {
+  date: string;
+  kwh: number;
+  baseCost: number;
+  vatAmount: number;
+  totalCost: number;
+}
+
+export interface FleetCostDeviceRow {
+  deviceId: string;
+  deviceName: string;
+  municipalityName: string | null;
+  kwh: number;
+  baseCost: number;
+  totalCost: number;
+}
+
+export interface FleetCost {
+  fromUtc: string;
+  toUtc: string;
+  totalKwh: number;
+  totalBaseCost: number;
+  totalVatAmount: number;
+  totalCost: number;
+  buckets: number;
+  bucketsWithoutTariff: number;
+  daily: FleetCostDay[];
+  perDevice: FleetCostDeviceRow[];
+  fixedMonthlyChargesIncluded: boolean;
+}
+
+export async function fetchFleetCustomerCost(
+  id: string,
+  fromUtc: string,
+  toUtc: string,
+): Promise<FleetCost> {
+  const { data } = await api.get<FleetCost>(
+    `/fleet/customers/${id}/cost`,
+    { params: { from: fromUtc, to: toUtc } },
+  );
+  return data;
+}

portal/frontend/src/pages/AdminCustomerDetailPage.tsx

@@ -1,16 +1,24 @@
-import { Card, Descriptions, Tabs, Table, Tag, Typography, Button, Space, Spin, Result, Tooltip } from 'antd';
+import { useState } from 'react';
+import {
+  Card, Descriptions, Tabs, Table, Tag, Typography, Button, Space, Spin, Result, Tooltip,
+  DatePicker, Statistic, Row, Col, Alert,
+} from 'antd';
 import type { ColumnsType } from 'antd/es/table';
-import { ArrowLeftOutlined, LineChartOutlined } from '@ant-design/icons';
+import { ArrowLeftOutlined, LineChartOutlined, ThunderboltOutlined, DollarOutlined } from '@ant-design/icons';
 import { useQuery } from '@tanstack/react-query';
 import { useNavigate, useParams } from 'react-router-dom';
+import dayjs, { type Dayjs } from 'dayjs';
 import {
-  fetchFleetCustomerDetail, type FleetSite, type FleetDevice,
+  fetchFleetCustomerDetail, fetchFleetCustomerCost,
+  type FleetSite, type FleetDevice,
   type FleetRecentMeasurement, type FleetIngestEvent,
   type FleetTariffView, type FleetTariffPeriodView,
+  type FleetCostDay, type FleetCostDeviceRow,
 } from '../api/fleet';
 import { fetchGrafanaConfig } from '../api/grafana';
 
 const { Text } = Typography;
+const { RangePicker } = DatePicker;
 
 // UID of the customer-drilldown dashboard provisioned in grafana/dashboards-admin/.
 // Coordinated change: rename here and in the JSON together.
@@ -135,6 +143,11 @@ export function AdminCustomerDetailPage() {
               label: `Tariffs (${data.tariffs.length})`,
               children: <TariffsTab tariffs={data.tariffs} municipalitiesCount={data.municipalities.length} />,
             },
+            {
+              key: 'cost',
+              label: 'Cost',
+              children: <CostTab customerId={data.id} />,
+            },
           ]}
         />
       </Card>
@@ -210,3 +223,102 @@ const DAY_LABELS = ['M', 'T', 'W', 'T', 'F', 'S', 'S'];
 function formatDays(mask: number): string {
   return DAY_LABELS.filter((_, i) => (mask & (1 << i)) !== 0).join('') || '—';
 }
+
+// ── Cost tab: per-customer cost over a chosen UTC range ────────────────────
+function CostTab({ customerId }: { customerId: string }) {
+  const [range, setRange] = useState<[Dayjs, Dayjs]>(() => [
+    dayjs().subtract(7, 'day').startOf('day'),
+    dayjs().add(1, 'day').startOf('day'),
+  ]);
+
+  const fromIso = range[0].toISOString();
+  const toIso = range[1].toISOString();
+
+  const { data, isLoading, error } = useQuery({
+    queryKey: ['fleet-customer-cost', customerId, fromIso, toIso],
+    queryFn: () => fetchFleetCustomerCost(customerId, fromIso, toIso),
+  });
+
+  const dayCols: ColumnsType<FleetCostDay> = [
+    { title: 'Date (UTC)', dataIndex: 'date', key: 'date' },
+    { title: 'kWh', dataIndex: 'kwh', key: 'kwh', render: (n: number) => n.toFixed(3) },
+    { title: 'Base cost', dataIndex: 'baseCost', key: 'b', render: (n: number) => n.toFixed(2) },
+    { title: 'VAT', dataIndex: 'vatAmount', key: 'v', render: (n: number) => n.toFixed(2) },
+    { title: 'Total', dataIndex: 'totalCost', key: 't', render: (n: number) => <Text strong>{n.toFixed(2)}</Text> },
+  ];
+
+  const deviceCols: ColumnsType<FleetCostDeviceRow> = [
+    { title: 'Device', dataIndex: 'deviceName', key: 'd', render: (v: string) => <Text strong>{v}</Text> },
+    {
+      title: 'Municipality', dataIndex: 'municipalityName', key: 'm',
+      render: (v: string | null) => v ?? <Text type="secondary">—</Text>
+    },
+    { title: 'kWh', dataIndex: 'kwh', key: 'kwh', render: (n: number) => n.toFixed(3) },
+    { title: 'Base cost', dataIndex: 'baseCost', key: 'b', render: (n: number) => n.toFixed(2) },
+    { title: 'Total', dataIndex: 'totalCost', key: 't', render: (n: number) => <Text strong>{n.toFixed(2)}</Text> },
+  ];
+
+  return (
+    <Space direction="vertical" size="middle" style={{ width: '100%' }}>
+      <Space>
+        <Text>Range (UTC):</Text>
+        <RangePicker
+          allowClear={false}
+          value={range}
+          showTime={false}
+          onChange={(v) => v && v[0] && v[1] && setRange([v[0].startOf('day'), v[1].endOf('day')])}
+          ranges={{
+            'Today': [dayjs().startOf('day'), dayjs().add(1, 'day').startOf('day')],
+            'Last 7d': [dayjs().subtract(7, 'day').startOf('day'), dayjs().add(1, 'day').startOf('day')],
+            'Last 30d': [dayjs().subtract(30, 'day').startOf('day'), dayjs().add(1, 'day').startOf('day')],
+            'This month': [dayjs().startOf('month'), dayjs().add(1, 'day').startOf('day')],
+          }}
+        />
+      </Space>
+
+      {isLoading && <Spin />}
+      {error && <Alert type="error" message="Failed to compute cost" description={(error as Error).message} />}
+
+      {data && (
+        <>
+          <Row gutter={16}>
+            <Col span={6}><Card><Statistic title="Total kWh" value={data.totalKwh} precision={3} prefix={<ThunderboltOutlined />} /></Card></Col>
+            <Col span={6}><Card><Statistic title="Base cost" value={data.totalBaseCost} precision={2} prefix={<DollarOutlined />} /></Card></Col>
+            <Col span={6}><Card><Statistic title="VAT" value={data.totalVatAmount} precision={2} prefix={<DollarOutlined />} /></Card></Col>
+            <Col span={6}><Card><Statistic title="Total" value={data.totalCost} precision={2} valueStyle={{ color: '#3f8600' }} prefix={<DollarOutlined />} /></Card></Col>
+          </Row>
+
+          {data.bucketsWithoutTariff > 0 && (
+            <Alert
+              type="warning"
+              showIcon
+              message={`${data.bucketsWithoutTariff} of ${data.buckets} hourly buckets had no active tariff (no municipality FK on the site, or no effective tariff for that municipality on the bucket's date). Those buckets are excluded from cost.`}
+            />
+          )}
+
+          {!data.fixedMonthlyChargesIncluded && (
+            <Alert
+              type="info"
+              showIcon
+              message="Fixed monthly charges are not included in this view — they're a whole-month billing concept. Add them separately at invoice time."
+            />
+          )}
+
+          <Card title="Per day" size="small">
+            <Table<FleetCostDay>
+              rowKey="date" size="small" pagination={false}
+              columns={dayCols} dataSource={data.daily}
+            />
+          </Card>
+
+          <Card title="Per device" size="small">
+            <Table<FleetCostDeviceRow>
+              rowKey="deviceId" size="small" pagination={false}
+              columns={deviceCols} dataSource={data.perDevice}
+            />
+          </Card>
+        </>
+      )}
+    </Space>
+  );
+}

portal/src/Tau.Acuvim.Portal/DTOs/FleetCostDtos.cs

@@ -0,0 +1,29 @@
+namespace Tau.Acuvim.Portal.DTOs;
+
+public sealed record FleetCostDayDto(
+    DateOnly Date,
+    double Kwh,
+    decimal BaseCost,
+    decimal VatAmount,
+    decimal TotalCost);
+
+public sealed record FleetCostDeviceDto(
+    Guid DeviceId,
+    string DeviceName,
+    string? MunicipalityName,
+    double Kwh,
+    decimal BaseCost,
+    decimal TotalCost);
+
+public sealed record FleetCostDto(
+    DateTime FromUtc,
+    DateTime ToUtc,
+    double TotalKwh,
+    decimal TotalBaseCost,
+    decimal TotalVatAmount,
+    decimal TotalCost,
+    int Buckets,
+    int BucketsWithoutTariff,
+    IReadOnlyList<FleetCostDayDto> Daily,
+    IReadOnlyList<FleetCostDeviceDto> PerDevice,
+    bool FixedMonthlyChargesIncluded);

portal/src/Tau.Acuvim.Portal/Endpoints/FleetDashboardEndpoints.cs

@@ -20,6 +20,20 @@ public static class FleetDashboardEndpoints
             return detail is null ? Results.NotFound() : Results.Ok(detail);
         });
 
+        group.MapGet("/customers/{id:guid}/cost",
+            async (Guid id, DateTime from, DateTime to, FleetCostService svc, CancellationToken ct) =>
+        {
+            try
+            {
+                var result = await svc.ComputeAsync(id, from, to, ct);
+                return Results.Ok(result);
+            }
+            catch (ArgumentException ex)
+            {
+                return Results.BadRequest(new { error = ex.Message });
+            }
+        });
+
         return app;
     }
 }

portal/src/Tau.Acuvim.Portal/Program.cs

@@ -149,6 +149,7 @@ try
         builder.Services.AddScoped<FleetIngestService>();
         builder.Services.AddScoped<FleetTimescaleBootstrapper>();
         builder.Services.AddScoped<FleetQueryService>();
+        builder.Services.AddScoped<FleetCostService>();
     }
 
     builder.Services.AddHealthChecks()

portal/src/Tau.Acuvim.Portal/Services/FleetCostService.cs

@@ -0,0 +1,189 @@
+using Microsoft.EntityFrameworkCore;
+using Npgsql;
+using Tau.Acuvim.Portal.Data;
+using Tau.Acuvim.Portal.Domain.Fleet;
+using Tau.Acuvim.Portal.Domain.Rates;
+using Tau.Acuvim.Portal.DTOs;
+
+namespace Tau.Acuvim.Portal.Services;
+
+public sealed class FleetCostService(AdminDbContext db, ILogger<FleetCostService> log)
+{
+    public static readonly TimeSpan MaxRange = TimeSpan.FromDays(366);
+
+    // Computes per-customer cost over [fromUtc, toUtc) by joining the hourly continuous
+    // aggregate against the device → site → municipality → active tariff → period chain.
+    //
+    // Per-bucket: rate is selected by converting the bucket start to the municipality's
+    // local time and matching against the tariff's TOU periods. Falls back to the tariff's
+    // DefaultRatePerKwh when no period matches. Buckets whose device's municipality has no
+    // active tariff are counted in BucketsWithoutTariff and excluded from cost.
+    //
+    // VAT is applied per bucket so cost stays correct across mid-window tariff changes.
+    // Fixed monthly charge is NOT applied (whole-month billing concept; out of scope here).
+    public async Task<FleetCostDto> ComputeAsync(
+        Guid customerId, DateTime fromUtc, DateTime toUtc, CancellationToken ct = default)
+    {
+        if (toUtc <= fromUtc) throw new ArgumentException("'to' must be after 'from'.");
+        if (toUtc - fromUtc > MaxRange) throw new ArgumentException($"Range must be <= {MaxRange.TotalDays:F0} days.");
+
+        // 1. Device → site → muni mapping (one query per customer, small data).
+        var deviceJoins = await (
+            from d in db.FleetDevices.AsNoTracking()
+            join s in db.FleetSites.AsNoTracking()
+                on new { d.CustomerId, SiteRef = d.SiteId } equals new { s.CustomerId, SiteRef = s.Id }
+            where d.CustomerId == customerId
+            select new { d.Id, d.Name, s.LocalMunicipalityId }
+        ).ToListAsync(ct);
+        var deviceMap = deviceJoins.ToDictionary(x => x.Id, x => (x.Name, x.LocalMunicipalityId));
+
+        // 2. Municipalities (TimeZoneId for period selection).
+        var munis = await db.FleetMunicipalities.AsNoTracking()
+            .Where(m => m.CustomerId == customerId)
+            .ToListAsync(ct);
+        var muniMap = munis.ToDictionary(m => m.Id);
+
+        // 3. Tariffs (with periods) per municipality, ordered by EffectiveFrom desc for
+        // active-tariff lookup.
+        var tariffs = await db.FleetTariffs.AsNoTracking()
+            .Include(t => t.Periods)
+            .Where(t => t.CustomerId == customerId && t.IsActive)
+            .ToListAsync(ct);
+        var tariffsByMuni = tariffs.GroupBy(t => t.MunicipalityId)
+            .ToDictionary(g => g.Key, g => g.OrderByDescending(t => t.EffectiveFrom).ToList());
+
+        // 4. Hourly buckets in range from the realtime CA.
+        var buckets = await ReadBucketsAsync(customerId, fromUtc, toUtc, ct);
+
+        // 5. Period-by-period accumulation.
+        var byDay = new Dictionary<DateOnly, (double Kwh, decimal Base, decimal Vat, decimal Total)>();
+        var byDevice = new Dictionary<Guid, (double Kwh, decimal Base, decimal Total)>();
+        int withoutTariff = 0;
+
+        foreach (var b in buckets)
+        {
+            if (!deviceMap.TryGetValue(b.DeviceId, out var deviceInfo))
+            {
+                withoutTariff++;
+                continue;
+            }
+            if (deviceInfo.LocalMunicipalityId is not int muniId
+                || !tariffsByMuni.TryGetValue(muniId, out var tariffsForMuni))
+            {
+                withoutTariff++;
+                continue;
+            }
+
+            var bucketDate = DateOnly.FromDateTime(b.Bucket);
+            var tariff = tariffsForMuni.FirstOrDefault(t =>
+                t.EffectiveFrom <= bucketDate &&
+                (t.EffectiveTo == null || t.EffectiveTo >= bucketDate));
+            if (tariff is null) { withoutTariff++; continue; }
+
+            // Local time in the municipality's timezone for period matching.
+            DateTime localBucket;
+            try
+            {
+                var tz = muniMap.TryGetValue(muniId, out var m) && !string.IsNullOrWhiteSpace(m.TimeZoneId)
+                    ? TimeZoneInfo.FindSystemTimeZoneById(m.TimeZoneId)
+                    : TimeZoneInfo.Utc;
+                localBucket = TimeZoneInfo.ConvertTimeFromUtc(
+                    DateTime.SpecifyKind(b.Bucket, DateTimeKind.Utc), tz);
+            }
+            catch (TimeZoneNotFoundException)
+            {
+                log.LogWarning("Unknown TimeZoneId for muni {Muni}; falling back to UTC", muniId);
+                localBucket = b.Bucket;
+            }
+
+            var rate = SelectRate(tariff.Periods, localBucket, tariff.DefaultRatePerKwh);
+            var baseCost = (decimal)b.Kwh * rate;
+            var vatAmount = Round(baseCost * tariff.VatPercentage / 100m);
+            var total = baseCost + vatAmount;
+
+            var dayKey = DateOnly.FromDateTime(b.Bucket);
+            byDay.TryGetValue(dayKey, out var dayAcc);
+            byDay[dayKey] = (dayAcc.Kwh + b.Kwh, dayAcc.Base + baseCost,
+                              dayAcc.Vat + vatAmount, dayAcc.Total + total);
+
+            byDevice.TryGetValue(b.DeviceId, out var devAcc);
+            byDevice[b.DeviceId] = (devAcc.Kwh + b.Kwh, devAcc.Base + baseCost, devAcc.Total + total);
+        }
+
+        // 6. Build response.
+        var daily = byDay.OrderBy(kv => kv.Key)
+            .Select(kv => new FleetCostDayDto(
+                kv.Key, kv.Value.Kwh, Round(kv.Value.Base), Round(kv.Value.Vat), Round(kv.Value.Total)))
+            .ToList();
+
+        var perDevice = byDevice.OrderByDescending(kv => kv.Value.Total)
+            .Select(kv =>
+            {
+                var info = deviceMap[kv.Key];
+                string? muniName = info.LocalMunicipalityId is int mid && muniMap.TryGetValue(mid, out var mm) ? mm.Name : null;
+                return new FleetCostDeviceDto(kv.Key, info.Name, muniName,
+                    kv.Value.Kwh, Round(kv.Value.Base), Round(kv.Value.Total));
+            })
+            .ToList();
+
+        return new FleetCostDto(
+            FromUtc: fromUtc,
+            ToUtc: toUtc,
+            TotalKwh: daily.Sum(d => d.Kwh),
+            TotalBaseCost: Round(daily.Sum(d => d.BaseCost)),
+            TotalVatAmount: Round(daily.Sum(d => d.VatAmount)),
+            TotalCost: Round(daily.Sum(d => d.TotalCost)),
+            Buckets: buckets.Count,
+            BucketsWithoutTariff: withoutTariff,
+            Daily: daily,
+            PerDevice: perDevice,
+            FixedMonthlyChargesIncluded: false);
+    }
+
+    // ── Period selection: matches CostCalculator.SelectRate behaviour but operates on
+    //    FleetTariffPeriod (different type, same shape). Intentionally duplicated; the
+    //    method is 5 lines and a generic abstraction across the two types is more code
+    //    than the duplication.
+    private static decimal SelectRate(
+        IEnumerable<FleetTariffPeriod> periods, DateTime localTime, decimal defaultRate)
+    {
+        var flag = localTime.DayOfWeek.ToFlag();
+        var t = TimeOnly.FromDateTime(localTime);
+        foreach (var p in periods.OrderBy(p => p.StartTime))
+        {
+            if ((p.DaysOfWeek & flag) == 0) continue;
+            if (t >= p.StartTime && t < p.EndTime) return p.RatePerKwh;
+        }
+        return defaultRate;
+    }
+
+    private async Task<List<(Guid DeviceId, DateTime Bucket, double Kwh)>> ReadBucketsAsync(
+        Guid customerId, DateTime fromUtc, DateTime toUtc, CancellationToken ct)
+    {
+        var conn = db.Database.GetDbConnection();
+        if (conn.State != System.Data.ConnectionState.Open) await conn.OpenAsync(ct);
+
+        await using var cmd = conn.CreateCommand();
+        cmd.CommandText = """
+            SELECT "DeviceId", bucket, COALESCE(kwh_imported_delta, 0) AS kwh
+            FROM fleet.hourly_per_device
+            WHERE "CustomerId" = @cust
+              AND bucket >= @from
+              AND bucket <  @to
+            ORDER BY bucket;
+            """;
+        cmd.Parameters.Add(new NpgsqlParameter("@cust", customerId));
+        cmd.Parameters.Add(new NpgsqlParameter("@from", DateTime.SpecifyKind(fromUtc, DateTimeKind.Utc)));
+        cmd.Parameters.Add(new NpgsqlParameter("@to",   DateTime.SpecifyKind(toUtc, DateTimeKind.Utc)));
+
+        var rows = new List<(Guid, DateTime, double)>();
+        await using var reader = await cmd.ExecuteReaderAsync(ct);
+        while (await reader.ReadAsync(ct))
+        {
+            rows.Add((reader.GetGuid(0), reader.GetDateTime(1), reader.GetDouble(2)));
+        }
+        return rows;
+    }
+
+    private static decimal Round(decimal v) => Math.Round(v, 4, MidpointRounding.AwayFromZero);
+}