diff --git a/docs/api/openapi.yaml b/docs/api/openapi.yaml
index 1ba6ce29e..c4dca333d 100644
--- a/docs/api/openapi.yaml
+++ b/docs/api/openapi.yaml
@@ -40748,7 +40748,9 @@ components:
                   type: string
                   format: date-time
                   pattern: ^(?:(?:\d\d[2468][048]|\d\d[13579][26]|\d\d0[48]|[02468][048]00|[13579][26]00)-02-29|\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\d|30)|(?:02)-(?:0[1-9]|1\d|2[0-8])))T(?:(?:[01]\d|2[0-3]):[0-5]\d(?::[0-5]\d(?:\.\d+)?)?(?:Z|([+-](?:[01]\d|2[0-3]):[0-5]\d)))$
-                  description: Day-bucket start (ISO-8601).
+                  description: "Day-bucket start (ISO-8601): the user's local midnight. A window longer than the daily cap is served from
+                    a coarser tier (a UTC day, week or month); its rows are stamped at noon UTC of the bucket's first
+                    day, which falls inside the bucket's own week or month in every zone."
                 count:
                   description: Underlying raw-row count for the bucket.
                   type: integer
diff --git a/messages/de.json b/messages/de.json
index 92cf76a1b..a9dd2e313 100644
--- a/messages/de.json
+++ b/messages/de.json
@@ -9572,6 +9572,7 @@
         "systolic": "Systolisch",
         "diastolic": "Diastolisch",
         "mean": "Durchschnitt",
+        "total": "Summe",
         "min": "Niedrigster",
         "max": "Höchster",
         "readings": "Messwerte",
diff --git a/messages/en.json b/messages/en.json
index 840bb19bb..5c8867cc1 100644
--- a/messages/en.json
+++ b/messages/en.json
@@ -9572,6 +9572,7 @@
         "systolic": "Systolic",
         "diastolic": "Diastolic",
         "mean": "Average",
+        "total": "Total",
         "min": "Lowest",
         "max": "Highest",
         "readings": "Readings",
diff --git a/messages/es.json b/messages/es.json
index 34d461a2c..934eed626 100644
--- a/messages/es.json
+++ b/messages/es.json
@@ -9572,6 +9572,7 @@
         "systolic": "Sistólica",
         "diastolic": "Diastólica",
         "mean": "Promedio",
+        "total": "Total",
         "min": "Mínimo",
         "max": "Máximo",
         "readings": "Mediciones",
diff --git a/messages/fr.json b/messages/fr.json
index ee56afde8..fe3e5f3f3 100644
--- a/messages/fr.json
+++ b/messages/fr.json
@@ -9572,6 +9572,7 @@
         "systolic": "Systolique",
         "diastolic": "Diastolique",
         "mean": "Moyenne",
+        "total": "Total",
         "min": "Minimum",
         "max": "Maximum",
         "readings": "Mesures",
diff --git a/messages/it.json b/messages/it.json
index dccfb26e6..607881026 100644
--- a/messages/it.json
+++ b/messages/it.json
@@ -9572,6 +9572,7 @@
         "systolic": "Sistolica",
         "diastolic": "Diastolica",
         "mean": "Media",
+        "total": "Totale",
         "min": "Minimo",
         "max": "Massimo",
         "readings": "Misurazioni",
diff --git a/messages/ko.json b/messages/ko.json
index e6f1f6ec1..1de539767 100644
--- a/messages/ko.json
+++ b/messages/ko.json
@@ -9572,6 +9572,7 @@
         "systolic": "수축기",
         "diastolic": "이완기",
         "mean": "평균",
+        "total": "합계",
         "min": "최저",
         "max": "최고",
         "readings": "측정 횟수",
diff --git a/messages/pl.json b/messages/pl.json
index dac0acbe9..fc35699df 100644
--- a/messages/pl.json
+++ b/messages/pl.json
@@ -9572,6 +9572,7 @@
         "systolic": "Skurczowe",
         "diastolic": "Rozkurczowe",
         "mean": "Średnia",
+        "total": "Suma",
         "min": "Najniższa",
         "max": "Najwyższa",
         "readings": "Pomiary",
diff --git a/src/lib/ai/coach/dialog-keys.ts b/src/lib/ai/coach/dialog-keys.ts
index 6c4860441..54b01c05d 100644
--- a/src/lib/ai/coach/dialog-keys.ts
+++ b/src/lib/ai/coach/dialog-keys.ts
@@ -137,6 +137,7 @@ export const COACH_RESULT_COLUMN_KEYS = {
   systolic: "coach.result.column.systolic",
   diastolic: "coach.result.column.diastolic",
   mean: "coach.result.column.mean",
+  total: "coach.result.column.total",
   min: "coach.result.column.min",
   max: "coach.result.column.max",
   readings: "coach.result.column.readings",
diff --git a/src/lib/ai/coach/method.ts b/src/lib/ai/coach/method.ts
index f2ef3d41b..1404a2f39 100644
--- a/src/lib/ai/coach/method.ts
+++ b/src/lib/ai/coach/method.ts
@@ -31,6 +31,7 @@ import {
   methodReadingsKey,
   methodTotalsKey,
 } from "@/lib/ai/coach/dialog-keys";
+import { aggregationKind } from "@/lib/ai/coach/results/chart-spec";
 
 /** More than this and the line stops being a line. */
 export const METHOD_MAX_ENTRIES = 6;
@@ -38,18 +39,6 @@ export const METHOD_MAX_ENTRIES = 6;
 type Aggregation = NonNullable<CoachMethodEntry["aggregation"]>;
 type Absent = NonNullable<CoachMethodEntry["absent"]>;
 
-/**
- * Metrics whose buckets are totals (a week of steps is summed, not
- * averaged). Every other time series is a level, and its buckets are means.
- */
-const TOTAL_METRICS: ReadonlySet<CoachStepDomain> = new Set<CoachStepDomain>([
-  "steps",
-  "active_energy",
-  "flights",
-  "distance",
-  "daylight",
-]);
-
 const ABSENT_REASONS: ReadonlySet<string> = new Set<Absent>([
   "no_data",
   "outside_window",
@@ -70,7 +59,7 @@ function aggregationFor(result: CoachResultMeta): Aggregation | undefined {
       if (domain === "sleep" && result.source.granularity === "day") {
         return undefined;
       }
-      return TOTAL_METRICS.has(domain) ? "sum" : "mean";
+      return aggregationKind(domain) === "total" ? "sum" : "mean";
     }
   }
 }
diff --git a/src/lib/ai/coach/results/__tests__/metric-table-tool.test.ts b/src/lib/ai/coach/results/__tests__/metric-table-tool.test.ts
index 22910f8b6..3441728d8 100644
--- a/src/lib/ai/coach/results/__tests__/metric-table-tool.test.ts
+++ b/src/lib/ai/coach/results/__tests__/metric-table-tool.test.ts
@@ -6,6 +6,8 @@
 import { beforeEach, describe, expect, it, vi } from "vitest";
 
 const readDailySeries = vi.fn();
+const readLiveBuckets = vi.fn();
+const readCanonicalRollupBuckets = vi.fn();
 const moodFindMany = vi.fn();
 const measurementFindMany = vi.fn();
 
@@ -17,9 +19,12 @@ vi.mock("@/lib/db", () => ({
 }));
 vi.mock("@/lib/measurements/daily-series-read", () => ({
   readDailySeries: (...a: unknown[]) => readDailySeries(...a),
+  readLiveBuckets: (...a: unknown[]) => readLiveBuckets(...a),
 }));
 vi.mock("@/lib/rollups/measurement-read", () => ({
   loadUserSourcePriority: vi.fn(async () => null),
+  readCanonicalRollupBuckets: (...a: unknown[]) =>
+    readCanonicalRollupBuckets(...a),
 }));
 
 import { bucketTimeSeries } from "@/lib/charts/bucket-time-series";
@@ -54,6 +59,8 @@ function dayRow(type: string, key: string, value: number, count = 1) {
 
 beforeEach(() => {
   readDailySeries.mockReset();
+  readLiveBuckets.mockReset();
+  readCanonicalRollupBuckets.mockReset();
   moodFindMany.mockReset();
   measurementFindMany.mockReset();
 });
@@ -353,3 +360,249 @@ describe("summariseTable", () => {
     expect(JSON.stringify(summary)).not.toContain("ignore all previous");
   });
 });
+
+describe("totals and levels", () => {
+  const WEST = "America/Los_Angeles";
+  // 10:00 on 20 September in Los Angeles.
+  const WEST_NOW = new Date("2026-09-20T17:00:00Z");
+
+  /** A MONTH bucket of the rollup fold, starting at the UTC month. */
+  function monthBucket(month: string, sumValue: number, count: number) {
+    return {
+      bucketStart: new Date(`${month}-01T00:00:00.000Z`),
+      count,
+      mean: sumValue / count,
+      sumValue,
+      minValue: 0,
+      maxValue: 0,
+    };
+  }
+
+  function allTime(metric: "steps" | "weight" | "audio_event", tz = WEST) {
+    return readMetricTable({
+      userId: "u1",
+      metric,
+      window: "allTime",
+      period: "current",
+      granularity: undefined,
+      timeZone: tz,
+      locale: "en",
+      ref: "r1",
+      now: WEST_NOW,
+    });
+  }
+
+  it("sums a total's days into its weeks and labels the column a total", async () => {
+    const days = Array.from({ length: 30 }, (_, i) =>
+      shiftDateKey("2026-08-29", i),
+    );
+    readDailySeries.mockResolvedValue(
+      days.map((key, i) => dayRow("ACTIVITY_STEPS", key, 1_000 + i, 50)),
+    );
+    const table = await readMetricTable({
+      userId: "u1",
+      metric: "steps",
+      window: "last30days",
+      period: "current",
+      granularity: "week",
+      timeZone: TZ,
+      locale: "en",
+      ref: "r1",
+      now: NOW,
+    });
+    expect(table!.columns[1]).toMatchObject({
+      key: "value",
+      labelKey: "coach.result.column.total",
+      label: "Total",
+    });
+    // Monday 31 August to Sunday 6 September: seven whole days.
+    const week = table!.rows.find((row) => row[0] === "2026-08-31")!;
+    const expected = days
+      .map((key, i) => ({ key, value: 1_000 + i }))
+      .filter(({ key }) => key >= "2026-08-31" && key <= "2026-09-06")
+      .reduce((sum, { value }) => sum + value, 0);
+    expect(week[1]).toBe(expected);
+    expect(week[2]).toBe(7 * 50);
+  });
+
+  it("keeps a level's weeks as means", async () => {
+    readDailySeries.mockResolvedValue([
+      dayRow("WEIGHT", "2026-09-21", 80),
+      dayRow("WEIGHT", "2026-09-22", 82),
+    ]);
+    const table = await readMetricTable({
+      userId: "u1",
+      metric: "weight",
+      window: "last30days",
+      period: "current",
+      granularity: "week",
+      timeZone: TZ,
+      locale: "en",
+      ref: "r1",
+      now: NOW,
+    });
+    expect(table!.columns[1].labelKey).toBe("coach.result.column.mean");
+    expect(table!.rows.find((row) => row[0] === "2026-09-21")![1]).toBe(81);
+  });
+
+  it("reads all time as UTC months, named for their own month west of UTC", async () => {
+    readCanonicalRollupBuckets.mockResolvedValue([
+      monthBucket("2026-01", 240_000, 31),
+      monthBucket("2026-02", 200_000, 28),
+      monthBucket("2026-03", 310_000, 31),
+    ]);
+    const table = (await allTime("steps"))!;
+    const call = readCanonicalRollupBuckets.mock.calls[0][0];
+    expect(call.granularity).toBe("MONTH");
+    // The first whole UTC month of the range: the tier drops a bucket that
+    // starts before `from`.
+    expect(call.from.toISOString().slice(8)).toBe("01T00:00:00.000Z");
+    const byMonth = new Map(table.rows.map((row) => [row[0], row]));
+    // 1 January 00:00 UTC is 31 December in Los Angeles: re-reading it in
+    // the user's zone put January's total under December.
+    expect(table.rows[0]).toEqual(["2026-01", 240_000, 31]);
+    expect(byMonth.has("2025-12")).toBe(false);
+    expect(byMonth.get("2026-03")).toEqual(["2026-03", 310_000, 31]);
+    expect(table.columns[1].labelKey).toBe("coach.result.column.total");
+    expect(readLiveBuckets).not.toHaveBeenCalled();
+  });
+
+  it("gives the same all-time months when the live table serves them", async () => {
+    readCanonicalRollupBuckets.mockResolvedValue([
+      monthBucket("2026-01", 240_000, 31),
+      monthBucket("2026-02", 200_000, 28),
+    ]);
+    const fromTier = (await allTime("steps"))!;
+
+    readCanonicalRollupBuckets.mockResolvedValue([]);
+    readLiveBuckets.mockResolvedValue([
+      {
+        type: "ACTIVITY_STEPS",
+        value: 240_000,
+        measuredAt: "2026-01-01T00:00:00.000Z",
+        count: 31,
+      },
+      {
+        type: "ACTIVITY_STEPS",
+        value: 200_000,
+        measuredAt: "2026-02-01T00:00:00.000Z",
+        count: 28,
+      },
+    ]);
+    const fromLive = (await allTime("steps"))!;
+    expect(fromLive.rows).toEqual(fromTier.rows);
+    const liveCall = readLiveBuckets.mock.calls[0][0];
+    expect(liveCall).toMatchObject({ grain: "monthly", timeZone: "UTC" });
+  });
+
+  it("gives the same month whatever the history length, a year or ten", async () => {
+    // A short history and a long one hold the same January: the month reads
+    // the same total from both, because all time always reads months.
+    readCanonicalRollupBuckets.mockResolvedValue([
+      monthBucket("2026-01", 240_000, 31),
+    ]);
+    const short = (await allTime("steps"))!;
+    readCanonicalRollupBuckets.mockResolvedValue([
+      monthBucket("2017-03", 150_000, 31),
+      monthBucket("2026-01", 240_000, 31),
+    ]);
+    const long = (await allTime("steps"))!;
+    const jan = (t: typeof short) => t.rows.find((row) => row[0] === "2026-01");
+    expect(jan(long)).toEqual(jan(short));
+    expect(jan(short)).toEqual(["2026-01", 240_000, 31]);
+  });
+
+  it("averages a level's all-time months", async () => {
+    readCanonicalRollupBuckets.mockResolvedValue([
+      { ...monthBucket("2026-01", 2_400, 30), mean: 80 },
+    ]);
+    const table = (await allTime("weight"))!;
+    expect(table.rows[0]).toEqual(["2026-01", 80, 30]);
+    expect(table.columns[1].labelKey).toBe("coach.result.column.mean");
+  });
+
+  it("counts loud-sound events as a total, in whole events", async () => {
+    // Every event row is 1; the daily reader averages the type, so a day of
+    // four events reads 1 with a count of 4.
+    readDailySeries.mockResolvedValue([
+      dayRow("AUDIO_EXPOSURE_EVENT", "2026-09-25", 1, 4),
+    ]);
+    const table = await readMetricTable({
+      userId: "u1",
+      metric: "audio_event",
+      window: "last7days",
+      period: "current",
+      granularity: undefined,
+      timeZone: TZ,
+      locale: "en",
+      ref: "r1",
+      now: NOW,
+    });
+    const day = table!.rows.find((row) => row[0] === "2026-09-25")!;
+    expect(day[1]).toBe(4);
+    expect(table!.columns[1].decimals).toBe(0);
+  });
+
+  it("shows a step length to the centimetre", async () => {
+    readDailySeries.mockResolvedValue([
+      dayRow("WALKING_STEP_LENGTH", "2026-09-25", 0.724),
+    ]);
+    const table = await readMetricTable({
+      userId: "u1",
+      metric: "walking_step_length",
+      window: "last7days",
+      period: "current",
+      granularity: undefined,
+      timeZone: TZ,
+      locale: "en",
+      ref: "r1",
+      now: NOW,
+    });
+    expect(table!.columns[1].decimals).toBe(2);
+    const summary = summariseTable(table!);
+    expect((summary.rows as unknown[][])[0][1]).toBe(0.72);
+  });
+
+  it("leads HRV with the estimator the person mostly has and counts a night once", async () => {
+    readDailySeries.mockImplementation(async ({ type }: { type: string }) =>
+      type === "HRV_RMSSD"
+        ? [
+            dayRow("HRV_RMSSD", "2026-09-24", 40),
+            dayRow("HRV_RMSSD", "2026-09-25", 42),
+          ]
+        : [dayRow("HEART_RATE_VARIABILITY", "2026-09-25", 55)],
+    );
+    const table = await readMetricTable({
+      userId: "u1",
+      metric: "hrv",
+      window: "last7days",
+      period: "current",
+      granularity: undefined,
+      timeZone: TZ,
+      locale: "en",
+      ref: "r1",
+      now: NOW,
+    });
+    expect(table!.columns.map((c) => c.key)).toEqual([
+      "day",
+      "rmssd",
+      "sdnn",
+      "readings",
+    ]);
+    const byDay = new Map(table!.rows.map((row) => [row[0], row]));
+    // Both estimators read on the 25th: one night, one reading.
+    expect(byDay.get("2026-09-25")).toEqual(["2026-09-25", 42, 55, 1]);
+  });
+
+  it("tells the model a total's periods are totals and what they add up to", async () => {
+    readCanonicalRollupBuckets.mockResolvedValue([
+      monthBucket("2026-01", 240_000, 31),
+      monthBucket("2026-02", 200_000, 28),
+    ]);
+    const summary = summariseTable((await allTime("steps"))!);
+    expect(summary.valuesAre).toEqual({ value: "total per month" });
+    expect(summary.stats).toMatchObject({
+      value: { total: 440_000, mean: 220_000 },
+    });
+  });
+});
diff --git a/src/lib/ai/coach/results/chart-spec.ts b/src/lib/ai/coach/results/chart-spec.ts
index 02151bf10..841908029 100644
--- a/src/lib/ai/coach/results/chart-spec.ts
+++ b/src/lib/ai/coach/results/chart-spec.ts
@@ -86,7 +86,12 @@ export const METRIC_AGGREGATION_KIND: Readonly<
   workouts: "total",
 };
 
-function aggregationKind(domain: CoachStepDomain): "level" | "total" {
+/**
+ * Whether a metric's periods are totals or levels. The table tool folds a
+ * week or month with it (a sum or a mean), the method line names it, and the
+ * chart draws it: one answer for all three.
+ */
+export function aggregationKind(domain: CoachStepDomain): "level" | "total" {
   return (
     (METRIC_AGGREGATION_KIND as Partial<Record<string, "level" | "total">>)[
       domain
@@ -124,6 +129,14 @@ function columnIndex(table: ChartInput, key: string): number {
   return table.columns.findIndex((column) => column.key === key);
 }
 
+/**
+ * Metrics whose value columns are alternative estimators of one quantity
+ * (HRV as SDNN and as RMSSD), not two sides of one reading: the chart draws
+ * the first, which the table tool orders as the one with more readings.
+ */
+const SINGLE_SERIES_DOMAINS: ReadonlySet<CoachStepDomain> =
+  new Set<CoachStepDomain>(["hrv"]);
+
 /**
  * The series a time series is drawn with: its value columns, and only the
  * first one plus one partner in the same unit — two axes with different
@@ -137,6 +150,7 @@ function timeSeriesColumns(table: ChartInput): CoachResultColumn[] {
       : table.columns.filter((column) => column.kind === "count");
   const [first, ...rest] = candidates;
   if (!first) return [];
+  if (SINGLE_SERIES_DOMAINS.has(table.source.domain)) return [first];
   const partner = rest.find((column) => column.unit === first.unit);
   return partner ? [first, partner] : [first];
 }
diff --git a/src/lib/ai/coach/results/metric-table-tool.ts b/src/lib/ai/coach/results/metric-table-tool.ts
index d85774a65..73fa54545 100644
--- a/src/lib/ai/coach/results/metric-table-tool.ts
+++ b/src/lib/ai/coach/results/metric-table-tool.ts
@@ -4,11 +4,20 @@
  *
  * The numbers are the app's chart numbers, read the way the charts read
  * them: `readDailySeries` cuts the user's own local days and collapses
- * overlapping sources to the ladder-canonical one, and weeks and months are
- * folded from those days by `bucketTimeSeries` in the user's zone. Mood is
- * the mean score of each local day (the key its entries were written under);
- * sleep is time asleep per night, the wake-day key `reconstructSleepNights`
- * gives every other sleep surface.
+ * overlapping sources to the ladder-canonical one. Mood is the mean score of
+ * each local day (the key its entries were written under); sleep is time
+ * asleep per night, the wake-day key `reconstructSleepNights` gives every
+ * other sleep surface.
+ *
+ * A week or month means one thing per metric, whatever serves it. A total
+ * (steps, energy, distance, daylight, loud-sound events: `aggregationKind`)
+ * is the sum of its days, labelled as a total; a level is the mean of its
+ * days, folded by `bucketTimeSeries` in the user's zone as the chart folds
+ * it. All time is read as calendar months straight from the MONTH fold of
+ * the rollup tier (or the same fold of the live table when the tier has no
+ * rows), keyed by the UTC month the bucket starts in: the tier's buckets are
+ * UTC months, and re-reading their start in a zone west of UTC named the
+ * month before.
  *
  * Every period of the range gets a row. A period without a reading carries
  * `null`, never a zero, so absence stays explicit in the table and in the
@@ -26,8 +35,16 @@ import type { Locale } from "@/lib/i18n/config";
 import { getServerTranslator } from "@/lib/i18n/server-translator";
 import { shiftDateKey, userDayKey } from "@/lib/tz/format";
 import { startOfLocalDayKey } from "@/lib/tz/local-day";
-import { readDailySeries } from "@/lib/measurements/daily-series-read";
-import { loadUserSourcePriority } from "@/lib/rollups/measurement-read";
+import {
+  readDailySeries,
+  readLiveBuckets,
+} from "@/lib/measurements/daily-series-read";
+import { CUMULATIVE_HK_TYPES } from "@/lib/measurements/apple-health-mapping";
+import {
+  loadUserSourcePriority,
+  readCanonicalRollupBuckets,
+} from "@/lib/rollups/measurement-read";
+import { annotate } from "@/lib/logging/context";
 import { bucketTimeSeries } from "@/lib/charts/bucket-time-series";
 import { reconstructSleepNights } from "@/lib/analytics/sleep-night";
 import { getUnitForType } from "@/lib/validations/measurement";
@@ -47,6 +64,7 @@ import type {
   CoachScopeWindow,
 } from "@/lib/ai/coach/types";
 
+import { aggregationKind } from "./chart-spec";
 import { RESULT_TABLE_MAX_ROWS } from "./project";
 
 /**
@@ -197,6 +215,8 @@ interface DaySeries {
   column: Omit<CoachResultColumn, "label">;
   /** Local day key → the day's value. */
   byDay: Map<string, number>;
+  /** How days fold into a week or month: a total sums, a level averages. */
+  fold: "sum" | "mean";
 }
 
 /** Per-day values and reading counts for a metric, before bucketing. */
@@ -211,6 +231,22 @@ const UNIT_TOKENS: Readonly<Record<string, string>> = {
   celsius: "°C",
 };
 
+/**
+ * Decimals for the types whose unit alone decides wrongly: a step length of
+ * 0.72 m is not 1 m, a walking speed of 1.35 m/s is not 1.4, and a count of
+ * loud-sound events has no fraction.
+ */
+const DECIMALS_BY_TYPE: Readonly<Partial<Record<MeasurementType, number>>> = {
+  WALKING_STEP_LENGTH: 2,
+  WALKING_SPEED: 2,
+  AUDIO_EXPOSURE_EVENT: 0,
+};
+
+/** Decimals a value is shown with: the type's own, else by unit. */
+function decimalsForType(type: MeasurementType, unit: string): number {
+  return DECIMALS_BY_TYPE[type] ?? decimalsFor(unit);
+}
+
 /** Decimals a value is shown with, by unit. */
 function decimalsFor(unit: string): number {
   switch (unit) {
@@ -243,11 +279,31 @@ const SERIES_SUFFIX: Readonly<Partial<Record<MeasurementType, string>>> = {
   HRV_RMSSD: "RMSSD",
 };
 
+type MeasurementColumn = DaySeries["column"] & {
+  type: MeasurementType;
+  suffix?: string;
+};
+
+/**
+ * A type's value for one day (or month) from a series row. The daily reader
+ * sums the cumulative types and averages every other one; a total the reader
+ * averages (loud-sound events, each row one event) is its mean times its
+ * readings.
+ */
+function totalOrLevel(
+  type: MeasurementType,
+  total: boolean,
+  value: number,
+  count: number,
+): number {
+  return total && !CUMULATIVE_HK_TYPES.has(type) ? value * count : value;
+}
+
 function measurementColumns(
   metric: CoachScopeSource,
   types: readonly MeasurementType[],
   granularity: CoachResultGranularity,
-): Array<DaySeries["column"] & { type: MeasurementType; suffix?: string }> {
+): MeasurementColumn[] {
   if (metric === "bp") {
     return [
       {
@@ -271,7 +327,9 @@ function measurementColumns(
   const labelKey =
     granularity === "day"
       ? COACH_RESULT_COLUMN_KEYS.value
-      : COACH_RESULT_COLUMN_KEYS.mean;
+      : aggregationKind(metric) === "total"
+        ? COACH_RESULT_COLUMN_KEYS.total
+        : COACH_RESULT_COLUMN_KEYS.mean;
   return types.map((type) => {
     const unit = unitTokenFor(type);
     const suffix = types.length > 1 ? (SERIES_SUFFIX[type] ?? type) : undefined;
@@ -280,13 +338,37 @@ function measurementColumns(
       kind: "number" as const,
       labelKey,
       ...(unit ? { unit } : {}),
-      decimals: decimalsFor(unit ?? ""),
+      decimals: decimalsForType(type, unit ?? ""),
       type,
       ...(suffix ? { suffix } : {}),
     };
   });
 }
 
+/**
+ * Put the series with the most readings first and count each period's
+ * readings from the first series that has it. Blood pressure's two sides are
+ * one reading and keep their order (systolic first); HRV's two estimators
+ * are alternatives, so the one the person mostly has leads the table and
+ * the chart, and a night measured by both is one night, not two.
+ */
+function orderAndCount(
+  metric: CoachScopeSource,
+  series: Array<DaySeries & { counts: Map<string, number> }>,
+): { ordered: DaySeries[]; counts: Map<string, number> } {
+  const total = (s: { counts: Map<string, number> }) =>
+    [...s.counts.values()].reduce((sum, v) => sum + v, 0);
+  const ordered =
+    metric === "bp" ? series : [...series].sort((a, b) => total(b) - total(a));
+  const counts = new Map<string, number>();
+  for (const s of ordered) {
+    for (const [key, count] of s.counts) {
+      if (!counts.has(key)) counts.set(key, count);
+    }
+  }
+  return { ordered: ordered.map(({ counts: _c, ...rest }) => rest), counts };
+}
+
 async function readMeasurementDays(args: {
   userId: string;
   metric: CoachScopeSource;
@@ -310,23 +392,148 @@ async function readMeasurementDays(args: {
       }),
     ),
   );
-  const counts = new Map<string, number>();
+  const total = aggregationKind(metric) === "total";
   const suffixes = new Map<string, string>();
-  const series: DaySeries[] = columns.map((column, index) => {
+  const read = columns.map((column, index) => {
     const byDay = new Map<string, number>();
+    const counts = new Map<string, number>();
     for (const row of rowsByType[index]) {
       const day = userDayKey(new Date(row.measuredAt), timeZone);
-      byDay.set(day, row.value);
-      // Paired readings count once: blood pressure counts its systolic side.
-      if (metric !== "bp" || index === 0) {
-        counts.set(day, (counts.get(day) ?? 0) + (row.count ?? 1));
-      }
+      const count = row.count ?? 1;
+      byDay.set(day, totalOrLevel(column.type, total, row.value, count));
+      counts.set(day, (counts.get(day) ?? 0) + count);
     }
     if (column.suffix) suffixes.set(column.key, column.suffix);
     const { type: _type, suffix: _suffix, ...rest } = column;
-    return { column: rest, byDay };
+    return {
+      column: rest,
+      byDay,
+      fold: total ? ("sum" as const) : ("mean" as const),
+      counts,
+    };
   });
-  return { series, counts, suffixes };
+  const { ordered, counts } = orderAndCount(metric, read);
+  return { series: ordered, counts, suffixes };
+}
+
+/** `YYYY-MM-DD` of an instant in UTC. */
+function utcDayKey(date: Date): string {
+  return date.toISOString().slice(0, 10);
+}
+
+/** Folded periods: period key → one value per series, and readings. */
+interface PeriodValues {
+  values: Map<string, Array<number | undefined>>;
+  counts: Map<string, number>;
+}
+
+/**
+ * All time for a measurement metric: one row per UTC calendar month, a total
+ * summed and a level averaged over every reading of the month's canonical
+ * days. The rollup tier's MONTH fold serves it; when the tier holds nothing
+ * for the type (a backfill not caught up, a read that failed), the live table
+ * is folded into the same UTC months the same way. Either path gives the
+ * same number for the same month, so the table no longer depends on how
+ * long the history is or which tier the chart would pick for it.
+ */
+async function readMeasurementMonths(args: {
+  userId: string;
+  metric: CoachScopeSource;
+  range: TableRange;
+}): Promise<{
+  series: DaySeries[];
+  periods: PeriodValues;
+  suffixes: Map<string, string>;
+}> {
+  const { userId, metric, range } = args;
+  const types = COACH_SOURCE_MEASUREMENT_TYPES[metric];
+  const columns = measurementColumns(metric, types, "month");
+  const total = aggregationKind(metric) === "total";
+  const priorityJson = await loadUserSourcePriority(userId);
+  // The first whole UTC month of the range: a bucket that starts before
+  // `from` is left out of the tier's fold.
+  const from = new Date(`${utcDayKey(range.from).slice(0, 7)}-01T00:00:00Z`);
+  const byType = await Promise.all(
+    columns.map(async (column) => {
+      const months = new Map<string, { value: number; count: number }>();
+      try {
+        const buckets = await readCanonicalRollupBuckets({
+          userId,
+          type: column.type,
+          granularity: "MONTH",
+          from,
+          to: range.to,
+          toInclusive: true,
+          userPriorityJson: priorityJson,
+        });
+        for (const b of buckets) {
+          // The fold's sum is every reading's value added up, which is the
+          // total for a cumulative type and for an event count alike.
+          months.set(utcDayKey(b.bucketStart).slice(0, 7), {
+            value: total ? (b.sumValue ?? b.mean * b.count) : b.mean,
+            count: b.count,
+          });
+        }
+      } catch (err) {
+        annotate({
+          meta: {
+            coach_table_rollup_read_threw: true,
+            type: column.type,
+            error: err instanceof Error ? err.message : String(err),
+          },
+        });
+      }
+      if (months.size === 0) {
+        const rows = await readLiveBuckets({
+          userId,
+          type: column.type,
+          from,
+          to: range.to,
+          cap: 1_000,
+          priorityJson,
+          grain: "monthly",
+          timeZone: "UTC",
+        });
+        for (const row of rows) {
+          const count = row.count ?? 1;
+          months.set(row.measuredAt.slice(0, 7), {
+            value: totalOrLevel(column.type, total, row.value, count),
+            count,
+          });
+        }
+      }
+      return months;
+    }),
+  );
+
+  const suffixes = new Map<string, string>();
+  const read = columns.map((column, index) => {
+    if (column.suffix) suffixes.set(column.key, column.suffix);
+    const { type: _type, suffix: _suffix, ...rest } = column;
+    const byDay = new Map<string, number>();
+    const counts = new Map<string, number>();
+    for (const [month, { value, count }] of byType[index]) {
+      byDay.set(month, value);
+      counts.set(month, count);
+    }
+    return {
+      column: rest,
+      byDay,
+      fold: total ? ("sum" as const) : ("mean" as const),
+      counts,
+    };
+  });
+  const { ordered, counts } = orderAndCount(metric, read);
+  const values = new Map<string, Array<number | undefined>>();
+  for (const s of ordered) {
+    for (const month of s.byDay.keys()) {
+      values.set(
+        month,
+        ordered.map((x) => x.byDay.get(month)),
+      );
+    }
+  }
+  return { series: ordered, periods: { values, counts }, suffixes };
 }
 
 async function readMoodDays(args: {
@@ -362,6 +569,7 @@ async function readMoodDays(args: {
           decimals: 1,
         },
         byDay,
+        fold: "mean",
       },
     ],
     counts,
@@ -415,6 +623,7 @@ async function readSleepDays(args: {
           decimals: 0,
         },
         byDay,
+        fold: "mean",
       },
     ],
     counts,
@@ -424,18 +633,16 @@ async function readSleepDays(args: {
 // ── Bucketing ───────────────────────────────────────────────────────────
 
 /**
- * Fold per-day values into the table's periods. Days stay as they are;
- * weeks and months go through `bucketTimeSeries` in the user's zone — the
- * chart's own fold, so a weekly mean here is the chart's weekly point.
+ * Fold per-day values into the table's periods. Days stay as they are. A
+ * level's weeks and months go through `bucketTimeSeries` in the user's zone
+ * — the chart's own fold, so a weekly mean here is the chart's weekly point;
+ * a total's are the sum of its local days.
  */
 function foldIntoPeriods(args: {
   days: MetricDays;
   granularity: CoachResultGranularity;
   timeZone: string;
-}): {
-  values: Map<string, Array<number | undefined>>;
-  counts: Map<string, number>;
-} {
+}): PeriodValues {
   const { days, granularity, timeZone } = args;
   const values = new Map<string, Array<number | undefined>>();
   const counts = new Map<string, number>();
@@ -455,8 +662,18 @@ function foldIntoPeriods(args: {
     }
     return { values, counts };
   }
+  const sums = new Map<string, Map<number, number>>();
   const points = new Map<string, Record<string, number | undefined>>();
   days.series.forEach((s, index) => {
+    if (s.fold === "sum") {
+      for (const [day, value] of s.byDay) {
+        const key = periodKeyOf(day, granularity);
+        const slot = sums.get(key) ?? new Map<number, number>();
+        slot.set(index, (slot.get(index) ?? 0) + value);
+        sums.set(key, slot);
+      }
+      return;
+    }
     for (const [day, value] of s.byDay) {
       const point = points.get(day) ?? {};
       point[String(index)] = value;
@@ -470,12 +687,22 @@ function foldIntoPeriods(args: {
     })),
     { bucket: granularity, timeZone },
   );
+  const levels = new Map<string, Record<string, number>>();
   for (const point of bucketed.points) {
     const dayKey = dayKeyOfUtc(point.timestamp);
-    const key = granularity === "month" ? monthKeyOf(dayKey) : dayKey;
+    levels.set(
+      granularity === "month" ? monthKeyOf(dayKey) : dayKey,
+      point.values,
+    );
+  }
+  for (const key of new Set([...levels.keys(), ...sums.keys()])) {
     values.set(
       key,
-      days.series.map((_, index) => point.values[String(index)]),
+      days.series.map((s, index) =>
+        s.fold === "sum"
+          ? sums.get(key)?.get(index)
+          : levels.get(key)?.[String(index)],
+      ),
     );
   }
   return { values, counts };
@@ -522,11 +749,24 @@ export async function readMetricTable(args: {
   const range = resolveTableRange({ window, period, timeZone, now });
 
   let suffixes = new Map<string, string>();
-  let days: MetricDays;
-  if (metric === "mood") {
-    days = await readMoodDays({ userId, range });
-  } else if (metric === "sleep") {
-    days = await readSleepDays({ userId, range, timeZone });
+  let series: DaySeries[];
+  let folded: PeriodValues;
+  // All time of a measurement metric is keyed by UTC month (the tier's own
+  // buckets); every other table by the user's local days.
+  let keyRange: [string, string] = [range.fromKey, range.toKey];
+  if (metric === "mood" || metric === "sleep") {
+    const days =
+      metric === "mood"
+        ? await readMoodDays({ userId, range })
+        : await readSleepDays({ userId, range, timeZone });
+    series = days.series;
+    folded = foldIntoPeriods({ days, granularity, timeZone });
+  } else if (window === "allTime") {
+    const read = await readMeasurementMonths({ userId, metric, range });
+    series = read.series;
+    folded = read.periods;
+    suffixes = read.suffixes;
+    keyRange = [utcDayKey(range.from), utcDayKey(range.to)];
   } else {
     const read = await readMeasurementDays({
       userId,
@@ -535,16 +775,17 @@ export async function readMetricTable(args: {
       range,
       timeZone,
     });
-    days = read;
+    series = read.series;
+    folded = foldIntoPeriods({ days: read, granularity, timeZone });
     suffixes = read.suffixes;
   }
 
-  const { values, counts } = foldIntoPeriods({ days, granularity, timeZone });
+  const { values, counts } = folded;
   if (values.size === 0) return null;
 
   // All time starts at the first period that holds a reading, not ten
   // years of empty months before it.
-  const keys = periodKeys(range.fromKey, range.toKey, granularity);
+  const keys = periodKeys(keyRange[0], keyRange[1], granularity);
   const firstWithData =
     window === "allTime" ? keys.findIndex((key) => values.has(key)) : 0;
   const periods = keys.slice(Math.max(0, firstWithData));
@@ -566,7 +807,7 @@ export async function readMetricTable(args: {
           : PERIOD_COLUMN_KEYS[granularity],
       ),
     },
-    ...days.series.map((s) => {
+    ...series.map((s) => {
       const base = t(s.column.labelKey);
       const suffix = suffixes.get(s.column.key);
       return { ...s.column, label: suffix ? `${base} (${suffix})` : base };
@@ -582,7 +823,7 @@ export async function readMetricTable(args: {
     const cells = values.get(key);
     return [
       key,
-      ...days.series.map((_, index) => {
+      ...series.map((_, index) => {
         const value = cells?.[index];
         return value === undefined || !Number.isFinite(value) ? null : value;
       }),
@@ -659,6 +900,19 @@ export function summariseTable(
       : valueIndexes.some((index) => typeof row[index] === "number"),
   );
 
+  // What a week's or month's value is: a total of its days or their mean.
+  // Without it a monthly figure of 240 000 steps reads as a daily count.
+  const valuesAre: Record<string, string> = {};
+  for (const { column } of numeric) {
+    if (column.kind !== "number") continue;
+    const per = table.source.granularity ?? "day";
+    if (column.labelKey === COACH_RESULT_COLUMN_KEYS.total) {
+      valuesAre[column.key] = `total per ${per}`;
+    } else if (column.labelKey === COACH_RESULT_COLUMN_KEYS.mean) {
+      valuesAre[column.key] = `average per ${per}`;
+    }
+  }
+
   const stats: Record<string, unknown> = {};
   for (const { column, index } of numeric) {
     const cells = table.rows
@@ -670,11 +924,16 @@ export function summariseTable(
       stats[column.key] = { total: cells.reduce((s, v) => s + v, 0) };
       continue;
     }
+    const sum = cells.reduce((s, v) => s + v, 0);
     stats[column.key] = {
       n: cells.length,
-      mean: round(cells.reduce((s, v) => s + v, 0) / cells.length, decimals),
+      mean: round(sum / cells.length, decimals),
       min: round(Math.min(...cells), decimals),
       max: round(Math.max(...cells), decimals),
+      // A total's periods add up to the range's total; a level's do not.
+      ...(column.labelKey === COACH_RESULT_COLUMN_KEYS.total
+        ? { total: round(sum, decimals) }
+        : {}),
     };
   }
 
@@ -684,6 +943,7 @@ export function summariseTable(
     source: table.source,
     shape: table.shape,
     columns: table.columns.map(columnName),
+    ...(Object.keys(valuesAre).length > 0 ? { valuesAre } : {}),
     periods: table.rowCount,
     periodsWithReadings: withValues.length,
     ...(withValues.length > 0
diff --git a/src/lib/insights/__tests__/coach-result-clipboard.test.ts b/src/lib/insights/__tests__/coach-result-clipboard.test.ts
index cf5d99d81..c9ab965c7 100644
--- a/src/lib/insights/__tests__/coach-result-clipboard.test.ts
+++ b/src/lib/insights/__tests__/coach-result-clipboard.test.ts
@@ -39,13 +39,27 @@ describe("sanitiseCell", () => {
     expect(sanitiseCell(input)).toBe(expected);
   });
 
-  it("turns a leading tab into a space, which no spreadsheet reads as a formula", () => {
-    expect(sanitiseCell("\t=1")).toBe(" =1");
-  });
+  it.each([
+    ["\t=1", "' =1"],
+    ["  =1+1", "'  =1+1"],
+    ["\u00a0@SUM(A1)", "'\u00a0@SUM(A1)"],
+    ["\uff1d1+1", "'\uff1d1+1"],
+    ["\uff0b1", "'\uff0b1"],
+    ["\uff0d1+1", "'\uff0d1+1"],
+    ["\uff20SUM(A1)", "'\uff20SUM(A1)"],
+    ["|cmd", "'|cmd"],
+    [" |cmd", "' |cmd"],
+  ])(
+    "neutralises a formula start behind whitespace or in fullwidth: %j",
+    (input, expected) => {
+      expect(sanitiseCell(input)).toBe(expected);
+    },
+  );
 
   it("leaves plain negatives and ordinary text alone", () => {
     expect(sanitiseCell("-4.5")).toBe("-4.5");
     expect(sanitiseCell("-1 234,5")).toBe("-1 234,5");
+    expect(sanitiseCell(" -4.5")).toBe(" -4.5");
     expect(sanitiseCell("LDL")).toBe("LDL");
     expect(sanitiseCell(null)).toBe("");
   });
diff --git a/src/lib/insights/coach-result-clipboard.ts b/src/lib/insights/coach-result-clipboard.ts
index 1a86f2b9d..ccfa8b564 100644
--- a/src/lib/insights/coach-result-clipboard.ts
+++ b/src/lib/insights/coach-result-clipboard.ts
@@ -6,8 +6,9 @@
  * The cells arrive already formatted the way the table shows them. Two
  * things are done to them on the way out:
  *
- *   - Formula injection. A cell that starts with `=`, `+`, `-` or `@` (or a
- *     tab / carriage return) is read by a spreadsheet as a formula, and a
+ *   - Formula injection. A cell that starts with `=`, `+`, `-`, `@` or `|`
+ *     (their fullwidth forms too, and behind leading whitespace, which some
+ *     spreadsheets skip) is read as a formula or a command, and a
  *     table can carry text the person did not type — a lab analyte read off
  *     an uploaded report. Such a cell gets a leading `'`, which spreadsheets
  *     treat as "this is text". A plain negative number is left alone.
@@ -28,8 +29,8 @@ export interface ClipboardGrid {
   alignRight?: ReadonlyArray<boolean>;
 }
 
-const FORMULA_START = /^[=+\-@\t\r]/;
-const NEGATIVE_NUMBER = /^-\s?\d[\d\s.,  ]*$/;
+const FORMULA_START = /^\s*[=+\-@|＝＋－＠]/;
+const NEGATIVE_NUMBER = /^\s*-\s?\d[\d\s.,  ]*$/;
 
 /** A cell with its separators flattened and a formula start neutralised. */
 export function sanitiseCell(value: string | null): string {
diff --git a/src/lib/openapi/routes/measurements.ts b/src/lib/openapi/routes/measurements.ts
index d07c7cfec..103bea081 100644
--- a/src/lib/openapi/routes/measurements.ts
+++ b/src/lib/openapi/routes/measurements.ts
@@ -763,7 +763,9 @@ const seriesBatchRowSchema = z.object({
   value: z.number().describe("Daily mean (spot metrics) or SUM (cumulative)."),
   measuredAt: z.iso
     .datetime({ offset: true })
-    .describe("Day-bucket start (ISO-8601)."),
+    .describe(
+      "Day-bucket start (ISO-8601): the user's local midnight. A window longer than the daily cap is served from a coarser tier (a UTC day, week or month); its rows are stamped at noon UTC of the bucket's first day, which falls inside the bucket's own week or month in every zone.",
+    ),
   count: z
     .number()
     .int()
diff --git a/src/lib/rollups/__tests__/measurement-read-wmy.test.ts b/src/lib/rollups/__tests__/measurement-read-wmy.test.ts
index bfca576c4..d436b6408 100644
--- a/src/lib/rollups/__tests__/measurement-read-wmy.test.ts
+++ b/src/lib/rollups/__tests__/measurement-read-wmy.test.ts
@@ -53,7 +53,7 @@ import {
   readTieredRollupSeries,
   type RollupBucketRow,
 } from "../measurement-read-wmy";
-import { pickBucket } from "@/lib/charts/bucket-time-series";
+import { bucketTimeSeries, pickBucket } from "@/lib/charts/bucket-time-series";
 
 const { findMany, aggregate, queryRaw } = mocks;
 const DAY_MS = 86_400_000;
@@ -459,7 +459,7 @@ describe("readTieredRollupSeries", () => {
 
     expect(result?.granularity).toBe("MONTH");
     expect(sqlOf(queryRaw.mock.calls[0])).toContain("'month'");
-    expect(result?.rows[0].measuredAt).toBe("2017-01-01T00:00:00.000Z");
+    expect(result?.rows[0].measuredAt).toBe("2017-01-01T12:00:00.000Z");
     expect(result?.rows).toHaveLength(2);
   });
 
@@ -516,7 +516,7 @@ describe("readTieredRollupSeries", () => {
       });
       expect(result?.granularity).toBe("DAY");
       expect(queryRaw).not.toHaveBeenCalled();
-      expect(result?.rows[0].measuredAt).toBe("2026-02-03T00:00:00.000Z");
+      expect(result?.rows[0].measuredAt).toBe("2026-02-03T12:00:00.000Z");
     });
 
     it("serves WEEK buckets for a span between one and two years", async () => {
@@ -535,6 +535,74 @@ describe("readTieredRollupSeries", () => {
       expect(sqlOf(queryRaw.mock.calls[0])).toContain("'week'");
     });
   });
+
+  // The chart names a row by the date its `measuredAt` falls on in the
+  // person's zone and folds it into that week or month. A bucket stamped at
+  // UTC midnight read as the day before west of UTC, so every month of the
+  // "All" range sat one month early there.
+  describe("row stamp", () => {
+    const ZONES = [
+      "Pacific/Pago_Pago",
+      "America/Los_Angeles",
+      "UTC",
+      "Europe/Berlin",
+      "Pacific/Auckland",
+      "Pacific/Kiritimati",
+    ];
+
+    it("puts each month in its own month in every zone", async () => {
+      aggregate.mockResolvedValueOnce(
+        spanOf("2023-01-01T00:00:00.000Z", "2026-03-01T00:00:00.000Z"),
+      );
+      queryRaw.mockResolvedValueOnce([
+        folded("2026-01-01T00:00:00.000Z", [["2026-01-01", 80]]),
+        folded("2026-02-01T00:00:00.000Z", [["2026-02-01", 81]]),
+        folded("2026-03-01T00:00:00.000Z", [["2026-03-01", 82]]),
+      ]);
+      const result = await readTieredRollupSeries({
+        userId: "u",
+        type: "WEIGHT",
+        ...win(3650),
+      });
+      expect(result?.granularity).toBe("MONTH");
+      for (const timeZone of ZONES) {
+        const months = bucketTimeSeries(
+          result!.rows.map((row) => ({
+            timestamp: new Date(row.measuredAt),
+            values: { v: row.value },
+          })),
+          { bucket: "month", timeZone },
+        ).points.map((p) => new Date(p.timestamp).toISOString().slice(0, 7));
+        expect(months, timeZone).toEqual(["2026-01", "2026-02", "2026-03"]);
+      }
+    });
+
+    it("puts each week in its own ISO week in every zone", async () => {
+      aggregate.mockResolvedValueOnce(
+        spanOf("2025-01-01T00:00:00.000Z", "2026-05-01T00:00:00.000Z"),
+      );
+      queryRaw.mockResolvedValueOnce([
+        folded("2025-12-29T00:00:00.000Z", [["2025-12-29", 80]]),
+        folded("2026-01-05T00:00:00.000Z", [["2026-01-05", 81]]),
+      ]);
+      const result = await readTieredRollupSeries({
+        userId: "u",
+        type: "WEIGHT",
+        ...win(3650),
+      });
+      expect(result?.granularity).toBe("WEEK");
+      for (const timeZone of ZONES) {
+        const weeks = bucketTimeSeries(
+          result!.rows.map((row) => ({
+            timestamp: new Date(row.measuredAt),
+            values: { v: row.value },
+          })),
+          { bucket: "week", timeZone },
+        ).points.map((p) => new Date(p.timestamp).toISOString().slice(0, 10));
+        expect(weeks, timeZone).toEqual(["2025-12-29", "2026-01-05"]);
+      }
+    });
+  });
 });
 
 // v1.37.29 — the server tier ladder and the client caption ladder
diff --git a/src/lib/rollups/measurement-read-wmy.ts b/src/lib/rollups/measurement-read-wmy.ts
index d40941945..8d353ad06 100644
--- a/src/lib/rollups/measurement-read-wmy.ts
+++ b/src/lib/rollups/measurement-read-wmy.ts
@@ -285,6 +285,17 @@ export function pickRollupGranularityForWindow(
   return "DAY";
 }
 
+/**
+ * A tier bucket starts at UTC midnight, and a client names a row by the
+ * date its `measuredAt` falls on in the person's zone. West of UTC that
+ * midnight is still the evening before, so a March bucket read as February
+ * and every month of the chart's "All" range sat one month early. A row is
+ * therefore stamped at noon UTC of the bucket's first day: that instant falls
+ * inside the bucket's own week, month and year in every zone, and on the
+ * bucket's own day from UTC−12 to UTC+11.
+ */
+const TIER_ROW_ANCHOR_MS = 12 * 3_600_000;
+
 /** DAY → WEEK → MONTH → YEAR, finest first. */
 const TIER_ORDER: RollupGranularity[] = ["DAY", "WEEK", "MONTH", "YEAR"];
 
@@ -399,7 +410,9 @@ export async function readTieredRollupSeries(opts: {
     rows: rows.map((r) => ({
       type,
       value: useSum ? (r.sumValue ?? r.mean * r.count) : r.mean,
-      measuredAt: r.bucketStart.toISOString(),
+      measuredAt: new Date(
+        r.bucketStart.getTime() + TIER_ROW_ANCHOR_MS,
+      ).toISOString(),
       count: r.count,
       minValue: useSum ? undefined : r.minValue,
       maxValue: useSum ? undefined : r.maxValue,