fix(hrv): file Fitbit and Google Health RMSSD as HRV_RMSSD

Fitbit's `dailyRmssd` and Google Health's daily HRV average are both RMSSD, but the mappers wrote them into HEART_RATE_VARIABILITY, the SDNN series. The `hrv` ladder ranks both above Apple Health, so an account with an Apple Watch and a Fitbit had a series that switched estimator from day to day. The mappers now write HRV_RMSSD, and the `hrvRmssd` ladder carries both sources where they sat on the SDNN one. Migration 0420 moves the rows already written (tombstones included, with a sync-version bump so the change reaches the phone), drops their SDNN rollup buckets and the RMSSD buckets of every account whose rows moved, so the boot-time rollup discovery folds those accounts again, and deletes the SDNN personal records those rows had set. One DO block, so the move and its cleanup land together.
2026-11-11 05:42:19 +00:00 · 2026-10-21 12:00:20 +02:00
1 parent d21d29572d
commit c5d2053e5a
@@ -0,0 +1,70 @@
+-- Fitbit and Google Health HRV is RMSSD; file it as such.
+--
+-- Both providers report a nightly RMSSD (`dailyRmssd`; Google documents its
+-- daily average as RMSSD too), but their mappers wrote it as
+-- `HEART_RATE_VARIABILITY`, the SDNN series. The `hrv` ladder ranks Fitbit and
+-- Google Health above Apple Health, so an account with both had a series that
+-- switched estimator from day to day, and every baseline, trend and
+-- correlation over it measured the switch. The mappers now write `HRV_RMSSD`;
+-- this moves the rows they wrote before.
+--
+-- Every `HEART_RATE_VARIABILITY` row under source FITBIT or GOOGLE_HEALTH came
+-- from that one daily-HRV mapper per provider (their externalIds end in
+-- `:hrv`), so source and type identify them. Tombstones move too, so the sync
+-- feed and a restore see the same type. A row whose RMSSD twin already exists
+-- under the `(user, type, source, externalId)` key stays where it is.
+--
+-- Derived state that would otherwise keep the old filing:
+--   - the FITBIT / GOOGLE_HEALTH `HEART_RATE_VARIABILITY` rollup buckets are
+--     dropped (no rows remain behind them);
+--   - every `HRV_RMSSD` rollup bucket of an account whose rows moved is
+--     dropped, so the per-type coverage probe reads that series live and the
+--     boot-time rollup discovery (`enqueueBootTimeRollupBackfill`, which flags
+--     any (user, type, day) with no DAY bucket) folds the account again on the
+--     next worker start. Dropping only the moved days would not do: a day that
+--     another source already covers would keep its bucket and never be
+--     flagged, and the moved rows would be missing from it;
+--   - personal records filed under `HEART_RATE_VARIABILITY` from those sources
+--     are deleted. They ranked an RMSSD value as an SDNN best; `HRV_RMSSD` keeps
+--     no records, and the detector re-derives the SDNN ones from what remains.
+--
+-- One `DO` block, so the move and its cleanup commit or roll back together
+-- (`migrate deploy` commits each top-level statement on its own). Running it
+-- again finds nothing to move and drops nothing a fold has not rebuilt.
+--
+-- Reversibility: the moved rows carry source FITBIT / GOOGLE_HEALTH and type
+-- `HRV_RMSSD`, which nothing else writes for those sources; setting the type
+-- back and dropping their rollups reverses it.
+
+DO $migration$
+BEGIN
+  WITH moved AS (
+    UPDATE "measurements" m
+    SET "type" = 'HRV_RMSSD',
+        "updated_at" = CURRENT_TIMESTAMP,
+        "sync_version" = m."sync_version" + 1
+    WHERE m."type" = 'HEART_RATE_VARIABILITY'
+      AND m."source" IN ('FITBIT', 'GOOGLE_HEALTH')
+      AND NOT EXISTS (
+        SELECT 1
+        FROM "measurements" twin
+        WHERE twin."user_id" = m."user_id"
+          AND twin."type" = 'HRV_RMSSD'
+          AND twin."source" = m."source"
+          AND twin."external_id" = m."external_id"
+      )
+    RETURNING m."user_id"
+  )
+  DELETE FROM "measurement_rollups" r
+  WHERE r."type" = 'HRV_RMSSD'
+    AND r."user_id" IN (SELECT DISTINCT "user_id" FROM moved);
+
+  DELETE FROM "measurement_rollups"
+  WHERE "type" = 'HEART_RATE_VARIABILITY'
+    AND "source" IN ('FITBIT', 'GOOGLE_HEALTH');
+
+  DELETE FROM "personal_records"
+  WHERE "metric_type" = 'HEART_RATE_VARIABILITY'
+    AND "source" IN ('FITBIT', 'GOOGLE_HEALTH');
+END
+$migration$;
@@ -332,13 +332,13 @@ describe("metric mappers (classic shapes)", () => {
    expect(out[0]!.fieldTag).toBe("2026-05-10:spo2");
  });

-  it("maps HRV dailyRmssd into the canonical HEART_RATE_VARIABILITY slot", () => {
+  it("maps HRV dailyRmssd into HRV_RMSSD, apart from the SDNN series", () => {
    const out = mapHeartRateVariability({
      hrv: [
        { dateTime: "2026-05-10", value: { dailyRmssd: 42.7, deepRmssd: 50 } },
      ],
    });
-    expect(out[0]!.type).toBe("HEART_RATE_VARIABILITY");
+    expect(out[0]!.type).toBe("HRV_RMSSD");
    expect(out[0]).toMatchObject({ value: 42.7, unit: "ms" });
    expect(out[0]!.fieldTag).toBe("2026-05-10:hrv");
  });
@@ -741,15 +741,16 @@ export function mapHeartRateVariability(
  body: unknown,
  tz?: string,
 ): FitbitMappedMeasurement[] {
-  // Fitbit's HRV summary is an RMSSD estimator (`value.dailyRmssd`). It lands in
-  // the canonical `HEART_RATE_VARIABILITY` slot that FITBIT occupies in the
-  // source-priority `hrv` ladder (alongside Apple / Oura), keeping cross-source
-  // comparison on one axis. (`HRV_RMSSD` is reserved for the WHOOP-native slot.)
+  // Fitbit's HRV summary is an RMSSD estimator (`value.dailyRmssd`), so it lands
+  // in `HRV_RMSSD` beside WHOOP / Oura / Polar. `HEART_RATE_VARIABILITY` is the
+  // SDNN series; the two estimators are not interchangeable, and a Fitbit night
+  // ranked into the SDNN ladder used to splice RMSSD values into an Apple
+  // Watch SDNN series day by day.
  const rows = readArray(body, "hrv") as FitbitDailyRow[];
  return mapDailySummary(
    rows,
    {
-      type: "HEART_RATE_VARIABILITY",
+      type: "HRV_RMSSD",
      unit: "ms",
      fieldTag: "hrv",
      leaves: ["dailyRmssd"],
@@ -987,9 +988,9 @@ export const FITBIT_FIELD_MAP: Record<
    note: "spo2 summary value.avg",
  },
  heartRateVariability: {
-    type: "HEART_RATE_VARIABILITY",
+    type: "HRV_RMSSD",
    unit: "ms",
-    note: "hrv summary value.dailyRmssd (RMSSD estimator); canonical HRV slot",
+    note: "hrv summary value.dailyRmssd (RMSSD estimator), apart from SDNN",
  },
  restingHeartRate: {
    type: "RESTING_HEART_RATE",
@@ -26,14 +26,14 @@ metric (kg / km); the US default is imperial.
 Scope: `weight`, `oxygen_saturation`, `heartrate`, `respiratory_rate`. Verified
 against the dev.fitbit.com reference (response shapes quoted there).

-| Endpoint                                       | MeasurementType          | Unit        | Source field                                | Grain | Note                                                        |
-| ---------------------------------------------- | ------------------------ | ----------- | ------------------------------------------- | ----- | ----------------------------------------------------------- |
-| `/1/user/-/body/log/weight/date/{s}/{e}.json`  | `WEIGHT`                 | kg          | `weight[].weight`                           | log   | externalId anchors on `logId`. Picker ranks Withings above. |
-| `/1/user/-/body/log/fat/date/{s}/{e}.json`     | `BODY_FAT`               | %           | `fat[].fat`                                 | log   | externalId anchors on `logId`.                              |
-| `/1/user/-/spo2/date/{s}/{e}.json`             | `OXYGEN_SATURATION`      | %           | `[].value.avg` (bare array)                 | daily | day-keyed externalId.                                       |
-| `/1/user/-/hrv/date/{s}/{e}.json`              | `HEART_RATE_VARIABILITY` | ms          | `hrv[].value.dailyRmssd`                    | daily | RMSSD estimator → canonical HRV slot (not `HRV_RMSSD`).     |
-| `/1/user/-/activities/heart/date/{s}/{e}.json` | `RESTING_HEART_RATE`     | bpm         | `activities-heart[].value.restingHeartRate` | daily | rows with no resting HR for the day are skipped.            |
-| `/1/user/-/br/date/{s}/{e}.json`               | `RESPIRATORY_RATE`       | breaths/min | `br[].value.breathingRate`                  | daily |                                                             |
+| Endpoint                                       | MeasurementType      | Unit        | Source field                                | Grain | Note                                                                |
+| ---------------------------------------------- | -------------------- | ----------- | ------------------------------------------- | ----- | ------------------------------------------------------------------- |
+| `/1/user/-/body/log/weight/date/{s}/{e}.json`  | `WEIGHT`             | kg          | `weight[].weight`                           | log   | externalId anchors on `logId`. Picker ranks Withings above.         |
+| `/1/user/-/body/log/fat/date/{s}/{e}.json`     | `BODY_FAT`           | %           | `fat[].fat`                                 | log   | externalId anchors on `logId`.                                      |
+| `/1/user/-/spo2/date/{s}/{e}.json`             | `OXYGEN_SATURATION`  | %           | `[].value.avg` (bare array)                 | daily | day-keyed externalId.                                               |
+| `/1/user/-/hrv/date/{s}/{e}.json`              | `HRV_RMSSD`          | ms          | `hrv[].value.dailyRmssd`                    | daily | RMSSD estimator, kept apart from the SDNN `HEART_RATE_VARIABILITY`. |
+| `/1/user/-/activities/heart/date/{s}/{e}.json` | `RESTING_HEART_RATE` | bpm         | `activities-heart[].value.restingHeartRate` | daily | rows with no resting HR for the day are skipped.                    |
+| `/1/user/-/br/date/{s}/{e}.json`               | `RESPIRATORY_RATE`   | breaths/min | `br[].value.breathingRate`                  | daily |                                                                     |

 Each daily-summary value passes a finite + strictly-positive guard (a 0/NaN is a
 garbage/empty reading and is dropped). Each endpoint caps its own date range
@@ -7,7 +7,7 @@
 *   - body/log/weight        → WEIGHT                  (kg)
 *   - body/log/fat           → BODY_FAT                (%)
 *   - spo2 summary           → OXYGEN_SATURATION       (%)
- *   - hrv summary            → HEART_RATE_VARIABILITY  (ms, dailyRmssd)
+ *   - hrv summary            → HRV_RMSSD               (ms, dailyRmssd)
 *   - activities/heart       → RESTING_HEART_RATE      (bpm)
 *   - br summary             → RESPIRATORY_RATE        (breaths/min)
 *
@@ -148,7 +148,7 @@ describe("mapOxygenSaturation — daily-oxygen-saturation summary", () => {
 });

 describe("mapHeartRateVariability — daily-heart-rate-variability summary", () => {
-  it("maps averageHeartRateVariabilityMilliseconds to the HRV slot in ms", () => {
+  it("maps the RMSSD daily average to HRV_RMSSD in ms", () => {
    const rows = mapHeartRateVariability({
      dailyHeartRateVariability: {
        averageHeartRateVariabilityMilliseconds: 42.5,
@@ -157,7 +157,7 @@ describe("mapHeartRateVariability — daily-heart-rate-variability summary", ()
    });
    expect(rows).toHaveLength(1);
    expect(rows[0]).toMatchObject({
-      type: "HEART_RATE_VARIABILITY",
+      type: "HRV_RMSSD",
      unit: "ms",
      value: 42.5,
      fieldTag: "2026-06-01:hrv",
@@ -511,16 +511,16 @@ export function mapHeartRateVariability(
  tz?: string,
 ): GoogleHealthMappedMeasurement[] {
  const dt = GOOGLE_HEALTH_DATA_TYPES.heartRateVariability;
-  // The daily field is an unlabelled "average HRV ms". Per the design decision
-  // it lands in the SDNN-lineage `HEART_RATE_VARIABILITY` slot
-  // (Apple-comparable), NOT WHOOP's `HRV_RMSSD` (reserved for the WHOOP-native
-  // estimator). The per-sample type carries explicit RMSSD + SDNN fields —
-  // re-confirm the estimator against live data and revisit if warranted.
+  // Google documents the daily average as RMSSD ("average heart rate
+  // variability calculated using the root mean square of successive
+  // differences"), the same estimator the classic Fitbit API reports as
+  // `dailyRmssd`. It lands in `HRV_RMSSD`, apart from the SDNN
+  // `HEART_RATE_VARIABILITY` series.
  return mapSimple(
    point,
    dt,
    {
-      type: "HEART_RATE_VARIABILITY",
+      type: "HRV_RMSSD",
      unit: "ms",
      fieldTag: "hrv",
      valuePaths: [`${dt.key}.averageHeartRateVariabilityMilliseconds`],
@@ -81,19 +81,19 @@ The exercise civil bound is derived from the watermark in the USER'S zone.

 Scope: `googlehealth.health_metrics_and_measurements.readonly`.

-| Data type (path)                      | Payload value read                                                    | MeasurementType          | Unit        | fieldTag     | Grain  | Note                                                                                                                                                                             |
-| ------------------------------------- | --------------------------------------------------------------------- | ------------------------ | ----------- | ------------ | ------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
-| `weight`                              | `weight.weightGrams` ÷ 1000                                           | `WEIGHT`                 | kg          | `weight`     | sample | Grams on the wire. Picker ranks a real Withings scale above Google Health.                                                                                                       |
-| `body-fat`                            | `bodyFat.percentage`                                                  | `BODY_FAT`               | %           | `body_fat`   | sample | Union key is camelCase `bodyFat`.                                                                                                                                                |
-| `daily-oxygen-saturation`             | `dailyOxygenSaturation.averagePercentage`                             | `OXYGEN_SATURATION`      | %           | `spo2`       | daily  | The bare `oxygen-saturation` type is per-SAMPLE and rejects a `.date` filter.                                                                                                    |
-| `daily-heart-rate-variability`        | `dailyHeartRateVariability.averageHeartRateVariabilityMilliseconds`   | `HEART_RATE_VARIABILITY` | ms          | `hrv`        | daily  | **Decision:** SDNN slot (Apple-comparable), NOT `HRV_RMSSD`. The daily field is an unlabelled "average HRV ms" — re-confirm estimator live.                                      |
-| `daily-resting-heart-rate`            | `dailyRestingHeartRate.beatsPerMinute` (int64 string)                 | `RESTING_HEART_RATE`     | bpm         | `rhr`        | daily  |                                                                                                                                                                                  |
-| `daily-respiratory-rate`              | `dailyRespiratoryRate.breathsPerMinute` (number)                      | `RESPIRATORY_RATE`       | breaths/min | `resp_rate`  | daily  | `respiratory-rate` does NOT exist in the catalogue. Schema is `{date, breathsPerMinute}` — the earlier `dailyRespiratoryRateBpm` leaf never existed.                             |
-| `heart-rate`                          | `heartRate.beatsPerMinute` (int64 string)                             | `PULSE`                  | bpm         | `hr`         | sample | Intraday spot HR; per-minute volume — consider the 14-day-max rollup if PULSE should stay coarse.                                                                                |
-| `blood-glucose`                       | `bloodGlucose.bloodGlucoseMilligramsPerDeciliter` (number)            | `BLOOD_GLUCOSE`          | mg/dL       | `glucose`    | sample | Already in the canonical mg/dL storage unit. Meal/timing/specimen enums not stored.                                                                                              |
-| `core-body-temperature`               | `coreBodyTemperature.temperatureCelsius` (number)                     | `BODY_TEMPERATURE`       | celsius     | `core_temp`  | sample | Core slot — distinct from SKIN_TEMPERATURE / WRIST_TEMPERATURE.                                                                                                                  |
-| `daily-sleep-temperature-derivations` | `dailySleepTemperatureDerivations.nightlyTemperatureCelsius` (number) | `WRIST_TEMPERATURE`      | celsius     | `wrist_temp` | daily  | ABSOLUTE nightly skin temperature (mean over the night's samples) — the schema refutes the earlier "deviation-only" premise. Baseline/stddev derivations not stored.             |
-| `height`                              | `height.heightMillimeters` (int64 string) ÷ 10                        | `User.heightCm`          | cm          | —            | sample | Profile seed — written ONLY when null; never a Measurement. List order is DESCENDING → the seed picks max(sampleTime) explicitly. The earlier `heightMeters` leaf never existed. |
+| Data type (path)                      | Payload value read                                                    | MeasurementType      | Unit        | fieldTag     | Grain  | Note                                                                                                                                                                             |
+| ------------------------------------- | --------------------------------------------------------------------- | -------------------- | ----------- | ------------ | ------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
+| `weight`                              | `weight.weightGrams` ÷ 1000                                           | `WEIGHT`             | kg          | `weight`     | sample | Grams on the wire. Picker ranks a real Withings scale above Google Health.                                                                                                       |
+| `body-fat`                            | `bodyFat.percentage`                                                  | `BODY_FAT`           | %           | `body_fat`   | sample | Union key is camelCase `bodyFat`.                                                                                                                                                |
+| `daily-oxygen-saturation`             | `dailyOxygenSaturation.averagePercentage`                             | `OXYGEN_SATURATION`  | %           | `spo2`       | daily  | The bare `oxygen-saturation` type is per-SAMPLE and rejects a `.date` filter.                                                                                                    |
+| `daily-heart-rate-variability`        | `dailyHeartRateVariability.averageHeartRateVariabilityMilliseconds`   | `HRV_RMSSD`          | ms          | `hrv`        | daily  | Google documents the daily average as RMSSD, so it lands in `HRV_RMSSD`, apart from the SDNN `HEART_RATE_VARIABILITY`.                                                           |
+| `daily-resting-heart-rate`            | `dailyRestingHeartRate.beatsPerMinute` (int64 string)                 | `RESTING_HEART_RATE` | bpm         | `rhr`        | daily  |                                                                                                                                                                                  |
+| `daily-respiratory-rate`              | `dailyRespiratoryRate.breathsPerMinute` (number)                      | `RESPIRATORY_RATE`   | breaths/min | `resp_rate`  | daily  | `respiratory-rate` does NOT exist in the catalogue. Schema is `{date, breathsPerMinute}` — the earlier `dailyRespiratoryRateBpm` leaf never existed.                             |
+| `heart-rate`                          | `heartRate.beatsPerMinute` (int64 string)                             | `PULSE`              | bpm         | `hr`         | sample | Intraday spot HR; per-minute volume — consider the 14-day-max rollup if PULSE should stay coarse.                                                                                |
+| `blood-glucose`                       | `bloodGlucose.bloodGlucoseMilligramsPerDeciliter` (number)            | `BLOOD_GLUCOSE`      | mg/dL       | `glucose`    | sample | Already in the canonical mg/dL storage unit. Meal/timing/specimen enums not stored.                                                                                              |
+| `core-body-temperature`               | `coreBodyTemperature.temperatureCelsius` (number)                     | `BODY_TEMPERATURE`   | celsius     | `core_temp`  | sample | Core slot — distinct from SKIN_TEMPERATURE / WRIST_TEMPERATURE.                                                                                                                  |
+| `daily-sleep-temperature-derivations` | `dailySleepTemperatureDerivations.nightlyTemperatureCelsius` (number) | `WRIST_TEMPERATURE`  | celsius     | `wrist_temp` | daily  | ABSOLUTE nightly skin temperature (mean over the night's samples) — the schema refutes the earlier "deviation-only" premise. Baseline/stddev derivations not stored.             |
+| `height`                              | `height.heightMillimeters` (int64 string) ÷ 10                        | `User.heightCm`      | cm          | —            | sample | Profile seed — written ONLY when null; never a Measurement. List order is DESCENDING → the seed picks max(sampleTime) explicitly. The earlier `heightMeters` leaf never existed. |

 Daily-summary `date` fields are `{year,month,day}` objects, anchored at
 UTC-midday so a timezone shift can't roll the civil day. Every value passes a
@@ -8,7 +8,7 @@
 *   - weight                                → WEIGHT
 *   - body-fat                              → BODY_FAT
 *   - daily-oxygen-saturation               → OXYGEN_SATURATION
- *   - daily-heart-rate-variability          → HEART_RATE_VARIABILITY (SDNN slot; see mapper)
+ *   - daily-heart-rate-variability          → HRV_RMSSD (RMSSD; see mapper)
 *   - daily-resting-heart-rate              → RESTING_HEART_RATE
 *   - daily-respiratory-rate                → RESPIRATORY_RATE
 *   - heart-rate (intraday)                 → PULSE
@@ -117,7 +117,7 @@ const METRIC_RESOURCES: MetricResource[] = [
    dataType: GOOGLE_HEALTH_DATA_TYPES.heartRateVariability,
    map: mapHeartRateVariability,
    verb: "fetchHrv",
-    type: "HEART_RATE_VARIABILITY",
+    type: "HRV_RMSSD",
  },
  {
    dataType: GOOGLE_HEALTH_DATA_TYPES.restingHeartRate,
@@ -404,8 +404,17 @@ export const DEFAULT_SOURCE_PRIORITY: Required<MetricPriority> = {
  // on now. Mirrors the recovery ladder's native-above-computed ordering.
  sleepDebt: ["WHOOP", "OURA", "POLAR", "COMPUTED"],
  // v1.42 (#1110) — the straps and rings that measure RMSSD overnight lead;
-  // the HealthKit relay of a third-party reading is the fallback.
-  hrvRmssd: ["WHOOP", "OURA", "POLAR", "APPLE_HEALTH"],
+  // the HealthKit relay of a third-party reading is the fallback. Fitbit and
+  // Google Health report RMSSD too and take the places they hold on the SDNN
+  // ladder they used to be filed under.
+  hrvRmssd: [
+    "WHOOP",
+    "FITBIT",
+    "GOOGLE_HEALTH",
+    "OURA",
+    "POLAR",
+    "APPLE_HEALTH",
+  ],
 };

 /**
@@ -0,0 +1,270 @@
+/**
+ * Migration 0420 moves the RMSSD rows Fitbit and Google Health wrote into the
+ * SDNN series over to `HRV_RMSSD`, and clears the derived state that kept the
+ * old filing: their SDNN rollup buckets, the RMSSD buckets of the accounts
+ * whose rows moved (so the boot-time discovery folds them again), and the
+ * SDNN personal records those rows set. Apple Health SDNN and WHOOP RMSSD are
+ * left exactly as they were, and a rerun changes nothing.
+ */
+import { readFileSync } from "node:fs";
+import { resolve } from "node:path";
+import { beforeAll, describe, expect, it, vi } from "vitest";
+
+import { getPrismaClient, truncateAllTables } from "./setup";
+import type { Prisma } from "@/generated/prisma/client";
+import {
+  enqueueBootTimeRollupBackfill,
+  recomputeUserRollups,
+} from "@/lib/rollups/measurement-rollups";
+
+vi.mock("@/lib/db-compat", () => ({
+  ensureDbCompatibility: vi.fn().mockResolvedValue(undefined),
+}));
+vi.mock("@/lib/jobs/boss-instance", () => ({
+  getGlobalBoss: vi.fn(() => null),
+}));
+import { getGlobalBoss } from "@/lib/jobs/boss-instance";
+
+const prisma = getPrismaClient();
+const USER = "hrv-rmssd-migration";
+const BYSTANDER = "hrv-rmssd-migration-apple-only";
+
+const MIGRATION = readFileSync(
+  resolve(
+    process.cwd(),
+    "prisma",
+    "migrations",
+    "0420_hrv_rmssd_from_fitbit_and_google_health",
+    "migration.sql",
+  ),
+  "utf8",
+);
+
+async function runMigration(): Promise<void> {
+  // The file is one `DO` block; the comments around it are harmless.
+  await prisma.$executeRawUnsafe(MIGRATION);
+}
+
+const DAY_MS = 86_400_000;
+/** Ten days ago at 07:00 UTC, so every row sits inside the fold window. */
+const D0 =
+  Math.floor(Date.now() / DAY_MS) * DAY_MS - 10 * DAY_MS + 7 * 3_600_000;
+const dayKey = (i: number) =>
+  new Date(D0 + i * DAY_MS).toISOString().slice(0, 10);
+
+function rows(): Prisma.MeasurementCreateManyInput[] {
+  const out: Prisma.MeasurementCreateManyInput[] = [];
+  for (let i = 0; i < 4; i += 1) {
+    const at = new Date(D0 + i * DAY_MS);
+    out.push(
+      {
+        id: `fitbit-${i}`,
+        userId: USER,
+        type: "HEART_RATE_VARIABILITY",
+        source: "FITBIT",
+        unit: "ms",
+        value: 40 + i,
+        measuredAt: at,
+        externalId: `${dayKey(i)}:hrv`,
+      },
+      {
+        id: `apple-${i}`,
+        userId: USER,
+        type: "HEART_RATE_VARIABILITY",
+        source: "APPLE_HEALTH",
+        unit: "ms",
+        value: 70 + i,
+        measuredAt: new Date(at.getTime() + 3_600_000),
+      },
+      // WHOOP covers the same nights in the RMSSD series already: the moved
+      // Fitbit rows land on days that already have an RMSSD bucket.
+      {
+        id: `whoop-${i}`,
+        userId: USER,
+        type: "HRV_RMSSD",
+        source: "WHOOP",
+        unit: "ms",
+        value: 55 + i,
+        measuredAt: new Date(at.getTime() + 1_800_000),
+        externalId: `sleep-${i}:hrv_rmssd`,
+      },
+      {
+        id: `bystander-${i}`,
+        userId: BYSTANDER,
+        type: "HEART_RATE_VARIABILITY",
+        source: "APPLE_HEALTH",
+        unit: "ms",
+        value: 80 + i,
+        measuredAt: at,
+      },
+    );
+  }
+  out.push(
+    {
+      // On a night WHOOP covers too: every live moved row lands on a day that
+      // already has an RMSSD bucket, so only the dropped buckets can get the
+      // account flagged for a fold.
+      id: "google-0",
+      userId: USER,
+      type: "HEART_RATE_VARIABILITY",
+      source: "GOOGLE_HEALTH",
+      unit: "ms",
+      value: 44,
+      measuredAt: new Date(D0 + DAY_MS + 7_200_000),
+      externalId: `${dayKey(1)}:hrv`,
+    },
+    // A tombstone moves too, so the sync feed reports one type for the id.
+    {
+      id: "fitbit-deleted",
+      userId: USER,
+      type: "HEART_RATE_VARIABILITY",
+      source: "FITBIT",
+      unit: "ms",
+      value: 39,
+      measuredAt: new Date(D0 + 6 * DAY_MS),
+      externalId: `${dayKey(6)}:hrv`,
+      deletedAt: new Date(),
+    },
+  );
+  return out;
+}
+
+type RollupRow = { type: string; source: string; granularity: string };
+const rollups = (userId: string) =>
+  prisma.$queryRaw<RollupRow[]>`
+    SELECT "type"::text AS type, "source"::text AS source,
+           "granularity"::text AS granularity
+    FROM measurement_rollups
+    WHERE "user_id" = ${userId}
+    ORDER BY 1, 2, 3
+  `;
+const pairs = (all: RollupRow[]) =>
+  [...new Set(all.map((r) => `${r.type}/${r.source}`))].sort();
+
+let bystanderBefore: RollupRow[] = [];
+
+beforeAll(async () => {
+  await truncateAllTables(prisma);
+  await prisma.user.createMany({
+    data: [
+      { id: USER, username: USER, timezone: "UTC" },
+      { id: BYSTANDER, username: BYSTANDER, timezone: "UTC" },
+    ],
+  });
+  await prisma.measurement.createMany({ data: rows() });
+  await recomputeUserRollups(USER);
+  await recomputeUserRollups(BYSTANDER);
+  await prisma.personalRecord.createMany({
+    data: [
+      {
+        userId: USER,
+        metricType: "HEART_RATE_VARIABILITY",
+        direction: "MAX",
+        value: 43,
+        unit: "ms",
+        achievedAt: new Date(D0 + 3 * DAY_MS),
+        source: "FITBIT",
+        sourceMeasurementId: "fitbit-3",
+      },
+      {
+        userId: USER,
+        metricType: "HEART_RATE_VARIABILITY",
+        direction: "MAX",
+        value: 73,
+        unit: "ms",
+        achievedAt: new Date(D0 + 3 * DAY_MS + 3_600_000),
+        source: "APPLE_HEALTH",
+        sourceMeasurementId: "apple-3",
+      },
+    ],
+  });
+  bystanderBefore = await rollups(BYSTANDER);
+  await runMigration();
+}, 120_000);
+
+describe("migration 0420", () => {
+  it("moves every Fitbit and Google Health SDNN row to HRV_RMSSD, tombstones included", async () => {
+    const moved = await prisma.measurement.findMany({
+      where: { userId: USER, source: { in: ["FITBIT", "GOOGLE_HEALTH"] } },
+      select: { id: true, type: true, syncVersion: true, value: true },
+      orderBy: { id: "asc" },
+    });
+    expect(moved).toHaveLength(6);
+    for (const row of moved) {
+      expect(row.type, row.id).toBe("HRV_RMSSD");
+      // A type change must reach the phone through the sync feed.
+      expect(row.syncVersion, row.id).toBe(2);
+    }
+  });
+
+  it("leaves Apple Health SDNN and WHOOP RMSSD rows alone", async () => {
+    const apple = await prisma.measurement.findMany({
+      where: { source: "APPLE_HEALTH" },
+      select: { type: true, syncVersion: true },
+    });
+    expect(apple).toHaveLength(8);
+    expect(apple.every((r) => r.type === "HEART_RATE_VARIABILITY")).toBe(true);
+    expect(apple.every((r) => r.syncVersion === 1)).toBe(true);
+    const whoop = await prisma.measurement.findMany({
+      where: { source: "WHOOP" },
+      select: { type: true, syncVersion: true },
+    });
+    expect(whoop.every((r) => r.type === "HRV_RMSSD")).toBe(true);
+    expect(whoop.every((r) => r.syncVersion === 1)).toBe(true);
+  });
+
+  it("drops the SDNN buckets of the moved sources and the account's RMSSD buckets", async () => {
+    expect(pairs(await rollups(USER))).toEqual([
+      "HEART_RATE_VARIABILITY/APPLE_HEALTH",
+    ]);
+    expect(await rollups(BYSTANDER)).toEqual(bystanderBefore);
+  });
+
+  it("leaves the account where the boot-time discovery folds it again", async () => {
+    const send = vi.fn(async () => "job-id");
+    vi.mocked(getGlobalBoss).mockReturnValue({ send } as never);
+    try {
+      const result = await enqueueBootTimeRollupBackfill();
+      expect(result.error).toBeNull();
+      const users = send.mock.calls.map(
+        (call) => (call as unknown as [string, { userId: string }])[1].userId,
+      );
+      expect(users).toContain(USER);
+      expect(users).not.toContain(BYSTANDER);
+    } finally {
+      vi.mocked(getGlobalBoss).mockReturnValue(null as never);
+    }
+  });
+
+  it("refolds into an RMSSD series that carries both straps", async () => {
+    await recomputeUserRollups(USER);
+    expect(pairs(await rollups(USER))).toEqual([
+      "HEART_RATE_VARIABILITY/APPLE_HEALTH",
+      "HRV_RMSSD/FITBIT",
+      "HRV_RMSSD/GOOGLE_HEALTH",
+      "HRV_RMSSD/WHOOP",
+    ]);
+  });
+
+  it("deletes the SDNN records the moved rows set and keeps the rest", async () => {
+    const records = await prisma.personalRecord.findMany({
+      where: { userId: USER },
+      select: { source: true, metricType: true },
+    });
+    expect(records).toEqual([
+      { source: "APPLE_HEALTH", metricType: "HEART_RATE_VARIABILITY" },
+    ]);
+  });
+
+  it("is idempotent", async () => {
+    const measurementsBefore = await prisma.measurement.findMany({
+      orderBy: { id: "asc" },
+    });
+    const rollupsBefore = await rollups(USER);
+    await runMigration();
+    expect(
+      await prisma.measurement.findMany({ orderBy: { id: "asc" } }),
+    ).toEqual(measurementsBefore);
+    expect(await rollups(USER)).toEqual(rollupsBefore);
+  });
+});