Merge branch 'fix/aggregation-day-boundaries' into release/v1.39.3

# Conflicts:
#	src/app/api/medications/[id]/route.ts

docs/api/openapi.yaml

@@ -55355,8 +55355,8 @@ components:
           description: Trailing-window length in days for the chosen range.
         granularity:
           type: string
-          description: Rollup granularity the read resolved against (`DAY` / `WEEK` / `MONTH` / `YEAR`, or `none` on a coverage
-            miss).
+          description: Rollup granularity the read resolved against (`DAY` / `WEEK` / `MONTH` / `YEAR`), `live` for SLEEP_DURATION
+            (nights are reconstructed from the stage rows), or `none` when there is no data.
         current:
           description: Aggregate over the current window `[now-N, now)`.
           $ref: "#/components/schemas/AnalyticsWindowAggregate"
@@ -55383,9 +55383,10 @@ components:
         - delta
         - deltaPct
       additionalProperties: false
-      description: Single-metric period-over-period aggregate. Reads the current and previous comparable windows from the WMY
-        rollup tier and composes a count-weighted-mean delta. `count/min/max/mean/sum` are linearly composable across
-        buckets; SD/slope/r² are intentionally excluded (not composable).
+      description: Single-metric period-over-period aggregate. Reads the current and previous comparable windows from the
+        rollup tier and composes a count-weighted-mean delta, one source per day. Step-like totals compare average daily
+        totals and SLEEP_DURATION compares average nights, not per-reading means. `count/min/max/mean/sum` are linearly
+        composable across buckets; SD/slope/r² are intentionally excluded (not composable).
     AnalyticsWindowAggregate:
       type: object
       properties:
@@ -55393,7 +55394,8 @@ components:
           type: integer
           minimum: -9007199254740991
           maximum: 9007199254740991
-          description: Reading count composed across buckets.
+          description: Reading count composed across buckets. For step-like totals it is the number of days with a total, for
+            SLEEP_DURATION the number of nights.
         min:
           anyOf:
             - type: number
@@ -55408,7 +55410,8 @@ components:
           anyOf:
             - type: number
             - type: "null"
-          description: Count-weighted mean across buckets; null when empty.
+          description: Count-weighted mean across buckets; null when empty. For step-like totals (steps, energy, distance,
+            flights) it is the average daily total, for SLEEP_DURATION the average time asleep per night.
         sum:
           anyOf:
             - type: number

eslint-plugins/healthlog/__tests__/no-default-zone-literal.test.mjs

@@ -0,0 +1,75 @@
+/**
+ * Unit tests for the `healthlog/no-default-zone-literal` rule: the literal is
+ * banned in application source, allowed in `src/lib/tz/` and in tests, and
+ * the pending files are exempt until their owner switches them.
+ */
+import { describe, it } from "vitest";
+import { RuleTester } from "eslint";
+import rule from "../no-default-zone-literal.js";
+
+RuleTester.describe = describe;
+RuleTester.it = it;
+RuleTester.itOnly = it.only;
+
+const ruleTester = new RuleTester({
+  languageOptions: {
+    ecmaVersion: 2023,
+    sourceType: "module",
+    parserOptions: { ecmaFeatures: { jsx: true } },
+  },
+});
+
+ruleTester.run("no-default-zone-literal", rule, {
+  valid: [
+    {
+      code: 'import { DEFAULT_TIMEZONE } from "@/lib/tz/format"; const tz = user.timezone || DEFAULT_TIMEZONE;',
+      filename: "/repo/src/app/api/insights/cards/route.ts",
+    },
+    {
+      // The one definition.
+      code: 'export const DEFAULT_TIMEZONE = "Europe/Berlin";',
+      filename: "/repo/src/lib/tz/format.ts",
+    },
+    {
+      // Fixtures pick a concrete zone on purpose.
+      code: 'const TZ = "Europe/Berlin";',
+      filename: "/repo/src/lib/insights/__tests__/graded-series.test.ts",
+    },
+    {
+      // Comments are not checked.
+      code: "// read on Europe/Berlin days before v1.39.3\nconst x = 1;",
+      filename: "/repo/src/lib/insights/graded-series.ts",
+    },
+    {
+      // Pending: owned by another change, switched at merge.
+      code: 'const DEFAULT_TZ = "Europe/Berlin";',
+      filename: "/repo/src/lib/medications/window-status.ts",
+    },
+    {
+      code: 'const other = "America/New_York";',
+      filename: "/repo/src/lib/insights/graded-series.ts",
+    },
+  ],
+  invalid: [
+    {
+      code: 'const tz = user.timezone || "Europe/Berlin";',
+      filename: "/repo/src/app/api/insights/cards/route.ts",
+      errors: [{ messageId: "zoneLiteral" }],
+    },
+    {
+      code: 'readDayAggregates({ timeZone: "Europe/Berlin" });',
+      filename: "/repo/src/lib/insights/graded-series.ts",
+      errors: [{ messageId: "zoneLiteral" }],
+    },
+    {
+      code: "const label = `Date: ${todayKey} (Europe/Berlin)`;",
+      filename: "/repo/src/lib/ai/prompts/pulse.ts",
+      errors: [{ messageId: "zoneLiteral" }],
+    },
+    {
+      code: '<input placeholder="Europe/Berlin" />',
+      filename: "/repo/src/components/settings/timezone-picker.tsx",
+      errors: [{ messageId: "zoneLiteral" }],
+    },
+  ],
+});

eslint-plugins/healthlog/index.js

@@ -10,6 +10,8 @@
  *                              and no off-scale `5` step on a bg-card shell.
  *   - `job-handler-outcome`  — pg-boss bindings route through createAndWork,
  *                              whose handler returns a JobOutcome.
+ *   - `no-default-zone-literal` — the default zone is DEFAULT_TIMEZONE from
+ *                              src/lib/tz/format, never written out.
  */
 
 "use strict";
@@ -20,6 +22,7 @@ const apiFetchRequired = require("./api-fetch-required.js");
 const noRawPaletteColor = require("./no-raw-palette-color.js");
 const spacingScale = require("./spacing-scale.js");
 const jobHandlerOutcome = require("./job-handler-outcome.js");
+const noDefaultZoneLiteral = require("./no-default-zone-literal.js");
 
 module.exports = {
   rules: {
@@ -34,5 +37,6 @@ module.exports = {
     // the semantic sweep). See the rule header.
     "no-dracula-utility": noRawPaletteColor,
     "job-handler-outcome": jobHandlerOutcome,
+    "no-default-zone-literal": noDefaultZoneLiteral,
   },
 };

eslint-plugins/healthlog/no-default-zone-literal.js

@@ -0,0 +1,102 @@
+/**
+ * @fileoverview ESLint rule — the default zone is named in one place.
+ *
+ * `"Europe/Berlin"` was written out in some eighty places: fallbacks for a
+ * user with no zone, day keys cut in Berlin whatever the user's zone, a
+ * graded series folded on Berlin days, a prompt that labelled every date as
+ * Berlin's. Each copy was a place where a user outside that zone got
+ * someone else's calendar. `DEFAULT_TIMEZONE` in `src/lib/tz/format.ts` is
+ * the one definition; everything else imports it, and a surface that means
+ * the user's own zone asks for it (`resolveUserTimezone`).
+ *
+ * The rule flags a string literal or template element containing
+ * `Europe/Berlin` in `src/`, outside `src/lib/tz/` and outside test files
+ * (fixtures pick concrete zones on purpose). Comments are not checked.
+ *
+ * WHAT THIS RULE DOES NOT CATCH
+ *
+ * A zone assembled from parts (`"Europe/" + city`), a different hard-coded
+ * zone, or a Berlin day computed through an `Intl.DateTimeFormat` built from
+ * a variable. It removes the literal, not every way to hard-code a calendar.
+ *
+ * `PENDING` lists files another change owns at the moment; they switch to the
+ * constant when that change lands, and the list shrinks to nothing.
+ */
+
+"use strict";
+
+const ZONE = "Europe/Berlin";
+
+const EXEMPT_ROOTS = ["src/lib/tz/"];
+
+// Owned by the medication-scheduling change in flight; switched at merge.
+const PENDING = [
+  "src/lib/medications/",
+  "src/lib/jobs/measurement-reminder.ts",
+  "src/lib/measurement-reminders/",
+  "src/app/api/measurement-reminders/",
+];
+
+function toPosix(filename) {
+  return filename.replace(/\\/g, "/");
+}
+
+function isTestFile(posix) {
+  return (
+    /\.test\.[cm]?[jt]sx?$/.test(posix) ||
+    /\.spec\.[cm]?[jt]sx?$/.test(posix) ||
+    posix.includes("/__tests__/") ||
+    posix.includes("/__mocks__/")
+  );
+}
+
+function isEnforced(filename) {
+  const posix = toPosix(filename);
+  if (!posix.includes("/src/") && !posix.startsWith("src/")) return false;
+  if (EXEMPT_ROOTS.some((root) => posix.includes(root))) return false;
+  if (PENDING.some((p) => posix.includes(p))) return false;
+  if (isTestFile(posix)) return false;
+  return true;
+}
+
+/** @type {import("eslint").Rule.RuleModule} */
+const noDefaultZoneLiteralRule = {
+  meta: {
+    type: "problem",
+    docs: {
+      description:
+        "Import DEFAULT_TIMEZONE from @/lib/tz/format instead of writing the zone out.",
+    },
+    schema: [],
+    messages: {
+      zoneLiteral:
+        'Do not write "Europe/Berlin" out. Import DEFAULT_TIMEZONE from "@/lib/tz/format" for a fallback, or use the user\'s own zone (resolveUserTimezone / the profile timezone) for a day boundary.',
+    },
+  },
+  create(context) {
+    const filename = context.filename ?? context.getFilename?.();
+    if (!filename || !isEnforced(filename)) {
+      return {};
+    }
+    return {
+      Literal(node) {
+        if (typeof node.value === "string" && node.value.includes(ZONE)) {
+          context.report({ node, messageId: "zoneLiteral" });
+        }
+      },
+      TemplateElement(node) {
+        const raw = node.value && (node.value.cooked ?? node.value.raw);
+        if (typeof raw === "string" && raw.includes(ZONE)) {
+          context.report({ node, messageId: "zoneLiteral" });
+        }
+      },
+      JSXText(node) {
+        if (typeof node.value === "string" && node.value.includes(ZONE)) {
+          context.report({ node, messageId: "zoneLiteral" });
+        }
+      },
+    };
+  },
+};
+
+module.exports = noDefaultZoneLiteralRule;

eslint.config.mjs

@@ -104,6 +104,10 @@ const eslintConfig = defineConfig([
       // catches the omission only — a handler that returns `{ ok: true }`
       // after swallowing still passes, and its header says so.
       "healthlog/job-handler-outcome": "error",
+      // The default zone is named once, in src/lib/tz/format.ts. A copy of the
+      // literal anywhere else is where a user outside that zone got someone
+      // else's calendar. src/lib/tz/ and test files are exempt; see the rule.
+      "healthlog/no-default-zone-literal": "error",
     },
   },
   // v1.28.17 — every recharts-rendering component funnels through the

src/__tests__/date-order-explicit-formatter-guard.test.ts

@@ -259,18 +259,10 @@ const RAW_ALLOWLIST: ReadonlyArray<{ file: string; why: string }> = [
     file: "src/components/measurement-reminders/vorsorge-section.tsx",
     why: "The ISO day the postpone request writes to the API. A wire value, and the wire format is ISO whatever the reader prefers.",
   },
-  {
-    file: "src/lib/gamification/achievements.ts",
-    why: "The day key streak arithmetic counts on.",
-  },
   {
     file: "src/lib/charts/bucket-time-series.ts",
     why: "Bucket boundary arithmetic. The bucket LABELS are a separate step and go through `makeBucketLabelFormatters`.",
   },
-  {
-    file: "src/lib/ai/prompts/insight-generator.ts",
-    why: "An ISO day inside a model prompt. The model reads ISO; the user never sees this string.",
-  },
   {
     file: "src/lib/jobs/measurement-reminder.ts",
     why: "The local day in the notification dedup key. Changing it with a display preference would re-send a claimed reminder.",
@@ -283,10 +275,6 @@ const RAW_ALLOWLIST: ReadonlyArray<{ file: string; why: string }> = [
     file: "src/lib/i18n/relative-time.ts",
     why: "The en-CA day keys that decide today / yesterday. A comparison between two keys, never printed.",
   },
-  {
-    file: "src/lib/tz/resolver.ts",
-    why: "The Berlin day formatter the zone arithmetic itself is built on.",
-  },
 ];
 
 /**

src/__tests__/measurement-write-tail-guard.test.ts

@@ -0,0 +1,171 @@
+/**
+ * Every place that writes `Measurement` rows either runs the shared
+ * post-write tail or says here why it does not.
+ *
+ * Two readers hang off every measurement write: the rollup buckets the write
+ * dirtied, and the cached status assessments of the types it touched. The
+ * shared tail (`afterMeasurementMutation`) runs both. Several write paths
+ * refreshed the rollups by hand and never re-warmed the assessments (the MCP
+ * writes, the Telegram reply, both importers), so a reading logged there kept
+ * the day's old assessment until the nightly pass. This guard freezes the set
+ * of write sites: a new one fails until it is listed with its tail.
+ *
+ * A tripwire, not a proof: it cannot tell whether a listed reason is still
+ * true, only that the set did not change without someone editing this file.
+ */
+import { describe, it, expect } from "vitest";
+import { readFileSync } from "node:fs";
+import { join } from "node:path";
+
+import { walkSourceFiles } from "./helpers/source-files";
+
+const SRC = join(process.cwd(), "src");
+
+/**
+ * `prisma.measurement.create(`, `tx.measurement.deleteMany(`, … Whitespace
+ * and line breaks between the parts are tolerated so a formatter reflow does
+ * not hide a site.
+ */
+const WRITE_RE =
+  /\.\s*measurement\s*\.\s*(?:create|createMany|createManyAndReturn|upsert|update|updateMany|delete|deleteMany)\s*\(/g;
+
+/** Runs `afterMeasurementMutation` on the rows it wrote. */
+const TAIL = "runs afterMeasurementMutation";
+
+/**
+ * Every file with a measurement write, and how it keeps the two readers
+ * current. A file listed here must still contain a write (a stale entry
+ * fails too).
+ */
+const WRITE_SITES: Record<string, string> = {
+  "app/api/import/csv/route.ts": TAIL,
+  "app/api/import/route.ts": TAIL,
+  "app/api/measurements/[id]/route.ts": TAIL,
+  "app/api/measurements/bulk-delete/route.ts": TAIL,
+  "app/api/measurements/by-external-ids/route.ts": TAIL,
+  "app/api/measurements/restore/route.ts": TAIL,
+  "app/api/measurements/route.ts": TAIL,
+  "app/api/mental-health/assessments/route.ts": TAIL,
+  "lib/insights/score-row.ts": TAIL,
+  "lib/mcp/writes.ts": TAIL,
+  "lib/measurements/create-from-telegram.ts": TAIL,
+  "lib/whoop/sync-body.ts": TAIL,
+  "lib/whoop/webhook-handler.ts": TAIL,
+  // Integration syncs: each collects the (type, day) pairs it touched and
+  // runs both legs itself at the end of the sync.
+  "lib/fitbit/sync-core.ts":
+    "refolds the touched days and re-warms the touched types at the end of the upsert",
+  "lib/google-health/sync-core.ts":
+    "refolds the touched days and re-warms the touched types at the end of the upsert",
+  "lib/nightscout/sync.ts":
+    "refolds the touched days and re-warms the touched types at the end of the sync",
+  "lib/withings/sync.ts":
+    "refolds the touched days and re-warms the touched types at the end of the sync",
+  "lib/withings/sync-activity.ts":
+    "refolds the touched days (and the day a moved row left) and re-warms the touched types",
+  "lib/withings/sync-ecg.ts":
+    "refolds the touched days and re-warms the touched types at the end of the sync",
+  // The reconcile primitive writes one row inside the caller's transaction;
+  // its callers (Polar, Oura, WHOOP, the Apple export import) collect the
+  // verdicts' dirty identities and run the tail once per batch.
+  "lib/measurements/reconcile-external-measurement.ts":
+    "a primitive; every caller runs the tail over the verdicts' dirty identities",
+  "lib/measurements/import-apple-health-export.ts":
+    "the import worker refolds the import's span and re-warms every imported type",
+  "lib/export/restore-backup.ts":
+    "a restore replaces the whole record: it refolds the whole window and drops every per-user cache",
+  // Value-preserving reshapes: the same readings folded into daily or hourly
+  // rows. The rollups are refolded; the figures an assessment reads do not
+  // change, so re-warming would only re-bill the same text.
+  "lib/measurements/consolidate-daily-mean.ts":
+    "value-preserving consolidation; refolds the touched days",
+  "lib/measurements/consolidate-legacy-steps.ts":
+    "value-preserving consolidation; refolds the touched days",
+  "lib/measurements/drain-per-sample-cumulative.ts":
+    "value-preserving consolidation; refolds the touched days",
+  "lib/measurements/dense-intraday-hourly-rebuild.ts":
+    "value-preserving hourly fold; refolds the touched spans",
+  "lib/measurements/dense-intraday-retention.ts":
+    "value-preserving retention fold; refolds the touched days",
+  "lib/jobs/sleep-timeline-backfill.ts":
+    "one-shot re-stamp of stored sleep rows onto their timeline; refolds the touched days",
+  "lib/jobs/step-consolidation-repair.ts":
+    "one-shot restore of step rows an old consolidation removed; refolds the touched days",
+  "lib/sleep/sweep-stale-segments.ts":
+    "tombstones re-scored sleep segments inside a sync; the calling sync refolds the night",
+  // Writes that do not change a reading.
+  "lib/jobs/note-encryption-backfill.ts":
+    "encrypts the note column in place; no value, instant or type changes",
+  "lib/jobs/measurement-tombstone-cleanup.ts":
+    "hard-deletes rows that were already soft-deleted and read nowhere",
+};
+
+function sourceFiles(): string[] {
+  return walkSourceFiles(SRC, { floor: 3000 })
+    .filter((p) => !p.startsWith("generated/"))
+    .filter((p) => !p.includes("__tests__"))
+    .filter((p) => !p.endsWith(".test.ts") && !p.endsWith(".test.tsx"))
+    .sort();
+}
+
+function writeCounts(): Map<string, number> {
+  const out = new Map<string, number>();
+  for (const rel of sourceFiles()) {
+    const matches = readFileSync(join(SRC, rel), "utf8").match(WRITE_RE);
+    if (matches && matches.length > 0) out.set(rel, matches.length);
+  }
+  return out;
+}
+
+describe("measurement write tail", () => {
+  const counts = writeCounts();
+
+  it("finds the write sites at all", () => {
+    // An empty match set would agree with any allowlist.
+    expect(counts.size).toBeGreaterThanOrEqual(30);
+  });
+
+  it("lists every file that writes measurements", () => {
+    const unlisted = [...counts.keys()].filter((f) => !(f in WRITE_SITES));
+    expect(
+      unlisted,
+      "a new measurement write site: run afterMeasurementMutation on the rows it writes, or list it here with the reason it does not",
+    ).toEqual([]);
+  });
+
+  it("has no stale entries", () => {
+    const stale = Object.keys(WRITE_SITES).filter((f) => !counts.has(f));
+    expect(stale).toEqual([]);
+  });
+
+  it("the files that claim the shared tail call it", () => {
+    const missing = Object.entries(WRITE_SITES)
+      .filter(([, reason]) => reason === TAIL)
+      .map(([file]) => file)
+      .filter(
+        (file) =>
+          !/afterMeasurementMutation\s*\(/.test(
+            readFileSync(join(SRC, file), "utf8"),
+          ),
+      );
+    expect(missing).toEqual([]);
+  });
+
+  it("the syncs that run both legs by hand call both", () => {
+    const handRolled = Object.entries(WRITE_SITES)
+      .filter(([, reason]) => reason.includes("re-warms"))
+      .map(([file]) => file)
+      .filter(
+        (file) => file !== "lib/measurements/import-apple-health-export.ts",
+      );
+    expect(handRolled.length).toBeGreaterThan(0);
+    const missing = handRolled.filter((file) => {
+      const src = readFileSync(join(SRC, file), "utf8");
+      return !(
+        /recomputeBucketsForMeasurement|afterMeasurementMutation/.test(src) &&
+        /invalidateStatusInsightsForTypes|afterMeasurementMutation/.test(src)
+      );
+    });
+    expect(missing).toEqual([]);
+  });
+});

src/app/api/admin/notifications/reminder-check/route.ts

@@ -9,6 +9,7 @@ import { parseScheduleRecurrence } from "@/lib/medication-schedule";
 import { dispatchLocalisedNotification } from "@/lib/notifications/dispatch-localised";
 import { getUserTodayBounds, getDayOfWeekInTz } from "@/lib/tz/local-day";
 import { TRACKED_INTAKE_WHERE } from "@/lib/medications/intake-tracking";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 
 export const dynamic = "force-dynamic";
 
@@ -116,7 +117,7 @@ export const POST = apiHandler(async (request: NextRequest) => {
   let notificationsSent = 0;
 
   for (const med of medications) {
-    const userTz = med.user.timezone || "Europe/Berlin";
+    const userTz = med.user.timezone || DEFAULT_TIMEZONE;
     const { start: todayStart, end: todayEnd } = getUserTodayBounds(
       now,
       userTz,

src/app/api/coach/reminder-suggestions/route.ts

@@ -44,8 +44,7 @@ import {
   type ReminderScheduleInput,
 } from "@/lib/measurement-reminders/scheduling";
 import { toMeasurementReminderDto } from "@/lib/measurement-reminders/dto";
-
-const DEFAULT_TIMEZONE = "Europe/Berlin";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 
 async function postAction(request: NextRequest): Promise<Response> {
   const { user } = await requireAuth();

src/app/api/coach/suggested-actions/route.ts

@@ -47,8 +47,8 @@ import {
   type ReminderScheduleInput,
 } from "@/lib/measurement-reminders/scheduling";
 import { toMeasurementReminderDto } from "@/lib/measurement-reminders/dto";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 
-const DEFAULT_TIMEZONE = "Europe/Berlin";
 const CHECKUP_NOTIFY_HOUR = 9;
 
 async function postAction(request: NextRequest): Promise<Response> {

src/app/api/cycle/calendar/route.ts

@@ -39,7 +39,8 @@ import {
 import { resolveCycleVerdict } from "@/lib/cycle/verdict";
 import { addDays, dayDiff } from "@/lib/cycle/day-math";
 import { BBT_WINDOW } from "@/lib/cycle/types";
-import { DEFAULT_TIMEZONE, moodDateKey } from "@/lib/mood/date-key";
+import { moodDateKey } from "@/lib/mood/date-key";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 import { getServerTranslator } from "@/lib/i18n/server-translator";
 import { resolveServerLocale } from "@/lib/i18n/server-locale";
 

src/app/api/cycle/day-logs/[id]/route.ts

@@ -28,7 +28,7 @@ import {
   ensureCycleForBleedingDay,
   removeCycleStartedOn,
 } from "@/lib/cycle/cycle-boundaries";
-import { DEFAULT_TIMEZONE } from "@/lib/mood/date-key";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 import { encrypt, decrypt } from "@/lib/crypto";
 import { getOrCreateCycleProfile } from "@/lib/cycle/profile";
 import { replaceSymptomLinks } from "@/lib/cycle/day-log-write";

src/app/api/cycle/day-logs/bulk/route.ts

@@ -40,7 +40,7 @@ import {
   type UnstableExternalIdShape,
 } from "@/lib/validations/external-id";
 import { upsertCycleDayLog } from "@/lib/cycle/day-log-write";
-import { DEFAULT_TIMEZONE } from "@/lib/mood/date-key";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 
 const BATCH_RATE_LIMIT_MAX = 60;
 const BATCH_RATE_LIMIT_WINDOW_MS = 60 * 1000;

src/app/api/cycle/day-logs/route.ts

@@ -40,7 +40,7 @@ import {
 import { upsertCycleDayLog } from "@/lib/cycle/day-log-write";
 import { findOwningCycleId } from "@/lib/cycle/cycle-attribution";
 import { toCycleDayLogDTO, dayLogSymptomInclude } from "@/lib/cycle/dto";
-import { DEFAULT_TIMEZONE } from "@/lib/mood/date-key";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 
 export const POST = apiHandler(withIdempotency<[NextRequest]>(postDayLog));
 

src/app/api/cycle/insights/route.ts

@@ -43,7 +43,8 @@ import {
   type SymptomDay,
 } from "@/lib/cycle/symptom-phase";
 import { addDays } from "@/lib/cycle/day-math";
-import { DEFAULT_TIMEZONE, moodDateKey } from "@/lib/mood/date-key";
+import { moodDateKey } from "@/lib/mood/date-key";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 
 /** Trailing window the phase-contrast walks (days). */
 const WINDOW_DAYS = 365;
@@ -228,6 +229,7 @@ export const GET = apiHandler(async () => {
     phaseByDay,
     measurements,
     userPriorityJson,
+    timeZone: tz,
   });
   const headline = selectHeadlinePhaseRow(rows);
   // The lagged rows are served with their narrated `interpretation` intact, so
@@ -239,6 +241,7 @@ export const GET = apiHandler(async () => {
     phaseByDay,
     measurements,
     userPriorityJson,
+    timeZone: tz,
     locale,
   });
 

src/app/api/cycle/period/route.ts

@@ -37,7 +37,7 @@ import {
   toMenstrualCycleDTO,
   dayLogSymptomInclude,
 } from "@/lib/cycle/dto";
-import { DEFAULT_TIMEZONE } from "@/lib/mood/date-key";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 import { openCycleAt, type MovedAnchors } from "@/lib/cycle/cycle-boundaries";
 
 export const POST = apiHandler(withIdempotency<[NextRequest]>(postPeriod));

src/app/api/dashboard/summary/route.ts

@@ -67,6 +67,7 @@ import { userDayKey, DEFAULT_TIMEZONE } from "@/lib/tz/resolver";
 import { validTimezoneOr } from "@/lib/tz/format";
 import { cachedSwr, caches, type ServerCache } from "@/lib/cache/server-cache";
 import { buildMedsTodayBlock } from "@/lib/dashboard/meds-today";
+import { computeStreak } from "@/lib/dashboard/streak";
 import {
   readLatestEver,
   readSparkBuckets,
@@ -256,53 +257,6 @@ function trendOf(values: number[]): MetricCard["trend"] {
   return delta > 0 ? "up" : "down";
 }
 
-interface StreakInfo {
-  currentDays: number;
-  longest: number;
-}
-
-/** Compute the current logging-day streak (days where any measurement or
- *  intake event was recorded, in the user's display timezone) plus the
- *  longest streak in the last `STREAK_WINDOW_DAYS` days.
- *
- *  v1.4.25 W7b — `userTz` parameterises the "today" pivot so a Pacific/
- *  Auckland user gets their Auckland-day streak rather than the Berlin
- *  one. The activity-day Set entries are already produced in the same
- *  zone by the caller (via `userDayKey`), so the cursor walk only needs
- *  the same zone here to align. */
-function computeStreak(activityDays: Set<string>, userTz: string): StreakInfo {
-  if (activityDays.size === 0) return { currentDays: 0, longest: 0 };
-
-  const sorted = [...activityDays].sort();
-  let longest = 1;
-  let run = 1;
-  for (let i = 1; i < sorted.length; i++) {
-    const prev = new Date(`${sorted[i - 1]}T00:00:00.000Z`).getTime();
-    const cur = new Date(`${sorted[i]}T00:00:00.000Z`).getTime();
-    if (cur - prev === 86_400_000) {
-      run += 1;
-      longest = Math.max(longest, run);
-    } else {
-      run = 1;
-    }
-  }
-
-  // Current streak: walk back from today (user's tz).
-  const todayKey = userDayKey(new Date(), userTz);
-  let currentDays = 0;
-  let cursor = new Date(`${todayKey}T00:00:00.000Z`);
-  // Allow yesterday's last day to count if today not yet logged.
-  if (!activityDays.has(userDayKey(cursor, userTz))) {
-    cursor = new Date(cursor.getTime() - 86_400_000);
-  }
-  while (activityDays.has(userDayKey(cursor, userTz))) {
-    currentDays += 1;
-    cursor = new Date(cursor.getTime() - 86_400_000);
-  }
-
-  return { currentDays, longest };
-}
-
 /** v1.4.38 W-F — distinct activity day-keys from the streak window.
  *  The route only needs YYYY-MM-DD strings, so the aggregate runs
  *  `date_trunc('day', m.measured_at AT TIME ZONE $userTz)` and returns

src/app/api/illness/episodes/[id]/correlation/route.ts

@@ -22,7 +22,7 @@ import { apiSuccess, apiError } from "@/lib/api-response";
 import { requireIllnessEnabled } from "@/lib/illness/gate";
 import { computeEpisodeCorrelation } from "@/lib/illness/correlation-read";
 import { notifyIllnessRedFlag } from "@/lib/illness/red-flag-notify";
-import { DEFAULT_TIMEZONE } from "@/lib/mood/date-key";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 
 type RouteParams = { params: Promise<{ id: string }> };
 

src/app/api/illness/episodes/[id]/day-logs/route.ts

@@ -34,7 +34,7 @@ import {
 } from "@/lib/validations/illness";
 import { upsertIllnessDayLog } from "@/lib/illness/day-log-write";
 import { toIllnessDayLogDTO, dayLogSymptomInclude } from "@/lib/illness/dto";
-import { DEFAULT_TIMEZONE } from "@/lib/mood/date-key";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 
 type RouteParams = { params: Promise<{ id: string }> };
 

src/app/api/import/csv/route.ts

@@ -11,10 +11,7 @@ import {
   parseCsvMeasurements,
   type CsvRowResult,
 } from "@/lib/import/csv-measurements";
-import {
-  collapseToTypeDayKeys,
-  recomputeBucketsForMeasurement,
-} from "@/lib/rollups/measurement-rollups";
+import { afterMeasurementMutation } from "@/lib/rollups/after-measurement-mutation";
 import type {
   MeasurementType,
   GlucoseContext,
@@ -317,24 +314,10 @@ export const POST = apiHandler(async (request: NextRequest) => {
     }
 
     // One bounded rollup re-fold per touched (type, day) — a 10 000-row CSV
-    // pays at most ~N (type, day) recomputes, not 10 000 per-row hooks.
-    // Best-effort: a populator hiccup never fails the importer.
-    if (touchedMeasurements.length > 0) {
-      try {
-        const keys = collapseToTypeDayKeys(touchedMeasurements);
-        for (const k of keys) {
-          await recomputeBucketsForMeasurement(userId, k.type, k.measuredAt);
-        }
-      } catch (err) {
-        annotate({
-          meta: {
-            measurement_rollup_csv_import_failed: true,
-            measurement_rollup_csv_import_error:
-              err instanceof Error ? err.message : String(err),
-          },
-        });
-      }
-    }
+    // pays at most ~N (type, day) recomputes, not 10 000 per-row hooks — and
+    // the status re-warm for the touched types. Best-effort: a populator
+    // hiccup never fails the importer.
+    await afterMeasurementMutation(userId, touchedMeasurements, "import.csv");
 
     await auditLog("import.csv.upload", {
       userId,

src/app/api/import/route.ts

@@ -32,15 +32,13 @@ import {
 } from "@/lib/validations/external-id";
 import { encryptNote } from "@/lib/crypto/note-cipher";
 import { recomputeUserMoodRollups } from "@/lib/rollups/mood-rollups";
-import {
-  collapseToTypeDayKeys,
-  recomputeBucketsForMeasurement,
-} from "@/lib/rollups/measurement-rollups";
+import { afterMeasurementMutation } from "@/lib/rollups/after-measurement-mutation";
 import type { MeasurementType } from "@/generated/prisma/client";
 import { emitInsertedMeasurementArrivals } from "@/lib/arrivals/measurement-emit";
 import { maybeEnqueueMorningRefresh } from "@/lib/daily/morning-refresh-trigger";
 import { isP2002, isP2025 } from "@/lib/prisma-errors";
-import { DEFAULT_TIMEZONE, moodDateKey } from "@/lib/mood/date-key";
+import { moodDateKey } from "@/lib/mood/date-key";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 import { deriveA1 } from "@/lib/mood/level-a";
 import { zonedWallClockToUtc } from "@/lib/tz/wall-clock";
 
@@ -481,27 +479,11 @@ export const POST = apiHandler(async (request: NextRequest) => {
     }
   }
 
-  // v1.4.39.1 — refresh the persistent measurement rollup table for
-  // every distinct (type, day) the import touched. Collapsed so a
-  // 10 000-row CSV restore pays at most ~N (type, day) recomputes
-  // rather than 10 000 per-row hooks. Best-effort: a populator hiccup
-  // never fails the importer.
-  if (touchedMeasurements.length > 0) {
-    try {
-      const keys = collapseToTypeDayKeys(touchedMeasurements);
-      for (const k of keys) {
-        await recomputeBucketsForMeasurement(userId, k.type, k.measuredAt);
-      }
-    } catch (err) {
-      annotate({
-        meta: {
-          measurement_rollup_import_failed: true,
-          measurement_rollup_import_error:
-            err instanceof Error ? err.message : String(err),
-        },
-      });
-    }
-  }
+  // Refresh the persistent measurement rollup table for every distinct
+  // (type, day) the import touched (collapsed, so a 10 000-row restore pays
+  // at most ~N recomputes) and re-warm the touched types' status
+  // assessments. Best-effort: a populator hiccup never fails the importer.
+  await afterMeasurementMutation(userId, touchedMeasurements, "import");
 
   annotate({
     meta: {

src/app/api/insights/cards/route.ts

@@ -34,6 +34,7 @@ import {
 } from "@/lib/analytics/compliance";
 import type { MeasurementType } from "@/generated/prisma/client";
 import { TRACKED_INTAKE_WHERE } from "@/lib/medications/intake-tracking";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 
 type Severity = "alert" | "caution" | "info" | "good";
 
@@ -216,7 +217,7 @@ export const GET = apiHandler(async () => {
       arr.push(e);
       eventsByMed.set(e.medicationId, arr);
     }
-    const tz = user.timezone || "Europe/Berlin";
+    const tz = user.timezone || DEFAULT_TIMEZONE;
     for (const med of activeMeds) {
       const events = eventsByMed.get(med.id) ?? [];
       const mapped = events.map((e) => ({

src/app/api/insights/comprehensive/route.ts

@@ -41,7 +41,7 @@ import {
   ensureUserMoodRollupsFresh,
   readMoodDayRollups,
 } from "@/lib/rollups/mood-rollups";
-import { userDayKey } from "@/lib/tz/format";
+import { userDayKey, DEFAULT_TIMEZONE } from "@/lib/tz/format";
 import { TRACKED_INTAKE_WHERE } from "@/lib/medications/intake-tracking";
 
 export const dynamic = "force-dynamic";
@@ -125,7 +125,7 @@ export async function buildComprehensiveResponse(user: AuthedUser) {
   // pass in this route (resting-pulse proxy, medication-continuity, BP
   // pairing). Was previously re-derived ad hoc (or hardcoded UTC) at each
   // call site.
-  const userTz = user.timezone || "Europe/Berlin";
+  const userTz = user.timezone || DEFAULT_TIMEZONE;
 
   // Fetch user profile (height + DOB drive BMI + BP targets).
   const dbUser = await prisma.user.findUnique({
@@ -445,7 +445,7 @@ export async function buildComprehensiveResponse(user: AuthedUser) {
     const medicationContext = buildComplianceMedicationContext(
       med,
       lastNonSkippedTakenAt(mapped),
-      user.timezone || "Europe/Berlin",
+      user.timezone || DEFAULT_TIMEZONE,
     );
     const c7 = calculateCompliance(mapped, med.schedules, 7, med.createdAt, {
       medicationContext,

src/app/api/insights/correlations/route.ts

@@ -41,6 +41,7 @@ import {
 } from "@/lib/insights/correlation-patterns";
 import { assembleDiscoveryMatrix } from "@/lib/insights/discovery-matrix";
 import { fetchLabDraws } from "@/lib/insights/correlation-channel-series";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 
 export const dynamic = "force-dynamic";
 
@@ -115,7 +116,7 @@ async function buildCorrelationsResponse(
     where: { id: userId },
     select: { timezone: true },
   });
-  const tz = profile?.timezone ?? "Europe/Berlin";
+  const tz = profile?.timezone ?? DEFAULT_TIMEZONE;
   const now = new Date();
   const since = new Date(now.getTime() - WINDOW_DAYS * MS_PER_DAY);
 

src/app/api/insights/generate/route.ts

@@ -692,6 +692,7 @@ export const POST = apiHandler((request: NextRequest) =>
       userId,
       dbUser?.displayName ?? null,
       locale,
+      await resolveUserTimezone(userId),
     );
 
     // v1.12.7 (B5) — inject the curated SOURCES block for the metric sections

src/app/api/measurements/route.ts

@@ -34,8 +34,8 @@ import { pickCanonicalSourceRows } from "@/lib/analytics/source-priority";
 import {
   canonicalDailyTimestamp,
   dayKeyForUserTz,
-  localDayWindow,
 } from "@/lib/measurements/drain-per-sample-cumulative";
+import { localDayWindow } from "@/lib/tz/local-day";
 import { withIdempotency } from "@/lib/idempotency";
 import { isP2002 } from "@/lib/prisma-errors";
 import { encryptNote, shapeMeasurementNotes } from "@/lib/crypto/note-cipher";
@@ -76,6 +76,7 @@ import type {
   MeasurementSource,
   GlucoseContext,
 } from "@/generated/prisma/client";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 
 export const GET = apiHandler(async (request: NextRequest) => {
   const { user } = await requireRecordAuth("read", "measurements");
@@ -192,7 +193,7 @@ export const GET = apiHandler(async (request: NextRequest) => {
     const tz =
       user.timezone && user.timezone.length > 0
         ? user.timezone
-        : "Europe/Berlin";
+        : DEFAULT_TIMEZONE;
     // Resolve `[dayStart, dayEnd)` for the requested calendar day in
     // the user's local zone. v1.4.37 W10 — `localDayWindow` honours
     // DST: the previous shape (`canonicalDailyTimestamp ± 12 h`)
@@ -242,7 +243,7 @@ export const GET = apiHandler(async (request: NextRequest) => {
     const tz =
       user.timezone && user.timezone.length > 0
         ? user.timezone
-        : "Europe/Berlin";
+        : DEFAULT_TIMEZONE;
     // v1.29.6 — DESC + take so a long history returns the MOST RECENT
     // window of raw samples for bucketing. The previous `orderBy: asc`
     // + `take: limit` sliced the OLDEST page of rows before the

src/app/api/medications/[id]/compliance/route.ts

@@ -9,6 +9,7 @@ import {
 } from "@/lib/medications/compliance-payload";
 import { cachedSwr, caches, type ServerCache } from "@/lib/cache/server-cache";
 import { checkRateLimit } from "@/lib/rate-limit";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 
 type RouteParams = { params: Promise<{ id: string }> };
 
@@ -43,7 +44,7 @@ export const GET = apiHandler(
       return apiError("Too many compliance requests. Please retry later.", 429);
     }
 
-    const userTz = user.timezone || "Europe/Berlin";
+    const userTz = user.timezone || DEFAULT_TIMEZONE;
 
     // Read-through the per-user compliance cache (15 min fresh TTL +
     // SWR window). The ownership guard and the medication read live

src/app/api/medications/[id]/dose-history/route.ts

@@ -41,6 +41,7 @@ import {
 } from "@/lib/medications/scheduling/worker-helpers";
 import { assertMedicationOwnership } from "@/lib/medications/route-guards";
 import { dueSchedules } from "@/lib/medications/intake-tracking";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 
 type RouteParams = { params: Promise<{ id: string }> };
 
@@ -120,7 +121,7 @@ export const GET = apiHandler(
     }
 
     const now = new Date();
-    const userTz = user.timezone || "Europe/Berlin";
+    const userTz = user.timezone || DEFAULT_TIMEZONE;
 
     const medication = await prisma.medication.findUnique({
       where: { id },

src/app/api/medications/[id]/efficacy/route.ts

@@ -2,6 +2,7 @@ import { apiHandler, requireAuth } from "@/lib/api-handler";
 import { apiSuccess, apiError } from "@/lib/api-response";
 import { checkRateLimit } from "@/lib/rate-limit";
 import { buildMedicationEfficacy } from "@/lib/medications/efficacy/build-efficacy";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 
 type RouteParams = { params: Promise<{ id: string }> };
 
@@ -31,7 +32,7 @@ export const GET = apiHandler(
       return apiError("Too many efficacy requests. Please retry later.", 429);
     }
 
-    const userTz = user.timezone || "Europe/Berlin";
+    const userTz = user.timezone || DEFAULT_TIMEZONE;
     const dto = await buildMedicationEfficacy(user.id, id, userTz);
     if (!dto) {
       return apiError("Medication not found", 404);

src/app/api/medications/[id]/route.ts

@@ -47,6 +47,7 @@ import {
   scheduleWireFields,
 } from "@/lib/medications/intake-tracking";
 import { floorWhole } from "@/lib/medications/units-per-dose";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 
 type RouteParams = { params: Promise<{ id: string }> };
 
@@ -176,7 +177,7 @@ export const GET = apiHandler(
       },
       schedules: liveSchedules,
       now,
-      userTz: user.timezone || "Europe/Berlin",
+      userTz: user.timezone || DEFAULT_TIMEZONE,
       lastIntakeAt: lastIntake?.takenAt ?? null,
       resolvedSlots: resolvedRows.map(toResolvedSlotMark),
       eraStart: latestRevision?.validUntil ?? null,
@@ -604,7 +605,7 @@ export const PUT = apiHandler(
       // `syncVersion` so delta-sync clients drop them. The projector and
       // the reminder worker re-mint the anchors for the new times on their
       // next pass — the route does not pre-create them.
-      const userTz = user.timezone || "Europe/Berlin";
+      const userTz = user.timezone || DEFAULT_TIMEZONE;
       const { start: todayStart } = getUserTodayBounds(new Date(), userTz);
       const tombstoneWhere = {
         userId: user.id,

src/app/api/medications/compliance/route.ts

@@ -12,6 +12,7 @@ import {
 import { cachedSwr, caches, type ServerCache } from "@/lib/cache/server-cache";
 import { checkRateLimit } from "@/lib/rate-limit";
 import { TRACKED_INTAKE_WHERE } from "@/lib/medications/intake-tracking";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 
 /**
  * Batched card-compliance read: one round trip for every medication the
@@ -43,7 +44,7 @@ export const GET = apiHandler(async () => {
     return apiError("Too many compliance requests. Please retry later.", 429);
   }
 
-  const userTz = user.timezone || "Europe/Berlin";
+  const userTz = user.timezone || DEFAULT_TIMEZONE;
 
   // Same ordering as the medications list so the page's card order and
   // this payload walk the same sequence.

src/app/api/mood-entries/[id]/route.ts

@@ -14,7 +14,8 @@ import { NextRequest } from "next/server";
 import { Prisma } from "@/generated/prisma/client";
 import { apiHandler, requireRecordAuth } from "@/lib/api-handler";
 import { annotate } from "@/lib/logging/context";
-import { moodDateKey, DEFAULT_TIMEZONE } from "@/lib/mood/date-key";
+import { moodDateKey } from "@/lib/mood/date-key";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 import { deriveA1, shapeLevelA } from "@/lib/mood/level-a";
 import { contextForWire, persistMoodContext } from "@/lib/mood/context";
 import { encryptNote, shapeMoodNote } from "@/lib/crypto/note-cipher";

src/app/api/mood-entries/bulk/route.ts

@@ -51,7 +51,8 @@ import {
   UNSTABLE_EXTERNAL_ID_REASON,
   type UnstableExternalIdShape,
 } from "@/lib/validations/external-id";
-import { moodDateKey, DEFAULT_TIMEZONE } from "@/lib/mood/date-key";
+import { moodDateKey } from "@/lib/mood/date-key";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 import { levelAForWrite } from "@/lib/mood/level-a";
 import { persistMoodContext } from "@/lib/mood/context";
 import { encryptNote } from "@/lib/crypto/note-cipher";

src/app/api/mood-entries/route.ts

@@ -24,7 +24,8 @@ import { apiHandler, requireRecordAuth } from "@/lib/api-handler";
 import { annotate } from "@/lib/logging/context";
 import { withIdempotency } from "@/lib/idempotency";
 import { encryptNote, shapeMoodNote } from "@/lib/crypto/note-cipher";
-import { moodDateKey, DEFAULT_TIMEZONE } from "@/lib/mood/date-key";
+import { moodDateKey } from "@/lib/mood/date-key";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 import { levelAForWrite, shapeLevelA } from "@/lib/mood/level-a";
 import { contextForWire, persistMoodContext } from "@/lib/mood/context";
 import { listMoodEntriesPage } from "@/lib/mood/list-read";

src/app/api/mood/linked-context/route.ts

@@ -38,8 +38,7 @@ import { apiSuccess, returnAllZodIssues } from "@/lib/api-response";
 import { annotate } from "@/lib/logging/context";
 import { requireModuleEnabled } from "@/lib/modules/gate";
 import { resolveLinkedDayContext } from "@/lib/mood/linked-context";
-import { DEFAULT_TIMEZONE } from "@/lib/mood/date-key";
-import { isValidTimezone } from "@/lib/tz/format";
+import { DEFAULT_TIMEZONE, isValidTimezone } from "@/lib/tz/format";
 
 export const dynamic = "force-dynamic";
 

src/app/api/sync/state/route.ts

@@ -42,6 +42,7 @@ import {
   NATIVE_REFRESH_TOKEN_DAYS,
   TOMBSTONE_RETENTION_DAYS,
 } from "@/lib/auth/native-client";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 
 export const GET = apiHandler(async (_request: NextRequest) => {
   const { user } = await requireAuth();
@@ -119,7 +120,7 @@ export const GET = apiHandler(async (_request: NextRequest) => {
 
   return apiSuccess({
     userId: user.id,
-    timezone: currentUser?.timezone ?? "Europe/Berlin",
+    timezone: currentUser?.timezone ?? DEFAULT_TIMEZONE,
     lastSyncedAt: lastSyncedAt?.toISOString() ?? null,
     serverNow: serverNow.toISOString(),
     measurements: {

src/app/medications/page-client.tsx

@@ -48,6 +48,7 @@ import { apiGet } from "@/lib/api/api-fetch";
 import { useMedicationComplianceSummaryAll } from "@/lib/queries/use-medication-compliance-summary";
 import { useMedicationListLayout } from "@/lib/queries/use-medication-list-layout";
 import { applyMedicationOrder } from "@/lib/medications/medication-order";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 
 interface Schedule {
   id: string;
@@ -397,7 +398,7 @@ export default function MedicationsPageClient() {
   // medications past their band tail stay takeable from the batch. Page
   // order is preserved so the confirm dialog lists medications as rendered.
   const dueMeds = deriveDueMedications(activeMeds, {
-    tz: user?.timezone || "Europe/Berlin",
+    tz: user?.timezone || DEFAULT_TIMEZONE,
     thresholds: thresholds ?? undefined,
     doseStatusById: new Map(
       (complianceRows ?? []).map((row) => [

src/components/charts/compliance-heatmap.tsx

@@ -1,7 +1,12 @@
 "use client";
 
 import { useState, useMemo, useEffect, useRef } from "react";
-import { useTranslations, useFormatters } from "@/lib/i18n/context";
+import {
+  useDisplayTimezone,
+  useFormatters,
+  useTranslations,
+} from "@/lib/i18n/context";
+import { heatmapDays } from "@/lib/charts/heatmap-days";
 
 interface DailyData {
   expected: number;
@@ -79,6 +84,7 @@ export function ComplianceHeatmap({
 }: ComplianceHeatmapProps) {
   const { t } = useTranslations();
   const fmt = useFormatters();
+  const timeZone = useDisplayTimezone();
   // Day keys are UTC-anchored "YYYY-MM-DD"; format at noon UTC so the
   // locale-aware renderer never lands a day off in either direction.
   const formatDay = (dateKey: string) =>
@@ -175,7 +181,6 @@ export function ComplianceHeatmap({
       t("charts.months.nov"),
       t("charts.months.dec"),
     ];
-    const now = new Date();
     const cellList: Array<{
       dateKey: string;
       col: number;
@@ -184,34 +189,18 @@ export function ComplianceHeatmap({
       data: DailyData;
     }> = [];
 
-    // Build array of dates from oldest to newest
-    const dates: Date[] = [];
-    for (let d = days - 1; d >= 0; d--) {
-      const date = new Date(now.getTime() - d * 24 * 60 * 60 * 1000);
-      dates.push(date);
-    }
-
-    // Start from the first date, align to Monday.
-    //
-    // v1.4.27 B7 / BL-P4-2 — read every weekday + month boundary off
-    // the UTC accessor pair (`getUTCDay`, `getUTCMonth`) so the
-    // computation matches the dateKey, which is also UTC-anchored
-    // (`toISOString().slice(0, 10)`). Reading in server-tz here would
-    // shift the Monday-alignment + month-marker placement when the
-    // SSR pass runs on a server in a non-Berlin timezone.
-    const firstDate = dates[0];
-    const firstDow = (firstDate.getUTCDay() + 6) % 7; // Monday = 0
+    // Oldest to newest, one entry per local day in the user's zone.
+    const dates = heatmapDays(new Date(), timeZone, days);
+    const firstDow = dates[0]?.dow ?? 0;
 
     let col = 0;
     const markers: Array<{ col: number; label: string }> = [];
     let lastMonth = -1;
 
     for (let i = 0; i < dates.length; i++) {
-      const date = dates[i];
-      const dow = (date.getUTCDay() + 6) % 7; // Monday = 0
+      const { dateKey, dow, month } = dates[i];
       const currentCol = Math.floor((i + firstDow) / 7);
       const row = dow;
-      const dateKey = date.toISOString().slice(0, 10);
       const data = dailyCompliance[dateKey] ?? {
         expected: 0,
         taken: 0,
@@ -219,7 +208,6 @@ export function ComplianceHeatmap({
       };
 
       // Track month boundaries
-      const month = date.getUTCMonth();
       if (month !== lastMonth) {
         markers.push({ col: currentCol, label: MONTH_LABELS[month] });
         lastMonth = month;
@@ -237,7 +225,7 @@ export function ComplianceHeatmap({
     }
 
     return { cells: cellList, weeks: col + 1, monthMarkers: markers };
-  }, [dailyCompliance, days, t]);
+  }, [dailyCompliance, days, t, timeZone]);
 
   const activeDays = cells.filter((cell) => cell.data.expected > 0).length;
   const summaryLabel =

src/components/charts/medication-compliance-chart.tsx

@@ -69,6 +69,7 @@ import { useViewportWidth } from "@/hooks/use-viewport-width";
 import { chooseTickInterval } from "@/lib/charts/x-axis-density";
 import { apiGet } from "@/lib/api/api-fetch";
 import { shouldFireDataReady } from "@/lib/charts/data-ready-latch";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 
 interface DailyCompliancePoint {
   /** Berlin calendar day, "YYYY-MM-DD". */
@@ -208,7 +209,7 @@ interface MedicationComplianceChartProps {
 
 export function MedicationComplianceChart({
   title,
-  userTimezone = "Europe/Berlin",
+  userTimezone = DEFAULT_TIMEZONE,
   compareBaseline,
   onDataReady,
 }: MedicationComplianceChartProps) {

src/components/charts/mood-heatmap.tsx

@@ -1,7 +1,12 @@
 "use client";
 
 import { useState, useMemo, useEffect, useRef } from "react";
-import { useTranslations, useFormatters } from "@/lib/i18n/context";
+import {
+  useDisplayTimezone,
+  useFormatters,
+  useTranslations,
+} from "@/lib/i18n/context";
+import { heatmapDays } from "@/lib/charts/heatmap-days";
 import { moodLabelKeyForScore } from "@/lib/mood/labels";
 
 /**
@@ -62,6 +67,7 @@ export function MoodHeatmap({
 }: MoodHeatmapProps) {
   const { t } = useTranslations();
   const fmt = useFormatters();
+  const timeZone = useDisplayTimezone();
   // Day keys are UTC-anchored "YYYY-MM-DD"; format at noon UTC so the
   // locale-aware renderer never lands a day off in either direction.
   const formatDay = (dateKey: string) =>
@@ -147,7 +153,6 @@ export function MoodHeatmap({
       t("charts.months.nov"),
       t("charts.months.dec"),
     ];
-    const now = new Date();
     const cellList: Array<{
       dateKey: string;
       col: number;
@@ -156,30 +161,19 @@ export function MoodHeatmap({
       cell: MoodHeatmapCell | null;
     }> = [];
 
-    const dates: Date[] = [];
-    for (let d = days - 1; d >= 0; d--) {
-      const date = new Date(now.getTime() - d * 24 * 60 * 60 * 1000);
-      dates.push(date);
-    }
-
-    // Monday-align + month markers read off the UTC accessors so the
-    // grid matches the UTC-anchored dateKey (mirrors compliance-heatmap).
-    const firstDate = dates[0];
-    const firstDow = (firstDate.getUTCDay() + 6) % 7; // Monday = 0
+    const dates = heatmapDays(new Date(), timeZone, days);
+    const firstDow = dates[0]?.dow ?? 0;
 
     let col = 0;
     const markers: Array<{ col: number; label: string }> = [];
     let lastMonth = -1;
 
     for (let i = 0; i < dates.length; i++) {
-      const date = dates[i];
-      const dow = (date.getUTCDay() + 6) % 7; // Monday = 0
+      const { dateKey, dow, month } = dates[i];
       const currentCol = Math.floor((i + firstDow) / 7);
       const row = dow;
-      const dateKey = date.toISOString().slice(0, 10);
       const cell = cellData[dateKey] ?? null;
 
-      const month = date.getUTCMonth();
       if (month !== lastMonth) {
         markers.push({ col: currentCol, label: MONTH_LABELS[month] });
         lastMonth = month;
@@ -197,7 +191,7 @@ export function MoodHeatmap({
     }
 
     return { cells: cellList, weeks: col + 1, monthMarkers: markers };
-  }, [cellData, days, t]);
+  }, [cellData, days, t, timeZone]);
 
   const loggedDays = cells.filter((cell) => cell.cell !== null).length;
   const summaryLabel =

src/components/dashboard/medication-intake-quick-add.tsx

@@ -31,6 +31,7 @@ import {
   intakeToastOptions,
   runUndoIntake,
 } from "@/components/medications/use-medication-intake";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 
 /**
  * v1.4.37 W7b — dashboard "Hinzufügen" → "Medikamenteneinnahme" quick-add.
@@ -115,7 +116,7 @@ export function MedicationIntakeQuickAdd({
   // source the cards use); Berlin stays the last-resort fallback so
   // logged-out mounts behave unchanged.
   const { user } = useAuth();
-  const userTz = user?.timezone || "Europe/Berlin";
+  const userTz = user?.timezone || DEFAULT_TIMEZONE;
   // The record this dose lands in, or null in the caller's own.
   const recordName = useActiveRecordName();
 

src/components/insights/intraday-pulse-chart.tsx

@@ -19,7 +19,7 @@ import { useAuth } from "@/hooks/use-auth";
 import { apiGet } from "@/lib/api/api-fetch";
 import { queryKeys } from "@/lib/query-keys";
 import { useTranslations, useFormatters } from "@/lib/i18n/context";
-import { userDayKey, shiftDateKey } from "@/lib/tz/format";
+import { userDayKey, shiftDateKey, DEFAULT_TIMEZONE } from "@/lib/tz/format";
 import { TileHeader } from "@/components/insights/tile-header";
 import { Button } from "@/components/ui/button";
 import { QueryErrorCard } from "@/components/ui/query-error-card";
@@ -94,7 +94,7 @@ export function IntradayPulseChart({
   const { isAuthenticated } = useAuth();
   const { t } = useTranslations();
   const fmt = useFormatters();
-  const tz = userTimezone ?? "Europe/Berlin";
+  const tz = userTimezone ?? DEFAULT_TIMEZONE;
   const todayKey = userDayKey(new Date(), tz);
   // `null` tracks "today" live (so a session left open across midnight keeps
   // following the current day); a non-null value pins the viewed day once

src/components/measurement-reminders/__tests__/vorsorge-section.test.tsx

@@ -34,7 +34,7 @@ vi.mock("@/hooks/use-measurement-reminders", () => ({
 }));
 
 import { VorsorgeSection, postponeOffsetTargets } from "../vorsorge-section";
-import { DISPLAY_TIMEZONE } from "@/lib/format-locale";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 
 /**
  * Noon on the day `offsetDays` from today, counted on the DISPLAY zone's
@@ -53,7 +53,7 @@ import { DISPLAY_TIMEZONE } from "@/lib/format-locale";
 function noonOnDisplayDay(offsetDays: number): Date {
   // `en-CA` formats as YYYY-MM-DD, which is the shape we want to add days to.
   const today = new Intl.DateTimeFormat("en-CA", {
-    timeZone: DISPLAY_TIMEZONE,
+    timeZone: DEFAULT_TIMEZONE,
     year: "numeric",
     month: "2-digit",
     day: "2-digit",
@@ -219,7 +219,7 @@ describe("<VorsorgeSection> loading + empty", () => {
     // the wall-clock gap to now exceeds the 24h a rolling delta would key on.
     // Anchor the due instant to noon on the DISPLAY zone's today, not the
     // process clock's. `vitest.config.mts` pins the suite to TZ=UTC while the
-    // component floors in the profile zone (`DISPLAY_TIMEZONE`, Europe/Berlin),
+    // component floors in the profile zone (`DEFAULT_TIMEZONE`, Europe/Berlin),
     // and those two disagree about the date for the two hours before UTC
     // midnight. Anchoring on `setHours` made this case fail every night in
     // that window, which is the same confusion of clocks the assertion exists

src/components/medications/card-parts/displayed-slot-instant.ts

@@ -1,3 +1,4 @@
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 /**
  * v1.12.3 — resolve the canonical slot instant of the dose a medication
  * card is currently surfacing, so the card's "Genommen" / "Skip" buttons
@@ -138,7 +139,7 @@ export function resolveDisplayedSlotInstant(
     currentWindowStatus,
     nextDueAt,
     now,
-    timeZone = "Europe/Berlin",
+    timeZone = DEFAULT_TIMEZONE,
   } = input;
 
   // The card surfaces the current/overdue dose band — record that band's

src/components/medications/dose-history-ledger.tsx

@@ -111,6 +111,7 @@ import {
   type LedgerRow,
 } from "@/components/medications/dose-history-ledger-compute";
 import { apiDelete, apiGet, apiPost, apiPut } from "@/lib/api/api-fetch";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 
 const DAY_MS = 24 * 60 * 60 * 1000;
 
@@ -182,7 +183,7 @@ export function DoseHistoryLedger({
   // marked — the most-encountered of the set.
   const recordName = useActiveRecordName();
   const queryClient = useQueryClient();
-  const timeZone = user?.timezone || "Europe/Berlin";
+  const timeZone = user?.timezone || DEFAULT_TIMEZONE;
 
   const [addOpen, setAddOpen] = useState(false);
   const [editingEvent, setEditingEvent] = useState<{

src/components/medications/glp1-medication-card.tsx

@@ -37,6 +37,7 @@ import {
 } from "@/components/medications/detail/supply-runway";
 import { useAuth } from "@/hooks/use-auth";
 import { useMedicationComplianceSummary } from "@/lib/queries/use-medication-compliance-summary";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 
 /**
  * v1.4.25 W4d — GLP-1 medication card variant.
@@ -202,7 +203,7 @@ export function Glp1MedicationCard({
   // v1.16.9 — the card reasons in the PROFILE timezone; Berlin stays the
   // last-resort fallback for logged-out mounts and legacy fixtures.
   const { user } = useAuth();
-  const userTz = user?.timezone || "Europe/Berlin";
+  const userTz = user?.timezone || DEFAULT_TIMEZONE;
   const fmt = useFormatters();
   // Issue #490 — the zone `fmt` renders dates in (mirror → Berlin). The
   // weekday name paired with `fmt.dateShort` must be derived in this SAME

src/components/medications/log-intake-dialog.tsx

@@ -44,6 +44,7 @@ import {
   runLogIntake,
   runUndoIntake,
 } from "@/components/medications/use-medication-intake";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 
 interface LogIntakeSchedule extends ScheduleWindowInput {
   label: string | null;
@@ -120,7 +121,7 @@ export function LogIntakeDialog({
   const recordName = useActiveRecordName();
   const queryClient = useQueryClient();
   const { user } = useAuth();
-  const userTz = user?.timezone || "Europe/Berlin";
+  const userTz = user?.timezone || DEFAULT_TIMEZONE;
   const formId = useId();
 
   const [medicationOverride, setMedicationOverride] = useState<string | null>(

src/components/medications/medication-card.tsx

@@ -34,6 +34,7 @@ import { LogInjectionSiteDialog } from "@/components/medications/log-injection-s
 import { useGlobalExcludedInjectionSites } from "@/lib/medications/use-injection-site-prefs";
 import { useAuth } from "@/hooks/use-auth";
 import type { InjectionSiteKey } from "@/lib/medications/injection-sites";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 
 interface Schedule {
   id: string;
@@ -149,7 +150,7 @@ export function MedicationCard({
   // session carries); Berlin stays the last-resort fallback so logged-out
   // mounts and legacy fixtures behave unchanged.
   const { user } = useAuth();
-  const userTz = user?.timezone || "Europe/Berlin";
+  const userTz = user?.timezone || DEFAULT_TIMEZONE;
   const fmt = useFormatters();
   const weekdayLabel = useWeekdayLabel();
   // v1.8.5 — post-dose injection-site prompt state. Holds the intake

src/components/medications/medication-table.tsx

@@ -43,6 +43,7 @@ import {
 } from "@/lib/queries/use-medication-compliance-summary";
 import { useAuth } from "@/hooks/use-auth";
 import { cn } from "@/lib/utils";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 
 /**
  * v1.16.10 — the compact table view for /medications (issue #316 item 3).
@@ -194,7 +195,7 @@ export function MedicationTable({
 }: MedicationTableProps) {
   const { t, locale } = useTranslations();
   const { user } = useAuth();
-  const userTz = user?.timezone || "Europe/Berlin";
+  const userTz = user?.timezone || DEFAULT_TIMEZONE;
   const [sort, setSort] = useState<MedicationTableSort | null>(initialSort);
   const [, forceUpdate] = useReducer((x: number) => x + 1, 0);
 

src/components/medications/take-all-due.ts

@@ -57,6 +57,7 @@ import {
 } from "@/lib/medications/window-status";
 import { resolveDisplayedSlotInstant } from "@/components/medications/card-parts/displayed-slot-instant";
 import type { DoseStatus } from "@/lib/analytics/compliance";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 
 type Translator = (
   key: string,
@@ -142,7 +143,7 @@ export function deriveDueMedications(
   } = {},
 ): DueMedication[] {
   const now = options.now ?? new Date();
-  const tz = options.tz ?? "Europe/Berlin";
+  const tz = options.tz ?? DEFAULT_TIMEZONE;
   const { lateMinutes, missedMinutes } =
     options.thresholds ?? DEFAULT_THRESHOLDS;
 

src/components/settings/account-section/index.tsx

@@ -33,7 +33,7 @@ import { TimeFormatSelect } from "@/components/settings/time-format-select";
 import { DateFormatSelect } from "@/components/settings/date-format-select";
 import { UnitPreferenceSelect } from "@/components/settings/unit-preference-select";
 import { GlucoseUnitSelect } from "@/components/settings/glucose-unit-select";
-import { detectBrowserTimezone } from "@/lib/tz/format";
+import { detectBrowserTimezone, DEFAULT_TIMEZONE } from "@/lib/tz/format";
 import { apiFetchRaw } from "@/lib/api/api-fetch";
 import {
   describeRejectedProfileField,
@@ -74,7 +74,7 @@ export function AccountSection() {
   const [height, setHeight] = useState<HeightDraft>(EMPTY_HEIGHT_DRAFT);
   const [dateOfBirth, setDateOfBirth] = useState("");
   const [gender, setGender] = useState<string>("");
-  const [timezone, setTimezone] = useState<string>("Europe/Berlin");
+  const [timezone, setTimezone] = useState<string>(DEFAULT_TIMEZONE);
   // v1.7.0 — optional patient-identity fields for the health-record export.
   const [fullName, setFullName] = useState("");
   const [insurerName, setInsurerName] = useState("");
@@ -84,7 +84,7 @@ export function AccountSection() {
     height: EMPTY_HEIGHT_DRAFT,
     dateOfBirth: "",
     gender: "",
-    timezone: "Europe/Berlin",
+    timezone: DEFAULT_TIMEZONE,
     fullName: "",
     insurerName: "",
     insuranceNumber: "",

src/components/settings/managed-record-settings-section.tsx

@@ -39,6 +39,7 @@ import { Switch } from "@/components/ui/switch";
 import { SettingsCardActions } from "./_card-actions";
 import { SettingsCardHeader } from "./_card-header";
 import { SettingsCard } from "./settings-card";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 
 interface ManagedRecordSettingsResponse {
   recordId: string;
@@ -414,7 +415,7 @@ function ProfileSettingsForm({
       <label className="grid gap-1 text-sm" htmlFor="managed-timezone">
         {t("settings.sharedRecord.managedSettings.profile.timezone")}
         <Input
-          defaultValue={asString(settings.timezone, "Europe/Berlin")}
+          defaultValue={asString(settings.timezone, DEFAULT_TIMEZONE)}
           disabled={disabled}
           id="managed-timezone"
           name="timezone"

src/components/settings/timezone-picker.tsx

@@ -26,7 +26,7 @@ import { useMemo } from "react";
 import { Input } from "@/components/ui/input";
 import { Label } from "@/components/ui/label";
 import { NativeSelect } from "@/components/ui/native-select";
-import { listSupportedTimezones } from "@/lib/tz/format";
+import { listSupportedTimezones, DEFAULT_TIMEZONE } from "@/lib/tz/format";
 import { useTranslations } from "@/lib/i18n/context";
 
 // v1.4.27 MB7 / CF-52 — the in-file `NATIVE_SELECT_CLASS` constant
@@ -67,7 +67,7 @@ export function TimezonePicker({
           id={id}
           value={value}
           onChange={(e) => onChange(e.target.value)}
-          placeholder="Europe/Berlin"
+          placeholder={DEFAULT_TIMEZONE}
           autoComplete="off"
         />
         <p className="text-muted-foreground text-xs">{labelHint}</p>

src/lib/ai/coach/cycle-snapshot.ts

@@ -41,7 +41,8 @@ import {
 import type { CrossMetricMeasurement } from "@/lib/insights/mood-aggregates";
 import { addDays } from "@/lib/cycle/day-math";
 import { readSourceDayAggregates } from "@/lib/measurements/day-aggregates";
-import { DEFAULT_TIMEZONE, moodDateKey } from "@/lib/mood/date-key";
+import { moodDateKey } from "@/lib/mood/date-key";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 
 /** Trailing window the phase contrast walks (days). Mirrors the read route. */
 const WINDOW_DAYS = 365;
@@ -200,12 +201,13 @@ export async function buildCycleSnapshotBlock(
       // many readings to hold as objects (#1023). The crosstab only needs
       // each day's sum and count per source and device, which is what the
       // per-source picker decides on, so the fold runs in SQL. Days are the
-      // Berlin days `metricDayMap` keys on.
+      // user's days, the ones `metricDayMap` keys on and the phase days are
+      // dated in.
       readSourceDayAggregates({
         userId,
         types: PHASE_CROSSTAB_METRIC_TYPES,
         since: new Date(Date.parse(`${from}T00:00:00Z`)),
-        timeZone: "Europe/Berlin",
+        timeZone: tz,
       }),
       prisma.user.findUnique({
         where: { id: userId },
@@ -292,6 +294,7 @@ export async function buildCycleSnapshotBlock(
       phaseByDay,
       measurements,
       userPriorityJson: userRow?.sourcePriorityJson ?? null,
+      timeZone: tz,
     }),
   );
 

src/lib/ai/coach/illness-snapshot.ts

@@ -17,7 +17,7 @@
 import { prisma } from "@/lib/db";
 import { isIllnessEnabled } from "@/lib/illness/gate";
 import { computeEpisodeCorrelation } from "@/lib/illness/correlation-read";
-import { DEFAULT_TIMEZONE } from "@/lib/mood/date-key";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 import { decryptFromBytes } from "@/lib/ai/coach/bytes-codec";
 import { sanitizeForPrompt } from "@/lib/insights/sanitize";
 

src/lib/ai/coach/snapshot-series.ts

@@ -206,6 +206,8 @@ export async function buildCoarseTimelineTail(
   type: MeasurementType,
   now: Date,
   tz: string,
+  /** The user's source-priority blob, already loaded by the caller. */
+  userPriorityJson: unknown,
 ): Promise<CoarseTimelineTail | undefined> {
   // `buildTieredSeries` reads fall back on miss — a coverage miss yields empty
   // bands, which collapse to `undefined` here. The try/catch keeps the coarse
@@ -222,6 +224,7 @@ export async function buildCoarseTimelineTail(
       now: now.getTime(),
       tz,
       coarseOnly: true,
+      userPriorityJson,
     });
   } catch {
     return undefined;

src/lib/ai/coach/snapshot.ts

@@ -548,6 +548,7 @@ async function buildCoachSnapshotImpl(
       "BLOOD_PRESSURE_SYS" as MeasurementType,
       now,
       userTz,
+      prefsRow?.sourcePriorityJson ?? null,
     );
   }
   if (wantsWeight) {
@@ -556,6 +557,7 @@ async function buildCoachSnapshotImpl(
       "WEIGHT" as MeasurementType,
       now,
       userTz,
+      prefsRow?.sourcePriorityJson ?? null,
     );
   }
   if (wantsPulse) {
@@ -564,6 +566,7 @@ async function buildCoachSnapshotImpl(
       "PULSE" as MeasurementType,
       now,
       userTz,
+      prefsRow?.sourcePriorityJson ?? null,
     );
   }
   const [bpCoarseTail, weightCoarseTail, pulseCoarseTail] = await Promise.all([

src/lib/ai/coach/tools/correlations-read.ts

@@ -56,6 +56,7 @@ import {
   loadBaselineProfile,
   isDerivedOk,
 } from "@/lib/insights/derived";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 
 const MS_PER_DAY = 24 * 60 * 60 * 1000;
 /** Trailing window for the discovery scan — mirrors the insight route. */
@@ -209,7 +210,7 @@ export async function readCoachCorrelations(
       where: { id: userId },
       select: { timezone: true },
     });
-    const tz = userRow?.timezone ?? "Europe/Berlin";
+    const tz = userRow?.timezone ?? DEFAULT_TIMEZONE;
     const since = new Date(Date.now() - WINDOW_DAYS * MS_PER_DAY);
 
     // The channel set is the shared one, so the Coach scans exactly what the

src/lib/ai/coach/workout-evidence-builder.ts

@@ -22,6 +22,7 @@ import {
   buildWorkoutEvidence,
   type WorkoutEvidenceInput,
 } from "./workout-evidence";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 
 interface WorkoutEvidenceRow {
   sportType: string;
@@ -108,7 +109,7 @@ export function createWorkoutEvidenceBuilder(
         sportType: row.sportType,
         source: row.source,
         startedAt: row.startedAt,
-        timezone: profile?.timezone ?? "Europe/Berlin",
+        timezone: profile?.timezone ?? DEFAULT_TIMEZONE,
         durationSec: row.durationSec,
         totalEnergyKcal: row.totalEnergyKcal,
         totalDistanceM: row.totalDistanceM,

src/lib/ai/prompts/__tests__/briefing-personalisation.test.ts

@@ -15,6 +15,7 @@ describe("buildBriefingPersonalisationBlock", () => {
       "user-1",
       null,
       "en",
+      "UTC",
       day("2026-06-27T08:00:00Z"),
     );
     expect(en).toContain("OPENER HINT:");
@@ -22,6 +23,7 @@ describe("buildBriefingPersonalisationBlock", () => {
       "user-1",
       null,
       "de",
+      "UTC",
       day("2026-06-27T08:00:00Z"),
     );
     expect(de).toContain("OPENER-HINWEIS:");
@@ -33,6 +35,7 @@ describe("buildBriefingPersonalisationBlock", () => {
         "user-1",
         null,
         "en",
+        "UTC",
         day(`2026-06-${String(d).padStart(2, "0")}T08:00:00Z`),
       );
       expect(out).not.toContain("NAME:");
@@ -47,6 +50,7 @@ describe("buildBriefingPersonalisationBlock", () => {
         "user-42",
         "Alex Rivera",
         "en",
+        "UTC",
         day(`2026-06-${String(d).padStart(2, "0")}T08:00:00Z`),
       );
       if (out.includes('"Alex"')) withName += 1;
@@ -62,6 +66,7 @@ describe("buildBriefingPersonalisationBlock", () => {
       "user-42",
       "Alex Rivera",
       "en",
+      "UTC",
       day("2026-06-30T08:00:00Z"),
     );
     expect(out).not.toContain("Rivera");

src/lib/ai/prompts/blood-pressure.ts

@@ -68,12 +68,12 @@ export function getBloodPressureUserPrompt(
       ? `\nOPENER HINT: ${openerHint}`
       : "";
   if (instructionLocale(locale) === "en") {
-    return `Date: ${todayKey} (Europe/Berlin)${openerLine}
+    return `Date: ${todayKey}${openerLine}
 Write one short assessment of this person's blood pressure. Open with what the reading MEANS in plain words — the overall read, not the number (e.g. "calm and right where you want it", "running a touch higher than your usual this week") — then bring in the systolic/diastolic figures right after as support, judged as ONE pair and placed against their own weekly/monthly baseline; never lead with the numbers. Close with one doable step only when the finding genuinely implies one; when nothing is, skip the step rather than manufacture filler. Judge confidence from the measurement count and recency.${ctxBlock}${extraBlock}
 
 ${snapshotJson}`;
   }
-  return `Datum: ${todayKey} (Europe/Berlin)${openerLine}
+  return `Datum: ${todayKey}${openerLine}
 Schreibe eine kurze Einschätzung zum Blutdruck dieser Person. Beginne mit der BEDEUTUNG in klaren Worten — dem Gesamteindruck, nicht der Zahl (z. B. "ruhig und genau da, wo du ihn haben willst", "diese Woche einen Tick höher als sonst") — und bring danach die systolischen/diastolischen Werte als Beleg, als EIN Paar beurteilt und gegen die eigene Wochen-/Monats-Baseline eingeordnet; führe nie mit den Werten. Schließe nur dann mit einem machbaren Schritt, wenn der Befund wirklich einen hergibt; ist nichts umsetzbar, lass den Schritt weg statt Fülltext zu erfinden. Konfidenz aus Messanzahl und Aktualität ableiten.${ctxBlock}${extraBlock}
 
 ${snapshotJson}`;

src/lib/ai/prompts/bmi.ts

@@ -55,12 +55,12 @@ export function getBmiUserPrompt(
       ? `\nOPENER HINT: ${openerHint}`
       : "";
   if (instructionLocale(locale) === "en") {
-    return `Date: ${todayKey} (Europe/Berlin)${openerLine}
+    return `Date: ${todayKey}${openerLine}
 Write one short assessment of this person's BMI. Open with what its band placement MEANS in plain words — where it sits and whether that's holding or shifting, not the number (e.g. "sitting comfortably in the healthy band", "edging toward the next band up") — then bring in the current value and WHO band right after as support, saying against their own weekly/monthly baseline whether it has crossed a band or is nearing a boundary; never lead with the value. Close with one doable step only when the finding genuinely implies one; when nothing is, skip the step rather than manufacture filler. Leave the weight pace to the weight card. Judge confidence from the measurement count and recency.${ctxBlock}${extraBlock}
 
 ${snapshotJson}`;
   }
-  return `Datum: ${todayKey} (Europe/Berlin)${openerLine}
+  return `Datum: ${todayKey}${openerLine}
 Schreibe eine kurze Einschätzung zum BMI dieser Person. Beginne mit der BEDEUTUNG der Bandlage in klaren Worten — wo er liegt und ob das hält oder sich verschiebt, nicht der Zahl (z. B. "liegt bequem im gesunden Band", "nähert sich dem nächsten Band") — und bring danach den aktuellen Wert und das WHO-Band als Beleg, samt Angabe gegen die eigene Wochen-/Monats-Baseline, ob er ein Band gewechselt hat oder sich einer Bandgrenze nähert; führe nie mit dem Wert. Schließe nur dann mit einem machbaren Schritt, wenn der Befund wirklich einen hergibt; ist nichts umsetzbar, lass den Schritt weg statt Fülltext zu erfinden. Das Gewichtstempo bleibt der Gewichts-Karte überlassen. Konfidenz aus Messanzahl und Aktualität ableiten.${ctxBlock}${extraBlock}
 
 ${snapshotJson}`;

src/lib/ai/prompts/general-status.ts

@@ -63,12 +63,12 @@ export function getGeneralStatusUserPrompt(
       ? `\nOPENER HINT: ${openerHint}`
       : "";
   if (instructionLocale(locale) === "en") {
-    return `Date: ${todayKey} (Europe/Berlin)${openerLine}
+    return `Date: ${todayKey}${openerLine}
 Write one short overall assessment across the available health metrics. Open with the overall read in plain words — how things are looking taken together, not a number (e.g. "a steady stretch across the board", "one thing standing out this week") — then bring in the one or two metrics that stand out as support, each placed against the person's own weekly/monthly baseline; never lead with a value. Close with the single most important doable step only when the overall picture genuinely implies one; when nothing is, skip the step rather than manufacture filler. Judge confidence from the measurement count, density and recency.${ctxBlock}${extraBlock}
 
 ${snapshotJson}`;
   }
-  return `Datum: ${todayKey} (Europe/Berlin)${openerLine}
+  return `Datum: ${todayKey}${openerLine}
 Schreibe eine kurze Gesamteinschätzung über die verfügbaren Gesundheitsdaten. Beginne mit dem Gesamteindruck in klaren Worten — wie es zusammengenommen aussieht, nicht mit einer Zahl (z. B. "über alles hinweg eine ruhige Phase", "diese Woche sticht eine Sache heraus") — und bring danach die ein bis zwei auffälligsten Metriken als Beleg, jeweils gegen die eigene Wochen-/Monats-Baseline eingeordnet; führe nie mit einem Wert. Schließe nur dann mit dem einen wichtigsten machbaren Schritt, wenn das Gesamtbild wirklich einen hergibt; ist nichts umsetzbar, lass den Schritt weg statt Fülltext zu erfinden. Konfidenz aus Messanzahl, Dichte und Aktualität ableiten.${ctxBlock}${extraBlock}
 
 ${snapshotJson}`;

src/lib/ai/prompts/insight-generator.ts

@@ -47,6 +47,7 @@ import {
   outlookContract,
   formattingContract,
 } from "./shared-contracts";
+import { userDayKey } from "@/lib/tz/format";
 
 /**
  * Stable identifier for the active system prompt revision.
@@ -63,16 +64,6 @@ import {
  */
 export const PROMPT_VERSION = "5.1.0" as const;
 
-/** Europe/Berlin YYYY-MM-DD day key — the rotation boundary for the opener. */
-function berlinDayKey(now: Date): string {
-  return new Intl.DateTimeFormat("en-CA", {
-    timeZone: "Europe/Berlin",
-    year: "numeric",
-    month: "2-digit",
-    day: "2-digit",
-  }).format(now);
-}
-
 /**
  * v1.22 (W6) — the daily-briefing personalization SYSTEM CONTEXT block.
  *
@@ -92,9 +83,11 @@ export function buildBriefingPersonalisationBlock(
   userId: string,
   displayName: string | null,
   locale: Locale,
+  /** The user's zone: the opener rotates at the user's own midnight. */
+  timeZone: string,
   now: Date = new Date(),
 ): string {
-  const dayKey = berlinDayKey(now);
+  const dayKey = userDayKey(now, timeZone);
   const hint = openerArchetypeHint(`${userId}:briefing:${dayKey}`, locale);
   const firstName = firstNameFromDisplayName(displayName);
   const useName =

src/lib/ai/prompts/medication-compliance.ts

@@ -57,12 +57,12 @@ export function getMedicationComplianceUserPrompt(
       ? `\nOPENER HINT: ${openerHint}`
       : "";
   if (instructionLocale(locale) === "en") {
-    return `Date: ${todayKey} (Europe/Berlin)${openerLine}
+    return `Date: ${todayKey}${openerLine}
 Write one short assessment of this person's medication adherence. Open with what it MEANS in plain words — how reliable the routine is looking, not the number (e.g. "your routine's been rock-solid", "a few doses have slipped lately") — then bring in the recent rate right after as support, placed against their own baseline (compliance7 vs compliance30); never lead with the value. Close with one doable, blame-free step only when the finding genuinely implies one; when nothing is, skip the step rather than manufacture filler. Judge confidence from the event count and recency.${ctxBlock}${extraBlock}
 
 ${snapshotJson}`;
   }
-  return `Datum: ${todayKey} (Europe/Berlin)${openerLine}
+  return `Datum: ${todayKey}${openerLine}
 Schreibe eine kurze Einschätzung zur Einnahmetreue dieser Person. Beginne mit der BEDEUTUNG in klaren Worten — wie verlässlich die Routine aussieht, nicht der Zahl (z. B. "deine Routine sitzt richtig gut", "zuletzt sind ein paar Dosen durchgerutscht") — und bring danach die jüngste Rate als Beleg, gegen die eigene Baseline eingeordnet (compliance7 vs. compliance30); führe nie mit dem Wert. Schließe nur dann mit einem machbaren, wertfreien Schritt, wenn der Befund wirklich einen hergibt; ist nichts umsetzbar, lass den Schritt weg statt Fülltext zu erfinden. Konfidenz aus Ereignisanzahl und Aktualität ableiten.${ctxBlock}${extraBlock}
 
 ${snapshotJson}`;

src/lib/ai/prompts/metric-archetypes.ts

@@ -165,12 +165,12 @@ export function getMetricArchetypeUserPrompt(
       ? `\nOPENER HINT: ${openerHint}`
       : "";
   if (instructionLocale(locale) === "en") {
-    return `Date: ${todayKey} (Europe/Berlin)${openerLine}
+    return `Date: ${todayKey}${openerLine}
 Write one short assessment of this person's ${meta.displayName.toLowerCase()}. Open with what it MEANS in plain words — the read, not the number (e.g. "running a little calmer than usual", "steady and right where it's been") — then bring in ONE concrete number from the snapshot right after as support, placed against their own weekly/monthly baseline; never lead with the value. Close with one doable step only when the finding genuinely implies one; when nothing is, skip the step rather than manufacture filler. Judge confidence from the measurement count and recency.${ctxBlock}${extraBlock}${interpBlock}
 
 ${snapshotJson}`;
   }
-  return `Datum: ${todayKey} (Europe/Berlin)${openerLine}
+  return `Datum: ${todayKey}${openerLine}
 Schreibe eine kurze Einschätzung zu ${meta.displayName} dieser Person. Beginne mit der BEDEUTUNG in klaren Worten — dem Eindruck, nicht der Zahl (z. B. "läuft gerade etwas ruhiger als sonst", "stabil und genau da, wo es war") — und bring danach EINE konkrete Zahl aus dem Snapshot als Beleg, gegen die eigene Wochen-/Monats-Baseline eingeordnet; führe nie mit dem Wert. Schließe nur dann mit einem machbaren Schritt, wenn der Befund wirklich einen hergibt; ist nichts umsetzbar, lass den Schritt weg statt Fülltext zu erfinden. Konfidenz aus Messanzahl und Aktualität ableiten.${ctxBlock}${extraBlock}${interpBlock}
 
 ${snapshotJson}`;

src/lib/ai/prompts/mood.ts

@@ -57,12 +57,12 @@ export function getMoodUserPrompt(
       ? `\nOPENER HINT: ${openerHint}`
       : "";
   if (instructionLocale(locale) === "en") {
-    return `Date: ${todayKey} (Europe/Berlin)${openerLine}
+    return `Date: ${todayKey}${openerLine}
 Write one short assessment of this person's mood. Open with what the recent pattern MEANS in plain words — the read, not the number (e.g. "a brighter stretch than usual", "steady, holding where it's been") — then bring in the recent level right after as support, placed against their own weekly/monthly baseline; never lead with the value. Close with one kind, doable step only when the finding genuinely implies one; when nothing is, skip the step rather than manufacture filler. Judge confidence from the entry count and recency.${ctxBlock}${extraBlock}
 
 ${snapshotJson}`;
   }
-  return `Datum: ${todayKey} (Europe/Berlin)${openerLine}
+  return `Datum: ${todayKey}${openerLine}
 Schreibe eine kurze Einschätzung zur Stimmung dieser Person. Beginne mit der BEDEUTUNG des jüngsten Musters in klaren Worten — dem Eindruck, nicht der Zahl (z. B. "eine hellere Phase als sonst", "stabil, hält sich, wo sie war") — und bring danach das jüngste Niveau als Beleg, gegen die eigene Wochen-/Monats-Baseline eingeordnet; führe nie mit dem Wert. Schließe nur dann mit einem freundlichen, machbaren Schritt, wenn der Befund wirklich einen hergibt; ist nichts umsetzbar, lass den Schritt weg statt Fülltext zu erfinden. Konfidenz aus Eintragsanzahl und Aktualität ableiten.${ctxBlock}${extraBlock}
 
 ${snapshotJson}`;

src/lib/ai/prompts/pulse.ts

@@ -55,12 +55,12 @@ export function getPulseUserPrompt(
       ? `\nOPENER HINT: ${openerHint}`
       : "";
   if (instructionLocale(locale) === "en") {
-    return `Date: ${todayKey} (Europe/Berlin)${openerLine}
+    return `Date: ${todayKey}${openerLine}
 Write one short assessment of this person's resting pulse. Open with what it MEANS in plain words — the read, not the number (e.g. "running a little calmer than usual", "steady, right where it's been") — then bring in ONE concrete number from the snapshot right after as support, placed against their own weekly/monthly baseline; never lead with the value. Close with one doable step only when the finding genuinely implies one; when nothing is, skip the step rather than manufacture filler. Judge confidence from the measurement count and recency.${ctxBlock}${extraBlock}
 
 ${snapshotJson}`;
   }
-  return `Datum: ${todayKey} (Europe/Berlin)${openerLine}
+  return `Datum: ${todayKey}${openerLine}
 Schreibe eine kurze Einschätzung zum Ruhepuls dieser Person. Beginne mit der BEDEUTUNG in klaren Worten — dem Eindruck, nicht der Zahl (z. B. "läuft gerade etwas ruhiger als sonst", "stabil, genau da, wo er war") — und bring danach EINE konkrete Zahl aus dem Snapshot als Beleg, gegen die eigene Wochen-/Monats-Baseline eingeordnet; führe nie mit dem Wert. Schließe nur dann mit einem machbaren Schritt, wenn der Befund wirklich einen hergibt; ist nichts umsetzbar, lass den Schritt weg statt Fülltext zu erfinden. Konfidenz aus Messanzahl und Aktualität ableiten.${ctxBlock}${extraBlock}
 
 ${snapshotJson}`;

src/lib/ai/prompts/weight.ts

@@ -63,12 +63,12 @@ export function getWeightUserPrompt(
       ? `\nOPENER HINT: ${openerHint}`
       : "";
   if (instructionLocale(locale) === "en") {
-    return `Date: ${todayKey} (Europe/Berlin)${openerLine}
+    return `Date: ${todayKey}${openerLine}
 Write one short assessment of this person's weight. Open with what the trend MEANS in plain words — the direction and momentum, not the number (e.g. "easing down steadily", "holding right where it's settled") — then bring in ONE concrete number from the snapshot right after as support, read as a continuous trend and pace against their own weekly/monthly baseline (kg/week, plateau, milestone — not the single value, and not the WHO band, which the BMI card covers); never lead with the value. Close with one doable step only when the finding genuinely implies one; when nothing is, skip the step rather than manufacture filler. Judge confidence from the measurement count and recency.${ctxBlock}${extraBlock}
 
 ${snapshotJson}`;
   }
-  return `Datum: ${todayKey} (Europe/Berlin)${openerLine}
+  return `Datum: ${todayKey}${openerLine}
 Schreibe eine kurze Einschätzung zum Gewicht dieser Person. Beginne mit der BEDEUTUNG in klaren Worten — Richtung und Tempo, nicht der Zahl (z. B. "geht ruhig nach unten", "hält sich genau da, wo es sich eingependelt hat") — und bring danach EINE konkrete Zahl aus dem Snapshot als Beleg, als kontinuierlichen Trend und Tempo gegen die eigene Wochen-/Monats-Baseline gelesen (kg/Woche, Plateau, Meilenstein — nicht der Einzelwert und nicht das WHO-Band, das die BMI-Karte trägt); führe nie mit dem Wert. Schließe nur dann mit einem machbaren Schritt, wenn der Befund wirklich einen hergibt; ist nichts umsetzbar, lass den Schritt weg statt Fülltext zu erfinden. Konfidenz aus Messanzahl und Aktualität ableiten.${ctxBlock}${extraBlock}
 
 ${snapshotJson}`;

src/lib/analytics/__tests__/intraday-pulse-io.test.ts

@@ -29,10 +29,9 @@ import {
   resolveRestingPulseSeries,
   type PulseSample,
 } from "@/lib/analytics/resting-pulse";
-import { toBerlinDayKey } from "@/lib/tz/resolver";
 import { userDayKey } from "@/lib/tz/format";
 import { percentile } from "@/lib/insights/strain-score";
-import { localDayWindow } from "@/lib/measurements/consolidation-tz";
+import { localDayWindow } from "@/lib/tz/local-day";
 
 /** Mirrors the private `median()` helper in `intraday-pulse-io.ts`. */
 function median(values: number[]): number | null {
@@ -96,7 +95,7 @@ describe("loadIntradayPulse", () => {
     // Sanity: under the OLD hardcoded-Berlin bug all six samples fall on the
     // SAME Berlin day — proving the two tz groupings genuinely diverge.
     const berlinDays = new Set(
-      [...dayA, ...dayB].map((d) => toBerlinDayKey(d)),
+      [...dayA, ...dayB].map((d) => userDayKey(d, "Europe/Berlin")),
     );
     expect(berlinDays.size).toBe(1);
 
@@ -151,7 +150,7 @@ describe("loadIntradayPulse", () => {
     const buggyBerlin = resolveRestingPulseSeries({
       restingSamples: [],
       pulseSamples: pulseHistory as PulseSample[],
-      dayKeyOf: (d) => toBerlinDayKey(d),
+      dayKeyOf: (d) => userDayKey(d, "Europe/Berlin"),
     });
     const buggyBaseline = median(
       buggyBerlin.series.slice(-30).map((p) => p.value),

src/lib/analytics/__tests__/range-delta-per-period.test.ts

@@ -0,0 +1,93 @@
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+const mocks = vi.hoisted(() => ({
+  readRollupBuckets: vi.fn(),
+  findMany: vi.fn(),
+}));
+
+vi.mock("@/lib/db", () => ({
+  prisma: { measurement: { findMany: mocks.findMany } },
+}));
+vi.mock("@/lib/rollups/measurement-rollups", () => ({
+  readRollupBuckets: mocks.readRollupBuckets,
+}));
+vi.mock("@/lib/rollups/measurement-read", () => ({
+  loadUserSourcePriority: vi.fn(async () => null),
+}));
+vi.mock("@/lib/rollups/measurement-read-wmy", () => ({
+  aggregateWmyBuckets: vi.fn(),
+  readBestGranularityRollups: vi.fn(async () => null),
+}));
+vi.mock("@/lib/tz/resolver", () => ({
+  resolveUserTimezone: vi.fn(async () => "UTC"),
+}));
+
+import { computeRangeDelta } from "@/lib/analytics/range-delta";
+
+const DAY_MS = 86_400_000;
+const NOW = Date.UTC(2026, 5, 30, 12);
+
+function dayRow(daysAgo: number, total: number, samples: number) {
+  const bucketStart = new Date(Date.UTC(2026, 5, 30) - daysAgo * DAY_MS);
+  return {
+    bucketStart,
+    count: samples,
+    mean: total / samples,
+    minValue: 0,
+    maxValue: total,
+    sd: null,
+    slope: null,
+    r2: null,
+    computedAt: bucketStart,
+  };
+}
+
+beforeEach(() => {
+  mocks.readRollupBuckets.mockReset();
+  mocks.findMany.mockReset();
+});
+
+describe("computeRangeDelta — per-day and per-night metrics", () => {
+  it("compares average daily step totals, not the mean of the readings", async () => {
+    // Six complete days of 8,000 in the previous week, and in the current
+    // week five drained days plus today still arriving as 200 samples.
+    mocks.readRollupBuckets.mockResolvedValue([
+      ...[8, 9, 10, 11, 12, 13].map((d) => dayRow(d, 8000, 1)),
+      ...[1, 2, 3, 4, 5].map((d) => dayRow(d, 8000, 1)),
+      dayRow(0, 4000, 200),
+    ]);
+
+    const result = await computeRangeDelta("u", "ACTIVITY_STEPS", "7d", NOW);
+
+    expect(result.granularity).toBe("DAY");
+    expect(result.previous).toMatchObject({ count: 6, mean: 8000 });
+    expect(result.current.count).toBe(6);
+    expect(result.current.mean).toBeCloseTo((5 * 8000 + 4000) / 6, 6);
+    expect(result.current.sum).toBeCloseTo(44_000, 6);
+  });
+
+  it("compares average nights of sleep, not the mean of stage rows", async () => {
+    const row = (iso: string, minutes: number, sleepStage: string) => ({
+      value: minutes,
+      measuredAt: new Date(iso),
+      sleepStage,
+      source: "APPLE_HEALTH",
+      deviceType: null,
+    });
+    // Two nights: 7 h asleep (split into three stage rows plus an in-bed
+    // envelope) and 6 h asleep.
+    mocks.findMany.mockResolvedValue([
+      row("2026-06-28T01:00:00.000Z", 480, "IN_BED"),
+      row("2026-06-28T02:00:00.000Z", 180, "CORE"),
+      row("2026-06-28T04:00:00.000Z", 120, "DEEP"),
+      row("2026-06-28T06:00:00.000Z", 120, "REM"),
+      row("2026-06-29T06:00:00.000Z", 360, "ASLEEP"),
+    ]);
+
+    const result = await computeRangeDelta("u", "SLEEP_DURATION", "7d", NOW);
+
+    expect(result.granularity).toBe("live");
+    expect(result.current.count).toBe(2);
+    expect(result.current.mean).toBeCloseTo(390, 6);
+  });
+});

src/lib/analytics/__tests__/resting-pulse.test.ts

@@ -13,6 +13,9 @@ import {
   type PulseSample,
 } from "../resting-pulse";
 import { zonedWallClockToUtc } from "@/lib/tz/wall-clock";
+import { userDayKey } from "@/lib/tz/format";
+
+const DAY_KEY = (d: Date) => userDayKey(d, "Europe/Berlin");
 
 /**
  * The zone `deriveRestingProxyFromPulse` buckets in by default
@@ -69,7 +72,7 @@ describe("deriveRestingProxyFromPulse", () => {
         ),
       );
     }
-    const proxy = deriveRestingProxyFromPulse(samples);
+    const proxy = deriveRestingProxyFromPulse(samples, DAY_KEY);
     expect(proxy).toHaveLength(1);
     // 510 samples, only 10 below ~80 — but the 20th percentile of the
     // whole day still lands in the workout band because 98 % of samples
@@ -94,7 +97,7 @@ describe("deriveRestingProxyFromPulse", () => {
     for (let i = 0; i < 10; i++) {
       samples.push(day(`2026-06-02T18:${String(i).padStart(2, "0")}:00`, 150));
     }
-    const proxy = deriveRestingProxyFromPulse(samples);
+    const proxy = deriveRestingProxyFromPulse(samples, DAY_KEY);
     expect(proxy).toHaveLength(1);
     // 20th percentile sits in the low band, well below the workout reads.
     expect(proxy[0].value).toBeLessThanOrEqual(80);
@@ -112,7 +115,7 @@ describe("deriveRestingProxyFromPulse", () => {
       day("2026-06-01T12:00:00", 64),
       day("2026-06-01T20:00:00", 68),
     ];
-    const proxy = deriveRestingProxyFromPulse(samples);
+    const proxy = deriveRestingProxyFromPulse(samples, DAY_KEY);
     expect(proxy).toHaveLength(2);
     expect(proxy[0].measuredAt.getTime()).toBeLessThan(
       proxy[1].measuredAt.getTime(),
@@ -125,7 +128,9 @@ describe("deriveRestingProxyFromPulse", () => {
     const oneSampleWorkoutDay: PulseSample[] = [
       day("2026-06-05T18:00:00", 165),
     ];
-    expect(deriveRestingProxyFromPulse(oneSampleWorkoutDay)).toEqual([]);
+    expect(deriveRestingProxyFromPulse(oneSampleWorkoutDay, DAY_KEY)).toEqual(
+      [],
+    );
 
     // A day below the min-sample floor is dropped; only the day with enough
     // samples contributes.
@@ -135,13 +140,13 @@ describe("deriveRestingProxyFromPulse", () => {
       day("2026-06-06T08:00:00", 62),
       day("2026-06-06T09:00:00", 64),
     ];
-    const proxy = deriveRestingProxyFromPulse(mixed);
+    const proxy = deriveRestingProxyFromPulse(mixed, DAY_KEY);
     expect(proxy).toHaveLength(1);
     expect(proxy[0].value).toBeLessThan(150);
   });
 
   it("returns empty for no samples", () => {
-    expect(deriveRestingProxyFromPulse([])).toEqual([]);
+    expect(deriveRestingProxyFromPulse([], DAY_KEY)).toEqual([]);
   });
 });
 
@@ -158,6 +163,7 @@ describe("resolveRestingPulseSeries", () => {
       day("2026-06-01T18:00:00", 150),
     );
     const { series, which } = resolveRestingPulseSeries({
+      dayKeyOf: DAY_KEY,
       restingSamples,
       pulseSamples,
     });
@@ -174,6 +180,7 @@ describe("resolveRestingPulseSeries", () => {
       day("2026-06-01T18:00:00", 150),
     ];
     const { series, which } = resolveRestingPulseSeries({
+      dayKeyOf: DAY_KEY,
       restingSamples: [],
       pulseSamples,
     });
@@ -184,7 +191,11 @@ describe("resolveRestingPulseSeries", () => {
 
   it("reports 'none' when neither series has data", () => {
     expect(
-      resolveRestingPulseSeries({ restingSamples: [], pulseSamples: [] }),
+      resolveRestingPulseSeries({
+        dayKeyOf: DAY_KEY,
+        restingSamples: [],
+        pulseSamples: [],
+      }),
     ).toEqual({ series: [], which: "none" });
   });
 
@@ -218,6 +229,7 @@ describe("resolveRestingPulseSeries", () => {
     }
 
     const { series, which } = resolveRestingPulseSeries({
+      dayKeyOf: DAY_KEY,
       restingSamples,
       pulseSamples,
     });
@@ -249,6 +261,7 @@ describe("resolveRestingPulseSeries", () => {
     // A native day must not be second-guessed by the proxy, and a native
     // account with no gap days keeps the honest 'resting' label.
     const { series, which } = resolveRestingPulseSeries({
+      dayKeyOf: DAY_KEY,
       restingSamples: [day("2026-06-01T04:00:00", 58)],
       pulseSamples: [
         day("2026-06-01T07:00:00", 80),
@@ -276,7 +289,7 @@ describe("deriveRestingProxyFromPulse — the day bucket is the PROFILE day", ()
       day("2026-06-02T15:00:00", 68),
       day("2026-06-02T21:00:00", 70),
     ];
-    const proxy = deriveRestingProxyFromPulse(samples);
+    const proxy = deriveRestingProxyFromPulse(samples, DAY_KEY);
     expect(proxy).toHaveLength(1);
   });
 
@@ -293,7 +306,7 @@ describe("deriveRestingProxyFromPulse — the day bucket is the PROFILE day", ()
       day("2026-06-02T00:30:00", 82),
       day("2026-06-02T00:50:00", 84),
     ];
-    const proxy = deriveRestingProxyFromPulse(samples);
+    const proxy = deriveRestingProxyFromPulse(samples, DAY_KEY);
     expect(proxy).toHaveLength(2);
   });
 

src/lib/analytics/__tests__/summaries-slice.test.ts

@@ -412,16 +412,9 @@ describe("computeSummariesSlice", () => {
       // call is the pre-fold all-time remainder splice.
       expect(RAW).toHaveBeenCalledTimes(2);
       expect(UNSAFE).toHaveBeenCalledTimes(3);
-      // v1.4.40 W-WMY-WIRE — the year-ago baseline probe runs
-      // `readBestGranularityRollups(userId, type, 395)` per
-      // type-with-data via `prisma.measurementRollup.findMany`. The
-      // 395-day window skips the YEAR floor (731 d) and walks MONTH
-      // → WEEK → DAY on full coverage miss; the default mock returns
-      // `[]` so all three reachable tiers probe.
-      //
-      // v1.20.0 F6 — plus the 90-day accumulator findMany the warm path
-      // now runs to compose slope / r² / sd: 1 accumulator + 3 WMY = 4.
-      expect(ROLLUP_FIND_MANY).toHaveBeenCalledTimes(4);
+      // The 90-day accumulator findMany plus one year-ago DAY read per
+      // type-with-data.
+      expect(ROLLUP_FIND_MANY).toHaveBeenCalledTimes(2);
     });
 
     // Watched red: with the pre-fold splice removed from the rollup path
@@ -483,28 +476,14 @@ describe("computeSummariesSlice", () => {
   });
 
   /**
-   * v1.4.40 W-WMY-WIRE — pin the wiring of the WMY readers into the
-   * slim slice. The pre-v1.4.40 shape hardcoded `avg30LastYear` to
-   * `null`; we now populate it from `readBestGranularityRollups` when
-   * the YEAR / MONTH / WEEK / DAY tier carries buckets that overlap
-   * the `[now-395d, now-365d)` slice.
+   * `avg30LastYear` is the mean over the exact 30 UTC days that start 395
+   * days ago, read from canonical DAY buckets.
    */
   describe("year-over-year wiring (avg30LastYear)", () => {
-    it("populates avg30LastYear from MONTH buckets that overlap the year-ago slice", async () => {
-      // Coverage probe shows WEIGHT covered → rollup happy path.
+    function warmPathMocks() {
       RAW.mockResolvedValueOnce([{ type: "WEIGHT", has_buckets: true }]);
       UNSAFE.mockResolvedValueOnce([
-        {
-          type: "WEIGHT",
-          avg7: 82,
-          avg30: 82.5,
-          slope7: 0,
-          r2_7: 0,
-          slope30: 0,
-          r2_30: 0,
-          slope90: 0,
-          r2_90: 0,
-        },
+        { type: "WEIGHT", avg7: 82, avg30: 82.5, median: 82 },
       ])
         .mockResolvedValueOnce([
           { type: "WEIGHT", value: 82.7, measured_at: new Date() },
@@ -512,120 +491,59 @@ describe("computeSummariesSlice", () => {
         .mockResolvedValueOnce([
           { type: "WEIGHT", count: 5, min: 82, max: 84, mean: 83 },
         ]);
-
-      // v1.20.0 F6 — the warm path runs the 90-day accumulator findMany
-      // first; return empty (slope composes to null, irrelevant to this
-      // year-over-year assertion) so the year-ago MONTH probe is call #2.
+      // The 90-day accumulator findMany runs first; empty (slope composes
+      // to null, irrelevant here) so the year-ago DAY read is call #1.
       ROLLUP_FIND_MANY.mockResolvedValueOnce([]);
-      // Year-ago slice MONTH bucket — `bucketStart` placed 380 days
-      // ago so it falls inside `[now-395d, now-365d)`. Single bucket
-      // (count=10, mean=85) → weighted mean = 85.
-      const yearAgoBucketStart = new Date(
-        Date.now() - 380 * 24 * 60 * 60 * 1000,
-      );
+    }
+    function dayBucket(daysAgo: number, count: number, mean: number) {
+      return {
+        bucketStart: startOfUtcDay(
+          new Date(Date.now() - daysAgo * 24 * 60 * 60 * 1000),
+        ),
+        source: "MANUAL",
+        count,
+        mean,
+        sd: 0,
+        slope: null,
+        r2: null,
+        sumValue: count * mean,
+        minValue: mean,
+        maxValue: mean,
+        sumX: null,
+        sumXy: null,
+        sumXx: null,
+        sumYy: null,
+        computedAt: new Date(),
+      };
+    }
+
+    it("reads exactly the 30 days that start 395 days ago", async () => {
+      warmPathMocks();
       ROLLUP_FIND_MANY.mockResolvedValueOnce([
-        {
-          bucketStart: yearAgoBucketStart,
-          count: 10,
-          mean: 85,
-          sd: 1,
-          slope: 0,
-          r2: 0,
-          sumValue: null,
-          minValue: 83,
-          maxValue: 87,
-        },
+        dayBucket(390, 10, 85),
+        dayBucket(370, 30, 81),
       ]);
 
       const result = await computeSummariesSlice("user-yoy");
 
-      expect(result.summaries.WEIGHT.avg30LastYear).toBe(85);
-      // Router asked MONTH first (395 > 181, 395 < 731 → skip YEAR). Call #0
-      // is the v1.20.0 F6 accumulator findMany (DAY); the WMY probe is #1.
-      expect(ROLLUP_FIND_MANY.mock.calls[1][0].where.granularity).toBe("MONTH");
+      expect(result.summaries.WEIGHT.avg30LastYear).toBe(82);
+      const where = ROLLUP_FIND_MANY.mock.calls[1][0].where;
+      expect(where.granularity).toBe("DAY");
+      const DAY = 24 * 60 * 60 * 1000;
+      expect(where.bucketStart).toEqual({
+        gte: startOfUtcDay(new Date(Date.now() - 395 * DAY)),
+        lt: startOfUtcDay(new Date(Date.now() - 365 * DAY)),
+      });
     });
 
-    it("leaves avg30LastYear null when no bucket overlaps the year-ago slice", async () => {
-      RAW.mockResolvedValueOnce([{ type: "WEIGHT", has_buckets: true }]);
-      UNSAFE.mockResolvedValueOnce([
-        {
-          type: "WEIGHT",
-          avg7: 82,
-          avg30: 82.5,
-          slope7: 0,
-          r2_7: 0,
-          slope30: 0,
-          r2_30: 0,
-          slope90: 0,
-          r2_90: 0,
-        },
-      ])
-        .mockResolvedValueOnce([
-          { type: "WEIGHT", value: 82.7, measured_at: new Date() },
-        ])
-        .mockResolvedValueOnce([
-          { type: "WEIGHT", count: 5, min: 82, max: 84, mean: 83 },
-        ]);
-
-      // v1.20.0 F6 — accumulator findMany runs first; empty so the WMY
-      // probe is call #2.
-      ROLLUP_FIND_MANY.mockResolvedValueOnce([]);
-      // MONTH bucket placed 30 days ago — inside the YEAR / MONTH /
-      // WEEK 395-day window the router asks for, but outside the
-      // `[now-395d, now-365d)` slice. The helper returns null.
-      const recentBucket = new Date(Date.now() - 30 * 24 * 60 * 60 * 1000);
-      ROLLUP_FIND_MANY.mockResolvedValueOnce([
-        {
-          bucketStart: recentBucket,
-          count: 10,
-          mean: 82,
-          sd: 1,
-          slope: 0,
-          r2: 0,
-          sumValue: null,
-          minValue: 80,
-          maxValue: 84,
-        },
-      ]);
-
-      const result = await computeSummariesSlice("user-recent");
-
-      expect(result.summaries.WEIGHT.avg30LastYear).toBeNull();
-    });
-
-    it("leaves avg30LastYear null when every granularity misses (no coverage)", async () => {
-      RAW.mockResolvedValueOnce([{ type: "WEIGHT", has_buckets: true }]);
-      UNSAFE.mockResolvedValueOnce([
-        {
-          type: "WEIGHT",
-          avg7: 82,
-          avg30: 82.5,
-          slope7: 0,
-          r2_7: 0,
-          slope30: 0,
-          r2_30: 0,
-          slope90: 0,
-          r2_90: 0,
-        },
-      ])
-        .mockResolvedValueOnce([
-          { type: "WEIGHT", value: 82.7, measured_at: new Date() },
-        ])
-        .mockResolvedValueOnce([
-          { type: "WEIGHT", count: 5, min: 82, max: 84, mean: 83 },
-        ]);
-
-      // Default mock returns `[]` for every findMany call → router
-      // walks YEAR → MONTH → WEEK → DAY and gives up.
+    it("leaves avg30LastYear null when no reading falls in the window", async () => {
+      warmPathMocks();
       ROLLUP_FIND_MANY.mockResolvedValue([]);
 
       const result = await computeSummariesSlice("user-empty-yoy");
 
       expect(result.summaries.WEIGHT.avg30LastYear).toBeNull();
-      // 395d window skips YEAR (floor 731 d) → MONTH → WEEK → DAY,
-      // three reachable tiers all probed on full coverage miss; plus the
-      // v1.20.0 F6 accumulator findMany = 4.
-      expect(ROLLUP_FIND_MANY).toHaveBeenCalledTimes(4);
+      expect(ROLLUP_FIND_MANY).toHaveBeenCalledTimes(2);
     });
 
     it("only probes types that actually have data in the current window", async () => {

src/lib/analytics/__tests__/summaries-slice.wmy-cap.test.ts

@@ -11,23 +11,30 @@
  * This test mirrors the v1.4.40 W-POOL pin
  * (`src/app/api/analytics/__tests__/route.test.ts` —
  * "pin concurrency cap and pool ceiling"). It mocks
- * `readBestGranularityRollups` with a controllable promise so we can
+ * `readRollupBuckets` with a controllable promise so we can
  * observe the in-flight count at the helper boundary and assert it
  * never exceeds 4 across a 15-type fan-out.
  */
 import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 
-vi.mock("@/lib/rollups/measurement-read-wmy", () => ({
-  readBestGranularityRollups: vi.fn(),
+vi.mock("@/lib/rollups/measurement-rollups", async (importOriginal) => ({
+  ...(await importOriginal<
+    typeof import("@/lib/rollups/measurement-rollups")
+  >()),
+  readRollupBuckets: vi.fn(),
+}));
+vi.mock("@/lib/rollups/measurement-read", async (importOriginal) => ({
+  ...(await importOriginal<typeof import("@/lib/rollups/measurement-read")>()),
+  loadUserSourcePriority: vi.fn(async () => null),
 }));
 
-import { readBestGranularityRollups } from "@/lib/rollups/measurement-read-wmy";
+import { readRollupBuckets } from "@/lib/rollups/measurement-rollups";
 import {
   WMY_FANOUT_CONCURRENCY,
   computeAvg30LastYearMap,
 } from "../summaries-slice";
 
-const READ = readBestGranularityRollups as unknown as ReturnType<typeof vi.fn>;
+const READ = readRollupBuckets as unknown as ReturnType<typeof vi.fn>;
 
 beforeEach(() => {
   READ.mockReset();
@@ -45,7 +52,7 @@ describe("computeAvg30LastYearMap — WMY fan-out cap (v1.4.43)", () => {
     expect(WMY_FANOUT_CONCURRENCY).toBe(4);
   });
 
-  it("holds at most 4 concurrent readBestGranularityRollups calls for a 15-type list", async () => {
+  it("holds at most 4 concurrent rollup reads for a 15-type list", async () => {
     let inFlight = 0;
     let peak = 0;
     const resolvers: Array<() => void> = [];
@@ -58,7 +65,7 @@ describe("computeAvg30LastYearMap — WMY fan-out cap (v1.4.43)", () => {
           inFlight -= 1;
           // Resolve with `null` — the helper treats no-coverage as
           // `null` in the output map, which is fine for this test.
-          resolve(null);
+          resolve([]);
         });
       });
     });

src/lib/analytics/intraday-pulse-io.ts

@@ -19,7 +19,7 @@ import { prisma } from "@/lib/db";
 import { annotate } from "@/lib/logging/context";
 import { percentile } from "@/lib/insights/strain-score";
 import { resolveRestingPulseSeries } from "@/lib/analytics/resting-pulse";
-import { localDayWindow } from "@/lib/measurements/consolidation-tz";
+import { localDayWindow } from "@/lib/tz/local-day";
 import { userDayKey } from "@/lib/tz/format";
 import {
   BUCKET_MINUTES,

src/lib/analytics/mood-prognosis/load.ts

@@ -22,7 +22,7 @@
  */
 import { prisma } from "@/lib/db";
 import { decodeKeyList } from "@/lib/mood/context-vocabulary";
-import { DEFAULT_TIMEZONE } from "@/lib/mood/date-key";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 import { resolveLinkedDayFigures } from "@/lib/mood/linked-context";
 
 import type { PrognosisDayInput } from "./features";

src/lib/analytics/mood-prognosis/read.ts

@@ -22,7 +22,8 @@ import {
   dayKeyAgeInDays,
   isCurrentForTodayClaim,
 } from "@/lib/insights/measurement-freshness";
-import { DEFAULT_TIMEZONE, moodDateKey } from "@/lib/mood/date-key";
+import { moodDateKey } from "@/lib/mood/date-key";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 
 import type { FeatureContribution } from "./forecast";
 import { countQualifyingDays } from "./load";

src/lib/analytics/range-delta.ts

@@ -25,14 +25,34 @@
  * a window aggregate built from WEEK / MONTH buckets equals the per-row
  * aggregate over the same span. SD / slope / r² are intentionally NOT part of
  * the delta — they do not compose, matching the rest of the WMY reader tier.
+ *
+ * Two kinds of metric are not averaged per reading:
+ *   - step-like totals (steps, energy, distance, flights, …) compare the
+ *     average DAILY total: a day's readings are pieces of one total, and the
+ *     last day and a half still arrives as many small samples before the
+ *     drain folds them, so a per-reading mean collapsed the current window;
+ *   - sleep compares the average NIGHT (time asleep, reconstructed from the
+ *     stage rows): a per-row mean averaged stage segments and in-bed
+ *     envelopes, which is no amount of sleep at all.
+ * For both, `count` is the number of days or nights.
  */
 import type { MeasurementType } from "@/generated/prisma/client";
 
+import { prisma } from "@/lib/db";
+import { CUMULATIVE_HK_TYPES } from "@/lib/measurements/apple-health-mapping";
+import {
+  reconstructSleepNights,
+  type SleepStageRow,
+} from "@/lib/analytics/sleep-night";
+import { readRollupBuckets } from "@/lib/rollups/measurement-rollups";
+import { loadUserSourcePriority } from "@/lib/rollups/measurement-read";
 import {
   aggregateWmyBuckets,
   readBestGranularityRollups,
   type RollupBucketRow,
 } from "@/lib/rollups/measurement-read-wmy";
+import { startOfUtcDay } from "@/lib/tz/start-of-utc-day";
+import { resolveUserTimezone } from "@/lib/tz/resolver";
 import {
   ANALYTICS_RANGES,
   rangeWindowDays,
@@ -86,6 +106,99 @@ export function sliceWindowDelta(
   };
 }
 
+/**
+ * Aggregate one value per day or night (a daily total, a night's time
+ * asleep): `count` is the number of days or nights, `mean` their average.
+ */
+export function aggregatePerPeriod(values: readonly number[]): WindowAggregate {
+  if (values.length === 0) {
+    return { count: 0, min: null, max: null, mean: null, sum: null };
+  }
+  let sum = 0;
+  let min = Infinity;
+  let max = -Infinity;
+  for (const v of values) {
+    sum += v;
+    if (v < min) min = v;
+    if (v > max) max = v;
+  }
+  return { count: values.length, min, max, mean: sum / values.length, sum };
+}
+
+/** Split `(at, value)` points into the current and previous halves. */
+function splitPerPeriod(
+  points: ReadonlyArray<{ at: Date; value: number }>,
+  windowDays: number,
+  now: number,
+): { current: WindowAggregate; previous: WindowAggregate } {
+  const currentStart = now - windowDays * DAY_MS;
+  const previousStart = now - 2 * windowDays * DAY_MS;
+  const current: number[] = [];
+  const previous: number[] = [];
+  for (const p of points) {
+    const t = p.at.getTime();
+    if (t >= currentStart && t < now) current.push(p.value);
+    else if (t >= previousStart && t < currentStart) previous.push(p.value);
+  }
+  return {
+    current: aggregatePerPeriod(current),
+    previous: aggregatePerPeriod(previous),
+  };
+}
+
+/** The canonical daily totals of a step-like metric, one point per day. */
+async function readDailyTotals(
+  userId: string,
+  type: MeasurementType,
+  windowDays: number,
+  now: number,
+): Promise<Array<{ at: Date; value: number }>> {
+  const rows = await readRollupBuckets(
+    userId,
+    type,
+    "DAY",
+    startOfUtcDay(new Date(now - 2 * windowDays * DAY_MS)),
+    new Date(now),
+  );
+  return rows.map((r) => ({ at: r.bucketStart, value: r.mean * r.count }));
+}
+
+/** Time asleep per reconstructed night, one point per night. */
+async function readNightlySleep(
+  userId: string,
+  windowDays: number,
+  now: number,
+): Promise<Array<{ at: Date; value: number }>> {
+  // A night's rows start the evening before its wake day: read one day more.
+  const rows = (await prisma.measurement.findMany({
+    where: {
+      userId,
+      type: "SLEEP_DURATION",
+      deletedAt: null,
+      measuredAt: {
+        gte: new Date(now - (2 * windowDays + 1) * DAY_MS),
+        lt: new Date(now),
+      },
+    },
+    orderBy: { measuredAt: "asc" },
+    select: {
+      value: true,
+      measuredAt: true,
+      sleepStage: true,
+      source: true,
+      deviceType: true,
+    },
+  })) as SleepStageRow[];
+  if (rows.length === 0) return [];
+  const [tz, priorityJson] = await Promise.all([
+    resolveUserTimezone(userId),
+    loadUserSourcePriority(userId),
+  ]);
+  return reconstructSleepNights(rows, tz, priorityJson)
+    .filter((n) => n.asleepMinutes > 0)
+    .map((n) => ({ at: n.measuredAt, value: n.asleepMinutes }));
+}
+
 /**
  * Compose the period-over-period delta from the two window aggregates.
  * Pure — pinned by unit test. Guards both the missing-data case (either
@@ -119,6 +232,30 @@ export async function computeRangeDelta(
   now: number = Date.now(),
 ): Promise<RangeDeltaResult> {
   const windowDays = rangeWindowDays(range);
+
+  if (type === "SLEEP_DURATION" || CUMULATIVE_HK_TYPES.has(type)) {
+    const points =
+      type === "SLEEP_DURATION"
+        ? await readNightlySleep(userId, windowDays, now)
+        : await readDailyTotals(userId, type, windowDays, now);
+    const { current, previous } = splitPerPeriod(points, windowDays, now);
+    const { delta, deltaPct } = composeDelta(current, previous);
+    return {
+      range,
+      windowDays,
+      granularity:
+        points.length === 0
+          ? "none"
+          : type === "SLEEP_DURATION"
+            ? "live"
+            : "DAY",
+      current,
+      previous,
+      delta,
+      deltaPct,
+    };
+  }
+
   // Read the full 2N span in one go so the current and previous halves share
   // a granularity; the router picks the coarsest tier that resolves 2N.
   const resolved = await readBestGranularityRollups(

src/lib/analytics/resting-pulse.ts

@@ -39,7 +39,6 @@
  * Pure & deterministic — unit-tested in `__tests__/resting-pulse.test.ts`.
  */
 import { percentile } from "@/lib/insights/strain-score";
-import { toBerlinDayKey } from "@/lib/tz/resolver";
 
 /** A timestamped heart-rate sample. */
 export interface PulseSample {
@@ -78,12 +77,11 @@ export const RESTING_PROXY_MIN_DAILY_SAMPLES = 3;
 export function deriveRestingProxyFromPulse(
   pulseSamples: ReadonlyArray<PulseSample>,
   /**
-   * Day-key function used to bucket samples. Defaults to Berlin-day so
-   * direct callers / tests stay zero-config; the targets route passes
-   * its own `userDayKey(d, userTz)` so the proxy buckets align with the
-   * route's consistency-strip day buckets for non-Berlin users.
+   * Day-key function used to bucket samples: the user's own day
+   * (`userDayKey(d, userTz)`), so the proxy buckets line up with every other
+   * day bucket the user sees.
    */
-  dayKeyOf: (d: Date) => string = toBerlinDayKey,
+  dayKeyOf: (d: Date) => string,
 ): PulseSample[] {
   if (pulseSamples.length === 0) return [];
   const byDay = new Map<string, { firstAt: Date; values: number[] }>();
@@ -139,10 +137,10 @@ export function deriveRestingProxyFromPulse(
 export function resolveRestingPulseSeries(input: {
   restingSamples: ReadonlyArray<PulseSample>;
   pulseSamples: ReadonlyArray<PulseSample>;
-  /** Optional day-key for the proxy buckets (defaults to Berlin-day). */
-  dayKeyOf?: (d: Date) => string;
+  /** Day key for the proxy buckets: the user's own day. */
+  dayKeyOf: (d: Date) => string;
 }): { series: PulseSample[]; which: "resting" | "proxy" | "none" } {
-  const dayKeyOf = input.dayKeyOf ?? toBerlinDayKey;
+  const dayKeyOf = input.dayKeyOf;
   const byTime = (a: PulseSample, b: PulseSample) =>
     a.measuredAt.getTime() - b.measuredAt.getTime();
 

src/lib/analytics/score/__tests__/pillars.test.ts

@@ -25,6 +25,16 @@ function days(count: number, value: number) {
   }));
 }
 
+/** `count` completed days ending yesterday (activity leaves today out). */
+function completedDays(count: number, value: number) {
+  return Array.from({ length: count }, (_, index) => ({
+    day: new Date(NOW.getTime() - (index + 1) * 86_400_000)
+      .toISOString()
+      .slice(0, 10),
+    value,
+  }));
+}
+
 describe("reference-score pillars", () => {
   it("requires twelve fresh paired blood-pressure readings", () => {
     const below = computeBloodPressurePillar({
@@ -174,7 +184,7 @@ describe("reference-score pillars", () => {
         ...live,
         asOf: NOW,
         ageYears: 40,
-        days: days(20, 10_000),
+        days: completedDays(20, 10_000),
         sources: ["APPLE_HEALTH"],
       }).status,
     ).toBe("insufficient");
@@ -183,14 +193,14 @@ describe("reference-score pillars", () => {
       ...live,
       asOf: NOW,
       ageYears: 40,
-      days: days(21, 12_000),
+      days: completedDays(21, 12_000),
       sources: ["APPLE_HEALTH"],
     });
     const older = computeActivityPillar({
       ...live,
       asOf: NOW,
       ageYears: 68,
-      days: days(21, 8_000),
+      days: completedDays(21, 8_000),
       sources: ["APPLE_HEALTH"],
     });
     expect(younger.status).toBe("ok");
@@ -209,7 +219,7 @@ describe("reference-score pillars", () => {
       asOf: NOW,
       timezone: "Europe/Berlin",
       ageYears: 40,
-      days: days(21, 8_500),
+      days: completedDays(21, 8_500),
       sources: ["APPLE_HEALTH"],
     };
     const liveResult = computeActivityPillar({ ...input, source: "live" });
@@ -224,7 +234,7 @@ describe("reference-score pillars", () => {
   });
 
   it("scores exactly 28 activity calendar keys", () => {
-    const points = days(29, 10_000);
+    const points = completedDays(29, 10_000);
     points[28] = { ...points[28], value: 0 };
     const result = computeActivityPillar({
       ...live,
@@ -237,6 +247,64 @@ describe("reference-score pillars", () => {
     if (result.status === "ok") expect(result.value.score).toBe(100);
   });
 
+  it("leaves today's partial step total out of the window", () => {
+    const withToday = [
+      { day: "2026-07-28", value: 400 },
+      ...completedDays(21, 10_000),
+    ];
+    const result = computeActivityPillar({
+      ...live,
+      asOf: NOW,
+      ageYears: 40,
+      days: withToday,
+      sources: ["APPLE_HEALTH"],
+    });
+    expect(result.status).toBe("ok");
+    if (result.status === "ok") expect(result.value.score).toBe(100);
+
+    // Twenty completed days plus today are not enough days.
+    expect(
+      computeActivityPillar({
+        ...live,
+        asOf: NOW,
+        ageYears: 40,
+        days: [{ day: "2026-07-28", value: 400 }, ...completedDays(20, 10_000)],
+        sources: ["APPLE_HEALTH"],
+      }).status,
+    ).toBe("insufficient");
+  });
+
+  it.each([
+    ["America/New_York", "2026-03-09T03:30:00.000Z", "2026-03-08"],
+    ["Pacific/Auckland", "2026-04-05T11:00:00.000Z", "2026-04-05"],
+    ["Pacific/Tongatapu", "2026-07-28T11:30:00.000Z", "2026-07-29"],
+    ["America/Santiago", "2026-09-06T04:30:00.000Z", "2026-09-06"],
+    ["Europe/Berlin", "2026-10-25T23:30:00.000Z", "2026-10-26"],
+  ])("cuts the window on local days in %s", (timezone, iso, today) => {
+    const asOf = new Date(iso);
+    const [y, m, d] = today.split("-").map(Number);
+    const key = (back: number) =>
+      new Date(Date.UTC(y, m - 1, d - back)).toISOString().slice(0, 10);
+    const window = Array.from({ length: 28 }, (_, i) => ({
+      day: key(i + 1),
+      value: 10_000,
+    }));
+    const result = computeActivityPillar({
+      source: "live",
+      readFailed: false,
+      timezone,
+      asOf,
+      ageYears: 40,
+      days: [{ day: today, value: 0 }, { day: key(29), value: 0 }, ...window],
+      sources: ["APPLE_HEALTH"],
+    });
+    expect(result.status).toBe("ok");
+    if (result.status === "ok") {
+      expect(result.value.score).toBe(100);
+      expect(result.coverage.historyDays).toBe(28);
+    }
+  });
+
   it("requires fourteen sleep nights, never penalises long sleep, and adds regularity at 21 nights", () => {
     const below = computeSleepPillar({
       ...live,

src/lib/analytics/score/activity.ts

@@ -1,5 +1,5 @@
 import type { Derived } from "@/lib/insights/derived/types";
-import { userDayKey } from "@/lib/tz/format";
+import { shiftDateKey, userDayKey } from "@/lib/tz/format";
 
 import type { ActivityPillarInput, PillarValue } from "./types";
 import {
@@ -18,6 +18,23 @@ export const OLDER_ADULT_AGE = 60;
 export const YOUNGER_STEP_PLATEAU = 10_000;
 export const OLDER_STEP_PLATEAU = 8_000;
 
+/**
+ * The activity window: the `ACTIVITY_WINDOW_DAYS` completed local days that
+ * end yesterday, as inclusive `YYYY-MM-DD` keys. Today is left out because
+ * its step total is still growing: counting it pulled every score computed
+ * during the day down by a partial day.
+ */
+export function activityWindowKeys(
+  asOf: Date,
+  timezone: string,
+): { startDay: string; endDay: string } {
+  const today = userDayKey(asOf, timezone);
+  return {
+    startDay: shiftDateKey(today, -ACTIVITY_WINDOW_DAYS),
+    endDay: shiftDateKey(today, -1),
+  };
+}
+
 export function computeActivityPillar(
   input: ActivityPillarInput,
 ): Derived<PillarValue> {
@@ -29,13 +46,9 @@ export function computeActivityPillar(
     });
   }
 
-  const asOfDay = userDayKey(input.asOf, input.timezone);
-  const sinceDay = userDayKey(
-    new Date(input.asOf.getTime() - (ACTIVITY_WINDOW_DAYS - 1) * 86_400_000),
-    input.timezone,
-  );
+  const { startDay, endDay } = activityWindowKeys(input.asOf, input.timezone);
   const points = input.days.filter(
-    (point) => point.day <= asOfDay && point.day >= sinceDay,
+    (point) => point.day <= endDay && point.day >= startDay,
   );
   if (points.length < ACTIVITY_MIN_DAYS) {
     return insufficientPillar({

src/lib/analytics/score/reader.ts

@@ -23,7 +23,7 @@ import { getAgeFromDateOfBirth } from "@/lib/analytics/pulse-targets";
 import { healthScoreNoticeItemKey } from "@/lib/daily/priority-item-key";
 import { annotate, getEvent } from "@/lib/logging/context";
 
-import { ACTIVITY_WINDOW_DAYS } from "./activity";
+import { ACTIVITY_WINDOW_DAYS, activityWindowKeys } from "./activity";
 import { SLEEP_WINDOW_DAYS } from "./sleep";
 import { attachScoreDelta } from "./composite";
 import {
@@ -239,9 +239,8 @@ export async function readActivityDays(args: {
       canonical
         .filter((row) => {
           const day = userDayKey(row.measuredAt, args.timezone);
-          const endDay = userDayKey(args.asOf, args.timezone);
-          const startDay = userDayKey(
-            new Date(args.asOf.getTime() - (ACTIVITY_WINDOW_DAYS - 1) * DAY_MS),
+          const { startDay, endDay } = activityWindowKeys(
+            args.asOf,
             args.timezone,
           );
           return day >= startDay && day <= endDay;
@@ -461,10 +460,7 @@ function scoreInputsFor(args: {
   const { asOf, input } = args;
   const ageYears = getAgeFromDateOfBirth(input.profile.dateOfBirth);
   const asOfDay = userDayKey(asOf, input.profile.timezone);
-  const activitySinceDay = userDayKey(
-    new Date(asOf.getTime() - (ACTIVITY_WINDOW_DAYS - 1) * DAY_MS),
-    input.profile.timezone,
-  );
+  const activityWindow = activityWindowKeys(asOf, input.profile.timezone);
   const sleepSinceDay = userDayKey(
     new Date(asOf.getTime() - (SLEEP_WINDOW_DAYS - 1) * DAY_MS),
     input.profile.timezone,
@@ -548,7 +544,11 @@ function scoreInputsFor(args: {
       days: args.activity.value.days,
       sources: uniqueSources(
         args.activity.value.sourceDays
-          .filter((row) => row.day >= activitySinceDay && row.day <= asOfDay)
+          .filter(
+            (row) =>
+              row.day >= activityWindow.startDay &&
+              row.day <= activityWindow.endDay,
+          )
           .map((row) => row.source),
       ),
     },
@@ -629,7 +629,7 @@ export async function computeUserHealthScore(
   const db = input.prisma ?? prisma;
   const since = new Date(input.now.getTime() - SCORE_READ_DAYS * DAY_MS);
   const activitySince = new Date(
-    input.now.getTime() - (28 + HISTORY_OFFSET_DAYS) * DAY_MS,
+    input.now.getTime() - (ACTIVITY_WINDOW_DAYS + HISTORY_OFFSET_DAYS) * DAY_MS,
   );
   const [
     glucose,

src/lib/analytics/source-rank-sql.ts

@@ -147,7 +147,7 @@ export function canonicalMeasurementsCte(
           WHERE "user_id" = $1
             AND "deleted_at" IS NULL
             ${sinceInner}
-          ORDER BY "type", date_trunc('day', "measured_at"), (${rankUnqualified}), "source"
+          ORDER BY "type", date_trunc('day', "measured_at"), (${rankUnqualified}), "source"::text
         ) c
           ON c.t = mm."type"
           AND c.d = date_trunc('day', mm."measured_at")

src/lib/analytics/summaries-slice.ts

@@ -57,6 +57,7 @@
 import pLimit from "p-limit";
 
 import type { MeasurementType } from "@/generated/prisma/client";
+import { Prisma } from "@/generated/prisma/client";
 
 import { prisma } from "@/lib/db";
 import type { DataSummary } from "@/lib/analytics/trends";
@@ -64,9 +65,11 @@ import { measurementTypeEnum } from "@/lib/validations/measurement";
 import { annotate } from "@/lib/logging/context";
 import {
   ensureUserRollupsFresh,
+  readRollupBuckets,
   ROLLUP_FOLD_WINDOW_MS,
 } from "@/lib/rollups/measurement-rollups";
 import {
+  aggregateBuckets,
   collapseRollupRowsBySource,
   composeWindowedRegression,
   hasPendingAccumulatorBackfill,
@@ -83,7 +86,6 @@ import {
   probeRollupCoverage,
   type RollupCoverageMap,
 } from "@/lib/rollups/measurement-coverage";
-import { readBestGranularityRollups } from "@/lib/rollups/measurement-read-wmy";
 import {
   summarizeSleepNights,
   type SleepSourceDiscrepancy,
@@ -423,6 +425,11 @@ async function computeFromRollups(userId: string): Promise<SummariesSlice> {
     '"source"',
   );
   const rankM = buildSourceRankCase(priorityJson, 'm."type"', 'm."source"');
+  const rankPerSource = buildSourceRankCase(
+    priorityJson,
+    'p."type"',
+    'p."source"',
+  );
 
   // v1.37.19 (A6-10) — where the fold window starts. DAY rollup buckets
   // only exist inside the trailing `ROLLUP_FOLD_WINDOW_MS` (5 y), so the
@@ -514,7 +521,7 @@ async function computeFromRollups(userId: string): Promise<SummariesSlice> {
         WHERE "user_id" = $1
           AND "granularity" = 'DAY'
           AND "bucket_start" >= $2
-        ORDER BY "type", "bucket_start", (${rankUnqualified}), "source"
+        ORDER BY "type", "bucket_start", (${rankUnqualified}), "source"::text
       )
       SELECT
         "type"::text                                       AS type,
@@ -559,16 +566,15 @@ async function computeFromRollups(userId: string): Promise<SummariesSlice> {
           sumYy: true,
         },
       }),
-      // v1.37.19 (A6-10) — all-time remainder OLDER than the fold window.
-      // One grouped aggregate over the pre-fold rows (index range scan on
-      // `(user_id, measured_at)`; empty for any account younger than the
-      // window). Spliced into the per-type figures below so "all-time"
-      // means all time on the rollup path too. Deliberately without the
-      // source-priority collapse: pre-fold history predates the rollup
-      // tier's per-day canonicalisation, and a per-day DISTINCT ON over a
-      // multi-year span is the cost this splice exists to avoid — for
-      // count/min/max/mean over years-old data the raw figures are the
-      // honest ones.
+      // v1.37.19 (A6-10) — all-time remainder OLDER than the fold window,
+      // spliced into the per-type figures below so "all-time" means all time
+      // on the rollup path too (empty for any account younger than the
+      // window). It keeps one source per (type, day) the way the rollup half
+      // and the live path do: without it, a vital recorded by two devices
+      // counted both of them on every pre-fold day. Each source is folded per
+      // day first (a hash aggregate, a few rows per day however dense the
+      // stream), each day then keeps its ladder-canonical source, so the
+      // sort never sees more than one row per source per day.
       prisma.$queryRaw<
         Array<{
           type: string;
@@ -578,17 +584,35 @@ async function computeFromRollups(userId: string): Promise<SummariesSlice> {
           mean: number;
         }>
       >`
+      WITH per_source AS (
+        SELECT
+          m."type",
+          m."source",
+          date_trunc('day', m."measured_at") AS day,
+          COUNT(*)::int                      AS cnt,
+          SUM(m."value")::double precision   AS total,
+          MIN(m."value")::double precision   AS min_value,
+          MAX(m."value")::double precision   AS max_value
+        FROM measurements m
+        WHERE m."user_id" = ${userId}
+          AND m."deleted_at" IS NULL
+          AND m."measured_at" < ${foldSplit}
+        GROUP BY m."type", m."source", 3
+      ),
+      canon AS (
+        SELECT DISTINCT ON (p."type", p.day)
+          p."type", p.cnt, p.total, p.min_value, p.max_value
+        FROM per_source p
+        ORDER BY p."type", p.day, (${Prisma.raw(rankPerSource)}), p."source"::text
+      )
       SELECT
-        m."type"::text                     AS type,
-        COUNT(*)::int                      AS count,
-        MIN(m."value")::double precision   AS min,
-        MAX(m."value")::double precision   AS max,
-        AVG(m."value")::double precision   AS mean
-      FROM measurements m
-      WHERE m."user_id" = ${userId}
-        AND m."deleted_at" IS NULL
-        AND m."measured_at" < ${foldSplit}
-      GROUP BY m."type"
+        c."type"::text                                  AS type,
+        SUM(c.cnt)::int                                 AS count,
+        MIN(c.min_value)::double precision              AS min,
+        MAX(c.max_value)::double precision              AS max,
+        (SUM(c.total) / SUM(c.cnt))::double precision   AS mean
+      FROM canon c
+      GROUP BY c."type"
     `,
     ]);
 
@@ -773,11 +797,10 @@ async function computeFromRollups(userId: string): Promise<SummariesSlice> {
     };
   }
 
-  // v1.4.40 W-WMY-WIRE — populate `avg30LastYear` per type from the
-  // WMY rollup tier. Only types with data in the current window are
-  // probed so we don't pay the per-type round-trip on the long tail
-  // of unlogged measurement enums. Types without YEAR/MONTH coverage
-  // surface as `null` (existing behaviour) — additive only.
+  // Populate `avg30LastYear` per type from the DAY rollup tier. Only types
+  // with data in the current window are probed so we don't pay the per-type
+  // round-trip on the long tail of unlogged measurement enums. Types with no
+  // reading in the year-ago window surface as `null`.
   const avg30LastYearMap = await computeAvg30LastYearMap(userId, typesWithData);
   let yearOverYearTypeCount = 0;
   for (const [type, value] of avg30LastYearMap.entries()) {
@@ -1016,13 +1039,10 @@ async function computeFromLiveAggregate(
     };
   }
 
-  // v1.4.40 W-WMY-WIRE — even on the live-aggregate fallback (DAY
-  // coverage incomplete), the YEAR / MONTH rollup tier may still
-  // carry the year-ago baseline because the boot-time backfill mints
-  // all granularities once per user. Probing here means a partial-
-  // coverage cold mount still surfaces `avg30LastYear` whenever the
-  // long-tail tier is populated, instead of waiting for the next
-  // refresh cycle.
+  // Even on the live-aggregate fallback (trailing DAY coverage incomplete),
+  // the year-ago DAY buckets may already exist because the boot-time
+  // backfill folds the whole history once per user, so a partial-coverage
+  // cold mount still surfaces `avg30LastYear`.
   const avg30LastYearMap = await computeAvg30LastYearMap(userId, typesWithData);
   let yearOverYearTypeCount = 0;
   for (const [type, value] of avg30LastYearMap.entries()) {
@@ -1051,118 +1071,51 @@ async function computeFromLiveAggregate(
 }
 
 /**
- * v1.4.39 W-WMY — long-window summary for a single `(userId, type)`
- * pair, served from the WEEK / MONTH / YEAR rollup tier when the
- * window justifies it.
+ * Year-ago 30-day baseline per type, served from the DAY rollup tier.
  *
- * Why this helper exists
- * ----------------------
- * The slim `computeSummariesSlice` caps its windowed columns at 90 d
- * (`slope7 / slope30`). The v1.5 multi-year trend feature
- * + the Coach drawer's "history" tile need linearly composable stats
- * (count / min / max / mean / sum) over much larger windows — 1 y,
- * 2 y, 3 y. Hitting the live `measurements` table for a 3-year span
- * walks every row the user has ever logged for that type, which on
- * the maintainer's tenant is tens of thousands of rows per type.
+ * `DataSummary.avg30LastYear` is the mean over the 30 days that start 395
+ * days ago, which the dashboard tile uses for "current average vs the same
+ * time last year". The window is exactly those 30 UTC days (the DAY-tier
+ * grain), read as canonical-source DAY buckets and composed count-weighted,
+ * so it is the same per-reading mean `avg30` reports for the last 30 days.
  *
- * The WMY rollup tier already carries the per-bucket stats we need:
- * the writer mints WEEK / MONTH / YEAR buckets via pg-boss on every
- * measurement write and the boot backfill fills the long tail. This
- * helper routes the requested window into the largest granularity
- * that still resolves it (via `readBestGranularityRollups`) and
- * composes the trailing-window aggregate in JS — typically 3-15
- * bucket rows on a multi-year window, vs the thousands of raw rows
- * the live aggregator would scan.
+ * Up to v1.39.2 this read the MONTH tier and kept the months whose first day
+ * fell inside the window, so the baseline was a whole calendar month that
+ * could start up to a month off, or nothing at all when no month began inside
+ * the window.
  *
- * Compositional caveats
- * ---------------------
- * `count / min / max / mean / sum` are mathematically exact across
- * any granularity (linearly composable). `sd / slope / r2` are NOT
- * exact across coarser buckets — this helper deliberately omits them
- * so callers cannot accidentally consume stale slope data. The v1.5
- * multi-year trend card derives its slope from the per-bucket `mean`
- * series instead.
- *
- * Coverage-miss policy
- * --------------------
- * `readBestGranularityRollups` falls back from YEAR → MONTH → WEEK
- * → DAY on per-tier coverage miss. Returns `null` only when the
- * user has zero buckets in the entire window — the caller treats
- * that as "no data" rather than "stale rollup". The route is
- * intentionally NOT wired to live SQL fallback here; the all-time
- * aggregate path inside `computeSummariesSlice` already covers the
- * "rollup tier empty" cold-mount case, and v1.5's multi-year card
- * accepts a `null` "no data yet" state.
- */
-
-/**
- * v1.4.40 W-WMY-WIRE — year-ago 30-day baseline per type, served from
- * the WEEK / MONTH / YEAR rollup tier.
- *
- * Why this helper exists
- * ----------------------
- * `DataSummary.avg30LastYear` is the mean over `[now-395d, now-365d)` —
- * the 30-day window starting 365 days ago. The dashboard tile-strip's
- * delta callout uses it to narrate "current avg vs same time last
- * year". Up to v1.4.39 the slim slice (and the comprehensive
- * aggregator's rollup branch) hardcoded the field to `null` because
- * the 90-day windowed `$queryRaw` cannot reach back a year, and the
- * live `measurements` table walk for a 395-day per-type window is
- * exactly the cold-path cost we're trying to avoid.
- *
- * The WMY rollup tier already carries the per-bucket stats this
- * window needs. `readBestGranularityRollups(userId, type, 395)`
- * routes the 395-day window through YEAR (if covered) → MONTH → WEEK
- * → DAY and returns the buckets whose `bucketStart` falls inside the
- * window. We then keep only the buckets that overlap the
- * `[now-395d, now-365d)` slice and compose `count / mean` linearly to
- * produce the year-ago baseline.
- *
- * Compositional contract
- * ----------------------
- * `count / mean` are linearly composable across any granularity, so
- * the year-ago mean derived from MONTH or YEAR buckets is
- * mathematically equivalent to the per-row average over the same
- * window. The bucket-overlap filter is conservative: we include only
- * buckets whose `bucketStart` is strictly inside the slice. On a
- * YEAR-granularity routing this collapses to at most one bucket and
- * approximates the 30-day mean by the surrounding yearly average —
- * acceptable for a UI hint that explicitly narrates "last year".
- *
- * Coverage-miss policy
- * --------------------
- * Returns `null` when `readBestGranularityRollups` returns null (no
- * coverage at any granularity) OR when no buckets overlap the
- * year-ago slice. The caller leaves the dashboard field as `null`,
- * which the UI already handles as "no comparison available".
+ * Returns `null` when no reading falls in the window; the UI treats that as
+ * "no comparison available".
  */
 async function computeAvg30LastYearForType(
   userId: string,
   type: MeasurementType,
+  priorityJson: unknown,
+  now: number,
 ): Promise<number | null> {
-  const resolved = await readBestGranularityRollups(userId, type, 395);
-  if (!resolved) return null;
-  const now = Date.now();
-  const sliceStart = now - 395 * DAY_MS;
-  const sliceEnd = now - 365 * DAY_MS;
-  const overlapping = resolved.rows.filter((row) => {
-    const t = row.bucketStart.getTime();
-    return t >= sliceStart && t < sliceEnd;
-  });
-  if (overlapping.length === 0) return null;
-  let totalCount = 0;
-  let weighted = 0;
-  for (const row of overlapping) {
-    totalCount += row.count;
-    weighted += row.count * row.mean;
-  }
-  if (totalCount === 0) return null;
-  return weighted / totalCount;
+  const rows = await readRollupBuckets(
+    userId,
+    type,
+    "DAY",
+    startOfUtcDay(new Date(now - 395 * DAY_MS)),
+    startOfUtcDay(new Date(now - 365 * DAY_MS)),
+    priorityJson,
+  );
+  const composed = aggregateBuckets(
+    rows.map((r) => ({
+      day: r.bucketStart,
+      count: r.count,
+      mean: r.mean,
+      minValue: r.minValue,
+      maxValue: r.maxValue,
+    })),
+  );
+  return composed.count > 0 ? composed.mean : null;
 }
 
 /**
  * v1.4.40 W-WMY-WIRE — fan out `computeAvg30LastYearForType` across
- * the types the caller actually surfaces. Runs the per-type WMY reads
+ * the types the caller actually surfaces. Runs the per-type rollup reads
  * in parallel so the long-tail of types doesn't serialise into a
  * per-type round-trip stack.
  *
@@ -1191,12 +1144,16 @@ export async function computeAvg30LastYearMap(
   const out = new Map<string, number | null>();
   if (types.length === 0) return out;
   const limit = pLimit(WMY_FANOUT_CONCURRENCY);
+  const priorityJson = await loadUserSourcePriority(userId);
+  const now = Date.now();
   const results = await Promise.all(
     types.map((type) =>
       limit(async () => {
         const value = await computeAvg30LastYearForType(
           userId,
           type as MeasurementType,
+          priorityJson,
+          now,
         );
         return [type, value] as const;
       }),

src/lib/charts/__tests__/heatmap-days.test.ts

@@ -0,0 +1,35 @@
+import { describe, expect, it } from "vitest";
+
+import { heatmapDays } from "../heatmap-days";
+
+describe("heatmapDays", () => {
+  it.each([
+    // 20:30 in New York is already the next UTC day.
+    ["America/New_York", "2026-03-09T00:30:00.000Z", "2026-03-08"],
+    // 08:00 in Auckland and Tonga is still the previous UTC day.
+    ["Pacific/Auckland", "2026-04-04T20:00:00.000Z", "2026-04-05"],
+    ["Pacific/Tongatapu", "2026-07-27T19:00:00.000Z", "2026-07-28"],
+    ["America/Santiago", "2026-09-06T03:30:00.000Z", "2026-09-05"],
+    ["Europe/Berlin", "2026-10-25T22:30:00.000Z", "2026-10-25"],
+  ])("ends on today's key in %s", (tz, iso, today) => {
+    const days = heatmapDays(new Date(iso), tz, 14);
+    expect(days).toHaveLength(14);
+    expect(days.at(-1)?.dateKey).toBe(today);
+    // Consecutive keys, one per day, no gap or repeat across DST.
+    for (let i = 1; i < days.length; i++) {
+      const prev = Date.parse(`${days[i - 1].dateKey}T00:00:00Z`);
+      const cur = Date.parse(`${days[i].dateKey}T00:00:00Z`);
+      expect(cur - prev).toBe(86_400_000);
+    }
+  });
+
+  it("reads weekday and month off the key", () => {
+    const [last] = heatmapDays(
+      new Date("2026-03-01T03:00:00.000Z"),
+      "America/New_York",
+      1,
+    );
+    // 22:00 on Saturday 28 February in New York.
+    expect(last).toEqual({ dateKey: "2026-02-28", dow: 5, month: 1 });
+  });
+});

src/lib/charts/heatmap-days.ts

@@ -0,0 +1,36 @@
+import { shiftDateKey, userDayKey } from "@/lib/tz/format";
+
+/** One calendar-heatmap column entry: a local day and where it sits. */
+export interface HeatmapDay {
+  /** `YYYY-MM-DD` in the user's zone. */
+  dateKey: string;
+  /** Weekday with Monday = 0 … Sunday = 6. */
+  dow: number;
+  /** Month index 0–11. */
+  month: number;
+}
+
+/**
+ * The last `days` local days in `timeZone`, oldest first, ending with today.
+ *
+ * Built from today's key in the user's zone and stepped on keys. The heatmaps
+ * used to take `now − n·24 h` and cut the key in UTC, so in the evening west
+ * of UTC (or the morning east of it) "today" was a different day from the one
+ * the server had keyed the user's readings on, and the newest cell showed the
+ * wrong day. Weekday and month come from the key itself.
+ */
+export function heatmapDays(
+  now: Date,
+  timeZone: string,
+  days: number,
+): HeatmapDay[] {
+  const today = userDayKey(now, timeZone);
+  const out: HeatmapDay[] = [];
+  for (let back = days - 1; back >= 0; back--) {
+    const dateKey = shiftDateKey(today, -back);
+    const [y, m, d] = dateKey.split("-").map(Number);
+    const utc = new Date(Date.UTC(y, m - 1, d));
+    out.push({ dateKey, dow: (utc.getUTCDay() + 6) % 7, month: m - 1 });
+  }
+  return out;
+}

src/lib/cycle/__tests__/phase-crosstab.test.ts

@@ -119,7 +119,11 @@ describe("computePhaseMetricCrosstab — MOOD + GLUCOSE outcomes (QA HIGH)", ()
 
   it("surfaces a luteal-vs-follicular GLUCOSE contrast", () => {
     const { phaseByDay, measurements } = contrastFor("BLOOD_GLUCOSE", 105, 92);
-    const rows = computePhaseMetricCrosstab({ phaseByDay, measurements });
+    const rows = computePhaseMetricCrosstab({
+      timeZone: "Europe/Berlin",
+      phaseByDay,
+      measurements,
+    });
     const glucose = rows.find((r) => r.metricKey === "bloodGlucose");
     expect(glucose).toBeDefined();
     expect(glucose!.display).toBe("glucose");
@@ -133,7 +137,11 @@ describe("computePhaseMetricCrosstab — MOOD + GLUCOSE outcomes (QA HIGH)", ()
       4.4,
       2.6,
     );
-    const rows = computePhaseMetricCrosstab({ phaseByDay, measurements });
+    const rows = computePhaseMetricCrosstab({
+      timeZone: "Europe/Berlin",
+      phaseByDay,
+      measurements,
+    });
     const mood = rows.find((r) => r.metricKey === "mood");
     expect(mood).toBeDefined();
     expect(mood!.display).toBe("mood");
@@ -164,7 +172,11 @@ describe("computePhaseMetricCrosstab", () => {
       lutealRhr: 63,
       follicularRhr: 57,
     });
-    const rows = computePhaseMetricCrosstab({ phaseByDay, measurements });
+    const rows = computePhaseMetricCrosstab({
+      timeZone: "Europe/Berlin",
+      phaseByDay,
+      measurements,
+    });
     const rhr = rows.find((r) => r.metricKey === "restingHeartRate");
     expect(rhr).toBeDefined();
     // luteal higher → positive delta (lutealAvg − follicularAvg)
@@ -183,7 +195,11 @@ describe("computePhaseMetricCrosstab", () => {
       lutealRhr: 63,
       follicularRhr: 57,
     });
-    const rows = computePhaseMetricCrosstab({ phaseByDay, measurements });
+    const rows = computePhaseMetricCrosstab({
+      timeZone: "Europe/Berlin",
+      phaseByDay,
+      measurements,
+    });
     expect(rows).toEqual([]);
   });
 
@@ -193,7 +209,11 @@ describe("computePhaseMetricCrosstab", () => {
       lutealRhr: 60,
       follicularRhr: 60,
     });
-    const rows = computePhaseMetricCrosstab({ phaseByDay, measurements });
+    const rows = computePhaseMetricCrosstab({
+      timeZone: "Europe/Berlin",
+      phaseByDay,
+      measurements,
+    });
     // No real separation → nothing clears p < 0.05.
     expect(
       rows.find((r) => r.metricKey === "restingHeartRate"),
@@ -216,7 +236,11 @@ describe("computePhaseMetricCrosstab", () => {
       phaseByDay.set(key, i % 2 === 0 ? "MENSTRUAL" : "OVULATORY");
       measurements.push(m("RESTING_HEART_RATE", key, 200));
     }
-    const rows = computePhaseMetricCrosstab({ phaseByDay, measurements });
+    const rows = computePhaseMetricCrosstab({
+      timeZone: "Europe/Berlin",
+      phaseByDay,
+      measurements,
+    });
     const rhr = rows.find((r) => r.metricKey === "restingHeartRate")!;
     // Means reflect only the luteal/follicular days, not the 200-bpm noise.
     expect(rhr.lutealAvg).toBeLessThan(70);
@@ -226,6 +250,7 @@ describe("computePhaseMetricCrosstab", () => {
   it("returns empty for an empty phase map", () => {
     expect(
       computePhaseMetricCrosstab({
+        timeZone: "Europe/Berlin",
         phaseByDay: new Map(),
         measurements: [m("RESTING_HEART_RATE", "2026-03-01", 60)],
       }),
@@ -287,6 +312,7 @@ describe("discoverPhaseCorrelations", () => {
       );
     }
     const result = discoverPhaseCorrelations({
+      timeZone: "Europe/Berlin",
       phaseByDay,
       measurements,
       locale: "en",
@@ -320,6 +346,7 @@ describe("discoverPhaseCorrelations", () => {
       measurements.push(m("RESTING_HEART_RATE", key, 60)); // constant → no variance
     }
     const result = discoverPhaseCorrelations({
+      timeZone: "Europe/Berlin",
       phaseByDay,
       measurements,
       locale: "en",

src/lib/cycle/phase-crosstab.ts

@@ -183,6 +183,8 @@ export function computePhaseMetricCrosstab(args: {
   measurements: CrossMetricMeasurement[];
   /** The user's source-priority blob (threaded into `metricDayMap`). */
   userPriorityJson?: unknown;
+  /** The user's zone, the calendar the phase days are keyed on. */
+  timeZone: string;
 }): PhaseMetricCrosstabRow[] {
   const { phaseByDay, measurements } = args;
   const userPriorityJson = args.userPriorityJson ?? null;
@@ -198,7 +200,12 @@ export function computePhaseMetricCrosstab(args: {
       (typeof PHASE_CROSSTAB_METRICS)[PhaseCrosstabMetricKey],
     ]
   >) {
-    const metricByDay = metricDayMap(measurements, cfg.type, userPriorityJson);
+    const metricByDay = metricDayMap(
+      measurements,
+      cfg.type,
+      userPriorityJson,
+      args.timeZone,
+    );
     if (metricByDay.size === 0) continue;
 
     const lutealVals: number[] = [];
@@ -293,6 +300,8 @@ export function discoverPhaseCorrelations(args: {
   phaseByDay: Map<string, CyclePhase>;
   measurements: CrossMetricMeasurement[];
   userPriorityJson?: unknown;
+  /** The user's zone, the calendar the phase days are keyed on. */
+  timeZone: string;
   /**
    * The reader's locale. Each surviving row carries a finished `interpretation`
    * sentence that the cycle route serves straight to the client, so it has to
@@ -307,7 +316,12 @@ export function discoverPhaseCorrelations(args: {
   const phaseSeries = buildPhaseDiscoverySeries(phaseByDay);
   const outcomeSeries: NamedSeries[] = [];
   for (const [, cfg] of Object.entries(PHASE_CROSSTAB_METRICS)) {
-    const byDay = metricDayMap(measurements, cfg.type, userPriorityJson);
+    const byDay = metricDayMap(
+      measurements,
+      cfg.type,
+      userPriorityJson,
+      args.timeZone,
+    );
     if (byDay.size === 0) continue;
     const points: DailySeriesPoint[] = [];
     for (const [day, value] of byDay) points.push({ day, value });

src/lib/cycle/prediction-refresh.ts

@@ -25,7 +25,8 @@ import {
 import { persistPredictionCache } from "@/lib/cycle/prediction-cache";
 import { addDays } from "@/lib/cycle/day-math";
 import { BBT_WINDOW } from "@/lib/cycle/types";
-import { DEFAULT_TIMEZONE, moodDateKey } from "@/lib/mood/date-key";
+import { moodDateKey } from "@/lib/mood/date-key";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 
 /** Day-log lookback: the calendar's default past span or the symptothermal
  *  window, whichever reaches further back. */

src/lib/daily/__tests__/load-digest.test.ts

@@ -63,6 +63,7 @@ import { readDashboardSnapshotCached } from "@/lib/dashboard/snapshot-read";
 import { resolveModuleMap } from "@/lib/modules/gate";
 import { probeRollupCoverage } from "@/lib/rollups/measurement-coverage";
 import { loadIntradayPulse } from "@/lib/analytics/intraday-pulse-io";
+import { readDayMeanSeries } from "@/lib/insights/derived/baseline";
 import { __resetAllCachesForTests } from "@/lib/cache/server-cache";
 import { invalidateUserMeasurements } from "@/lib/cache/invalidate";
 import { PRIORITY_ITEM_KINDS } from "@/lib/daily/priority-item";
@@ -118,6 +119,36 @@ beforeEach(() => {
   vi.mocked(aiCapabilityToServe).mockResolvedValue(AI_AVAILABLE);
 });
 
+describe("loadDailyDigest — milestone day", () => {
+  // 21:30 on 16 July in New York is already 17 July in UTC. A best set at
+  // 19:00 local that evening was reached today, on the user's calendar.
+  const NY_USER = { ...USER, timezone: "America/New_York" } as User;
+  const NY_EVENING = new Date("2026-07-17T01:30:00.000Z");
+
+  it("keys today and a new record on the user's own day", async () => {
+    vi.mocked(prisma.personalRecord.findMany).mockResolvedValueOnce([
+      {
+        metricType: "RESTING_HEART_RATE",
+        achievedAt: new Date("2026-07-16T23:00:00.000Z"),
+      },
+    ] as never);
+
+    const digest = await loadDailyDigest(NY_USER, NY_EVENING);
+
+    expect(digest.worthALook.some((i) => i.kind === "milestone")).toBe(true);
+  });
+
+  it("folds the streak series on the user's days", async () => {
+    vi.mocked(probeRollupCoverage).mockResolvedValue(
+      new Map([["RESTING_HEART_RATE", true]]) as never,
+    );
+    await loadDailyDigest(NY_USER, NY_EVENING);
+    const calls = vi.mocked(readDayMeanSeries).mock.calls;
+    expect(calls.length).toBeGreaterThan(0);
+    for (const call of calls) expect(call[5]).toBe("America/New_York");
+  });
+});
+
 describe("loadDailyDigest — S11/S12 extras cache", () => {
   it("gathers the milestone + tension inputs once, then serves the second poll from cache", async () => {
     await loadDailyDigest(USER, NOW);

src/lib/daily/daily-briefing-push.ts

@@ -33,7 +33,7 @@ import { resolveJobLocale } from "@/lib/i18n/job-locale";
 import { getServerTranslator } from "@/lib/i18n/server-translator";
 import type { ServerTranslator } from "@/lib/i18n/server-translator";
 import { wallClockInTz } from "@/lib/tz/wall-clock";
-import { userDayKey } from "@/lib/tz/format";
+import { userDayKey, DEFAULT_TIMEZONE } from "@/lib/tz/format";
 import { dispatchNotification } from "@/lib/notifications/dispatcher";
 import { loadDailyDigest } from "@/lib/daily/load-digest";
 import type { DailyDigest } from "@/lib/daily/digest";
@@ -175,7 +175,7 @@ export async function maybeDispatchDailyBriefing(
       return "opted-out";
     }
 
-    const tz = user.timezone || "Europe/Berlin";
+    const tz = user.timezone || DEFAULT_TIMEZONE;
     const { hour } = wallClockInTz(now, tz);
     if (
       hour < DAILY_BRIEFING_MORNING_EARLIEST_HOUR ||

src/lib/daily/load-digest.ts

@@ -101,11 +101,6 @@ const MILESTONE_STREAK_WINDOW_DAYS = 30;
 /** How far back to scan for a just-set personal best (a couple of days is ample). */
 const MILESTONE_RECORD_LOOKBACK_MS = 2 * 24 * 60 * 60 * 1000;
 
-/** UTC-ISO day key — the space the streak series + rollup tier already emit. */
-function utcDayKey(date: Date): string {
-  return date.toISOString().slice(0, 10);
-}
-
 /**
  * S12 — gather today's single freshly-reached milestone (or null) from the
  * engines that ALREADY exist. Two cheap, fail-soft reads reused verbatim:
@@ -117,9 +112,13 @@ function utcDayKey(date: Date): string {
  */
 async function gatherFreshMilestone(
   userId: string,
+  timezone: string,
   now: Date,
 ): Promise<Milestone | null> {
-  const todayKey = utcDayKey(now);
+  // Every day key here is the user's own calendar day: today's key, the
+  // streak series (folded on local days) and each record's day. UTC keys
+  // named tomorrow "today" through a New York evening.
+  const todayKey = userDayKey(now, timezone);
   const candidates: Milestone[] = [];
 
   const coverage = await probeRollupCoverage(userId).catch(() => null);
@@ -133,6 +132,7 @@ async function gatherFreshMilestone(
             MILESTONE_STREAK_WINDOW_DAYS,
             now,
             coverage,
+            timezone,
           );
           if (points.length === 0) return [] as Milestone[];
           const series: StreakPoint[] = points.map((p) => ({
@@ -164,7 +164,10 @@ async function gatherFreshMilestone(
     });
     for (const record of records) {
       candidates.push(
-        milestoneFromRecord(record.metricType, utcDayKey(record.achievedAt)),
+        milestoneFromRecord(
+          record.metricType,
+          userDayKey(record.achievedAt, timezone),
+        ),
       );
     }
   } catch {
@@ -234,7 +237,7 @@ async function loadDailyDigestExtrasCached(
       // internally (a milestone read-hiccup or a tension-read failure leaves
       // its own field quiet rather than breaking the other).
       const [milestone, tensionWindow, sameTime] = await Promise.all([
-        gatherFreshMilestone(userId, now),
+        gatherFreshMilestone(userId, timezone, now),
         loadIntradayPulse(userId, timezone, todayLocalDate)
           .then((r) => (r.tension ? { partOfDay: r.tension.partOfDay } : null))
           .catch(() => null),

src/lib/dashboard/__tests__/streak.test.ts

@@ -0,0 +1,77 @@
+import { describe, expect, it } from "vitest";
+
+import { computeStreak } from "../streak";
+import { userDayKey } from "@/lib/tz/format";
+
+const ZONES = [
+  "America/New_York",
+  "America/Santiago",
+  "Pacific/Auckland",
+  "Pacific/Tongatapu",
+  "Europe/Berlin",
+  "UTC",
+];
+
+/** The last `n` local days ending with today's key in `tz`. */
+function lastDays(now: Date, tz: string, n: number, skipToday = false) {
+  const keys = new Set<string>();
+  const today = userDayKey(now, tz);
+  const [y, m, d] = today.split("-").map(Number);
+  for (let i = skipToday ? 1 : 0; i < n + (skipToday ? 1 : 0); i++) {
+    keys.add(new Date(Date.UTC(y, m - 1, d - i)).toISOString().slice(0, 10));
+  }
+  return keys;
+}
+
+describe("computeStreak", () => {
+  // Evening in New York is already the next UTC day, and the early hours in
+  // Auckland or Tonga are still the previous UTC day: both ends of the walk.
+  const INSTANTS = [
+    "2026-03-08T01:30:00.000Z",
+    "2026-03-08T23:30:00.000Z",
+    "2026-04-05T13:00:00.000Z",
+    "2026-09-06T03:30:00.000Z",
+    "2026-10-25T00:30:00.000Z",
+    "2026-11-01T06:00:00.000Z",
+  ];
+
+  for (const tz of ZONES) {
+    for (const iso of INSTANTS) {
+      const now = new Date(iso);
+      it(`counts three logged days ending today in ${tz} at ${iso}`, () => {
+        const streak = computeStreak(lastDays(now, tz, 3), tz, now);
+        expect(streak.currentDays).toBe(3);
+        expect(streak.longest).toBe(3);
+      });
+      it(`counts from yesterday when today is not logged yet in ${tz} at ${iso}`, () => {
+        const streak = computeStreak(lastDays(now, tz, 4, true), tz, now);
+        expect(streak.currentDays).toBe(4);
+      });
+    }
+  }
+
+  it("breaks the current streak on a gap", () => {
+    const now = new Date("2026-06-10T20:00:00.000Z");
+    const tz = "America/New_York";
+    const streak = computeStreak(
+      new Set([
+        "2026-06-10",
+        "2026-06-09",
+        "2026-06-07",
+        "2026-06-06",
+        "2026-06-05",
+      ]),
+      tz,
+      now,
+    );
+    expect(streak.currentDays).toBe(2);
+    expect(streak.longest).toBe(3);
+  });
+
+  it("returns zeros for no activity", () => {
+    expect(computeStreak(new Set(), "UTC")).toEqual({
+      currentDays: 0,
+      longest: 0,
+    });
+  });
+});

src/lib/dashboard/batch-chart-types.ts

@@ -25,16 +25,12 @@
  *    prefetch-off / legacy / fail-soft paths where no prop arrives.
  *
  * Import-safe from the server RSC and the client component alike: pure, no
- * Prisma / db / `node:*` imports (only the client-safe `@/lib/tz/format`
- * Intl helpers and the layout type).
+ * Prisma / db / `node:*` imports (only the client-safe `@/lib/tz` Intl
+ * helpers and the layout type).
  */
 import type { DashboardLayout } from "@/lib/dashboard-layout";
-import {
-  DEFAULT_TIMEZONE,
-  isValidTimezone,
-  tzOffsetMinutes,
-  userDayKey,
-} from "@/lib/tz/format";
+import { DEFAULT_TIMEZONE, isValidTimezone, userDayKey } from "@/lib/tz/format";
+import { localDayWindow } from "@/lib/tz/local-day";
 
 /**
  * Day-span the batched dashboard series (`series-batch`) fetches. Threaded to
@@ -97,21 +93,13 @@ export interface BatchWindow {
 }
 
 /**
- * End-of-day of `now` in `timezone`, as a UTC instant. Falls back to the
- * project default zone for an unusable IANA id. Two-step offset refine so the
- * rare DST edge (a transition between the as-if-UTC guess and the true local
- * instant) still resolves to the right offset.
+ * Last millisecond of the local day `now` falls on in `timezone`, as a UTC
+ * instant. Falls back to the project default zone for an unusable IANA id.
  */
 function endOfLocalDayUtc(now: Date, timezone: string): Date {
   const safeTz = isValidTimezone(timezone) ? timezone : DEFAULT_TIMEZONE;
-  const dayKey = userDayKey(now, safeTz); // YYYY-MM-DD in the zone
-  const [year, month, day] = dayKey.split("-").map(Number);
-  // Wall-clock 23:59:59.999 treated as-if-UTC, then shifted by the zone offset.
-  const asIfUtc = Date.UTC(year, month - 1, day, 23, 59, 59, 999);
-  const offset1 = tzOffsetMinutes(new Date(asIfUtc), safeTz);
-  const corrected = new Date(asIfUtc - offset1 * 60_000);
-  const offset2 = tzOffsetMinutes(corrected, safeTz);
-  return new Date(asIfUtc - offset2 * 60_000);
+  const { dayEnd } = localDayWindow(userDayKey(now, safeTz), safeTz);
+  return new Date(dayEnd.getTime() - 1);
 }
 
 /**

src/lib/dashboard/streak.ts

@@ -0,0 +1,47 @@
+import { shiftDateKey, userDayKey } from "@/lib/tz/format";
+
+export interface StreakInfo {
+  currentDays: number;
+  longest: number;
+}
+
+/**
+ * The current logging-day streak (days where any measurement or intake
+ * event was recorded, in the user's zone) plus the longest streak among
+ * `activityDays`.
+ *
+ * `activityDays` holds `YYYY-MM-DD` keys already cut in `userTz`. The walk
+ * steps through day KEYS (`shiftDateKey`), never instants: stepping back from
+ * UTC midnight of today's key read that instant in the user's zone, which
+ * west of UTC is still yesterday, so the streak started one day early and
+ * came out one day short. Yesterday counts as the streak's head when today
+ * has not been logged yet.
+ */
+export function computeStreak(
+  activityDays: ReadonlySet<string>,
+  userTz: string,
+  now: Date = new Date(),
+): StreakInfo {
+  if (activityDays.size === 0) return { currentDays: 0, longest: 0 };
+
+  const sorted = [...activityDays].sort();
+  let longest = 1;
+  let run = 1;
+  for (let i = 1; i < sorted.length; i++) {
+    if (shiftDateKey(sorted[i - 1], 1) === sorted[i]) {
+      run += 1;
+      longest = Math.max(longest, run);
+    } else {
+      run = 1;
+    }
+  }
+
+  let cursor = userDayKey(now, userTz);
+  if (!activityDays.has(cursor)) cursor = shiftDateKey(cursor, -1);
+  let currentDays = 0;
+  while (activityDays.has(cursor)) {
+    currentDays += 1;
+    cursor = shiftDateKey(cursor, -1);
+  }
+  return { currentDays, longest };
+}

src/lib/doctor-report-pdf-core.ts

@@ -22,7 +22,6 @@ import {
 import { getUnitForType } from "./validations/measurement";
 import {
   makeFormatters,
-  DISPLAY_TIMEZONE,
   type DateFormatPreference,
   type TimeFormatPreference,
 } from "./format-locale";
@@ -39,6 +38,7 @@ import {
   pdfCursorState,
   type DoctorReportPdfRenderContext,
 } from "./doctor-report-pdf/render-context";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 
 type T = (key: string, params?: Record<string, string | number>) => string;
 
@@ -236,7 +236,7 @@ export function buildDoctorReportPdfDocument(
     formatters.number(value, decimals);
   const fmtDate = (iso: string) => formatters.date(iso);
   const footerTz =
-    userTz && isValidTimezone(userTz) ? userTz : DISPLAY_TIMEZONE;
+    userTz && isValidTimezone(userTz) ? userTz : DEFAULT_TIMEZONE;
 
   const unitFor = (type: string): string => {
     const staticUnit = DOCTOR_REPORT_TYPE_UNIT_KEYS[type];

src/lib/doctor-report/collect.ts

@@ -61,7 +61,7 @@ import { loadDenseMeasurementBuckets } from "./dense-buckets";
 import { summariseDenseBuckets } from "./measurement-series";
 import { emptyGlucoseClinical } from "./glucose-panel";
 import { buildAdministrationLedger, buildGlp1Block } from "./medications";
-import { validTimezoneOr } from "@/lib/tz/format";
+import { validTimezoneOr, DEFAULT_TIMEZONE } from "@/lib/tz/format";
 import {
   loadAllergies,
   loadAnamnesis,
@@ -147,7 +147,7 @@ export async function collectDoctorReportData(
       insurerIkNumber: true,
     },
   });
-  const reportTz = validTimezoneOr(userProfile?.timezone, "Europe/Berlin");
+  const reportTz = validTimezoneOr(userProfile?.timezone, DEFAULT_TIMEZONE);
 
   const aggregateDenseTypes = days > DENSE_REPORT_RAW_WINDOW_DAYS;
   const densePulse = aggregateDenseTypes && !excluded.includes("PULSE");
@@ -189,7 +189,34 @@ export async function collectDoctorReportData(
       }),
       wantsMedications
         ? prisma.medication.findMany({
-            where: { userId, active: true },
+            // The report describes its window, and a link can pin that window
+            // in the past: a medication whose course had not begun by the
+            // window's end, or had ended before it began, is not part of it.
+            // One with a dose scheduled inside the window was taken then,
+            // whenever it was entered. Dose history and the last intake stop
+            // at the window's end too, so a report for March does not show a
+            // dose set in June.
+            where: {
+              userId,
+              active: true,
+              AND: [
+                {
+                  OR: [
+                    { startsOn: { lte: end } },
+                    { startsOn: null, createdAt: { lte: end } },
+                    {
+                      intakeEvents: {
+                        some: {
+                          deletedAt: null,
+                          scheduledFor: { gte: start, lte: end },
+                        },
+                      },
+                    },
+                  ],
+                },
+                { OR: [{ endsOn: null }, { endsOn: { gte: start } }] },
+              ],
+            },
             include: {
               schedules: {
                 select: { ...SCHEDULE_COMPLIANCE_SELECT, label: true },
@@ -205,9 +232,12 @@ export async function collectDoctorReportData(
                 },
               },
               pauseEras: { select: { pausedAt: true, resumedAt: true } },
-              doseChanges: { orderBy: { effectiveFrom: "asc" } },
+              doseChanges: {
+                where: { effectiveFrom: { lte: end } },
+                orderBy: { effectiveFrom: "asc" },
+              },
               intakeEvents: {
-                where: { takenAt: { not: null } },
+                where: { takenAt: { not: null, lte: end } },
                 orderBy: { takenAt: "desc" },
                 take: 1,
                 select: { takenAt: true, injectionSite: true },

src/lib/encounters/service.ts

@@ -27,8 +27,7 @@ import {
   reanchorAppointmentReminder,
   type AppointmentReminderInput,
 } from "@/lib/encounters/appointment-reminder";
-
-const DEFAULT_TIMEZONE = "Europe/Berlin";
+import { DEFAULT_TIMEZONE } from "@/lib/tz/format";
 
 /**
  * The record owner's zone AND language, read together.

src/lib/fitbit/__tests__/client.test.ts

@@ -398,6 +398,56 @@ describe("VO2 max", () => {
   });
 });
 
+describe("mappers in the user's zone", () => {
+  it("reads a weigh-in's logged wall clock in the user's zone", () => {
+    const entry = {
+      weight: [
+        { date: "2026-05-10", time: "07:30:00", weight: 81.4, logId: 7 },
+      ],
+    };
+    expect(
+      mapWeight(entry, "Pacific/Auckland")[0]!.measuredAt.toISOString(),
+    ).toBe("2026-05-09T19:30:00.000Z");
+    expect(
+      mapWeight(entry, "America/New_York")[0]!.measuredAt.toISOString(),
+    ).toBe("2026-05-10T11:30:00.000Z");
+    // The externalId does not depend on the zone.
+    expect(mapWeight(entry, "Pacific/Auckland")[0]!.fieldTag).toBe("7:weight");
+  });
+
+  it("keeps a logId-less weigh-in's externalId as earlier versions spelled it", () => {
+    const out = mapWeight(
+      { weight: [{ date: "2026-05-10", time: "07:30:00", weight: 81.4 }] },
+      "Pacific/Auckland",
+    );
+    expect(out[0]!.fieldTag).toBe("2026-05-10T07:30:00.000Z:weight");
+  });
+
+  it.each([
+    ["Pacific/Tongatapu", "2026-05-09T23:00:00.000Z"],
+    ["Pacific/Auckland", "2026-05-10T00:00:00.000Z"],
+    ["America/Santiago", "2026-05-10T16:00:00.000Z"],
+    ["America/New_York", "2026-05-10T16:00:00.000Z"],
+    ["Europe/Berlin", "2026-05-10T10:00:00.000Z"],
+  ])(
+    "anchors a daily total at local noon in %s, on the same day there",
+    (tz, iso) => {
+      const [steps] = mapSteps(
+        { "activities-steps": [{ dateTime: "2026-05-10", value: "8421" }] },
+        tz,
+      );
+      expect(steps!.measuredAt.toISOString()).toBe(iso);
+      expect(steps!.fieldTag).toBe("steps:2026-05-10");
+      const [spo2] = mapOxygenSaturation(
+        [{ dateTime: "2026-05-10", value: { avg: 97 } }],
+        tz,
+      );
+      expect(spo2!.measuredAt.toISOString()).toBe(iso);
+      expect(spo2!.fieldTag).toBe("2026-05-10:spo2");
+    },
+  );
+});
+
 describe("activity mappers (cumulative daily)", () => {
   it("maps steps from the string value, preserving a zero, with a day-keyed externalId", () => {
     const out = mapSteps({

src/lib/fitbit/__tests__/sync.test.ts

@@ -288,7 +288,12 @@ describe("upsertFitbitMeasurements — batched write, tombstones resurrect", ()
     const measuredAt = new Date("2026-05-10T07:00:00.000Z");
     // A re-fetched daily summary: the live row already exists.
     prismaMock.measurement.findMany.mockResolvedValue([
-      { id: "m-live", type: "WEIGHT", externalId: "stats:weight:2026-05-10" },
+      {
+        id: "m-live",
+        type: "WEIGHT",
+        externalId: "stats:weight:2026-05-10",
+        measuredAt,
+      },
     ]);
 
     const { imported } = await upsertFitbitMeasurements("user1", [
@@ -319,7 +324,12 @@ describe("upsertFitbitMeasurements — batched write, tombstones resurrect", ()
     // probe returns it; planning an insert instead would be dropped silently
     // by `skipDuplicates` and wedge the key forever.
     prismaMock.measurement.findMany.mockResolvedValue([
-      { id: "m-dead", type: "WEIGHT", externalId: "stats:weight:2026-05-10" },
+      {
+        id: "m-dead",
+        type: "WEIGHT",
+        externalId: "stats:weight:2026-05-10",
+        measuredAt,
+      },
     ]);
 
     const { imported } = await upsertFitbitMeasurements("user1", [
@@ -342,11 +352,52 @@ describe("upsertFitbitMeasurements — batched write, tombstones resurrect", ()
     expect(updateArg.data.deletedAt).toBeNull();
   });
 
+  it("moves a daily row to its new anchor and refolds the day it left", async () => {
+    // A step total written at the old noon-UTC anchor, re-fetched for a user
+    // in Tonga, whose local noon is 23:00 UTC the day before.
+    const legacy = new Date("2026-05-10T12:00:00.000Z");
+    const localNoon = new Date("2026-05-09T23:00:00.000Z");
+    prismaMock.measurement.findMany.mockResolvedValue([
+      {
+        id: "m-steps",
+        type: "ACTIVITY_STEPS",
+        externalId: "stats:steps:2026-05-10",
+        value: 8421,
+        unit: "steps",
+        measuredAt: legacy,
+        sleepStage: null,
+        deletedAt: null,
+      },
+    ]);
+
+    const { touched } = await upsertFitbitMeasurements("user1", [
+      {
+        type: "ACTIVITY_STEPS",
+        value: 8421,
+        unit: "steps",
+        measuredAt: localNoon,
+        externalId: "stats:steps:2026-05-10",
+      },
+    ]);
+
+    expect(prismaMock.measurement.createManyAndReturn).not.toHaveBeenCalled();
+    expect(prismaMock.measurement.update).toHaveBeenCalledTimes(1);
+    const updateArg = prismaMock.measurement.update.mock.calls[0]![0] as {
+      data: { measuredAt: Date };
+    };
+    expect(updateArg.data.measuredAt).toEqual(localNoon);
+    expect(touched.map((t) => t.measuredAt.toISOString())).toEqual(
+      expect.arrayContaining([localNoon.toISOString(), legacy.toISOString()]),
+    );
+  });
+
   it("splits a mixed batch: matched-live → update, unmatched → createMany", async () => {
     const measuredAt = new Date("2026-05-10T07:00:00.000Z");
-    prismaMock.measurement.findMany.mockResolvedValue([
-      { id: "m-live", type: "WEIGHT", externalId: "live-key" },
-    ]);
+    prismaMock.measurement.findMany
+      .mockResolvedValueOnce([
+        { id: "m-live", type: "WEIGHT", externalId: "live-key", measuredAt },
+      ])
+      .mockResolvedValueOnce([]); // natural-key rescue: no twin
 
     const { imported } = await upsertFitbitMeasurements("user1", [
       {
@@ -438,7 +489,7 @@ describe("upsertFitbitMeasurements — write-catch ledger (F-2)", () => {
     // fresh → create branch. Second findMany is the natural-key rescue probe.
     prismaMock.measurement.findMany
       .mockResolvedValueOnce([
-        { id: "m-live", type: "WEIGHT", externalId: "live-key" },
+        { id: "m-live", type: "WEIGHT", externalId: "live-key", measuredAt },
       ])
       .mockResolvedValueOnce([]); // natural-key rescue: no twin
     prismaMock.measurement.createManyAndReturn.mockRejectedValueOnce(
@@ -478,8 +529,8 @@ describe("upsertFitbitMeasurements — write-catch ledger (F-2)", () => {
     // throws; the loop must continue to the second, and the create still runs.
     prismaMock.measurement.findMany
       .mockResolvedValueOnce([
-        { id: "m-live-1", type: "WEIGHT", externalId: "live-1" },
-        { id: "m-live-2", type: "WEIGHT", externalId: "live-2" },
+        { id: "m-live-1", type: "WEIGHT", externalId: "live-1", measuredAt },
+        { id: "m-live-2", type: "WEIGHT", externalId: "live-2", measuredAt },
       ])
       .mockResolvedValueOnce([]); // natural-key rescue: no twin
     prismaMock.measurement.update