From a9c2e25099836ae31635d7337ce7c187ccdcfe2d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marc-Andr=C3=A9=20Bombeck?= <mbombeck@gmail.com>
Date: Thu, 29 Oct 2026 10:13:22 +0100
Subject: [PATCH] fix(rollups): trail the rollup window from the caller's
 moment

readBestGranularityRollups opened its window at the wall clock, while the
live fallback beside it used the caller's now. A read anchored on another
moment saw different days depending on whether the account already had
DAY buckets; the Today overview's integration test turned red once its
fixed morning fell out of the wall-clock window. Every caller that holds a
now passes it through.
---
 src/lib/analytics/range-delta.ts        | 2 ++
 src/lib/illness/correlation-read.ts     | 8 +++++++-
 src/lib/insights/derived/baseline.ts    | 8 +++++++-
 src/lib/insights/graded-series.ts       | 2 ++
 src/lib/rollups/measurement-read-wmy.ts | 6 +++++-
 5 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/src/lib/analytics/range-delta.ts b/src/lib/analytics/range-delta.ts
index 4bee215a5..64c056aec 100644
--- a/src/lib/analytics/range-delta.ts
+++ b/src/lib/analytics/range-delta.ts
@@ -316,6 +316,8 @@ export async function computeRangeDelta(
     userId,
     type,
     windowDays * 2,
+    undefined,
+    new Date(now),
   );
   if (!resolved) {
     const empty: WindowAggregate = {
diff --git a/src/lib/illness/correlation-read.ts b/src/lib/illness/correlation-read.ts
index aa50005d1..2b6f983bd 100644
--- a/src/lib/illness/correlation-read.ts
+++ b/src/lib/illness/correlation-read.ts
@@ -217,7 +217,13 @@ async function readWindowMeans(
       1,
       Math.ceil((to.getTime() - from.getTime()) / MS_PER_DAY),
     );
-    const resolved = await readBestGranularityRollups(userId, type, windowDays);
+    const resolved = await readBestGranularityRollups(
+      userId,
+      type,
+      windowDays,
+      undefined,
+      now,
+    );
     if (
       resolved &&
       resolved.granularity === "DAY" &&
diff --git a/src/lib/insights/derived/baseline.ts b/src/lib/insights/derived/baseline.ts
index f17913712..7b0f2a6bd 100644
--- a/src/lib/insights/derived/baseline.ts
+++ b/src/lib/insights/derived/baseline.ts
@@ -274,7 +274,13 @@ export async function readDayMeanSeries(
     // band from WEEK/MONTH `sd`, and the center reads the DAY `mean`
     // which composes exactly. `readBestGranularityRollups` with a
     // window < 91 days resolves to DAY by construction.
-    const resolved = await readBestGranularityRollups(userId, type, windowDays);
+    const resolved = await readBestGranularityRollups(
+      userId,
+      type,
+      windowDays,
+      undefined,
+      now,
+    );
     if (
       resolved &&
       resolved.granularity === "DAY" &&
diff --git a/src/lib/insights/graded-series.ts b/src/lib/insights/graded-series.ts
index 4f82da485..616745700 100644
--- a/src/lib/insights/graded-series.ts
+++ b/src/lib/insights/graded-series.ts
@@ -537,6 +537,7 @@ export async function buildGradedSeriesWithRollups(
     type,
     365,
     priority,
+    now,
   );
   // Yearly slice: route a multi-year window through the tier.
   const yearlyRouted = await readBestGranularityRollups(
@@ -544,6 +545,7 @@ export async function buildGradedSeriesWithRollups(
     type,
     1095,
     priority,
+    now,
   );
 
   const monthlyCovered =
diff --git a/src/lib/rollups/measurement-read-wmy.ts b/src/lib/rollups/measurement-read-wmy.ts
index 7ba0e5648..026b79f7d 100644
--- a/src/lib/rollups/measurement-read-wmy.ts
+++ b/src/lib/rollups/measurement-read-wmy.ts
@@ -116,12 +116,16 @@ export async function readBestGranularityRollups(
   type: MeasurementType,
   windowDays: number,
   userPriorityJson?: unknown,
+  now: Date = new Date(),
 ): Promise<{
   granularity: RollupGranularity;
   rows: RollupBucketRow[];
 } | null> {
   if (!Number.isFinite(windowDays) || windowDays <= 0) return null;
-  const since = new Date(Date.now() - windowDays * 24 * 60 * 60 * 1000);
+  // The window trails the caller's `now`, so a read anchored on another
+  // moment than the wall clock sees the same days through the rollups as
+  // through the live fallback.
+  const since = new Date(now.getTime() - windowDays * 24 * 60 * 60 * 1000);
   // v1.11.1 — load the source-priority blob once and thread it into every
   // granularity probe so the collapse never re-queries the user per floor.
   const priority =