diff --git a/src/components/day/__tests__/chart-day.test.ts b/src/components/day/__tests__/chart-day.test.ts
index f29ae03cf..7677fa894 100644
--- a/src/components/day/__tests__/chart-day.test.ts
+++ b/src/components/day/__tests__/chart-day.test.ts
@@ -3,6 +3,7 @@ import { describe, expect, it } from "vitest";
 import {
   chartPointDayKey,
   rugFraction,
+  rugEntries,
   rugPosition,
   timeRugFraction,
 } from "../chart-day";
@@ -191,3 +192,36 @@ describe("rug on a time axis drawn from real instants", () => {
     expect(timeRugFraction("2026-03-06", points, days)).toBeNull();
   });
 });
+
+describe("rugEntries", () => {
+  const points = ["2026-09-01", "2026-09-04", "2026-09-08", "2026-09-12"].map(
+    (day) => ({ timestamp: noon(day) }),
+  );
+  const everyDay = Array.from(
+    { length: 12 },
+    (_, i) => `2026-09-${String(i + 1).padStart(2, "0")}`,
+  );
+
+  it("marks only the chart's own points on an index axis", () => {
+    // Days between two points have no place on an axis that spaces points;
+    // interpolated, a week of them ran together into a bar in one gap.
+    const entries = rugEntries(everyDay, points, "index");
+    expect(entries.map((e) => e.day)).toEqual([
+      "2026-09-01",
+      "2026-09-04",
+      "2026-09-08",
+      "2026-09-12",
+    ]);
+    expect(entries.map((e) => e.at)).toEqual([0, 1 / 3, 2 / 3, 1]);
+  });
+
+  it("keeps every day of the span on a time axis", () => {
+    expect(rugEntries(everyDay, points, "time")).toHaveLength(12);
+  });
+
+  it("never puts two dots closer than one point step on an index axis", () => {
+    const entries = rugEntries(everyDay, points, "index");
+    const gaps = entries.slice(1).map((e, i) => e.at - entries[i]!.at);
+    expect(Math.min(...gaps)).toBeCloseTo(1 / (points.length - 1));
+  });
+});
diff --git a/src/components/day/chart-day.tsx b/src/components/day/chart-day.tsx
index 538c1354e..0a1a22e70 100644
--- a/src/components/day/chart-day.tsx
+++ b/src/components/day/chart-day.tsx
@@ -168,6 +168,38 @@ export function timeRugFraction(
   return Math.min(1, Math.max(0, (t - first) / (last - first)));
 }
 
+/**
+ * The rug's dots: each day that holds anything, where it sits along the plot.
+ *
+ * On an index or band axis a day has a place only if it is one of the
+ * chart's points, because the axis spaces points, not days. A day between
+ * two points used to be interpolated into the gap between them, so a sparse
+ * series (blood pressure taken twice a week beside a mood logged every day)
+ * squeezed a week of other days into one gap and their dots ran together
+ * into bars. A time axis spaces days and keeps every day of its span.
+ */
+export function rugEntries(
+  days: readonly string[],
+  points: readonly RugPoint[],
+  axis: ChartDayAxis,
+  pointDays?: ReadonlyArray<DateKey | null>,
+): Array<{ day: string; at: number }> {
+  const onPoints =
+    axis === "time"
+      ? null
+      : new Set(points.map((point) => chartPointDayKey(point.timestamp)));
+  return days
+    .filter((day) => onPoints === null || onPoints.has(day))
+    .map((day) => ({
+      day,
+      at:
+        axis === "time" && pointDays !== undefined
+          ? timeRugFraction(day as DateKey, points, pointDays)
+          : rugFraction(day as DateKey, points, axis),
+    }))
+    .filter((entry): entry is { day: string; at: number } => entry.at !== null);
+}
+
 /**
  * The row of day dots under a daily chart. `insetLeft` / `insetRight` are the
  * pixels between the chart box and the first and last point (margin, axis,
@@ -216,15 +248,12 @@ export function DayRug({
   const index = useDayIndex(from, to);
   const data = index.data;
   const notable = new Set(data?.notable ?? []);
-  const days = Object.keys(data?.days ?? {})
-    .filter((day) => isOpenableDay(day, today))
-    .map((day) => ({
-      day,
-      at: byDays
-        ? timeRugFraction(day, points, pointDays)
-        : rugFraction(day, points, axis),
-    }))
-    .filter((entry): entry is { day: string; at: number } => entry.at !== null);
+  const days = rugEntries(
+    Object.keys(data?.days ?? {}).filter((day) => isOpenableDay(day, today)),
+    points,
+    axis,
+    byDays ? pointDays : undefined,
+  );
   return (
     <div
       aria-hidden="true"