From 8d42395938006e16aafea9c19c84fea684e2b235 Mon Sep 17 00:00:00 2001
From: Petar Petrov <MindFreeze@users.noreply.github.com>
Date: Fri, 6 Mar 2026 19:42:52 +0100
Subject: [PATCH] Fix stale data point in history-graph cards with sub-hour
 windows (#29998)

Skip fetching hourly statistics when hours_to_show < 1 since hourly
aggregates produce stale outlier points in sub-hour chart windows
(e.g. hours_to_show: 0.1 or 0.05).

Also fix Date object handling in ha-chart-base downsampling bounds
extraction.
---
 src/components/chart/ha-chart-base.ts          | 18 ++++++++++++++----
 .../lovelace/cards/hui-history-graph-card.ts   |  4 ++++
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/src/components/chart/ha-chart-base.ts b/src/components/chart/ha-chart-base.ts
index e0c759cdfc..19f1d1bbe3 100644
--- a/src/components/chart/ha-chart-base.ts
+++ b/src/components/chart/ha-chart-base.ts
@@ -877,10 +877,20 @@ export class HaChartBase extends LitElement {
           };
         }
         if (s.sampling === "minmax") {
-          const minX =
-            xAxis?.min && typeof xAxis.min === "number" ? xAxis.min : undefined;
-          const maxX =
-            xAxis?.max && typeof xAxis.max === "number" ? xAxis.max : undefined;
+          const minX = xAxis?.min
+            ? xAxis.min instanceof Date
+              ? xAxis.min.getTime()
+              : typeof xAxis.min === "number"
+                ? xAxis.min
+                : undefined
+            : undefined;
+          const maxX = xAxis?.max
+            ? xAxis.max instanceof Date
+              ? xAxis.max.getTime()
+              : typeof xAxis.max === "number"
+                ? xAxis.max
+                : undefined
+            : undefined;
           return {
             ...s,
             sampling: undefined,
diff --git a/src/panels/lovelace/cards/hui-history-graph-card.ts b/src/panels/lovelace/cards/hui-history-graph-card.ts
index b570839860..23e40041f8 100644
--- a/src/panels/lovelace/cards/hui-history-graph-card.ts
+++ b/src/panels/lovelace/cards/hui-history-graph-card.ts
@@ -185,6 +185,10 @@ export class HuiHistoryGraphCard extends LitElement implements LovelaceCard {
   }
 
   private async _fetchStatistics(sensorNumericDeviceClasses: string[]) {
+    if (this._hoursToShow < 1) {
+      // Statistics are hourly aggregates, not useful for sub-hour windows
+      return;
+    }
     const now = new Date();
     const start = new Date();
     start.setHours(start.getHours() - this._hoursToShow - 1);