From ff5d81badacb0261b4b1a30cc9fd9abf79bceeb1 Mon Sep 17 00:00:00 2001
From: Cameron DeCoster <cameron.decoster@gmail.com>
Date: Mon, 25 Aug 2025 16:19:43 -0600
Subject: [PATCH 1/2] Calculate colorscale properly for histogram

---
 src/traces/histogram/calc.js | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/src/traces/histogram/calc.js b/src/traces/histogram/calc.js
index e705ddd36fa..ec10098692d 100644
--- a/src/traces/histogram/calc.js
+++ b/src/traces/histogram/calc.js
@@ -5,6 +5,9 @@ var isNumeric = require('fast-isnumeric');
 var Lib = require('../../lib');
 var Registry = require('../../registry');
 var Axes = require('../../plots/cartesian/axes');
+const { hasColorscale } = require('../../components/colorscale/helpers');
+const colorscaleCalc = require('../../components/colorscale/calc');
+
 
 var arraysToCalcdata = require('../bar/arrays_to_calcdata');
 var binFunctions = require('./bin_functions');
@@ -202,6 +205,22 @@ function calc(gd, trace) {
         cd[0].width1 = Axes.tickIncrement(cd[0].p, binSpec.size, false, calendar) - cd[0].p;
     }
 
+    // auto-z and autocolorscale if applicable
+    if(hasColorscale(trace, 'marker')) {
+        colorscaleCalc(gd, trace, {
+            vals: trace.marker.color,
+            containerStr: 'marker',
+            cLetter: 'c'
+        });
+    }
+    if(hasColorscale(trace, 'marker.line')) {
+        colorscaleCalc(gd, trace, {
+            vals: trace.marker.line.color,
+            containerStr: 'marker.line',
+            cLetter: 'c'
+        });
+    }
+
     arraysToCalcdata(cd, trace);
 
     if(Lib.isArrayOrTypedArray(trace.selectedpoints)) {

From dfc74027748cc3751f42fe9f3c347bf3170e2b5c Mon Sep 17 00:00:00 2001
From: Cameron DeCoster <cameron.decoster@gmail.com>
Date: Tue, 26 Aug 2025 09:24:22 -0600
Subject: [PATCH 2/2] Add draftlog

---
 draftlogs/7534_fix.md | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 draftlogs/7534_fix.md

diff --git a/draftlogs/7534_fix.md b/draftlogs/7534_fix.md
new file mode 100644
index 00000000000..7b7d6334c5d
--- /dev/null
+++ b/draftlogs/7534_fix.md
@@ -0,0 +1 @@
+- Calculate colorscale properly for histogram when marker `cmin`/`cmax`/`cmid` values are undefined [[#7534](https://github.com/plotly/plotly.js/pull/7534)]