From 786309b3fb7c3a02ba055fdcefa541e7d220f3e7 Mon Sep 17 00:00:00 2001
From: Ya-Fan Chen <20377719+Lexachoc@users.noreply.github.com>
Date: Thu, 15 Oct 2026 17:49:01 +0200
Subject: [PATCH 1/3] Fix interval constraint value normalization in contour
 traces

---
 src/traces/contour/constraint_defaults.js |  6 ++--
 test/jasmine/tests/contour_test.js        | 39 +++++++++++++++++++++++
 2 files changed, 42 insertions(+), 3 deletions(-)

diff --git a/src/traces/contour/constraint_defaults.js b/src/traces/contour/constraint_defaults.js
index 2b0178d940f..280bef22dd6 100644
--- a/src/traces/contour/constraint_defaults.js
+++ b/src/traces/contour/constraint_defaults.js
@@ -57,10 +57,10 @@ function handleConstraintValueDefaults(coerce, contours) {
                 contours.value = [zvalue, zvalue + 1];
             }
         } else if(contours.value.length > 2) {
-            contours.value = contours.value.slice(2);
-        } else if(contours.length === 0) {
+            contours.value = contours.value.slice(0, 2);
+        } else if(contours.value.length === 0) {
             contours.value = [0, 1];
-        } else if(contours.length < 2) {
+        } else if(contours.value.length < 2) {
             zvalue = parseFloat(contours.value[0]);
             contours.value = [zvalue, zvalue + 1];
         } else {
diff --git a/test/jasmine/tests/contour_test.js b/test/jasmine/tests/contour_test.js
index ae098a30702..5a842fce097 100644
--- a/test/jasmine/tests/contour_test.js
+++ b/test/jasmine/tests/contour_test.js
@@ -115,6 +115,45 @@ describe('contour defaults', function() {
         expect(traceOut.xcalendar).toBe('coptic');
         expect(traceOut.ycalendar).toBe('ethiopian');
     });
+
+    it('should coerce constraint interval values to two numbers', function() {
+        var specs = [
+            {
+                value: [],
+                expected: [0, 1]
+            },
+            {
+                value: [5],
+                expected: [5, 6]
+            },
+            {
+                value: [10, 20],
+                expected: [10, 20]
+            },
+            {
+                value: [10, 20, 30],
+                expected: [10, 20]
+            }
+        ];
+    
+        specs.forEach(function(spec) {
+            traceIn = {
+                type: 'contour',
+                z: [[0, 1], [2, 3]],
+                contours: {
+                    type: 'constraint',
+                    operation: '[]',
+                    value: spec.value
+                }
+            };
+    
+            traceOut = {};
+    
+            supplyDefaults(traceIn, traceOut, defaultColor, layout);
+    
+            expect(traceOut.contours.value).toEqual(spec.expected);
+        });
+    });
 });
 
 describe('contour makeColorMap', function() {

From 13379ae63a1388309c48c6c2c793f1136b82ef50 Mon Sep 17 00:00:00 2001
From: Ya-Fan Chen <20377719+Lexachoc@users.noreply.github.com>
Date: Thu, 15 Oct 2026 17:57:16 +0200
Subject: [PATCH 2/3] add draftlog

---
 draftlogs/8125.md | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 draftlogs/8125.md

diff --git a/draftlogs/8125.md b/draftlogs/8125.md
new file mode 100644
index 00000000000..19f43ac6ccf
--- /dev/null
+++ b/draftlogs/8125.md
@@ -0,0 +1 @@
+ - Fix normalization of `contours.value` for interval constraints in `contour` and `contourcarpet` [[#8125](https://github.com/plotly/plotly.js/pull/8125)]
\ No newline at end of file

From e26ff9c0d0797526e40e5daa085f12d04d5cdf7c Mon Sep 17 00:00:00 2001
From: Ya-Fan Chen <20377719+Lexachoc@users.noreply.github.com>
Date: Thu, 15 Oct 2026 17:59:20 +0200
Subject: [PATCH 3/3] Rename draftlogs/8125.md to draftlogs/8125_fix.md

---
 draftlogs/{8125.md => 8125_fix.md} | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
 rename draftlogs/{8125.md => 8125_fix.md} (82%)

diff --git a/draftlogs/8125.md b/draftlogs/8125_fix.md
similarity index 82%
rename from draftlogs/8125.md
rename to draftlogs/8125_fix.md
index 19f43ac6ccf..ed4aa06379b 100644
--- a/draftlogs/8125.md
+++ b/draftlogs/8125_fix.md
@@ -1 +1 @@
- - Fix normalization of `contours.value` for interval constraints in `contour` and `contourcarpet` [[#8125](https://github.com/plotly/plotly.js/pull/8125)]
\ No newline at end of file
+ - Fix normalization of `contours.value` for interval constraints in `contour` and `contourcarpet` [[#8125](https://github.com/plotly/plotly.js/pull/8125)]