From a0d4a74c5ebe40331f571a3648315e9d8a2ec011 Mon Sep 17 00:00:00 2001
From: themavik <themavik@users.noreply.github.com>
Date: Thu, 19 Mar 2026 08:46:20 -0400
Subject: [PATCH 1/2] fix: allow null values from --values to override parent
 chart values

Fixes #31919. Null values in override files now correctly remove parent chart defaults.

Made-with: Cursor
---
 pkg/chart/common/util/coalesce.go | 20 ++++++--------------
 1 file changed, 6 insertions(+), 14 deletions(-)

diff --git a/pkg/chart/common/util/coalesce.go b/pkg/chart/common/util/coalesce.go
index 5994febbc..7b3dbe8c5 100644
--- a/pkg/chart/common/util/coalesce.go
+++ b/pkg/chart/common/util/coalesce.go
@@ -302,28 +302,20 @@ func coalesceTablesFullKey(printf printFn, dst, src map[string]any, prefix strin
 	if dst == nil {
 		return src
 	}
-	// Track original non-nil src keys before modifying src
-	// This lets us distinguish between user nullifying a chart default vs
-	// user setting nil for a key not in chart defaults.
-	srcOriginalNonNil := make(map[string]bool)
-	for key, val := range src {
-		if val != nil {
-			srcOriginalNonNil[key] = true
-		}
-	}
 	for key, val := range dst {
 		if val == nil {
-			src[key] = nil
+			if _, inSrc := src[key]; inSrc {
+				src[key] = nil
+			}
 		}
 	}
 	// Because dest has higher precedence than src, dest values override src
 	// values.
 	for key, val := range src {
 		fullkey := concatPrefix(prefix, key)
-		if dv, ok := dst[key]; ok && !merge && dv == nil && srcOriginalNonNil[key] {
-			// When coalescing (not merging), if dst has nil and src has a non-nil
-			// value, the user is nullifying a chart default - remove the key.
-			// But if src also has nil (or key not in src), preserve the nil
+		if dv, ok := dst[key]; ok && !merge && dv == nil {
+			// When coalescing (not merging), if dst has nil, remove the key.
+			// This allows null from --values to override and remove parent chart defaults.
 			delete(dst, key)
 		} else if !ok {
 			// key not in user values, preserve src value (including nil)

From a8fec71650782443c529f420845c1eeaeb699ed1 Mon Sep 17 00:00:00 2001
From: themavik <themavik@users.noreply.github.com>
Date: Thu, 19 Mar 2026 08:58:49 -0400
Subject: [PATCH 2/2] test: add regression test for null values merge (#31919)

Signed-off-by: themavik <themavik@users.noreply.github.com>
Made-with: Cursor
---
 pkg/chart/common/util/coalesce_test.go | 27 ++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/pkg/chart/common/util/coalesce_test.go b/pkg/chart/common/util/coalesce_test.go
index 1d0baa84d..068b279eb 100644
--- a/pkg/chart/common/util/coalesce_test.go
+++ b/pkg/chart/common/util/coalesce_test.go
@@ -765,3 +765,30 @@ func TestCoalesceValuesEmptyMapWithNils(t *testing.T) {
 	is.True(ok, "Expected data.baz key to be present but it was removed")
 	is.Nil(data["baz"], "Expected data.baz key to be nil but it is not")
 }
+
+
+// TestCoalesceTablesNullNullRegression tests regression #31919: when lower-precedence map has key with nil
+// and override also sets it to null, the key should be removed from coalesced values.
+func TestCoalesceTablesNullNullRegression(t *testing.T) {
+	tests := []struct {
+		name     string
+		dst      map[string]any
+		src      map[string]any
+		expected map[string]any
+	}{
+		{
+			name:     "null values merge regression #31919",
+			dst:      map[string]any{"key": nil},
+			src:      map[string]any{"key": nil},
+			expected: map[string]any{},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			dst := make(map[string]any)
+			maps.Copy(dst, tt.dst)
+			CoalesceTables(dst, tt.src)
+			assert.Equal(t, tt.expected, dst)
+		})
+	}
+}