From 05e5313ab80925cbab62c13fde85bfeed631ef13 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Wed, 20 May 2026 03:23:55 +0000
Subject: [PATCH] fix: sanitize defaultInherit values and dedupe applied
 templates

Agent-Logs-Url: https://github.com/helmfile/helmfile/sessions/85a8e815-3701-4b48-a28d-6bb2d50a3b40

Co-authored-by: yxxhero <11087727+yxxhero@users.noreply.github.com>
---
 pkg/state/state.go                | 34 +++++++++++++++++++++++++------
 pkg/state/state_exec_tmpl.go      |  9 ++++++++
 pkg/state/state_exec_tmpl_test.go | 21 +++++++++++++++++++
 3 files changed, 58 insertions(+), 6 deletions(-)

diff --git a/pkg/state/state.go b/pkg/state/state.go
index 2eafa151..181f36f2 100644
--- a/pkg/state/state.go
+++ b/pkg/state/state.go
@@ -522,19 +522,41 @@ func (r *Inherits) UnmarshalYAML(unmarshal func(any) error) error {
 type DefaultInherits []string
 
 func (r *DefaultInherits) UnmarshalYAML(unmarshal func(any) error) error {
-	var single string
-	if err := unmarshal(&single); err == nil {
-		*r = []string{single}
+	var list []string
+	if err := unmarshal(&list); err == nil {
+		*r = normalizeDefaultInherits(list)
 		return nil
 	}
-	var list []string
-	if err := unmarshal(&list); err != nil {
+
+	var single string
+	if err := unmarshal(&single); err != nil {
 		return err
 	}
-	*r = list
+	*r = normalizeDefaultInherits([]string{single})
 	return nil
 }
 
+func normalizeDefaultInherits(in []string) []string {
+	if len(in) == 0 {
+		return nil
+	}
+
+	out := make([]string, 0, len(in))
+	for _, name := range in {
+		name = strings.TrimSpace(name)
+		if name == "" {
+			continue
+		}
+		out = append(out, name)
+	}
+
+	if len(out) == 0 {
+		return nil
+	}
+
+	return out
+}
+
 // ChartPathOrName returns ChartPath if it is non-empty, and returns Chart otherwise.
 // This is useful to redirect helm commands like `helm template`, `helm dependency update`, `helm diff`, and `helm upgrade --install` to
 // our modified version of the chart, in case the user configured Helmfile to do modify the chart before being passed to Helm.
diff --git a/pkg/state/state_exec_tmpl.go b/pkg/state/state_exec_tmpl.go
index b838e964..9e77912b 100644
--- a/pkg/state/state_exec_tmpl.go
+++ b/pkg/state/state_exec_tmpl.go
@@ -237,13 +237,22 @@ func (st *HelmState) applyDefaultInherit(releaseInherit Inherits) Inherits {
 
 	existing := make(map[string]bool, len(releaseInherit))
 	for _, inh := range releaseInherit {
+		if inh.Template == "" {
+			continue
+		}
 		existing[inh.Template] = true
 	}
 
 	result := make(Inherits, 0, len(st.DefaultInherit)+len(releaseInherit))
 	for _, name := range st.DefaultInherit {
+		name = strings.TrimSpace(name)
+		if name == "" {
+			continue
+		}
+
 		if !existing[name] {
 			result = append(result, Inherit{Template: name})
+			existing[name] = true
 		}
 	}
 	result = append(result, releaseInherit...)
diff --git a/pkg/state/state_exec_tmpl_test.go b/pkg/state/state_exec_tmpl_test.go
index 7da374bd..d66a1bb7 100644
--- a/pkg/state/state_exec_tmpl_test.go
+++ b/pkg/state/state_exec_tmpl_test.go
@@ -334,6 +334,12 @@ func TestApplyDefaultInherit(t *testing.T) {
 			releaseInherit: nil,
 			want:           Inherits{{Template: "default"}},
 		},
+		{
+			name:           "default inherit deduplicates and skips empty values",
+			defaultInherit: DefaultInherits{"default", " ", "default", "ops"},
+			releaseInherit: Inherits{{Template: "foo"}},
+			want:           Inherits{{Template: "default"}, {Template: "ops"}, {Template: "foo"}},
+		},
 	}
 
 	for i := range tests {
@@ -437,6 +443,21 @@ func TestDefaultInherits_UnmarshalYAML(t *testing.T) {
 			input: `["a", "b"]`,
 			want:  DefaultInherits{"a", "b"},
 		},
+		{
+			name:  "null value",
+			input: `null`,
+			want:  nil,
+		},
+		{
+			name:  "empty string value",
+			input: `""`,
+			want:  nil,
+		},
+		{
+			name:  "list trims and drops empty names",
+			input: `[" a ", "", " ", "b"]`,
+			want:  DefaultInherits{"a", "b"},
+		},
 	}
 
 	for _, tt := range tests {