From 03ad22535623f03ce4af84cc119e7ab79a67848a Mon Sep 17 00:00:00 2001
From: Dhrupo <dhrupo@gmail.com>
Date: Fri, 6 Nov 2026 23:43:53 +0600
Subject: [PATCH 1/2] Report an error when `wp theme mod set` cannot save the
 value

---
 features/theme-mod.feature | 18 ++++++++++++++++++
 src/Theme_Mod_Command.php  |  2 +-
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/features/theme-mod.feature b/features/theme-mod.feature
index 24ad1d71..3609627f 100644
--- a/features/theme-mod.feature
+++ b/features/theme-mod.feature
@@ -159,6 +159,24 @@ Feature: Manage WordPress theme mods
       Success: Theme mod background_color set to 123456.
       """
 
+  Scenario: Setting a theme mod that does not get saved
+    Given a WP install
+    And a wp-content/mu-plugins/override-theme-mod.php file:
+      """
+      <?php
+      add_filter( 'pre_set_theme_mod_background_color', function () {
+        return 'ffffff';
+      } );
+      """
+
+    When I try `wp theme mod set background_color 123456`
+    Then STDERR should be:
+      """
+      Error: Could not update theme mod background_color.
+      """
+    And STDOUT should be empty
+    And the return code should be 1
+
   Scenario: Removing theme mods
     Given a WP install
 
diff --git a/src/Theme_Mod_Command.php b/src/Theme_Mod_Command.php
index 9fd08a0d..5aebf779 100644
--- a/src/Theme_Mod_Command.php
+++ b/src/Theme_Mod_Command.php
@@ -341,7 +341,7 @@ public function set( $args, $assoc_args ) {
 		if ( get_theme_mod( $mod ) === $value ) {
 			WP_CLI::success( "Theme mod {$mod} set to {$value}." );
 		} else {
-			WP_CLI::success( "Could not update theme mod {$mod}." );
+			WP_CLI::error( "Could not update theme mod {$mod}." );
 		}
 	}
 }

From ee9e5074d8929068f3c5402f1bc23d476b680f74 Mon Sep 17 00:00:00 2001
From: Dhrupo <dhrupo@gmail.com>
Date: Sat, 7 Nov 2026 00:29:48 +0600
Subject: [PATCH 2/2] Compare the stored theme mod when checking that `wp theme
 mod set` saved it

---
 features/theme-mod.feature | 16 ++++++++++++++++
 src/Theme_Mod_Command.php  |  4 +++-
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/features/theme-mod.feature b/features/theme-mod.feature
index 3609627f..4fe86cae 100644
--- a/features/theme-mod.feature
+++ b/features/theme-mod.feature
@@ -177,6 +177,22 @@ Feature: Manage WordPress theme mods
     And STDOUT should be empty
     And the return code should be 1
 
+  Scenario: Setting a theme mod whose value is changed when it is read
+    Given a WP install
+    And a wp-content/mu-plugins/filter-theme-mod.php file:
+      """
+      <?php
+      add_filter( 'theme_mod_background_color', function () {
+        return 'ffffff';
+      } );
+      """
+
+    When I run `wp theme mod set background_color 123456`
+    Then STDOUT should be:
+      """
+      Success: Theme mod background_color set to 123456.
+      """
+
   Scenario: Removing theme mods
     Given a WP install
 
diff --git a/src/Theme_Mod_Command.php b/src/Theme_Mod_Command.php
index 5aebf779..c1646e00 100644
--- a/src/Theme_Mod_Command.php
+++ b/src/Theme_Mod_Command.php
@@ -338,7 +338,9 @@ public function set( $args, $assoc_args ) {
 
 		set_theme_mod( $mod, $value );
 
-		if ( get_theme_mod( $mod ) === $value ) {
+		// Read the stored mods, as a theme_mod_{$mod} filter can change get_theme_mod() without changing what was saved.
+		$mods = get_theme_mods();
+		if ( isset( $mods[ $mod ] ) && $mods[ $mod ] === $value ) {
 			WP_CLI::success( "Theme mod {$mod} set to {$value}." );
 		} else {
 			WP_CLI::error( "Could not update theme mod {$mod}." );