Plugin Conflicts Guardian: default pcg_guard_activation to true

projects/packages/jetpack-mu-wpcom/changelog/pcg-guard-activation-default-true

@@ -0,0 +1,4 @@
+Significance: minor
+Type: changed
+
+Plugin Conflicts Guardian: pcg_guard_activation now defaults to true, enabling the activation probe and install/update parse-error gate by default.

projects/packages/jetpack-mu-wpcom/src/features/plugin-conflicts-guardian/README.md

@@ -2,10 +2,10 @@
 
 Pre-flight plugin-activation check. When an admin clicks Activate (or finishes an Upload Plugin install), this feature loads the plugin in an isolated HTTP request and refuses the activation if that probe captures a fatal — the site stays up instead of entering recovery mode.
 
-Ships dark. Three independent filters, all default `false`:
+Two independent filters:
 
-- `pcg_guard_activation` — enables the activation probe and the syntax-only install/update gate.
-- `pcg_guard_updates` — enables the post-update health check + rollback flow.
+- `pcg_guard_activation` — enables the activation probe and the syntax-only install/update gate. Defaults `true`.
+- `pcg_guard_updates` — enables the post-update health check + rollback flow. Defaults `false`.
 
 ## Files
 

projects/packages/jetpack-mu-wpcom/src/features/plugin-conflicts-guardian/activation-guard.php

@@ -15,7 +15,7 @@
  * plugin being activated and redirects with a notice on any failure.
  */
 function pcg_guard_maybe_block_activation() {
-	if ( ! apply_filters( 'pcg_guard_activation', false ) ) {
+	if ( ! apply_filters( 'pcg_guard_activation', true ) ) {
 		return;
 	}
 	if ( ! current_user_can( 'activate_plugins' ) ) {

projects/packages/jetpack-mu-wpcom/src/features/plugin-conflicts-guardian/probe-endpoint.php

@@ -49,8 +49,10 @@ function pcg_maybe_handle_probe() {
 	// Gate per mode: activation probes need pcg_guard_activation, update
 	// probes need pcg_guard_updates. Otherwise enabling either flow would
 	// pull in the other as an unintended dependency.
-	$gate_filter = PCG_Load_Tester::MODE_UPDATE === $mode ? 'pcg_guard_updates' : 'pcg_guard_activation';
-	if ( ! apply_filters( $gate_filter, false ) ) {
+	$is_update_mode = PCG_Load_Tester::MODE_UPDATE === $mode;
+	$gate_filter    = $is_update_mode ? 'pcg_guard_updates' : 'pcg_guard_activation';
+	$gate_default   = ! $is_update_mode;
+	if ( ! apply_filters( $gate_filter, $gate_default ) ) {
 		pcg_probe_bail_error( 'Plugin Conflicts Guardian is disabled.', 403 );
 	}
 

projects/packages/jetpack-mu-wpcom/src/features/plugin-conflicts-guardian/update-guard.php

@@ -32,7 +32,7 @@ function pcg_update_guard_check( $source, $remote_source, $upgrader, $hook_extra
 	if ( is_wp_error( $source ) ) {
 		return $source;
 	}
-	if ( ! apply_filters( 'pcg_guard_activation', false ) ) {
+	if ( ! apply_filters( 'pcg_guard_activation', true ) ) {
 		return $source;
 	}
 	$type   = $hook_extra['type'] ?? '';