diff --git a/config/functions_queue.php b/config/functions_queue.php
index 91e9854..6481fcb 100644
--- a/config/functions_queue.php
+++ b/config/functions_queue.php
@@ -128,8 +128,21 @@ function _flush_email(array $row): void {
     // the EMAIL_DEV_REDIRECT safety net itself, including the [DEV] subject
     // prefix and the banner naming the original recipient, so that logic no
     // longer lives here.
-    require_once __DIR__ . '/../shared/platform-tools/functions_mail.php';
-    require_once __DIR__ . '/../shared/platform-tools/functions_settings.php';
+    // A bare require_once would be a FATAL when shared/platform-tools lags the
+    // pinned commit (this install is deployed by file upload, so it does lag).
+    // A fatal here kills the whole request; flush_message()'s catch never runs
+    // and the row stays in 'sending' forever with no explanation. Throwing puts
+    // the reason in last_error, where the Monitor page shows it.
+    $_ptRoot = __DIR__ . '/../shared/platform-tools/';
+    foreach (['functions_mail.php', 'functions_settings.php'] as $_ptFile) {
+        if (!is_file($_ptRoot . $_ptFile)) {
+            throw new RuntimeException(
+                "shared/platform-tools/{$_ptFile} em falta — o submódulo está desactualizado. "
+                . 'Actualize-o em Sistema → Actualizações.'
+            );
+        }
+        require_once $_ptRoot . $_ptFile;
+    }
 
     // Settings come from system_settings first, .env second -- the fleet-wide
     // standard. This install stores them there via setting_or_env(); this
diff --git a/config/functions_secrets.php b/config/functions_secrets.php
index 754d030..45f5756 100644
--- a/config/functions_secrets.php
+++ b/config/functions_secrets.php
@@ -17,7 +17,41 @@
 // (secret_encrypt, secret_decrypt, secret_is_encrypted, secret_mask,
 // secrets_available, SECRET_PREFIX) that the sysadmin pages already call.
 
-require_once dirname(__DIR__) . '/shared/platform-tools/compat_secrets.php';
+// Loaded on every request, so a hard require_once here takes the entire site
+// down — public pages included — whenever shared/platform-tools is older than
+// the code that needs it. That is not hypothetical: this install is deployed by
+// uploading files, and the submodule lags behind the rest of the tree every
+// time "Atualizar submódulo" fails. It did, and the site 500'd on a missing
+// compat_secrets.php with nothing but a PHP warning to explain it.
+//
+// So: degrade instead. Without the shared implementation the site keeps
+// serving, secrets are stored as-is, and secrets_available() reports false —
+// which is what the Comunicações page already renders a warning banner for.
+// Nothing silently pretends to be encrypted.
+$_compat_secrets = dirname(__DIR__) . '/shared/platform-tools/compat_secrets.php';
+if (is_file($_compat_secrets)) {
+    require_once $_compat_secrets;
+} else {
+    error_log(
+        '[secrets] shared/platform-tools/compat_secrets.php is missing — the submodule is '
+        . 'behind the pinned commit. Settings secrets are NOT encrypted until it is updated.'
+    );
+    if (!defined('SECRET_PREFIX'))              define('SECRET_PREFIX', 'enc:v1:');
+    if (!function_exists('secret_encrypt'))     { function secret_encrypt(string $plain): string { return $plain; } }
+    if (!function_exists('secret_decrypt'))     { function secret_decrypt(?string $stored): string { return (string) $stored; } }
+    if (!function_exists('secret_is_encrypted')){ function secret_is_encrypted(string $stored): bool { return str_starts_with($stored, SECRET_PREFIX); } }
+    if (!function_exists('secret_mask'))        { function secret_mask(string $plain, string $key = ''): string { return $plain === '' ? '' : '••••••••'; } }
+    if (!function_exists('secrets_available'))  { function secrets_available(): bool { return false; } }
+    if (!function_exists('secrets_key_available')) { function secrets_key_available(): bool { return false; } }
+    // Read paths used by the SMTP resolution below and by the Comunicações page.
+    if (!function_exists('platform_settings_secret_available')) { function platform_settings_secret_available(): bool { return false; } }
+    if (!function_exists('platform_settings_is_secret')) {
+        function platform_settings_is_secret(string $key): bool {
+            return (bool) preg_match('/_(password|secret|token|api_key)$/', $key);
+        }
+    }
+}
+unset($_compat_secrets);
 
 // ─── Read helpers (site-specific, not crypto) ────────────────────────────────
 //
diff --git a/views/sysadmin/comms.php b/views/sysadmin/comms.php
index fdaa506..0c40045 100644
--- a/views/sysadmin/comms.php
+++ b/views/sysadmin/comms.php
@@ -12,8 +12,27 @@ require __DIR__ . '/../../config/db.php';
 require __DIR__ . '/../../config/functions.php';
 $user = require_sysadmin();
 
-require_once __DIR__ . '/../../shared/platform-tools/functions_mail.php';
-require_once __DIR__ . '/../../shared/platform-tools/functions_settings.php';
+// Same reasoning as config/functions_queue.php: a stale submodule should show
+// an explanation, not a blank 500 on the page you would go to in order to
+// diagnose mail.
+$_ptRoot  = __DIR__ . '/../../shared/platform-tools/';
+$_ptMissing = [];
+foreach (['functions_mail.php', 'functions_settings.php'] as $_ptFile) {
+    is_file($_ptRoot . $_ptFile) ? require_once $_ptRoot . $_ptFile : $_ptMissing[] = $_ptFile;
+}
+if ($_ptMissing) {
+    $page_title = 'Comunicações';
+    include __DIR__ . '/../../includes/header.php';
+    echo '<div class="container" style="max-width:720px;"><div class="alert alert-danger">'
+       . '<h1 class="h5">Submódulo desactualizado</h1>'
+       . '<p class="mb-1">Faltam em <code>shared/platform-tools/</code>: <code>'
+       . htmlspecialchars(implode('</code>, <code>', $_ptMissing)) . '</code>.</p>'
+       . '<p class="mb-0">Actualize o submódulo em <a href="' . htmlspecialchars(base_url('views/sysadmin/platform_update.php'))
+       . '">Sistema → Actualizações</a> (ou envie a pasta por FTP) e volte a esta página.</p>'
+       . '</div></div>';
+    include __DIR__ . '/../../includes/footer.php';
+    exit;
+}
 
 $repo_root = dirname(__DIR__, 2);
 $saved     = false;