First working version.

src/salvium_tipbot_common.php

@@ -0,0 +1,24 @@
+<?php
+function sendMessage(int $chatId, string $text, array $options = []): void {
+    global $config;
+    $url = "https://api.telegram.org/bot{$config['TELEGRAM_BOT_TOKEN']}/sendMessage";
+    $payload = array_merge(['chat_id' => $chatId, 'text' => $text], $options);
+
+    $ch = curl_init();
+    curl_setopt($ch, CURLOPT_URL, $url);
+    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
+    curl_setopt($ch, CURLOPT_POST, true);
+    curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($payload));
+    if (!empty($config['IPV4_ONLY'])) {
+        curl_setopt($ch, CURLOPT_IPRESOLVE, CURL_IPRESOLVE_V4);
+    }
+    curl_exec($ch);
+    curl_close($ch);
+}
+
+function isValidSalviumAddress(string $address): bool {
+    // Accepts standard and subaddress prefixes for Salvium (e.g. SaLvd, SaLvs)
+    return preg_match('/^SaLv[a-zA-Z0-9]{95}$/', $address) === 1;
+}
+
+?>