refactor(telegram): simplify send/dispatch/target handling (#17819)

Merged via /review-pr -> /prepare-pr -> /merge-pr.

Prepared head SHA: fcb7aeeca3
Co-authored-by: obviyus <22031114+obviyus@users.noreply.github.com>
Co-authored-by: obviyus <22031114+obviyus@users.noreply.github.com>
Reviewed-by: @obviyus

src/telegram/targets.ts

@@ -1,6 +1,7 @@
 export type TelegramTarget = {
   chatId: string;
   messageThreadId?: number;
+  chatType: "direct" | "group" | "unknown";
 };
 
 export function stripTelegramInternalPrefixes(to: string): string {
@@ -33,6 +34,17 @@ export function stripTelegramInternalPrefixes(to: string): string {
  * - `chatId:topicId` (numeric topic/thread ID)
  * - `chatId:topic:topicId` (explicit topic marker; preferred)
  */
+function resolveTelegramChatType(chatId: string): "direct" | "group" | "unknown" {
+  const trimmed = chatId.trim();
+  if (!trimmed) {
+    return "unknown";
+  }
+  if (/^-?\d+$/.test(trimmed)) {
+    return trimmed.startsWith("-") ? "group" : "direct";
+  }
+  return "unknown";
+}
+
 export function parseTelegramTarget(to: string): TelegramTarget {
   const normalized = stripTelegramInternalPrefixes(to);
 
@@ -41,6 +53,7 @@ export function parseTelegramTarget(to: string): TelegramTarget {
     return {
       chatId: topicMatch[1],
       messageThreadId: Number.parseInt(topicMatch[2], 10),
+      chatType: resolveTelegramChatType(topicMatch[1]),
     };
   }
 
@@ -49,8 +62,16 @@ export function parseTelegramTarget(to: string): TelegramTarget {
     return {
       chatId: colonMatch[1],
       messageThreadId: Number.parseInt(colonMatch[2], 10),
+      chatType: resolveTelegramChatType(colonMatch[1]),
     };
   }
 
-  return { chatId: normalized };
+  return {
+    chatId: normalized,
+    chatType: resolveTelegramChatType(normalized),
+  };
+}
+
+export function resolveTelegramTargetChatType(target: string): "direct" | "group" | "unknown" {
+  return parseTelegramTarget(target).chatType;
 }