fix(bot): harden webhook processing and purchase defaults

apps/bot/src/telegram-chat-action.ts

@@ -0,0 +1,55 @@
+import type { Context } from 'grammy'
+
+const TYPING_REFRESH_INTERVAL_MS = 4_000
+
+export interface ActiveChatAction {
+  stop(): void
+}
+
+export function startTypingIndicator(ctx: Context): ActiveChatAction {
+  const chatId = ctx.chat?.id
+  if (!chatId) {
+    return {
+      stop() {}
+    }
+  }
+
+  const messageThreadId =
+    ctx.msg && 'message_thread_id' in ctx.msg ? ctx.msg.message_thread_id : undefined
+
+  let active = true
+
+  const sendTypingAction = async () => {
+    if (!active) {
+      return
+    }
+
+    const options =
+      messageThreadId !== undefined
+        ? {
+            message_thread_id: messageThreadId
+          }
+        : undefined
+
+    try {
+      await ctx.api.sendChatAction(chatId, 'typing', options)
+    } catch {}
+  }
+
+  void sendTypingAction()
+
+  const interval = setInterval(() => {
+    void sendTypingAction()
+  }, TYPING_REFRESH_INTERVAL_MS)
+
+  if (typeof interval.unref === 'function') {
+    interval.unref()
+  }
+
+  return {
+    stop() {
+      active = false
+      clearInterval(interval)
+    }
+  }
+}