fix(discord): route audioAsVoice payloads through voice message API

deliverDiscordReply now checks payload.audioAsVoice and routes through
sendVoiceMessageDiscord instead of sendMessageDiscord when true.

This matches the existing Telegram behavior where audioAsVoice triggers
the voice message path (wantsVoice: true).

Fixes #17990

src/discord/monitor/reply-delivery.ts

@@ -5,7 +5,7 @@ import type { MarkdownTableMode } from "../../config/types.base.js";
 import type { RuntimeEnv } from "../../runtime.js";
 import { convertMarkdownTables } from "../../markdown/tables.js";
 import { chunkDiscordTextWithMode } from "../chunk.js";
-import { sendMessageDiscord } from "../send.js";
+import { sendMessageDiscord, sendVoiceMessageDiscord } from "../send.js";
 
 export async function deliverDiscordReply(params: {
   replies: ReplyPayload[];
@@ -62,6 +62,35 @@ export async function deliverDiscordReply(params: {
     if (!firstMedia) {
       continue;
     }
+
+    // Voice message path: audioAsVoice flag routes through sendVoiceMessageDiscord
+    if (payload.audioAsVoice) {
+      await sendVoiceMessageDiscord(params.target, firstMedia, {
+        token: params.token,
+        rest: params.rest,
+        accountId: params.accountId,
+        replyTo,
+      });
+      // Voice messages cannot include text; send remaining text separately if present
+      if (text.trim()) {
+        await sendMessageDiscord(params.target, text, {
+          token: params.token,
+          rest: params.rest,
+          accountId: params.accountId,
+        });
+      }
+      // Additional media items are sent as regular attachments (voice is single-file only)
+      for (const extra of mediaList.slice(1)) {
+        await sendMessageDiscord(params.target, "", {
+          token: params.token,
+          rest: params.rest,
+          mediaUrl: extra,
+          accountId: params.accountId,
+        });
+      }
+      continue;
+    }
+
     await sendMessageDiscord(params.target, text, {
       token: params.token,
       rest: params.rest,