fix: format verbose tool output by channel

src/utils/message-channel.ts

@@ -17,6 +17,15 @@ import { getActivePluginRegistry } from "../plugins/runtime.js";
 export const INTERNAL_MESSAGE_CHANNEL = "webchat" as const;
 export type InternalMessageChannel = typeof INTERNAL_MESSAGE_CHANNEL;
 
+const MARKDOWN_CAPABLE_CHANNELS = new Set<string>([
+  "slack",
+  "telegram",
+  "signal",
+  "discord",
+  "tui",
+  INTERNAL_MESSAGE_CHANNEL,
+]);
+
 export { GATEWAY_CLIENT_NAMES, GATEWAY_CLIENT_MODES };
 export type { GatewayClientName, GatewayClientMode };
 export { normalizeGatewayClientName, normalizeGatewayClientMode };
@@ -112,3 +121,9 @@ export function resolveMessageChannel(
 ): string | undefined {
   return normalizeMessageChannel(primary) ?? normalizeMessageChannel(fallback);
 }
+
+export function isMarkdownCapableMessageChannel(raw?: string | null): boolean {
+  const channel = normalizeMessageChannel(raw);
+  if (!channel) return false;
+  return MARKDOWN_CAPABLE_CHANNELS.has(channel);
+}