feat: add typing mode controls

src/auto-reply/reply/typing-mode.ts

@@ -0,0 +1,25 @@
+import type { TypingMode } from "../../config/types.js";
+
+export type TypingModeContext = {
+  configured?: TypingMode;
+  isGroupChat: boolean;
+  wasMentioned: boolean;
+  isHeartbeat: boolean;
+};
+
+export const DEFAULT_GROUP_TYPING_MODE: TypingMode = "message";
+
+export function resolveTypingMode({
+  configured,
+  isGroupChat,
+  wasMentioned,
+  isHeartbeat,
+}: TypingModeContext): TypingMode {
+  if (isHeartbeat) return "never";
+  if (configured) return configured;
+  if (!isGroupChat || wasMentioned) return "instant";
+  return DEFAULT_GROUP_TYPING_MODE;
+}
+
+export const shouldStartTypingImmediately = (mode: TypingMode) =>
+  mode === "instant";