refactor: unify typing dispatch lifecycle and policy boundaries

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

@@ -0,0 +1,35 @@
+import { INTERNAL_MESSAGE_CHANNEL } from "../../utils/message-channel.js";
+import type { TypingPolicy } from "../types.js";
+
+export type ResolveRunTypingPolicyParams = {
+  requestedPolicy?: TypingPolicy;
+  suppressTyping?: boolean;
+  isHeartbeat?: boolean;
+  originatingChannel?: string;
+  systemEvent?: boolean;
+};
+
+export type ResolvedRunTypingPolicy = {
+  typingPolicy: TypingPolicy;
+  suppressTyping: boolean;
+};
+
+export function resolveRunTypingPolicy(
+  params: ResolveRunTypingPolicyParams,
+): ResolvedRunTypingPolicy {
+  const typingPolicy = params.isHeartbeat
+    ? "heartbeat"
+    : params.originatingChannel === INTERNAL_MESSAGE_CHANNEL
+      ? "internal_webchat"
+      : params.systemEvent
+        ? "system_event"
+        : (params.requestedPolicy ?? "auto");
+
+  const suppressTyping =
+    params.suppressTyping === true ||
+    typingPolicy === "heartbeat" ||
+    typingPolicy === "system_event" ||
+    typingPolicy === "internal_webchat";
+
+  return { typingPolicy, suppressTyping };
+}