Extract auto-reply helpers into modules

src/auto-reply/templating.ts

@@ -0,0 +1,20 @@
+export type MsgContext = {
+	Body?: string;
+	From?: string;
+	To?: string;
+	MessageSid?: string;
+};
+
+export type TemplateContext = MsgContext & {
+	BodyStripped?: string;
+	SessionId?: string;
+	IsNewSession?: string;
+};
+
+export function applyTemplate(str: string, ctx: TemplateContext) {
+	// Simple {{Placeholder}} interpolation using inbound message context.
+	return str.replace(/{{\s*(\w+)\s*}}/g, (_, key) => {
+		const value = (ctx as Record<string, unknown>)[key];
+		return value == null ? "" : String(value);
+	});
+}