feat: surface system presence for the agent

src/infra/system-events.ts

@@ -0,0 +1,33 @@
+// Lightweight in-memory queue for human-readable system events that should be
+// prefixed to the next main-session prompt/heartbeat. We intentionally avoid
+// persistence to keep events ephemeral.
+
+type SystemEvent = { text: string; ts: number };
+
+const MAX_EVENTS = 20;
+const queue: SystemEvent[] = [];
+let lastText: string | null = null;
+
+export function enqueueSystemEvent(text: string) {
+  const cleaned = text.trim();
+  if (!cleaned) return;
+  if (lastText === cleaned) return; // skip consecutive duplicates
+  lastText = cleaned;
+  queue.push({ text: cleaned, ts: Date.now() });
+  if (queue.length > MAX_EVENTS) queue.shift();
+}
+
+export function drainSystemEvents(): string[] {
+  const out = queue.map((e) => e.text);
+  queue.length = 0;
+  lastText = null;
+  return out;
+}
+
+export function peekSystemEvents(): string[] {
+  return queue.map((e) => e.text);
+}
+
+export function hasSystemEvents() {
+  return queue.length > 0;
+}