fix: emit delta-only node system events

src/infra/system-events.ts

@@ -7,10 +7,30 @@ type SystemEvent = { text: string; ts: number };
 const MAX_EVENTS = 20;
 const queue: SystemEvent[] = [];
 let lastText: string | null = null;
+let lastContextKey: string | null = null;
 
-export function enqueueSystemEvent(text: string) {
+type SystemEventOptions = {
+  contextKey?: string | null;
+};
+
+function normalizeContextKey(key?: string | null): string | null {
+  if (!key) return null;
+  const trimmed = key.trim();
+  if (!trimmed) return null;
+  return trimmed.toLowerCase();
+}
+
+export function isSystemEventContextChanged(
+  contextKey?: string | null,
+): boolean {
+  const normalized = normalizeContextKey(contextKey);
+  return normalized !== lastContextKey;
+}
+
+export function enqueueSystemEvent(text: string, options?: SystemEventOptions) {
   const cleaned = text.trim();
   if (!cleaned) return;
+  lastContextKey = normalizeContextKey(options?.contextKey);
   if (lastText === cleaned) return; // skip consecutive duplicates
   lastText = cleaned;
   queue.push({ text: cleaned, ts: Date.now() });
@@ -21,6 +41,7 @@ export function drainSystemEvents(): string[] {
   const out = queue.map((e) => e.text);
   queue.length = 0;
   lastText = null;
+  lastContextKey = null;
   return out;
 }
 

src/infra/system-presence.ts

@@ -16,6 +16,14 @@ export type SystemPresence = {
   ts: number;
 };
 
+export type SystemPresenceUpdate = {
+  key: string;
+  previous?: SystemPresence;
+  next: SystemPresence;
+  changes: Partial<SystemPresence>;
+  changedKeys: (keyof SystemPresence)[];
+};
+
 const entries = new Map<string, SystemPresence>();
 const TTL_MS = 5 * 60 * 1000; // 5 minutes
 const MAX_ENTRIES = 200;
@@ -154,7 +162,9 @@ type SystemPresencePayload = {
   tags?: string[];
 };
 
-export function updateSystemPresence(payload: SystemPresencePayload) {
+export function updateSystemPresence(
+  payload: SystemPresencePayload,
+): SystemPresenceUpdate {
   ensureSelfPresence();
   const parsed = parsePresence(payload.text);
   const key =
@@ -164,6 +174,7 @@ export function updateSystemPresence(payload: SystemPresencePayload) {
     parsed.ip ||
     parsed.text.slice(0, 64) ||
     os.hostname().toLowerCase();
+  const hadExisting = entries.has(key);
   const existing = entries.get(key) ?? ({} as SystemPresence);
   const merged: SystemPresence = {
     ...existing,
@@ -185,6 +196,25 @@ export function updateSystemPresence(payload: SystemPresencePayload) {
     ts: Date.now(),
   };
   entries.set(key, merged);
+  const trackKeys = ["host", "ip", "version", "mode", "reason"] as const;
+  type TrackKey = (typeof trackKeys)[number];
+  const changes: Partial<Pick<SystemPresence, TrackKey>> = {};
+  const changedKeys: TrackKey[] = [];
+  for (const k of trackKeys) {
+    const prev = existing[k];
+    const next = merged[k];
+    if (prev !== next) {
+      changes[k] = next;
+      changedKeys.push(k);
+    }
+  }
+  return {
+    key,
+    previous: hadExisting ? existing : undefined,
+    next: merged,
+    changes,
+    changedKeys,
+  } satisfies SystemPresenceUpdate;
 }
 
 export function upsertPresence(key: string, presence: Partial<SystemPresence>) {