fix(presence): keep peers online across rApp navigation in same space

- Drop beforeunload leave broadcast — was flashing users offline during
  intra-space page nav between rApps
- Heartbeat 10s → 5s; GC stale threshold 15s → 12s
- Presence payload now carries userId; overlay keys peer map by userId
  so reconnects with a new WS peerId map back to the same row
- uniquePeers() prefers entries with module/context metadata so the panel
  shows which rApp a peer is in, even alongside cursor-only awareness

shared/collab-presence.ts

@@ -57,6 +57,7 @@ export function broadcastPresence(opts: PresenceOpts): void {
 		noteId: opts.noteId,
 		itemId: opts.itemId,
 		username: session.username,
+		userId: session.userId,
 		color: userColor(session.userId),
 	});
 }
@@ -75,21 +76,17 @@ export function broadcastLeave(): void {
 }
 
 /**
- * Start a 10-second heartbeat that broadcasts presence.
+ * Start a 5-second heartbeat that broadcasts presence.
  * Returns a cleanup function to stop the heartbeat.
  *
+ * No beforeunload leave — navigating between rApps in the same space would
+ * otherwise flash the user offline to peers. Peers GC us after ~12s if we
+ * truly close the tab.
+ *
  * @param getOpts - Called each heartbeat to get current presence state
  */
 export function startPresenceHeartbeat(getOpts: () => PresenceOpts): () => void {
 	broadcastPresence(getOpts());
-	const timer = setInterval(() => broadcastPresence(getOpts()), 10_000);
-
-	// Clean up immediately on page unload
-	const onUnload = () => broadcastLeave();
-	window.addEventListener('beforeunload', onUnload);
-
-	return () => {
-		clearInterval(timer);
-		window.removeEventListener('beforeunload', onUnload);
-	};
+	const timer = setInterval(() => broadcastPresence(getOpts()), 5_000);
+	return () => clearInterval(timer);
 }

shared/components/rstack-collab-overlay.ts

@@ -27,6 +27,7 @@ const PEER_COLORS = [
 
 interface PeerState {
 	peerId: string;
+	userId?: string;   // stable identity across page nav / peerId churn
 	username: string;
 	color: string;
 	cursor: { x: number; y: number } | null;
@@ -242,16 +243,25 @@ export class RStackCollabOverlay extends HTMLElement {
 			this.#connectToDoc();
 		}
 
-		// Listen for space-wide presence broadcasts (module context from all rApps)
+		// Listen for space-wide presence broadcasts (module context from all rApps).
+		// Key by userId when available so a peer navigating between rApps (new WS peerId
+		// each page) maps back to the same row instead of flashing offline.
 		this.#unsubPresence = runtime.onCustomMessage('presence', (msg: any) => {
 			if (!msg.username) return;
-			// Use peerId from server relay, or fall back to a hash of username
 			const pid = msg.peerId || `anon-${msg.username}`;
 			if (pid === this.#localPeerId) return; // ignore self
 
-			const existing = this.#peers.get(pid);
-			this.#peers.set(pid, {
+			const key = msg.userId || pid;
+			// Drop any stale entry keyed by the old peerId for this same userId
+			if (msg.userId) {
+				for (const [k, p] of this.#peers) {
+					if (k !== key && p.userId === msg.userId) this.#peers.delete(k);
+				}
+			}
+			const existing = this.#peers.get(key);
+			this.#peers.set(key, {
 				peerId: pid,
+				userId: msg.userId || existing?.userId,
 				username: msg.username || existing?.username || 'Anonymous',
 				color: msg.color || existing?.color || this.#colorForPeer(pid),
 				cursor: existing?.cursor ?? null,
@@ -499,7 +509,7 @@ export class RStackCollabOverlay extends HTMLElement {
 
 	#gcPeers() {
 		const now = Date.now();
-		const staleThreshold = this.#externalPeers ? 30000 : 15000;
+		const staleThreshold = this.#externalPeers ? 30000 : 12000;
 		let changed = false;
 		for (const [id, peer] of this.#peers) {
 			if (now - peer.lastSeen > staleThreshold) {
@@ -522,13 +532,27 @@ export class RStackCollabOverlay extends HTMLElement {
 		}
 	}
 
-	/** Deduplicate peers by username, keeping the most recently seen entry per user. */
+	/**
+	 * Deduplicate peers for display. Keyed by username (lowercase) so a user
+	 * appearing twice — e.g. old awareness entry (peerId-keyed) alongside a new
+	 * presence entry (userId-keyed) after navigating rApps — collapses to one
+	 * row. Prefers entries carrying module/context metadata so the panel shows
+	 * which rApp the peer is in.
+	 */
 	#uniquePeers(): PeerState[] {
 		const byName = new Map<string, PeerState>();
 		for (const peer of this.#peers.values()) {
 			const key = peer.username.toLowerCase();
 			const existing = byName.get(key);
-			if (!existing || peer.lastSeen > existing.lastSeen) {
+			if (!existing) {
+				byName.set(key, peer);
+				continue;
+			}
+			const peerHasMeta = !!(peer.module || peer.context);
+			const existingHasMeta = !!(existing.module || existing.context);
+			if (peerHasMeta && !existingHasMeta) {
+				byName.set(key, peer);
+			} else if (peerHasMeta === existingHasMeta && peer.lastSeen > existing.lastSeen) {
 				byName.set(key, peer);
 			}
 		}