fix(sync): keep session renames stable (#2043)

* fix(sync): keep session renames stable

* fix(sync): clarify rename mirror flow

* fix(sync): clarify archive comment

---------

Co-authored-by: bashrusakh <bashrusakh@users.noreply.github.com>
Co-authored-by: Bohdan Triapitsyn <artmore@protonmail.com>

packages/ui/src/sync/session-event-freshness.ts

@@ -0,0 +1,15 @@
+import type { Session } from "@opencode-ai/sdk/v2"
+
+const getSessionRecencyTimestamp = (session: Session): number => {
+  const updatedAt = session.time?.updated
+  if (typeof updatedAt === "number" && Number.isFinite(updatedAt)) {
+    return updatedAt
+  }
+  const createdAt = session.time?.created
+  return typeof createdAt === "number" && Number.isFinite(createdAt) ? createdAt : 0
+}
+
+export const shouldSkipStaleSessionEvent = (currentSession: Session | null, incomingSession: Session): boolean => {
+  if (!currentSession) return false
+  return getSessionRecencyTimestamp(incomingSession) < getSessionRecencyTimestamp(currentSession)
+}