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/event-reducer.ts

@@ -14,6 +14,7 @@ import type { FileDiff, GlobalState, State } from "./types"
 import { dropSessionCaches } from "./session-cache"
 import { stripSessionDiffSnapshots } from "./sanitize"
 import { syncDebug } from "./debug"
+import { shouldSkipStaleSessionEvent } from "./session-event-freshness"
 
 const SKIP_PARTS = new Set(["patch", "step-start", "step-finish"])
 const DELTA_OVERLAP_FIELDS = ["text", "output"] as const
@@ -226,6 +227,9 @@ export function applyDirectoryEvent(
       const info = stripSessionDiffSnapshots((event.properties as { info: Session }).info)
       const sessions = draft.session
       const result = Binary.search(sessions, info.id, (s) => s.id)
+      if (result.found && shouldSkipStaleSessionEvent(sessions[result.index], info)) {
+        return false
+      }
       if (result.found) {
         sessions[result.index] = info
       } else {
@@ -240,6 +244,13 @@ export function applyDirectoryEvent(
       const info = stripSessionDiffSnapshots((event.properties as { info: Session }).info)
       const sessions = draft.session
       const result = Binary.search(sessions, info.id, (s) => s.id)
+      // Keep the freshness check ahead of the archive branch: direct archive
+      // responses handle the store update on their own (optimistic removal +
+      // SDK response), so stale SSE echoes should not win just because they
+      // mark the session archived.
+      if (result.found && shouldSkipStaleSessionEvent(sessions[result.index], info)) {
+        return false
+      }
 
       if (info.time.archived) {
         if (result.found) sessions.splice(result.index, 1)