docs: file #356 closed-issue record for the focus-loss crash

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

docs/ISSUES.md

@@ -24,6 +24,19 @@ What does NOT go here:
 - Every session: scan OPEN issues at start; promote/close anything we touched during the session before ending.
 - Promoting to a Phase: mark as `DONE (promoted to Phase X)` + commit SHA where the Phase entry landed.
 
+## #356 — Alt-tab during login crashed the client: focus loss faulted on an unpublished movement controller
+
+**Status:** CLOSED 2026-08-08 — `972c7ab3`. Window focus loss runs
+`MouseLookController.EndForLifecycle` → `PlayerMovementController.EndMouseLook`,
+whose `EnsurePublishedForRuntimeOperation` throws for a controller that exists
+but is UNPUBLISHED (mid-login) or retired (post-logout); a focus callback can
+land in either window, so alt-tabbing during the login stream killed the
+process with an unhandled `InvalidOperationException`. Hit live during the
+Campaign A listening-session launches. Fixed by completing the existing
+null-guard with `CanExecuteLiveMovement` (the exact lifecycle set the throw
+helper accepts); cursor restore still runs unconditionally, and
+published-controller behaviour is unchanged.
+
 ## #357 — Login stalls: reveal reaches ready=True but the player is never placed; UI + sky render, world never opens
 
 **Status:** OPEN — filed 2026-08-08 during the Campaign A listening session,