The in-game live-event $effect read `view`/`moves`/`placement` (via cacheSnapshot
and direct reads) AND wrote `view` in its branches, so those reads became the
effect's own dependencies: writing `view = …` re-ran the effect, and with
app.lastEvent unchanged it re-entered the same branch and wrote `view` again — a
tight self-invalidating loop that pinned the main thread, freezing the board and
rack. opponent_moved escaped it only because applyMoveDelta is idempotent on the
move count (no cache → no write on the second pass); opponent_joined and game_over
have no such guard, so an opponent joining hung the whole screen. Tracking
`placement` similarly re-fired the handler on every tile the player placed after
an opponent's move (a spurious reload).
Fix: the effect must depend only on app.lastEvent and process each event once.
Wrap the branch body in `untrack`, scoping its view/moves/placement reads out of
the effect's dependency set; the writes inside no longer re-trigger it.
e2e: after the opponent joins, placing a rack tile must render a pending tile —
verified RED (frozen, 0 pending tiles, both engines) before the fix, GREEN after.
Ilia Denisov
1cc6c0d56e