Document first-report ordering limitation (Refs #144)

docs/guides/beta-test-plans.md

@@ -214,9 +214,18 @@ key starts a new game before the previous keyed game's `game_end` arrives,
 Matches labels the previous game **End report missing**. A later `game_end`
 completes its own match without changing the newer game. Missing sequence counts
 are diagnostic: they do not invent absent rounds, rosters, or an ending.
-Duplicate and older reports do not advance beta requirements or replace the
-current scoreboard. A successful response acknowledges the submitted report;
-it does not mean that report became the current game state.
+Duplicate sequences, lower-sequence reports, and reports for known older keys do
+not advance beta requirements or replace the current scoreboard. A successful
+response acknowledges the submitted report; it does not mean that report became
+the current game state.
+
+Preserve delivery order across games as well: keep queued retries ahead of
+newer games' reports. An unseen key is always treated as the next game, even if
+its first report was delayed from an older game. `seq` cannot resolve this because
+it orders reports only within a game. A persistent per-server game counter or
+equivalent ordering metadata would require a protocol extension. See the
+[first-report ordering limitation](leaderboard.md#persistence-and-match-boundaries)
+for its effect on match history and the live scoreboard.
 
 Electric Cherry saves the latest accepted report, including player stats, and
 streams it to connected clients. A new start clears the previous round display;