Reject an upload for a player who is back, and take an empty reply as stored

A player rejoining before the controller's reply was skipped by
reject_upload, and the join then kept the copy the controller refused.
The rejection now counts while the join still waits for its acquire
reply, which the controller sends after it.

A controller from before the upload response replies with nothing. That
failed validation on a newer host, so its uploads were never confirmed.
It is taken as stored, as before.

Co-Authored-By: Claude Fable 5.2 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JyNnVzRW4jPWaoWTxCyhM7

plugins/player_sync/messages.ts

@@ -269,12 +269,13 @@ export class UploadResponse {
 	) {
 	}
 
-	static jsonSchema = Type.Object({
-		"stored": Type.Boolean(),
+	// No type: a controller from before this response replies with nothing, which counts as stored
+	static jsonSchema = Type.Unsafe<{ stored: boolean } | undefined>({
+		properties: { "stored": { type: "boolean" } },
 	});
 
 	static fromJSON(json: Static<typeof UploadResponse.jsonSchema>) {
-		return new this(json.stored);
+		return new this(json?.stored ?? true);
 	}
 }
 

plugins/player_sync/module/player_sync.lua

@@ -735,10 +735,15 @@ end
 -- too, and then downloads what this save sent.
 function player_sync.reject_upload(player_name, generation)
 	local player = game.get_player(player_name)
-	if not player or player.connected then
+	if not player then
 		return
 	end
 	local script_data = get_script_data()
+	-- A player who is back already still waits for the acquire reply, which the controller sent after this one, and
+	-- that join then downloads. Past that reply the join has decided and this is not about the copy here any more.
+	if player.connected and not script_data.players_waiting_for_acquire[player_name] then
+		return
+	end
 	local player_record = script_data.players[player.name]
 	if not player_record or player_record.generation ~= generation then
 		return

plugins/player_sync/test/plugin.js

@@ -60,6 +60,14 @@ describe("player_sync plugin", function() {
 				assert(!validate({ instanceId: 1, playerName: "player", playerData: data }), `accepted ${deleted}`);
 			}
 		});
+		it("should take the empty reply of an older controller as a stored upload", function() {
+			const validate = lib.compile(msg.UploadResponse.jsonSchema);
+			assert(validate(undefined));
+			assert.equal(msg.UploadResponse.fromJSON(undefined).stored, true);
+			assert(validate({ stored: false }));
+			assert.equal(msg.UploadResponse.fromJSON({ stored: false }).stored, false);
+			assert(!validate({ stored: "no" }));
+		});
 		describe("SetPlayerDataRequest schema", function() {
 			const validate = lib.compile(msg.SetPlayerDataRequest.jsonSchema);
 			// Shaped like module/serialize.lua output