Add private chat to multiplayer rooms

tests/multiplayer.test.ts

@@ -4,9 +4,45 @@ import {
   createRoomSchema,
   joinRoomSchema,
   roomGuessSchema,
+  chatMessageSchema,
 } from "../shared/multiplayer";
 
 const map = "00000000-0000-4000-8000-000000000000";
+test("chat accepts plain multilingual text and rejects blank, oversized or hidden-control messages", () => {
+  assert.equal(
+    chatMessageSchema.parse({ clientId: map, text: " Привет (: " }).text,
+    "Привет (:",
+  );
+  assert.equal(
+    chatMessageSchema.safeParse({ clientId: map, text: "x".repeat(500) })
+      .success,
+    true,
+  );
+  for (const text of [
+    "",
+    "   ",
+    "x".repeat(501),
+    "hidden\u202e",
+    "hidden\u0085",
+    "x\nname",
+    "x\u0000name",
+  ])
+    assert.equal(
+      chatMessageSchema.safeParse({ clientId: map, text }).success,
+      false,
+    );
+  assert.equal(
+    chatMessageSchema.safeParse({ clientId: "wrong", text: "hi" }).success,
+    false,
+  );
+  assert.equal(
+    chatMessageSchema.parse({
+      clientId: map,
+      text: "<script>alert(1)</script>",
+    }).text,
+    "<script>alert(1)</script>",
+  );
+});
 test("room limits include the owner and stay between 2 and 16", () => {
   for (const playerLimit of [2, 16])
     assert.equal(