fix: collision-free (seed,label) encoding in rollFor (review)

2026-06-12 13:57:20 +00:00
parent 52d5008cdf
commit 3682205580
1 changed files with 3 additions and 1 deletions
@@ -24,5 +24,7 @@ export function makeRng(seed) {
 // This is the whole hidden-variable mechanism: outcomes are fixed
 // the moment their label exists, revealed whenever first asked for.
 export function rollFor(seed, label) {
-  return makeRng(hash32(seed + ':' + label))();
+  // Length-prefix the seed so (seed, label) -> string is injective
+  // even though seeds and labels themselves contain ':'.
+  return makeRng(hash32(seed.length + ':' + seed + ':' + label))();
 }