diff --git a/packages/runs/src/runs.mjs b/packages/runs/src/runs.mjs
index 03730c33..3814b6a5 100644
--- a/packages/runs/src/runs.mjs
+++ b/packages/runs/src/runs.mjs
@@ -26,7 +26,7 @@ export function listRunIds(dataRoot) {
     if (isMissing(error)) return [];
     throw new RunsError(`cannot read ${root}: ${error.code ?? error.message}`);
   }
-  return names.filter((name) => name.startsWith("r-")).sort();
+  return names.filter(isRunId).sort();
 }
 
 // One of RUN_DOCUMENTS from a run, or null when it is missing, unreadable,