diff --git a/ci/llgo-size/README.md b/ci/llgo-size/README.md
index bed1512..5bfc871 100644
--- a/ci/llgo-size/README.md
+++ b/ci/llgo-size/README.md
@@ -43,7 +43,9 @@ time use separate commit matrices on the same page; each cell is ranked against
 the other build modes for the same benchmark and commit, with smaller values
 receiving the stronger favorable background. Matrix rows are visually grouped
 by benchmark: the benchmark name appears once at the start of its build modes,
-and a full-width separator marks the next benchmark.
+and a full-width separator marks the next benchmark. The row set is the union
+of every published run, so a historical benchmark remains visible with `—` in
+commit columns where it was not produced.
 
 The `llgo-main-updated` repository-dispatch event from `xgo-dev/llgo` first
 updates `LLGO_COMMIT` on the benchmarks `main` branch, then explicitly starts a
diff --git a/ci/llgo-size/site/app.js b/ci/llgo-size/site/app.js
index f5e9770..d44067f 100644
--- a/ci/llgo-size/site/app.js
+++ b/ci/llgo-size/site/app.js
@@ -130,6 +130,14 @@ function benchmarkMap(document) {
   return new Map((document && document.benchmarks || []).map(function (item) { return [item.name, item]; }));
 }
 
+function benchmarkNamesFromDocuments(documents) {
+  const names = new Set();
+  documents.forEach(function (document) {
+    (document && document.benchmarks || []).forEach(function (benchmark) { names.add(benchmark.name); });
+  });
+  return Array.from(names).sort(function (a, b) { return a.localeCompare(b, undefined, { sensitivity: "base" }); });
+}
+
 function parseBuildTimes(text) {
   const lines = String(text || "").trim().split(/\r?\n/);
   if (lines.length < 2) return new Map();
@@ -563,8 +571,8 @@ async function main() {
     if (!response.ok) throw new Error("Cannot load the run index");
     state.index = await response.json();
     if (!state.index.runs || !state.index.runs.length) throw new Error("No benchmark runs are available");
-    const latest = await loadRun(state.index.runs[0]);
-    state.benchmarkNames = (latest.benchmarks || []).map(function (benchmark) { return benchmark.name; });
+    const documents = await Promise.all(state.index.runs.map(loadRun));
+    state.benchmarkNames = benchmarkNamesFromDocuments(documents);
     state.activeBenchmark = state.benchmarkNames[0] || "";
     configs.forEach(function (config) { state.activeConfigs.add(config); });
     dom.benchmarkSelect.innerHTML = state.benchmarkNames.map(function (name) { return '<option value="' + escapeHtml(name) + '">' + escapeHtml(name) + "</option>"; }).join("");