diff --git a/.github/workflows/llgo-binary-size.yml b/.github/workflows/llgo-binary-size.yml
index 63f0513..167285a 100644
--- a/.github/workflows/llgo-binary-size.yml
+++ b/.github/workflows/llgo-binary-size.yml
@@ -51,35 +51,31 @@ permissions:
   contents: read
   actions: read
 
-concurrency:
-  # Keep benchmark builds in their own queue. The Pages-only workflow has a
-  # separate queue; sharing one group would let a newer pending Pages run
-  # replace a pending binary-size run even with cancel-in-progress disabled.
-  group: llgo-binary-size-build
-  cancel-in-progress: false
-
 jobs:
   update-pin:
     if: github.event_name == 'repository_dispatch'
     permissions:
       contents: write
-      actions: write
     runs-on: ubuntu-24.04
+    concurrency:
+      # Pin updates may be coalesced because the file only records the latest
+      # LLGo main revision. The benchmark job below is not part of this queue:
+      # every distinct dispatched LLGo commit still gets its own result.
+      group: llgo-binary-size-pin
+      cancel-in-progress: false
     steps:
       - uses: actions/checkout@v4
         with:
-          # A dispatch can wait behind a long binary-size build. Start from
-          # the current branch tip instead of the SHA captured when the event
-          # was created.
+          # A coalesced pin update can start after main has advanced. Always
+          # rebuild its one-file commit from the current branch tip.
           ref: main
           fetch-depth: 0
 
-      - name: Update the committed LLGo pin and start the build
+      - name: Update the committed LLGo pin
         env:
           DISPATCH_SOURCE_REPOSITORY: ${{ github.event.client_payload.source_repository }}
           DISPATCH_LLGO_REPOSITORY: ${{ github.event.client_payload.llgo_repository }}
           DISPATCH_LLGO_COMMIT: ${{ github.event.client_payload.llgo_commit }}
-          GH_TOKEN: ${{ github.token }}
         run: |
           set -euo pipefail
           if [[ "$DISPATCH_SOURCE_REPOSITORY" != "xgo-dev/llgo" || \
@@ -92,6 +88,18 @@ jobs:
             exit 1
           fi
 
+          # A newer notification may replace an older pending pin update. Pin
+          # the current LLGo main tip so a delayed notification cannot move
+          # the committed default backwards.
+          target_commit="$(git ls-remote \
+            "https://github.com/${DISPATCH_LLGO_REPOSITORY}.git" \
+            refs/heads/main | awk 'NR == 1 { print $1 }')"
+          if [[ ! "$target_commit" =~ ^[0-9a-f]{40}$ ]]; then
+            echo "could not resolve ${DISPATCH_LLGO_REPOSITORY} main" >&2
+            exit 1
+          fi
+          echo "Pinning current LLGo main $target_commit (notification requested $DISPATCH_LLGO_COMMIT)"
+
           git config user.name "github-actions[bot]"
           git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
 
@@ -104,16 +112,16 @@ jobs:
             git checkout --detach origin/main
 
             current_commit="$(awk -F= '$1 == "LLGO_COMMIT" { print $2 }' ci/llgo-size/llgo-version.env)"
-            if [[ "$current_commit" == "$DISPATCH_LLGO_COMMIT" ]]; then
-              echo "LLGo pin is already $DISPATCH_LLGO_COMMIT"
+            if [[ "$current_commit" == "$target_commit" ]]; then
+              echo "LLGo pin is already $target_commit"
               pin_ready=true
               break
             fi
 
-            sed -i "s/^LLGO_COMMIT=.*/LLGO_COMMIT=${DISPATCH_LLGO_COMMIT}/" \
+            sed -i "s/^LLGO_COMMIT=.*/LLGO_COMMIT=${target_commit}/" \
               ci/llgo-size/llgo-version.env
             git add ci/llgo-size/llgo-version.env
-            git commit -m "ci: pin LLGo ${DISPATCH_LLGO_COMMIT:0:12}"
+            git commit -m "ci: pin LLGo ${target_commit:0:12}"
             if git push origin HEAD:main; then
               pin_ready=true
               break
@@ -132,20 +140,6 @@ jobs:
             exit 1
           fi
 
-          # Dispatch even when the pin was already current. A retry may be
-          # recovering from a prior run that pushed the pin but failed before
-          # it could start the actual binary-size build.
-          payload="$(jq -cn \
-            --arg ref main \
-            --arg llgo_commit "$DISPATCH_LLGO_COMMIT" \
-            '{ref: $ref, inputs: {llgo_commit: $llgo_commit}}')"
-          curl --fail-with-body --location --request POST \
-            --header 'Accept: application/vnd.github+json' \
-            --header "Authorization: Bearer ${GH_TOKEN}" \
-            --header 'X-GitHub-Api-Version: 2022-11-28' \
-            "https://api.github.com/repos/${GITHUB_REPOSITORY}/actions/workflows/llgo-binary-size.yml/dispatches" \
-            --data "$payload"
-
   pr-scope:
     if: github.event_name == 'pull_request'
     permissions:
@@ -186,18 +180,29 @@ jobs:
 
   binary-size:
     if: >-
-      always() && github.event_name != 'repository_dispatch' &&
-      (github.event_name != 'pull_request' || needs.pr-scope.outputs.full_matrix == 'true')
+      always() &&
+      (github.event_name != 'pull_request' || needs.pr-scope.outputs.full_matrix == 'true') &&
+      !(github.event_name == 'push' && github.actor == 'github-actions[bot]' &&
+        startsWith(github.event.head_commit.message, 'ci: pin LLGo '))
     needs: pr-scope
     permissions:
       contents: write
     runs-on: ubuntu-24.04
     timeout-minutes: 120
+    concurrency:
+      # Different LLGo revisions never share a pending slot. Duplicate
+      # notifications for the same revision may be coalesced safely because
+      # published history is keyed by the full LLGo commit.
+      group: llgo-binary-size-${{ github.event.client_payload.llgo_commit || inputs.llgo_commit || github.sha }}
+      cancel-in-progress: false
     steps:
       - uses: actions/checkout@v4
 
       - name: Read pinned toolchain versions
         env:
+          DISPATCH_SOURCE_REPOSITORY: ${{ github.event.client_payload.source_repository }}
+          DISPATCH_LLGO_REPOSITORY: ${{ github.event.client_payload.llgo_repository }}
+          DISPATCH_LLGO_COMMIT: ${{ github.event.client_payload.llgo_commit }}
           MANUAL_LLGO_COMMIT: ${{ inputs.llgo_commit }}
         run: |
           set -euo pipefail
@@ -205,7 +210,19 @@ jobs:
           source ci/llgo-size/llgo-version.env
           set +a
 
-          if [[ -n "$MANUAL_LLGO_COMMIT" ]]; then
+          if [[ "$GITHUB_EVENT_NAME" == "repository_dispatch" ]]; then
+            if [[ "$DISPATCH_SOURCE_REPOSITORY" != "xgo-dev/llgo" || \
+                  "$DISPATCH_LLGO_REPOSITORY" != "xgo-dev/llgo" ]]; then
+              echo "refusing binary-size dispatch from ${DISPATCH_SOURCE_REPOSITORY:-unknown}" >&2
+              exit 1
+            fi
+            if [[ ! "$DISPATCH_LLGO_COMMIT" =~ ^[0-9a-f]{40}$ ]]; then
+              echo "invalid dispatched LLGo commit: ${DISPATCH_LLGO_COMMIT:-missing}" >&2
+              exit 1
+            fi
+            LLGO_REPOSITORY="$DISPATCH_LLGO_REPOSITORY"
+            LLGO_COMMIT="$DISPATCH_LLGO_COMMIT"
+          elif [[ -n "$MANUAL_LLGO_COMMIT" ]]; then
             if [[ ! "$MANUAL_LLGO_COMMIT" =~ ^[0-9a-f]{40}$ ]]; then
               echo "manual LLGo commit must be a full 40-character SHA" >&2
               exit 1
@@ -263,6 +280,13 @@ jobs:
             git -C .ci/llgo fetch --progress --no-tags --depth=1 origin "$LLGO_COMMIT"
           time_command "Check out pinned LLGo commit" \
             git -C .ci/llgo checkout --detach "$LLGO_COMMIT"
+          git -C .ci/llgo fetch --no-tags origin main
+          git -C .ci/llgo rev-list --first-parent --reverse origin/main > .ci/llgo-main-history.txt
+          llgo_main_index="$(awk -v commit="$LLGO_COMMIT" '$0 == commit { print NR; exit }' \
+            .ci/llgo-main-history.txt)"
+          llgo_committed_at="$(git -C .ci/llgo show -s --format=%cI "$LLGO_COMMIT")"
+          printf 'LLGO_MAIN_INDEX=%s\n' "$llgo_main_index" >> "$GITHUB_ENV"
+          printf 'LLGO_COMMITTED_AT=%s\n' "$llgo_committed_at" >> "$GITHUB_ENV"
       - name: Build LLGo and the LTO plugin
         run: |
           set -euo pipefail
@@ -335,14 +359,27 @@ jobs:
           GH_TOKEN: ${{ github.token }}
         run: |
           set -euo pipefail
-          pages_dir="$GITHUB_WORKSPACE/.ci/pages"
-          bash ci/llgo-size/prepare-pages-branch.sh \
-            "$pages_dir" \
-            "https://x-access-token:${PAGES_TOKEN}@github.com/${GITHUB_REPOSITORY}.git"
-          ci/llgo-size/publish.sh \
-            .ci/bent-run/results \
-            "$pages_dir" \
-            ci/llgo-size/site
+          published=false
+          for attempt in 1 2 3 4; do
+            pages_dir="$GITHUB_WORKSPACE/.ci/pages-$attempt"
+            bash ci/llgo-size/prepare-pages-branch.sh \
+              "$pages_dir" \
+              "https://x-access-token:${PAGES_TOKEN}@github.com/${GITHUB_REPOSITORY}.git"
+            if ci/llgo-size/publish.sh \
+                .ci/bent-run/results \
+                "$pages_dir" \
+                ci/llgo-size/site \
+                .ci/llgo-main-history.txt; then
+              published=true
+              break
+            fi
+            echo "Pages advanced during publication; retrying from its latest tip"
+            sleep $((attempt * 2))
+          done
+          if [[ "$published" != true ]]; then
+            echo "failed to publish binary-size history after 4 attempts" >&2
+            exit 1
+          fi
   deploy-pages:
     if: >-
       always() && github.ref == 'refs/heads/main' &&
diff --git a/ci/llgo-size/README.md b/ci/llgo-size/README.md
index 58dea10..69cebaf 100644
--- a/ci/llgo-size/README.md
+++ b/ci/llgo-size/README.md
@@ -47,14 +47,14 @@ 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
-`workflow_dispatch` build with that complete SHA. This makes the version-file
-update and the published result one ordered operation without relying on a
-`GITHUB_TOKEN`-created push to trigger another workflow. The exact commit is
-retained in `results.json` and the Pages history, so every LLGo `main` update
-has a comparable data point. GitHub requires the receiver workflow to be on
-the benchmarks repository's default branch before it can receive this event.
+The `llgo-main-updated` repository-dispatch event from `xgo-dev/llgo` starts a
+binary-size build directly with the complete dispatched SHA. A separate,
+coalescible job updates `LLGO_COMMIT` on the benchmarks `main` branch to the
+current LLGo main tip; coalescing that bookkeeping cannot discard a benchmark
+revision. Distinct LLGo commits use distinct build concurrency keys, so a burst
+of merges may run in parallel but every LLGo `main` update retains a comparable
+data point. GitHub requires the receiver workflow to be on the benchmarks
+repository's default branch before it can receive this event.
 The workflow sources `timing.sh` for its shared CI step timing output.
 Bent schedules benchmark/configuration builds serially; each LLGo invocation
 uses the compiler's own package-level parallelism.
@@ -81,9 +81,12 @@ separate `llgo-binary-size-pages.yml` workflow. That path publishes the updated
 site directly without rebuilding benchmarks, and its publication jobs are
 restricted to `main`; pull-request builds cannot publish Pages.
 
-The benchmark and page-only workflows use separate concurrency queues. A page
-refresh can therefore wait independently without replacing a pending
-binary-size run.
+The benchmark and page-only workflows use separate concurrency keys. Pages
+publication retries from the latest `pages` tip if parallel benchmark runs
+finish together. The index records each result's position on LLGo's first-parent
+`main` history and displays commits in that order rather than build completion
+order; the dashboard opens on the newest page while keeping its columns oldest
+to newest.
 
 Pull requests that change the committed LLGo version, Bent, the LLGo-size
 benchmark/configuration files, or the suite definitions used by those cases
diff --git a/ci/llgo-size/enrich_pull_requests.py b/ci/llgo-size/enrich_pull_requests.py
index 1167195..ac973f4 100644
--- a/ci/llgo-size/enrich_pull_requests.py
+++ b/ci/llgo-size/enrich_pull_requests.py
@@ -110,6 +110,34 @@ def repository_from_result(run, data_dir):
     return str(result_document(run, data_dir).get("run", {}).get("llgoRepository", ""))
 
 
+def load_main_history(path):
+    if path is None:
+        return []
+    with path.open(encoding="utf-8") as history_file:
+        commits = [line.strip().lower() for line in history_file if line.strip()]
+    invalid = [commit for commit in commits if not COMMIT_RE.fullmatch(commit)]
+    if invalid:
+        raise ValueError("invalid LLGo main commit in history: " + repr(invalid[0]))
+    return commits
+
+
+def order_runs(index, main_history):
+    positions = {commit: position for position, commit in enumerate(main_history, start=1)}
+    for run in index.get("runs", []):
+        commit = str(run.get("llgoCommit", "")).lower()
+        if commit in positions:
+            run["llgoMainIndex"] = positions[commit]
+
+    def order_key(run):
+        position = run.get("llgoMainIndex")
+        if isinstance(position, int) and not isinstance(position, bool):
+            return (0, position, "", str(run.get("key", "")))
+        committed_at = str(run.get("llgoCommittedAt") or run.get("createdAt") or "")
+        return (1, 0, committed_at, str(run.get("key", "")))
+
+    index.setdefault("runs", []).sort(key=order_key)
+
+
 def legacy_wall_times(run, document, data_dir):
     native_path = document.get("native", {}).get("buildTimes")
     path = result_path(run, data_dir)
@@ -221,6 +249,11 @@ def parse_args(argv):
         "--api-url",
         default=os.environ.get("GITHUB_API_URL", "https://api.github.com"),
     )
+    parser.add_argument(
+        "--main-history",
+        type=Path,
+        help="first-parent LLGo main commits, oldest first",
+    )
     return parser.parse_args(argv)
 
 
@@ -232,6 +265,8 @@ def main(argv=None):
         index = json.load(index_file)
     token = os.environ.get("GH_TOKEN") or os.environ.get("GITHUB_TOKEN", "")
 
+    order_runs(index, load_main_history(args.main_history))
+
     def lookup(repository, commit):
         return github_pull_request_lookup(repository, commit, args.api_url, token)
 
diff --git a/ci/llgo-size/publish.sh b/ci/llgo-size/publish.sh
index df2dfaf..30c559b 100755
--- a/ci/llgo-size/publish.sh
+++ b/ci/llgo-size/publish.sh
@@ -5,8 +5,9 @@ script_dir="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)"
 results_dir="$1"
 pages_dir="$2"
 site_dir="$3"
+main_history="${4:-}"
 if [[ -z "$results_dir" || -z "$pages_dir" || -z "$site_dir" ]]; then
-  echo "usage: publish.sh RESULTS_DIR PAGES_DIR SITE_DIR" >&2
+  echo "usage: publish.sh RESULTS_DIR PAGES_DIR SITE_DIR [LLGO_MAIN_HISTORY]" >&2
   exit 2
 fi
 
@@ -133,6 +134,8 @@ for path in glob.glob(os.path.join(data_dir, "runs", "*", "results.json")):
         "ref": run.get("ref", ""),
         "llgoRepository": run.get("llgoRepository", ""),
         "llgoCommit": run.get("llgoCommit", ""),
+        "llgoMainIndex": run.get("llgoMainIndex"),
+        "llgoCommittedAt": run.get("llgoCommittedAt", ""),
         "goVersion": run.get("goVersion", ""),
         "llvmVersion": run.get("llvmVersion", ""),
         "workflowUrl": run.get("workflowUrl", ""),
@@ -149,7 +152,6 @@ for path in glob.glob(os.path.join(data_dir, "runs", "*", "results.json")):
         if field in previous:
             item[field] = previous[field]
     runs.append(item)
-runs.sort(key=lambda item: item["createdAt"], reverse=True)
 
 index = {
     "schemaVersion": 1,
@@ -160,7 +162,11 @@ with open(runs_index_path, "w", encoding="utf-8") as f:
     json.dump(index, f, indent=2)
     f.write("\n")
 PY
-python3 "$script_dir/enrich_pull_requests.py" "$pages_dir/data/index.json"
+enrich_args=("$pages_dir/data/index.json")
+if [[ -n "$main_history" && -s "$main_history" ]]; then
+  enrich_args+=(--main-history "$main_history")
+fi
+python3 "$script_dir/enrich_pull_requests.py" "${enrich_args[@]}"
 
 git -C "$pages_dir" config user.name "github-actions[bot]"
 git -C "$pages_dir" config user.email "41898282+github-actions[bot]@users.noreply.github.com"
diff --git a/ci/llgo-size/report.sh b/ci/llgo-size/report.sh
index b1fdb06..55abc40 100755
--- a/ci/llgo-size/report.sh
+++ b/ci/llgo-size/report.sh
@@ -165,6 +165,8 @@ run = {
     "ref": env("LLGO_SIZE_REF", "GITHUB_REF_NAME"),
     "llgoRepository": os.environ.get("LLGO_REPOSITORY", ""),
     "llgoCommit": os.environ.get("LLGO_COMMIT", ""),
+    "llgoMainIndex": number("LLGO_MAIN_INDEX", ""),
+    "llgoCommittedAt": os.environ.get("LLGO_COMMITTED_AT", ""),
     "goVersion": os.environ.get("GO_VERSION", ""),
     "llvmVersion": os.environ.get("LLVM_VERSION", ""),
     "event": env("LLGO_SIZE_EVENT", "GITHUB_EVENT_NAME"),
diff --git a/ci/llgo-size/site/app.js b/ci/llgo-size/site/app.js
index 700ec05..87890ea 100644
--- a/ci/llgo-size/site/app.js
+++ b/ci/llgo-size/site/app.js
@@ -255,6 +255,11 @@ function findMeta(key) {
   return state.index && state.index.runs.find(function (run) { return run.key === key; });
 }
 
+function latestRun() {
+  const runs = state.index && state.index.runs || [];
+  return runs[runs.length - 1];
+}
+
 function measureValue(benchmark, config, measure) {
   if (!benchmark) return NaN;
   if (measure === "size") return Number(benchmark.values && benchmark.values[config]);
@@ -271,7 +276,7 @@ function filteredRuns() {
   const query = state.query.trim().toLowerCase();
   if (!query) return state.index.runs;
   return state.index.runs.filter(function (run) {
-    return [commitLabel(run), run.llgoCommit, run.sourceCommit, run.ref, run.createdAt, run.key]
+    return [commitLabel(run), run.llgoCommit, run.sourceCommit, run.ref, run.llgoCommittedAt, run.createdAt, run.key]
       .some(function (value) { return String(value || "").toLowerCase().includes(query); });
   });
 }
@@ -331,7 +336,7 @@ function headerHtml(run) {
   const selected = state.selectedKeys.indexOf(run.key);
   const marker = selected >= 0 ? '<b class="pick-marker">' + (selected === 0 ? "A" : "B") + "</b>" : "";
   const commit = commitLinkHtml(run, "<code>" + escapeHtml(commitLabel(run)) + "</code>", "commit-link", commitLinkTitle(run) + ": " + commitLabel(run));
-  const date = escapeHtml(dateLabel(run.createdAt));
+  const date = escapeHtml(dateLabel(run.llgoCommittedAt || run.createdAt));
   const detail = state.comparisonMode
     ? '<button class="commit-select" type="button" data-run-key="' + escapeHtml(run.key) + '" title="Select ' + escapeHtml(commitLabel(run)) + ' for comparison">' + marker + "<span>" + date + "</span></button>"
     : '<span class="commit-date">' + date + "</span>";
@@ -441,8 +446,9 @@ function goVersionLabel(value) {
 }
 
 async function renderEnvironment() {
-  const key = state.selectedKeys.length === 2 ? state.selectedKeys[1] : state.index.runs[0].key;
-  const meta = findMeta(key) || state.index.runs[0];
+  const newest = latestRun();
+  const key = state.selectedKeys.length === 2 ? state.selectedKeys[1] : newest.key;
+  const meta = findMeta(key) || newest;
   const document = await loadRun(meta);
   const run = document.run || {};
   dom.envRunner.textContent = normalizeRunner(run);
@@ -463,8 +469,7 @@ async function renderTables() {
 
 function chartRuns() {
   const limit = Number(dom.historyRange.value);
-  const newest = limit > 0 ? state.index.runs.slice(0, limit) : state.index.runs.slice();
-  return newest.reverse();
+  return limit > 0 ? state.index.runs.slice(-limit) : state.index.runs.slice();
 }
 
 function chartBand(documents, metas, benchmarkName, measure, title) {
@@ -635,9 +640,10 @@ 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");
+    state.page = Math.max(1, Math.ceil(state.index.runs.length / state.pageSize));
     state.benchmarkNames = sortedBenchmarkNames(state.index.benchmarkNames);
     if (!state.benchmarkNames.length) {
-      state.benchmarkNames = benchmarkNamesFromDocuments([await loadRun(state.index.runs[0])]);
+      state.benchmarkNames = benchmarkNamesFromDocuments([await loadRun(latestRun())]);
     }
     state.activeBenchmark = state.benchmarkNames[0] || "";
     configs.forEach(function (config) { state.activeConfigs.add(config); });
@@ -646,7 +652,7 @@ async function main() {
     renderConfigFilter();
     attachEvents();
     await refreshAll();
-    dom.status.textContent = "Updated " + dateLabel(state.index.generatedAt || state.index.runs[0].createdAt);
+    dom.status.textContent = "Updated " + dateLabel(state.index.generatedAt || latestRun().createdAt);
   } catch (error) {
     dom.status.textContent = error.message;
     dom.status.classList.add("error");
diff --git a/ci/llgo-size/test_enrich_pull_requests.py b/ci/llgo-size/test_enrich_pull_requests.py
index 1467e27..f4eef28 100644
--- a/ci/llgo-size/test_enrich_pull_requests.py
+++ b/ci/llgo-size/test_enrich_pull_requests.py
@@ -79,6 +79,43 @@ def test_retries_public_lookup_when_repository_token_is_scoped(self):
 
 
 class IndexEnrichmentTest(unittest.TestCase):
+    def test_orders_runs_by_llgo_main_history_instead_of_build_completion(self):
+        first = "a" * 40
+        second = "b" * 40
+        index = {
+            "runs": [
+                {
+                    "key": second,
+                    "llgoCommit": second,
+                    "createdAt": "2026-08-21T01:00:00Z",
+                },
+                {
+                    "key": first,
+                    "llgoCommit": first,
+                    "createdAt": "2026-08-21T02:00:00Z",
+                },
+            ]
+        }
+
+        MODULE.order_runs(index, [first, second])
+
+        self.assertEqual([run["key"] for run in index["runs"]], [first, second])
+        self.assertEqual([run["llgoMainIndex"] for run in index["runs"]], [1, 2])
+
+    def test_places_non_main_runs_after_topological_history(self):
+        main = "a" * 40
+        manual = "c" * 40
+        index = {
+            "runs": [
+                {"key": manual, "llgoCommit": manual, "createdAt": "2026-01-01T00:00:00Z"},
+                {"key": main, "llgoCommit": main, "createdAt": "2026-08-01T00:00:00Z"},
+            ]
+        }
+
+        MODULE.order_runs(index, [main])
+
+        self.assertEqual([run["key"] for run in index["runs"]], [main, manual])
+
     def test_builds_compact_trends_and_historical_benchmark_union(self):
         with tempfile.TemporaryDirectory() as temporary:
             data_dir = Path(temporary)