From 515af66b314bdf1a2b0dd78e06a6c455c7ee0aab Mon Sep 17 00:00:00 2001
From: Oseltamivir <58582368+Oseltamivir@users.noreply.github.com>
Date: Fri, 19 Jun 2026 12:01:46 +0800
Subject: [PATCH 1/6] ci: remove production changelog gate

---
 .github/workflows/README.md                   |  14 +-
 .github/workflows/run-sweep.yml               | 130 +++++++--------
 KLAUD_DEBUG.md                                |   7 +-
 .../test_run_sweep_gating.py                  | 153 +++++-------------
 .../test_validate_perf_changelog.py           |  47 ++----
 utils/merge_with_reuse.sh                     |  51 +-----
 utils/validate_perf_changelog.py              |   2 +-
 7 files changed, 128 insertions(+), 276 deletions(-)

diff --git a/.github/workflows/README.md b/.github/workflows/README.md
index ee5330602..f2e513843 100644
--- a/.github/workflows/README.md
+++ b/.github/workflows/README.md
@@ -204,20 +204,14 @@ must still contain complete artifacts for the merge run's expected matrix.
 
 The comment is the reuse authorization, so adding it does not trigger or cancel
 a PR sweep. Once the comment is present, later commits pushed to a PR with a
-full-sweep label do not start another benchmark sweep. GitHub still runs the
-CPU-only `check-changelog` job on the new commit before inspecting the reuse
-authorization. That job validates the complete YAML/schema, append-only entry
-ordering, duplicate YAML keys, byte-for-byte preservation of historical
-content, PR links, the generated sweep config, and sweep-label exclusivity.
-Link-only correction PRs stop after this CPU check because they have no
-benchmark matrix to generate. Only appended entries can continue to the reuse
-gate and sweep setup. Removing and re-adding a sweep label explicitly starts a
-new sweep.
+full-sweep label do not start another benchmark sweep. The synchronize run
+checks the authorization before setup. Removing and re-adding a sweep label
+explicitly starts a new sweep.
 
 `utils/merge_with_reuse.sh <pr-number>` is the supported merge path for reuse.
 It merges `main`, preserves the current main changelog bytes, canonicalizes an
 appended `XXX` link to the PR URL, pushes a fresh synchronization commit, and
-waits for `check-changelog` on that exact SHA before merging.
+waits for the PR checks before merging.
 
 On the push-to-main run, `run-sweep.yml` resolves the merged PR from the merge
 commit, verifies the source run is an eligible `pull_request` `run-sweep.yml`
diff --git a/.github/workflows/run-sweep.yml b/.github/workflows/run-sweep.yml
index e496f372b..71b37fc60 100644
--- a/.github/workflows/run-sweep.yml
+++ b/.github/workflows/run-sweep.yml
@@ -34,76 +34,13 @@ on:
             - "perf-changelog.yaml"
 
 jobs:
-    check-changelog:
-        runs-on: ubuntu-latest
-        if: >-
-            github.event_name != 'pull_request' ||
-            !github.event.pull_request.draft
-        outputs:
-            has-additions: ${{ steps.validate.outputs.has-additions }}
-            metadata-only: ${{ steps.validate.outputs.metadata-only }}
-        steps:
-            - name: Reject conflicting sweep labels
-              if: github.event_name == 'pull_request'
-              env:
-                  SWEEP_LABELS: ${{ toJson(github.event.pull_request.labels.*.name) }}
-              run: |
-                  count=$(jq '
-                    [
-                      .[] |
-                      select(
-                        . == "sweep-enabled" or
-                        . == "full-sweep-enabled" or
-                        . == "non-canary-full-sweep-enabled" or
-                        . == "full-sweep-fail-fast" or
-                        . == "full-sweep-fail-fast-no-canary"
-                      )
-                    ] |
-                    length
-                  ' <<<"$SWEEP_LABELS")
-                  if [ "$count" -gt 1 ]; then
-                      echo "::error::PR has multiple conflicting sweep labels. Pick exactly one."
-                      exit 1
-                  fi
-
-            - name: Checkout code
-              uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
-              with:
-                  fetch-depth: 0
-
-            - name: Validate perf-changelog.yaml
-              id: validate
-              run: |
-                  pip install pydantic pyyaml
-
-                  PR_ARGS=()
-                  if [ "${{ github.event_name }}" = "pull_request" ]; then
-                      BASE_REF="origin/${{ github.base_ref }}"
-                      HEAD_REF="${{ github.event.pull_request.head.sha }}"
-                      PR_ARGS=(--pr-number "${{ github.event.pull_request.number }}")
-                  else
-                      BASE_REF="${{ github.event.before }}"
-                      HEAD_REF="${{ github.event.after }}"
-                  fi
-
-                  python3 utils/validate_perf_changelog.py \
-                    --changelog-file perf-changelog.yaml \
-                    --base-ref "$BASE_REF" \
-                    --head-ref "$HEAD_REF" \
-                    --github-output "$GITHUB_OUTPUT" \
-                    "${PR_ARGS[@]}"
-
     reuse-sweep-gate:
-        needs: check-changelog
         runs-on: ubuntu-latest
         permissions:
             contents: read
             issues: read
             pull-requests: read
         if: >-
-            always() &&
-            needs.check-changelog.result == 'success' &&
-            needs.check-changelog.outputs.has-additions == 'true' &&
             github.event_name == 'pull_request' &&
             github.event.action == 'synchronize' &&
             !github.event.pull_request.draft &&
@@ -133,13 +70,45 @@ jobs:
                     --ref "${{ github.ref }}" \
                     --workflow-id "run-sweep.yml"
 
+    check-newline:
+        needs: reuse-sweep-gate
+        runs-on: ubuntu-latest
+        if: >-
+            always() &&
+            (
+              needs.reuse-sweep-gate.result == 'skipped' ||
+              (
+                needs.reuse-sweep-gate.result == 'success' &&
+                needs.reuse-sweep-gate.outputs.skip-pr-sweep != 'true'
+              )
+            ) &&
+            github.event_name == 'pull_request' &&
+            !github.event.pull_request.draft &&
+            (
+              (github.event.action != 'labeled' && github.event.action != 'unlabeled') ||
+              github.event.label.name == 'sweep-enabled' ||
+              github.event.label.name == 'full-sweep-enabled' ||
+              github.event.label.name == 'non-canary-full-sweep-enabled' ||
+              github.event.label.name == 'full-sweep-fail-fast' ||
+              github.event.label.name == 'full-sweep-fail-fast-no-canary'
+            )
+        steps:
+            - name: Checkout code
+              uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+
+            - name: Check perf-changelog.yaml ends with newline
+              run: |
+                  if [ -n "$(tail -c 1 perf-changelog.yaml)" ]; then
+                      echo "::error::perf-changelog.yaml must end with a newline character"
+                      echo "Please add a newline at the end of the file to avoid diff issues in subsequent PRs."
+                      exit 1
+                  fi
+
     setup:
-        needs: [check-changelog, reuse-sweep-gate]
+        needs: reuse-sweep-gate
         runs-on: ubuntu-latest
         if: >-
             always() &&
-            needs.check-changelog.result == 'success' &&
-            needs.check-changelog.outputs.has-additions == 'true' &&
             (
               needs.reuse-sweep-gate.result == 'skipped' ||
               (
@@ -181,6 +150,29 @@ jobs:
             reuse-source-pr-number: ${{ steps.setup.outputs.reuse-source-pr-number }}
             reuse-source-head-sha: ${{ steps.setup.outputs.reuse-source-head-sha }}
         steps:
+            - name: Reject conflicting sweep labels
+              if: github.event_name == 'pull_request'
+              env:
+                  SWEEP_LABELS: ${{ toJson(github.event.pull_request.labels.*.name) }}
+              run: |
+                  count=$(jq '
+                    [
+                      .[] |
+                      select(
+                        . == "sweep-enabled" or
+                        . == "full-sweep-enabled" or
+                        . == "non-canary-full-sweep-enabled" or
+                        . == "full-sweep-fail-fast" or
+                        . == "full-sweep-fail-fast-no-canary"
+                      )
+                    ] |
+                    length
+                  ' <<<"$SWEEP_LABELS")
+                  if [ "$count" -gt 1 ]; then
+                      echo "::error::PR has multiple conflicting sweep labels. Pick exactly one."
+                      exit 1
+                  fi
+
             - name: Checkout code
               uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
               with:
@@ -626,9 +618,9 @@ jobs:
 
     reuse-ingest-artifacts:
         needs: setup
-        # `setup` runs via always() and depends on `check-changelog` plus
-        # `reuse-sweep-gate`, which is skipped on every push-to-main. Without
-        # always() here, that skipped gate poisons this job's implicit
+        # `setup` runs via always() and depends on `reuse-sweep-gate`, which is
+        # skipped on every push-to-main. Without always() here, that skipped
+        # gate poisons this job's implicit
         # success() check and it is skipped even when setup succeeded with
         # reuse-enabled=true — silently breaking the merge-time ingest. Guard
         # explicitly on setup success instead (same pattern as
diff --git a/KLAUD_DEBUG.md b/KLAUD_DEBUG.md
index 06290692d..118c279a1 100644
--- a/KLAUD_DEBUG.md
+++ b/KLAUD_DEBUG.md
@@ -33,10 +33,9 @@ python3 -c "import yaml; yaml.safe_load(open('perf-changelog.yaml'))"
 
 Do **not** try a 3-way merge of `perf-changelog.yaml` — whitespace edits will silently re-trigger the deletion check.
 
-After committing and pushing the resolution, wait for `check-changelog` on the
-new head SHA. `/reuse-sweep-run` skips setup and GPU jobs only after this
-CPU-only validation succeeds. `utils/merge_with_reuse.sh <PR>` performs this
-wait automatically.
+After committing and pushing the resolution, the synchronize run checks the
+reuse authorization before setup. `utils/merge_with_reuse.sh <PR>` performs
+the push and waits for the PR checks automatically.
 
 ---
 
diff --git a/utils/changelog_gate_tests/test_run_sweep_gating.py b/utils/changelog_gate_tests/test_run_sweep_gating.py
index e8530aafa..e158e18f1 100644
--- a/utils/changelog_gate_tests/test_run_sweep_gating.py
+++ b/utils/changelog_gate_tests/test_run_sweep_gating.py
@@ -1,15 +1,10 @@
-"""Exhaustively verify run-sweep.yml's changelog gating for every case.
+"""Exhaustively verify run-sweep.yml's sweep gating for every case.
 
 The simulation jobs in `.github/workflows/test-changelog-gate.yml` hand-copy
-two of the gating `if` conditions and exercise two scenarios. This test instead
-parses the REAL `check-changelog` -> `reuse-sweep-gate` -> `setup` conditions
-out of `run-sweep.yml` and evaluates them with a minimal GitHub Actions
-expression engine, so it cannot drift from production and it covers every
-distinct skip/run decision (PR and push, draft, label, reuse, metadata-only,
-and validation-failure paths).
-
-The engine is grounded against a real GitHub outcome in
-`test_engine_matches_real_github_run`.
+two of the gating `if` conditions and exercise two scenarios. This test parses
+the real `reuse-sweep-gate` -> `setup` conditions out of `run-sweep.yml` and
+evaluates them with a minimal GitHub Actions expression engine, so it cannot
+drift from production and it covers every distinct skip/run decision.
 """
 
 from __future__ import annotations
@@ -27,7 +22,6 @@
     (REPO_ROOT / ".github/workflows/run-sweep.yml").read_text(),
     Loader=yaml.BaseLoader,
 )
-CHECK_IF = _WF["jobs"]["check-changelog"]["if"]
 GATE_IF = _WF["jobs"]["reuse-sweep-gate"]["if"]
 SETUP_IF = _WF["jobs"]["setup"]["if"]
 PR_TYPES = set(_WF["on"]["pull_request"]["types"])
@@ -188,7 +182,7 @@ def _eval(expr: str, ctx: dict) -> bool:
 
 
 # --------------------------------------------------------------------------
-# DAG evaluation: check-changelog -> reuse-sweep-gate -> setup
+# DAG evaluation: reuse-sweep-gate -> setup
 # --------------------------------------------------------------------------
 def _ctx(sc: dict) -> dict:
     return {
@@ -201,35 +195,10 @@ def _ctx(sc: dict) -> dict:
     }
 
 
-def _ran_check_outcome(sc: dict) -> tuple[str, str]:
-    """Outcome of a check-changelog job that actually runs (not a draft PR).
-
-    Models the PR-only "Reject conflicting sweep labels" step (which fails the
-    job when more than one sweep label is present); otherwise the validator
-    step's success/failure governs, and has-additions is empty unless success.
-    """
-    labels = set(sc.get("labels", []))
-    if sc["event"] == "pull_request" and len(labels & SWEEP_LABELS) > 1:
-        return "failure", ""
-    result = sc["check"]
-    return result, (sc.get("has", "") if result == "success" else "")
-
-
-def run_dag(sc: dict) -> tuple[str, str, str]:
-    """Return (check-changelog result, reuse-sweep-gate result, setup decision).
-
-    The job `if` conditions are evaluated from the REAL run-sweep.yml strings;
-    only the in-job step outcomes (validator / conflicting-labels) are modelled.
-    """
+def run_dag(sc: dict) -> tuple[str, str]:
+    """Return (reuse-sweep-gate result, setup decision)."""
     ctx = _ctx(sc)
 
-    if not _eval(CHECK_IF, ctx):
-        cc_result, has = "skipped", ""
-    else:
-        cc_result, has = _ran_check_outcome(sc)
-    ctx["needs.check-changelog.result"] = cc_result
-    ctx["needs.check-changelog.outputs.has-additions"] = has
-
     if not _eval(GATE_IF, ctx):
         gate_result, skip = "skipped", ""
     else:
@@ -239,83 +208,54 @@ def run_dag(sc: dict) -> tuple[str, str, str]:
     ctx["needs.reuse-sweep-gate.outputs.skip-pr-sweep"] = skip
 
     setup = "RUN" if _eval(SETUP_IF, ctx) else "SKIP"
-    return cc_result, gate_result, setup
+    return gate_result, setup
 
 
-_PR = {"event": "pull_request", "draft": False, "check": "success"}
+_PR = {"event": "pull_request", "draft": False}
 
-# (id, scenario, expected (check, reuse, setup))
+# (id, scenario, expected (reuse, setup))
 CASES = [
     ("PR-sync-full-noreuse",
      {**_PR, "action": "synchronize", "labels": ["full-sweep-enabled"],
-      "has": "true", "reuse_auth": False}, ("success", "success", "RUN")),
+      "reuse_auth": False}, ("success", "RUN")),
     ("PR-sync-full-reuse-authorized",
      {**_PR, "action": "synchronize", "labels": ["full-sweep-enabled"],
-      "has": "true", "reuse_auth": True}, ("success", "success", "SKIP")),
+      "reuse_auth": True}, ("success", "SKIP")),
     ("PR-sync-trim-sweep-enabled",
-     {**_PR, "action": "synchronize", "labels": ["sweep-enabled"],
-      "has": "true"}, ("success", "skipped", "RUN")),
+     {**_PR, "action": "synchronize", "labels": ["sweep-enabled"]},
+     ("skipped", "RUN")),
     ("PR-sync-no-sweep-label",
-     {**_PR, "action": "synchronize", "labels": [], "has": "true"},
-     ("success", "skipped", "SKIP")),
+     {**_PR, "action": "synchronize", "labels": []},
+     ("skipped", "SKIP")),
     ("PR-labeled-with-sweep-label",
      {**_PR, "action": "labeled", "label_name": "full-sweep-enabled",
-      "labels": ["full-sweep-enabled"], "has": "true"},
-     ("success", "skipped", "RUN")),
+      "labels": ["full-sweep-enabled"]}, ("skipped", "RUN")),
     ("PR-labeled-with-unrelated-label",
      {**_PR, "action": "labeled", "label_name": "documentation",
-      "labels": ["full-sweep-enabled"], "has": "true"},
-     ("success", "skipped", "SKIP")),
+      "labels": ["full-sweep-enabled"]}, ("skipped", "SKIP")),
     ("PR-unlabeled-removed-sweep-label",
      {**_PR, "action": "unlabeled", "label_name": "full-sweep-enabled",
-      "labels": [], "has": "true"}, ("success", "skipped", "SKIP")),
+      "labels": []}, ("skipped", "SKIP")),
     ("PR-draft",
      {**_PR, "action": "synchronize", "draft": True,
-      "labels": ["full-sweep-enabled"], "has": "true"},
-     ("skipped", "skipped", "SKIP")),
+      "labels": ["full-sweep-enabled"]}, ("skipped", "SKIP")),
     ("PR-ready-for-review",
      {**_PR, "action": "ready_for_review", "labels": ["full-sweep-enabled"],
-      "has": "true", "reuse_auth": False}, ("success", "skipped", "RUN")),
-    ("PR-sync-metadata-only",
-     {**_PR, "action": "synchronize", "labels": ["full-sweep-enabled"],
-      "has": "false"}, ("success", "skipped", "SKIP")),
-    ("PR-sync-changelog-invalid",
-     {**_PR, "action": "synchronize", "labels": ["full-sweep-enabled"],
-      "check": "failure"}, ("failure", "skipped", "SKIP")),
-    ("PR-sync-conflicting-sweep-labels",
-     {**_PR, "action": "synchronize",
-      "labels": ["sweep-enabled", "full-sweep-enabled"], "check": "failure"},
-     ("failure", "skipped", "SKIP")),
+      "reuse_auth": False}, ("skipped", "RUN")),
     ("push-additions-no-skip",
-     {"event": "push", "check": "success", "has": "true",
-      "msg": "feat: add model"}, ("success", "skipped", "RUN")),
+     {"event": "push", "msg": "feat: add model"}, ("skipped", "RUN")),
     ("push-skip-sweep-tag",
-     {"event": "push", "check": "success", "has": "true",
-      "msg": "fix: x [skip-sweep]"}, ("success", "skipped", "SKIP")),
-    ("push-metadata-only",
-     {"event": "push", "check": "success", "has": "false",
-      "msg": "fix: link"}, ("success", "skipped", "SKIP")),
-    # malformed changelog merged to main -> ingest blocked (recovery needed).
-    ("push-changelog-invalid",
-     {"event": "push", "check": "failure", "msg": "feat: add model"},
-     ("failure", "skipped", "SKIP")),
+     {"event": "push", "msg": "fix: x [skip-sweep]"},
+     ("skipped", "SKIP")),
 ]
 
 
 @pytest.mark.parametrize("scenario,expected", [(c[1], c[2]) for c in CASES],
                          ids=[c[0] for c in CASES])
-def test_gating_decision(scenario: dict, expected: tuple[str, str, str]) -> None:
+def test_gating_decision(scenario: dict, expected: tuple[str, str]) -> None:
     assert run_dag(scenario) == expected
 
 
-def test_engine_matches_real_github_run() -> None:
-    # Ground truth: run-sweep run 27737489942 on PR #1821 (no labels, not a
-    # draft, metadata-only) recorded check-changelog=success,
-    # reuse-sweep-gate=skipped, setup=skipped.
-    real = {**_PR, "action": "synchronize", "labels": [], "has": "false"}
-    assert run_dag(real) == ("success", "skipped", "SKIP")
-
-
 def test_engine_self_consistency() -> None:
     checks = [
         ("always()", {}, True),
@@ -349,24 +289,14 @@ def test_trigger_types_enable_gated_events() -> None:
 # both the reference spec and the engine driving the REAL run-sweep.yml `if`
 # strings; any disagreement is either a spec error or a gating bug.
 # --------------------------------------------------------------------------
-def reference_gate(sc: dict) -> tuple[str, str, str]:
-    """Hand-written reference for (check, reuse, setup) from documented intent."""
+def reference_gate(sc: dict) -> tuple[str, str]:
+    """Hand-written reference for (reuse, setup) from documented intent."""
     labels = set(sc.get("labels", []))
     draft = sc.get("draft", False)
     is_pr = sc["event"] == "pull_request"
 
-    if is_pr and draft:
-        check, has = "skipped", ""
-    elif is_pr and len(labels & SWEEP_LABELS) > 1:
-        check, has = "failure", ""
-    else:
-        check = sc["check"]
-        has = sc.get("has", "") if check == "success" else ""
-
     gate_runs = (
-        check == "success"
-        and has == "true"
-        and is_pr
+        is_pr
         and sc.get("action") == "synchronize"
         and not draft
         and bool(labels & REUSE_ELIGIBLE_LABELS)
@@ -384,8 +314,8 @@ def reference_gate(sc: dict) -> tuple[str, str, str]:
     else:
         event_ok = "[skip-sweep]" not in sc.get("msg", "")
 
-    runs = check == "success" and has == "true" and reuse_clause and event_ok
-    return check, reuse, ("RUN" if runs else "SKIP")
+    runs = reuse_clause and event_ok
+    return reuse, ("RUN" if runs else "SKIP")
 
 
 def _all_scenarios() -> list[dict]:
@@ -405,23 +335,16 @@ def _all_scenarios() -> list[dict]:
         [False, True],                      # draft
         label_cfgs,                         # labels
         ["full-sweep-enabled", "sweep-enabled", "documentation", None],  # label.name
-        ["success", "failure"],             # validator outcome
-        ["true", "false"],                  # has-additions
         [False, True],                      # reuse authorized
     )
     scenarios = [
         {"event": "pull_request", "action": a, "draft": d, "labels": labs,
-         "label_name": ln, "check": chk, "has": h, "reuse_auth": r}
-        for a, d, labs, ln, chk, h, r in pr_axes
+         "label_name": ln, "reuse_auth": r}
+        for a, d, labs, ln, r in pr_axes
     ]
-    push_axes = itertools.product(
-        ["success", "failure"],                       # validator outcome
-        ["true", "false"],                            # has-additions
-        ["feat: add model", "fix: thing [skip-sweep]"],  # commit message
-    )
     scenarios += [
-        {"event": "push", "check": chk, "has": h, "msg": m}
-        for chk, h, m in push_axes
+        {"event": "push", "msg": msg}
+        for msg in ("feat: add model", "fix: thing [skip-sweep]")
     ]
     return scenarios
 
@@ -435,9 +358,9 @@ def test_exhaustive_cross_product() -> None:
     ]
     assert not mismatches, mismatches[:10]
     # Sanity: confirm the sweep actually covered the whole input space
-    # (4 actions x 2 draft x 9 label-configs x 4 label-names x 2 check x
-    # 2 has-additions x 2 reuse = 2304 PR cases, plus 8 push cases).
-    assert len(scenarios) == 2312
+    # (4 actions x 2 draft x 9 label-configs x 4 label-names x 2 reuse =
+    # 576 PR cases, plus 2 push cases).
+    assert len(scenarios) == 578
 
 
 def test_named_cases_match_reference_spec() -> None:
diff --git a/utils/changelog_gate_tests/test_validate_perf_changelog.py b/utils/changelog_gate_tests/test_validate_perf_changelog.py
index 34316e7c9..1c67d9514 100644
--- a/utils/changelog_gate_tests/test_validate_perf_changelog.py
+++ b/utils/changelog_gate_tests/test_validate_perf_changelog.py
@@ -203,7 +203,7 @@ def test_raw_correction_rejects_whitespace_only_history_change() -> None:
         )
 
 
-def test_run_sweep_checks_changelog_before_reuse_and_setup() -> None:
+def test_run_sweep_does_not_prevalidate_changelog_before_setup() -> None:
     repo_root = Path(__file__).resolve().parents[2]
     workflow = yaml.load(
         (repo_root / ".github/workflows/run-sweep.yml").read_text(),
@@ -212,59 +212,40 @@ def test_run_sweep_checks_changelog_before_reuse_and_setup() -> None:
     jobs = workflow["jobs"]
     pull_request_types = workflow["on"]["pull_request"]["types"]
 
-    assert "needs" not in jobs["check-changelog"]
+    assert "check-changelog" not in jobs
+    assert "check-newline" in jobs
     # opened/reopened are intentionally excluded so opening or reopening a PR
     # that already carries a sweep label does not start a sweep.
     assert {"synchronize", "labeled", "unlabeled", "ready_for_review"}.issubset(
         set(pull_request_types)
     )
     assert {"opened", "reopened"}.isdisjoint(set(pull_request_types))
-    check_step_names = [
-        step.get("name")
-        for step in jobs["check-changelog"]["steps"]
-    ]
     setup_step_names = [
         step.get("name")
         for step in jobs["setup"]["steps"]
     ]
-    assert "Reject conflicting sweep labels" in check_step_names
-    assert "Reject conflicting sweep labels" not in setup_step_names
-    assert jobs["check-changelog"]["outputs"]["has-additions"] == (
-        "${{ steps.validate.outputs.has-additions }}"
-    )
-    assert jobs["reuse-sweep-gate"]["needs"] == "check-changelog"
-    assert (
-        "needs.check-changelog.result == 'success'"
-        in jobs["reuse-sweep-gate"]["if"]
-    )
-    assert (
-        "needs.check-changelog.outputs.has-additions == 'true'"
-        in jobs["reuse-sweep-gate"]["if"]
-    )
-    assert jobs["setup"]["needs"] == [
-        "check-changelog",
-        "reuse-sweep-gate",
-    ]
-    assert "needs.check-changelog.result == 'success'" in jobs["setup"]["if"]
-    assert (
-        "needs.check-changelog.outputs.has-additions == 'true'"
-        in jobs["setup"]["if"]
-    )
+    assert "Reject conflicting sweep labels" in setup_step_names
+    assert "needs" not in jobs["reuse-sweep-gate"]
+    assert jobs["setup"]["needs"] == "reuse-sweep-gate"
+    assert "needs.check-changelog" not in jobs["reuse-sweep-gate"]["if"]
+    assert "needs.check-changelog" not in jobs["setup"]["if"]
 
 
-def test_merge_helper_waits_for_changelog_check_before_merge() -> None:
+def test_merge_helper_waits_for_pr_checks_before_merge() -> None:
     repo_root = Path(__file__).resolve().parents[2]
     script = (repo_root / "utils/merge_with_reuse.sh").read_text()
 
     push_index = script.index('git push origin "${LOCAL_BRANCH}:${HEAD_BRANCH}"')
-    wait_index = script.index(
-        'wait_for_check "$POST_MERGE" "check-changelog"'
+    checks_index = script.index(
+        'gh pr checks "$PR" --repo "$REPO" --watch --fail-fast'
     )
     merge_index = script.index(
         'gh pr merge "$PR" --repo "$REPO" --squash --admin'
     )
 
-    assert push_index < wait_index < merge_index
+    assert push_index < checks_index < merge_index
+    assert "wait_for_check" not in script
+    assert "check-changelog" not in script
     assert "prepare_perf_changelog_merge.py" in script
     assert "git commit --allow-empty" in script
     assert script.count('CURRENT_HEAD="$(gh pr view') == 2
diff --git a/utils/merge_with_reuse.sh b/utils/merge_with_reuse.sh
index e5387d296..a29004640 100755
--- a/utils/merge_with_reuse.sh
+++ b/utils/merge_with_reuse.sh
@@ -6,21 +6,18 @@
 #   2. Merge origin/main into the PR branch.  Any `perf-changelog.yaml`
 #      conflict is auto-resolved by accepting main's entries and re-appending
 #      the PR's entry at the bottom with `XXX` -> the canonical PR URL.
-#   3. Canonicalize appended links, push a fresh commit, and wait for
-#      `check-changelog` on that exact SHA.
-#      The PR synchronize run then observes the reuse authorization and skips
-#      sweep setup and benchmark jobs.
-#   4. Squash-merge the PR to main (--admin) only after validation succeeds.
+#   3. Canonicalize appended links and push a fresh synchronization commit.
+#      The PR run observes the reuse authorization and skips sweep setup and
+#      benchmark jobs.
+#   4. Wait for the PR checks, then squash-merge the PR to main (--admin).
 #
 # Usage: utils/merge_with_reuse.sh <pr-number>
 # Env:   REPO (default SemiAnalysisAI/InferenceX)
-#        CHECK_TIMEOUT_SECONDS (default 900)
 
 set -euo pipefail
 
 REPO="${REPO:-SemiAnalysisAI/InferenceX}"
 CHANGELOG="perf-changelog.yaml"
-CHECK_TIMEOUT_SECONDS="${CHECK_TIMEOUT_SECONDS:-900}"
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 
 if [ $# -ne 1 ] || ! [[ "$1" =~ ^[0-9]+$ ]]; then
@@ -35,38 +32,6 @@ die() { printf '\033[1;31m✗\033[0m %s\n' "$*" >&2; exit 1; }
 
 [ -z "$(git status --porcelain)" ] || die "Working tree is not clean"
 
-wait_for_check() {
-    local sha="$1"
-    local check_name="$2"
-    local deadline=$((SECONDS + CHECK_TIMEOUT_SECONDS))
-
-    log "Waiting for ${check_name} on ${sha:0:8}"
-    while ((SECONDS < deadline)); do
-        local checks check status conclusion details
-        checks="$(gh api "repos/${REPO}/commits/${sha}/check-runs?per_page=100")"
-        check="$(jq -c --arg name "$check_name" '
-            [.check_runs[] | select(.name == $name)]
-            | sort_by(.started_at)
-            | last // {}
-        ' <<<"$checks")"
-        status="$(jq -r '.status // ""' <<<"$check")"
-        conclusion="$(jq -r '.conclusion // ""' <<<"$check")"
-        details="$(jq -r '.details_url // ""' <<<"$check")"
-
-        if [ "$status" = "completed" ]; then
-            if [ "$conclusion" = "success" ]; then
-                ok "${check_name} passed${details:+ — ${details}}"
-                return 0
-            fi
-            die "${check_name} concluded ${conclusion:-unknown}${details:+ — ${details}}"
-        fi
-
-        sleep 5
-    done
-
-    die "Timed out after ${CHECK_TIMEOUT_SECONDS}s waiting for ${check_name} on ${sha}"
-}
-
 ORIGINAL_BRANCH="$(git symbolic-ref --quiet --short HEAD || git rev-parse HEAD)"
 LOCAL_BRANCH=""
 cleanup() {
@@ -194,19 +159,17 @@ if ! git diff --quiet -- "$CHANGELOG"; then
 fi
 
 # Always create a synchronize event when the branch was already prepared.
-# This guarantees that check-changelog exists for the exact SHA we validate.
+# This guarantees the reuse gate sees the authorization on the current SHA.
 if [ "$PRE_MERGE" = "$(git rev-parse HEAD)" ]; then
     git commit --allow-empty \
-        -m "chore: validate PR #${PR} changelog before reuse [skip-sweep]"
+        -m "chore: refresh PR #${PR} for sweep reuse [skip-sweep]"
 fi
 
 # --- step 3: push prepared commit --------------------------------------------
 POST_MERGE="$(git rev-parse HEAD)"
 log "Pushing prepared commit ${POST_MERGE:0:8}"
 git push origin "${LOCAL_BRANCH}:${HEAD_BRANCH}"
-ok "Push complete; changelog validation will run before the reuse gate"
-
-wait_for_check "$POST_MERGE" "check-changelog"
+ok "Push complete; reuse authorization will be evaluated on the new head"
 
 # --- step 4: squash-merge to main -------------------------------------------
 CURRENT_HEAD="$(gh pr view "$PR" --repo "$REPO" --json headRefOid --jq '.headRefOid')"
diff --git a/utils/validate_perf_changelog.py b/utils/validate_perf_changelog.py
index a020365aa..d1d8c6bfc 100644
--- a/utils/validate_perf_changelog.py
+++ b/utils/validate_perf_changelog.py
@@ -1,5 +1,5 @@
 #!/usr/bin/env python3
-"""Validate perf-changelog.yaml before sweep reuse can skip setup."""
+"""Validate append-only perf-changelog.yaml changes."""
 
 from __future__ import annotations
 

From 92d1aad4ba9871f7902431772ca4fa2139a5df96 Mon Sep 17 00:00:00 2001
From: Oseltamivir <58582368+Oseltamivir@users.noreply.github.com>
Date: Fri, 19 Jun 2026 12:04:30 +0800
Subject: [PATCH 2/6] ci: run newline check before reuse gate

---
 .github/workflows/README.md                   |  5 +-
 .github/workflows/run-sweep.yml               | 72 ++++++++-------
 KLAUD_DEBUG.md                                |  5 +-
 .../test_run_sweep_gating.py                  | 90 ++++++++++++-------
 .../test_validate_perf_changelog.py           | 16 +++-
 5 files changed, 113 insertions(+), 75 deletions(-)

diff --git a/.github/workflows/README.md b/.github/workflows/README.md
index f2e513843..2c34cf332 100644
--- a/.github/workflows/README.md
+++ b/.github/workflows/README.md
@@ -205,8 +205,9 @@ must still contain complete artifacts for the merge run's expected matrix.
 The comment is the reuse authorization, so adding it does not trigger or cancel
 a PR sweep. Once the comment is present, later commits pushed to a PR with a
 full-sweep label do not start another benchmark sweep. The synchronize run
-checks the authorization before setup. Removing and re-adding a sweep label
-explicitly starts a new sweep.
+checks the changelog's final newline before inspecting the authorization and
+continuing to setup. Removing and re-adding a sweep label explicitly starts a
+new sweep.
 
 `utils/merge_with_reuse.sh <pr-number>` is the supported merge path for reuse.
 It merges `main`, preserves the current main changelog bytes, canonicalizes an
diff --git a/.github/workflows/run-sweep.yml b/.github/workflows/run-sweep.yml
index 71b37fc60..86018e303 100644
--- a/.github/workflows/run-sweep.yml
+++ b/.github/workflows/run-sweep.yml
@@ -34,13 +34,41 @@ on:
             - "perf-changelog.yaml"
 
 jobs:
+    check-newline:
+        runs-on: ubuntu-latest
+        if: >-
+            github.event_name == 'pull_request' &&
+            !github.event.pull_request.draft &&
+            (
+              (github.event.action != 'labeled' && github.event.action != 'unlabeled') ||
+              github.event.label.name == 'sweep-enabled' ||
+              github.event.label.name == 'full-sweep-enabled' ||
+              github.event.label.name == 'non-canary-full-sweep-enabled' ||
+              github.event.label.name == 'full-sweep-fail-fast' ||
+              github.event.label.name == 'full-sweep-fail-fast-no-canary'
+            )
+        steps:
+            - name: Checkout code
+              uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+
+            - name: Check perf-changelog.yaml ends with newline
+              run: |
+                  if [ -n "$(tail -c 1 perf-changelog.yaml)" ]; then
+                      echo "::error::perf-changelog.yaml must end with a newline character"
+                      echo "Please add a newline at the end of the file to avoid diff issues in subsequent PRs."
+                      exit 1
+                  fi
+
     reuse-sweep-gate:
+        needs: check-newline
         runs-on: ubuntu-latest
         permissions:
             contents: read
             issues: read
             pull-requests: read
         if: >-
+            always() &&
+            needs.check-newline.result == 'success' &&
             github.event_name == 'pull_request' &&
             github.event.action == 'synchronize' &&
             !github.event.pull_request.draft &&
@@ -70,45 +98,15 @@ jobs:
                     --ref "${{ github.ref }}" \
                     --workflow-id "run-sweep.yml"
 
-    check-newline:
-        needs: reuse-sweep-gate
+    setup:
+        needs: [check-newline, reuse-sweep-gate]
         runs-on: ubuntu-latest
         if: >-
             always() &&
             (
-              needs.reuse-sweep-gate.result == 'skipped' ||
-              (
-                needs.reuse-sweep-gate.result == 'success' &&
-                needs.reuse-sweep-gate.outputs.skip-pr-sweep != 'true'
-              )
+              needs.check-newline.result == 'success' ||
+              needs.check-newline.result == 'skipped'
             ) &&
-            github.event_name == 'pull_request' &&
-            !github.event.pull_request.draft &&
-            (
-              (github.event.action != 'labeled' && github.event.action != 'unlabeled') ||
-              github.event.label.name == 'sweep-enabled' ||
-              github.event.label.name == 'full-sweep-enabled' ||
-              github.event.label.name == 'non-canary-full-sweep-enabled' ||
-              github.event.label.name == 'full-sweep-fail-fast' ||
-              github.event.label.name == 'full-sweep-fail-fast-no-canary'
-            )
-        steps:
-            - name: Checkout code
-              uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
-
-            - name: Check perf-changelog.yaml ends with newline
-              run: |
-                  if [ -n "$(tail -c 1 perf-changelog.yaml)" ]; then
-                      echo "::error::perf-changelog.yaml must end with a newline character"
-                      echo "Please add a newline at the end of the file to avoid diff issues in subsequent PRs."
-                      exit 1
-                  fi
-
-    setup:
-        needs: reuse-sweep-gate
-        runs-on: ubuntu-latest
-        if: >-
-            always() &&
             (
               needs.reuse-sweep-gate.result == 'skipped' ||
               (
@@ -618,9 +616,9 @@ jobs:
 
     reuse-ingest-artifacts:
         needs: setup
-        # `setup` runs via always() and depends on `reuse-sweep-gate`, which is
-        # skipped on every push-to-main. Without always() here, that skipped
-        # gate poisons this job's implicit
+        # `setup` runs via always() and depends on `check-newline` and
+        # `reuse-sweep-gate`, which are skipped on every push-to-main. Without
+        # always() here, those skipped jobs poison this job's implicit
         # success() check and it is skipped even when setup succeeded with
         # reuse-enabled=true — silently breaking the merge-time ingest. Guard
         # explicitly on setup success instead (same pattern as
diff --git a/KLAUD_DEBUG.md b/KLAUD_DEBUG.md
index 118c279a1..9d1995e44 100644
--- a/KLAUD_DEBUG.md
+++ b/KLAUD_DEBUG.md
@@ -34,8 +34,9 @@ python3 -c "import yaml; yaml.safe_load(open('perf-changelog.yaml'))"
 Do **not** try a 3-way merge of `perf-changelog.yaml` — whitespace edits will silently re-trigger the deletion check.
 
 After committing and pushing the resolution, the synchronize run checks the
-reuse authorization before setup. `utils/merge_with_reuse.sh <PR>` performs
-the push and waits for the PR checks automatically.
+changelog's final newline and then the reuse authorization before setup.
+`utils/merge_with_reuse.sh <PR>` performs the push and waits for the PR checks
+automatically.
 
 ---
 
diff --git a/utils/changelog_gate_tests/test_run_sweep_gating.py b/utils/changelog_gate_tests/test_run_sweep_gating.py
index e158e18f1..7e6622159 100644
--- a/utils/changelog_gate_tests/test_run_sweep_gating.py
+++ b/utils/changelog_gate_tests/test_run_sweep_gating.py
@@ -2,9 +2,10 @@
 
 The simulation jobs in `.github/workflows/test-changelog-gate.yml` hand-copy
 two of the gating `if` conditions and exercise two scenarios. This test parses
-the real `reuse-sweep-gate` -> `setup` conditions out of `run-sweep.yml` and
-evaluates them with a minimal GitHub Actions expression engine, so it cannot
-drift from production and it covers every distinct skip/run decision.
+the real `check-newline` -> `reuse-sweep-gate` -> `setup` conditions out of
+`run-sweep.yml` and evaluates them with a minimal GitHub Actions expression
+engine, so it cannot drift from production and it covers every distinct
+skip/run decision.
 """
 
 from __future__ import annotations
@@ -22,6 +23,7 @@
     (REPO_ROOT / ".github/workflows/run-sweep.yml").read_text(),
     Loader=yaml.BaseLoader,
 )
+NEWLINE_IF = _WF["jobs"]["check-newline"]["if"]
 GATE_IF = _WF["jobs"]["reuse-sweep-gate"]["if"]
 SETUP_IF = _WF["jobs"]["setup"]["if"]
 PR_TYPES = set(_WF["on"]["pull_request"]["types"])
@@ -182,7 +184,7 @@ def _eval(expr: str, ctx: dict) -> bool:
 
 
 # --------------------------------------------------------------------------
-# DAG evaluation: reuse-sweep-gate -> setup
+# DAG evaluation: check-newline -> reuse-sweep-gate -> setup
 # --------------------------------------------------------------------------
 def _ctx(sc: dict) -> dict:
     return {
@@ -195,10 +197,16 @@ def _ctx(sc: dict) -> dict:
     }
 
 
-def run_dag(sc: dict) -> tuple[str, str]:
-    """Return (reuse-sweep-gate result, setup decision)."""
+def run_dag(sc: dict) -> tuple[str, str, str]:
+    """Return (check-newline result, reuse-sweep-gate result, setup decision)."""
     ctx = _ctx(sc)
 
+    if not _eval(NEWLINE_IF, ctx):
+        newline_result = "skipped"
+    else:
+        newline_result = sc.get("newline", "success")
+    ctx["needs.check-newline.result"] = newline_result
+
     if not _eval(GATE_IF, ctx):
         gate_result, skip = "skipped", ""
     else:
@@ -208,51 +216,58 @@ def run_dag(sc: dict) -> tuple[str, str]:
     ctx["needs.reuse-sweep-gate.outputs.skip-pr-sweep"] = skip
 
     setup = "RUN" if _eval(SETUP_IF, ctx) else "SKIP"
-    return gate_result, setup
+    return newline_result, gate_result, setup
 
 
 _PR = {"event": "pull_request", "draft": False}
 
-# (id, scenario, expected (reuse, setup))
+# (id, scenario, expected (newline, reuse, setup))
 CASES = [
     ("PR-sync-full-noreuse",
      {**_PR, "action": "synchronize", "labels": ["full-sweep-enabled"],
-      "reuse_auth": False}, ("success", "RUN")),
+      "reuse_auth": False}, ("success", "success", "RUN")),
     ("PR-sync-full-reuse-authorized",
      {**_PR, "action": "synchronize", "labels": ["full-sweep-enabled"],
-      "reuse_auth": True}, ("success", "SKIP")),
+      "reuse_auth": True}, ("success", "success", "SKIP")),
+    ("PR-sync-full-newline-failure",
+     {**_PR, "action": "synchronize", "labels": ["full-sweep-enabled"],
+      "newline": "failure"}, ("failure", "skipped", "SKIP")),
     ("PR-sync-trim-sweep-enabled",
      {**_PR, "action": "synchronize", "labels": ["sweep-enabled"]},
-     ("skipped", "RUN")),
+     ("success", "skipped", "RUN")),
     ("PR-sync-no-sweep-label",
      {**_PR, "action": "synchronize", "labels": []},
-     ("skipped", "SKIP")),
+     ("success", "skipped", "SKIP")),
     ("PR-labeled-with-sweep-label",
      {**_PR, "action": "labeled", "label_name": "full-sweep-enabled",
-      "labels": ["full-sweep-enabled"]}, ("skipped", "RUN")),
+      "labels": ["full-sweep-enabled"]}, ("success", "skipped", "RUN")),
     ("PR-labeled-with-unrelated-label",
      {**_PR, "action": "labeled", "label_name": "documentation",
-      "labels": ["full-sweep-enabled"]}, ("skipped", "SKIP")),
+      "labels": ["full-sweep-enabled"]}, ("skipped", "skipped", "SKIP")),
     ("PR-unlabeled-removed-sweep-label",
      {**_PR, "action": "unlabeled", "label_name": "full-sweep-enabled",
-      "labels": []}, ("skipped", "SKIP")),
+      "labels": []}, ("success", "skipped", "SKIP")),
     ("PR-draft",
      {**_PR, "action": "synchronize", "draft": True,
-      "labels": ["full-sweep-enabled"]}, ("skipped", "SKIP")),
+      "labels": ["full-sweep-enabled"]}, ("skipped", "skipped", "SKIP")),
     ("PR-ready-for-review",
      {**_PR, "action": "ready_for_review", "labels": ["full-sweep-enabled"],
-      "reuse_auth": False}, ("skipped", "RUN")),
+      "reuse_auth": False}, ("success", "skipped", "RUN")),
     ("push-additions-no-skip",
-     {"event": "push", "msg": "feat: add model"}, ("skipped", "RUN")),
+     {"event": "push", "msg": "feat: add model"},
+     ("skipped", "skipped", "RUN")),
     ("push-skip-sweep-tag",
      {"event": "push", "msg": "fix: x [skip-sweep]"},
-     ("skipped", "SKIP")),
+     ("skipped", "skipped", "SKIP")),
 ]
 
 
 @pytest.mark.parametrize("scenario,expected", [(c[1], c[2]) for c in CASES],
                          ids=[c[0] for c in CASES])
-def test_gating_decision(scenario: dict, expected: tuple[str, str]) -> None:
+def test_gating_decision(
+    scenario: dict,
+    expected: tuple[str, str, str],
+) -> None:
     assert run_dag(scenario) == expected
 
 
@@ -289,14 +304,26 @@ def test_trigger_types_enable_gated_events() -> None:
 # both the reference spec and the engine driving the REAL run-sweep.yml `if`
 # strings; any disagreement is either a spec error or a gating bug.
 # --------------------------------------------------------------------------
-def reference_gate(sc: dict) -> tuple[str, str]:
-    """Hand-written reference for (reuse, setup) from documented intent."""
+def reference_gate(sc: dict) -> tuple[str, str, str]:
+    """Hand-written reference for (newline, reuse, setup) from intent."""
     labels = set(sc.get("labels", []))
     draft = sc.get("draft", False)
     is_pr = sc["event"] == "pull_request"
+    action = sc.get("action")
 
-    gate_runs = (
+    newline_runs = (
         is_pr
+        and not draft
+        and (
+            action not in ("labeled", "unlabeled")
+            or sc.get("label_name") in SWEEP_LABELS
+        )
+    )
+    newline = sc.get("newline", "success") if newline_runs else "skipped"
+
+    gate_runs = (
+        newline == "success"
+        and is_pr
         and sc.get("action") == "synchronize"
         and not draft
         and bool(labels & REUSE_ELIGIBLE_LABELS)
@@ -306,7 +333,6 @@ def reference_gate(sc: dict) -> tuple[str, str]:
     reuse_clause = (reuse == "skipped") or (reuse == "success" and not authorized)
 
     if is_pr:
-        action = sc.get("action")
         action_ok = action not in ("labeled", "unlabeled") or (
             sc.get("label_name") in SWEEP_LABELS
         )
@@ -314,8 +340,9 @@ def reference_gate(sc: dict) -> tuple[str, str]:
     else:
         event_ok = "[skip-sweep]" not in sc.get("msg", "")
 
-    runs = reuse_clause and event_ok
-    return reuse, ("RUN" if runs else "SKIP")
+    newline_clause = newline in ("success", "skipped")
+    runs = newline_clause and reuse_clause and event_ok
+    return newline, reuse, ("RUN" if runs else "SKIP")
 
 
 def _all_scenarios() -> list[dict]:
@@ -336,11 +363,12 @@ def _all_scenarios() -> list[dict]:
         label_cfgs,                         # labels
         ["full-sweep-enabled", "sweep-enabled", "documentation", None],  # label.name
         [False, True],                      # reuse authorized
+        ["success", "failure"],             # newline outcome when it runs
     )
     scenarios = [
         {"event": "pull_request", "action": a, "draft": d, "labels": labs,
-         "label_name": ln, "reuse_auth": r}
-        for a, d, labs, ln, r in pr_axes
+         "label_name": ln, "reuse_auth": r, "newline": nl}
+        for a, d, labs, ln, r, nl in pr_axes
     ]
     scenarios += [
         {"event": "push", "msg": msg}
@@ -358,9 +386,9 @@ def test_exhaustive_cross_product() -> None:
     ]
     assert not mismatches, mismatches[:10]
     # Sanity: confirm the sweep actually covered the whole input space
-    # (4 actions x 2 draft x 9 label-configs x 4 label-names x 2 reuse =
-    # 576 PR cases, plus 2 push cases).
-    assert len(scenarios) == 578
+    # (4 actions x 2 draft x 9 label-configs x 4 label-names x 2 reuse x
+    # 2 newline outcomes = 1152 PR cases, plus 2 push cases).
+    assert len(scenarios) == 1154
 
 
 def test_named_cases_match_reference_spec() -> None:
diff --git a/utils/changelog_gate_tests/test_validate_perf_changelog.py b/utils/changelog_gate_tests/test_validate_perf_changelog.py
index 1c67d9514..aacefa3c3 100644
--- a/utils/changelog_gate_tests/test_validate_perf_changelog.py
+++ b/utils/changelog_gate_tests/test_validate_perf_changelog.py
@@ -203,7 +203,7 @@ def test_raw_correction_rejects_whitespace_only_history_change() -> None:
         )
 
 
-def test_run_sweep_does_not_prevalidate_changelog_before_setup() -> None:
+def test_run_sweep_checks_newline_before_reuse_and_setup() -> None:
     repo_root = Path(__file__).resolve().parents[2]
     workflow = yaml.load(
         (repo_root / ".github/workflows/run-sweep.yml").read_text(),
@@ -225,8 +225,18 @@ def test_run_sweep_does_not_prevalidate_changelog_before_setup() -> None:
         for step in jobs["setup"]["steps"]
     ]
     assert "Reject conflicting sweep labels" in setup_step_names
-    assert "needs" not in jobs["reuse-sweep-gate"]
-    assert jobs["setup"]["needs"] == "reuse-sweep-gate"
+    assert "needs" not in jobs["check-newline"]
+    assert jobs["reuse-sweep-gate"]["needs"] == "check-newline"
+    assert jobs["setup"]["needs"] == [
+        "check-newline",
+        "reuse-sweep-gate",
+    ]
+    assert (
+        "needs.check-newline.result == 'success'"
+        in jobs["reuse-sweep-gate"]["if"]
+    )
+    assert "needs.check-newline.result == 'success'" in jobs["setup"]["if"]
+    assert "needs.check-newline.result == 'skipped'" in jobs["setup"]["if"]
     assert "needs.check-changelog" not in jobs["reuse-sweep-gate"]["if"]
     assert "needs.check-changelog" not in jobs["setup"]["if"]
 

From c73adedca15c31081bf8250c2fafd3e7c128b980 Mon Sep 17 00:00:00 2001
From: Oseltamivir <58582368+Oseltamivir@users.noreply.github.com>
Date: Fri, 19 Jun 2026 12:10:43 +0800
Subject: [PATCH 3/6] ci: validate changelog matrix before sweep reuse

---
 .github/workflows/README.md                   |  7 +-
 .github/workflows/run-sweep.yml               | 29 ++++---
 KLAUD_DEBUG.md                                |  7 +-
 .../test_run_sweep_gating.py                  | 46 +++++------
 .../test_validate_perf_changelog.py           | 61 +++++++++++---
 utils/validate_perf_changelog.py              | 81 ++++++++++++++++++-
 6 files changed, 177 insertions(+), 54 deletions(-)

diff --git a/.github/workflows/README.md b/.github/workflows/README.md
index 2c34cf332..5916afc3c 100644
--- a/.github/workflows/README.md
+++ b/.github/workflows/README.md
@@ -205,9 +205,10 @@ must still contain complete artifacts for the merge run's expected matrix.
 The comment is the reuse authorization, so adding it does not trigger or cancel
 a PR sweep. Once the comment is present, later commits pushed to a PR with a
 full-sweep label do not start another benchmark sweep. The synchronize run
-checks the changelog's final newline before inspecting the authorization and
-continuing to setup. Removing and re-adding a sweep label explicitly starts a
-new sweep.
+checks that the changelog diff can generate the setup matrix before inspecting
+the authorization and continuing to setup. This catches malformed conflict
+resolutions before reuse can skip setup. Removing and re-adding a sweep label
+explicitly starts a new sweep.
 
 `utils/merge_with_reuse.sh <pr-number>` is the supported merge path for reuse.
 It merges `main`, preserves the current main changelog bytes, canonicalizes an
diff --git a/.github/workflows/run-sweep.yml b/.github/workflows/run-sweep.yml
index 86018e303..77c0f7623 100644
--- a/.github/workflows/run-sweep.yml
+++ b/.github/workflows/run-sweep.yml
@@ -34,7 +34,7 @@ on:
             - "perf-changelog.yaml"
 
 jobs:
-    check-newline:
+    check-changelog:
         runs-on: ubuntu-latest
         if: >-
             github.event_name == 'pull_request' &&
@@ -50,17 +50,20 @@ jobs:
         steps:
             - name: Checkout code
               uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+              with:
+                  fetch-depth: 0
 
-            - name: Check perf-changelog.yaml ends with newline
+            - name: Validate perf-changelog matrix
               run: |
-                  if [ -n "$(tail -c 1 perf-changelog.yaml)" ]; then
-                      echo "::error::perf-changelog.yaml must end with a newline character"
-                      echo "Please add a newline at the end of the file to avoid diff issues in subsequent PRs."
-                      exit 1
-                  fi
+                  pip install pydantic pyyaml
+                  python3 utils/validate_perf_changelog.py \
+                    --matrix-compatible \
+                    --changelog-file perf-changelog.yaml \
+                    --base-ref "origin/${{ github.base_ref }}" \
+                    --head-ref "${{ github.event.pull_request.head.sha }}"
 
     reuse-sweep-gate:
-        needs: check-newline
+        needs: check-changelog
         runs-on: ubuntu-latest
         permissions:
             contents: read
@@ -68,7 +71,7 @@ jobs:
             pull-requests: read
         if: >-
             always() &&
-            needs.check-newline.result == 'success' &&
+            needs.check-changelog.result == 'success' &&
             github.event_name == 'pull_request' &&
             github.event.action == 'synchronize' &&
             !github.event.pull_request.draft &&
@@ -99,13 +102,13 @@ jobs:
                     --workflow-id "run-sweep.yml"
 
     setup:
-        needs: [check-newline, reuse-sweep-gate]
+        needs: [check-changelog, reuse-sweep-gate]
         runs-on: ubuntu-latest
         if: >-
             always() &&
             (
-              needs.check-newline.result == 'success' ||
-              needs.check-newline.result == 'skipped'
+              needs.check-changelog.result == 'success' ||
+              needs.check-changelog.result == 'skipped'
             ) &&
             (
               needs.reuse-sweep-gate.result == 'skipped' ||
@@ -616,7 +619,7 @@ jobs:
 
     reuse-ingest-artifacts:
         needs: setup
-        # `setup` runs via always() and depends on `check-newline` and
+        # `setup` runs via always() and depends on `check-changelog` and
         # `reuse-sweep-gate`, which are skipped on every push-to-main. Without
         # always() here, those skipped jobs poison this job's implicit
         # success() check and it is skipped even when setup succeeded with
diff --git a/KLAUD_DEBUG.md b/KLAUD_DEBUG.md
index 9d1995e44..29360e056 100644
--- a/KLAUD_DEBUG.md
+++ b/KLAUD_DEBUG.md
@@ -34,9 +34,10 @@ python3 -c "import yaml; yaml.safe_load(open('perf-changelog.yaml'))"
 Do **not** try a 3-way merge of `perf-changelog.yaml` — whitespace edits will silently re-trigger the deletion check.
 
 After committing and pushing the resolution, the synchronize run checks the
-changelog's final newline and then the reuse authorization before setup.
-`utils/merge_with_reuse.sh <PR>` performs the push and waits for the PR checks
-automatically.
+changelog with the same matrix processor used by setup, then checks the reuse
+authorization. This catches deleted history or malformed appended entries
+before reuse can skip setup. `utils/merge_with_reuse.sh <PR>` performs the push
+and waits for the PR checks automatically.
 
 ---
 
diff --git a/utils/changelog_gate_tests/test_run_sweep_gating.py b/utils/changelog_gate_tests/test_run_sweep_gating.py
index 7e6622159..9ce38ba42 100644
--- a/utils/changelog_gate_tests/test_run_sweep_gating.py
+++ b/utils/changelog_gate_tests/test_run_sweep_gating.py
@@ -2,7 +2,7 @@
 
 The simulation jobs in `.github/workflows/test-changelog-gate.yml` hand-copy
 two of the gating `if` conditions and exercise two scenarios. This test parses
-the real `check-newline` -> `reuse-sweep-gate` -> `setup` conditions out of
+the real `check-changelog` -> `reuse-sweep-gate` -> `setup` conditions out of
 `run-sweep.yml` and evaluates them with a minimal GitHub Actions expression
 engine, so it cannot drift from production and it covers every distinct
 skip/run decision.
@@ -23,7 +23,7 @@
     (REPO_ROOT / ".github/workflows/run-sweep.yml").read_text(),
     Loader=yaml.BaseLoader,
 )
-NEWLINE_IF = _WF["jobs"]["check-newline"]["if"]
+CHECK_IF = _WF["jobs"]["check-changelog"]["if"]
 GATE_IF = _WF["jobs"]["reuse-sweep-gate"]["if"]
 SETUP_IF = _WF["jobs"]["setup"]["if"]
 PR_TYPES = set(_WF["on"]["pull_request"]["types"])
@@ -184,7 +184,7 @@ def _eval(expr: str, ctx: dict) -> bool:
 
 
 # --------------------------------------------------------------------------
-# DAG evaluation: check-newline -> reuse-sweep-gate -> setup
+# DAG evaluation: check-changelog -> reuse-sweep-gate -> setup
 # --------------------------------------------------------------------------
 def _ctx(sc: dict) -> dict:
     return {
@@ -198,14 +198,14 @@ def _ctx(sc: dict) -> dict:
 
 
 def run_dag(sc: dict) -> tuple[str, str, str]:
-    """Return (check-newline result, reuse-sweep-gate result, setup decision)."""
+    """Return (check-changelog result, reuse-sweep-gate result, setup decision)."""
     ctx = _ctx(sc)
 
-    if not _eval(NEWLINE_IF, ctx):
-        newline_result = "skipped"
+    if not _eval(CHECK_IF, ctx):
+        check_result = "skipped"
     else:
-        newline_result = sc.get("newline", "success")
-    ctx["needs.check-newline.result"] = newline_result
+        check_result = sc.get("check", "success")
+    ctx["needs.check-changelog.result"] = check_result
 
     if not _eval(GATE_IF, ctx):
         gate_result, skip = "skipped", ""
@@ -216,12 +216,12 @@ def run_dag(sc: dict) -> tuple[str, str, str]:
     ctx["needs.reuse-sweep-gate.outputs.skip-pr-sweep"] = skip
 
     setup = "RUN" if _eval(SETUP_IF, ctx) else "SKIP"
-    return newline_result, gate_result, setup
+    return check_result, gate_result, setup
 
 
 _PR = {"event": "pull_request", "draft": False}
 
-# (id, scenario, expected (newline, reuse, setup))
+# (id, scenario, expected (check, reuse, setup))
 CASES = [
     ("PR-sync-full-noreuse",
      {**_PR, "action": "synchronize", "labels": ["full-sweep-enabled"],
@@ -229,9 +229,9 @@ def run_dag(sc: dict) -> tuple[str, str, str]:
     ("PR-sync-full-reuse-authorized",
      {**_PR, "action": "synchronize", "labels": ["full-sweep-enabled"],
       "reuse_auth": True}, ("success", "success", "SKIP")),
-    ("PR-sync-full-newline-failure",
+    ("PR-sync-full-changelog-failure",
      {**_PR, "action": "synchronize", "labels": ["full-sweep-enabled"],
-      "newline": "failure"}, ("failure", "skipped", "SKIP")),
+      "check": "failure"}, ("failure", "skipped", "SKIP")),
     ("PR-sync-trim-sweep-enabled",
      {**_PR, "action": "synchronize", "labels": ["sweep-enabled"]},
      ("success", "skipped", "RUN")),
@@ -305,13 +305,13 @@ def test_trigger_types_enable_gated_events() -> None:
 # strings; any disagreement is either a spec error or a gating bug.
 # --------------------------------------------------------------------------
 def reference_gate(sc: dict) -> tuple[str, str, str]:
-    """Hand-written reference for (newline, reuse, setup) from intent."""
+    """Hand-written reference for (check, reuse, setup) from intent."""
     labels = set(sc.get("labels", []))
     draft = sc.get("draft", False)
     is_pr = sc["event"] == "pull_request"
     action = sc.get("action")
 
-    newline_runs = (
+    check_runs = (
         is_pr
         and not draft
         and (
@@ -319,10 +319,10 @@ def reference_gate(sc: dict) -> tuple[str, str, str]:
             or sc.get("label_name") in SWEEP_LABELS
         )
     )
-    newline = sc.get("newline", "success") if newline_runs else "skipped"
+    check = sc.get("check", "success") if check_runs else "skipped"
 
     gate_runs = (
-        newline == "success"
+        check == "success"
         and is_pr
         and sc.get("action") == "synchronize"
         and not draft
@@ -340,9 +340,9 @@ def reference_gate(sc: dict) -> tuple[str, str, str]:
     else:
         event_ok = "[skip-sweep]" not in sc.get("msg", "")
 
-    newline_clause = newline in ("success", "skipped")
-    runs = newline_clause and reuse_clause and event_ok
-    return newline, reuse, ("RUN" if runs else "SKIP")
+    check_clause = check in ("success", "skipped")
+    runs = check_clause and reuse_clause and event_ok
+    return check, reuse, ("RUN" if runs else "SKIP")
 
 
 def _all_scenarios() -> list[dict]:
@@ -363,12 +363,12 @@ def _all_scenarios() -> list[dict]:
         label_cfgs,                         # labels
         ["full-sweep-enabled", "sweep-enabled", "documentation", None],  # label.name
         [False, True],                      # reuse authorized
-        ["success", "failure"],             # newline outcome when it runs
+        ["success", "failure"],             # changelog outcome when it runs
     )
     scenarios = [
         {"event": "pull_request", "action": a, "draft": d, "labels": labs,
-         "label_name": ln, "reuse_auth": r, "newline": nl}
-        for a, d, labs, ln, r, nl in pr_axes
+         "label_name": ln, "reuse_auth": r, "check": chk}
+        for a, d, labs, ln, r, chk in pr_axes
     ]
     scenarios += [
         {"event": "push", "msg": msg}
@@ -387,7 +387,7 @@ def test_exhaustive_cross_product() -> None:
     assert not mismatches, mismatches[:10]
     # Sanity: confirm the sweep actually covered the whole input space
     # (4 actions x 2 draft x 9 label-configs x 4 label-names x 2 reuse x
-    # 2 newline outcomes = 1152 PR cases, plus 2 push cases).
+    # 2 changelog outcomes = 1152 PR cases, plus 2 push cases).
     assert len(scenarios) == 1154
 
 
diff --git a/utils/changelog_gate_tests/test_validate_perf_changelog.py b/utils/changelog_gate_tests/test_validate_perf_changelog.py
index aacefa3c3..ffdf520c1 100644
--- a/utils/changelog_gate_tests/test_validate_perf_changelog.py
+++ b/utils/changelog_gate_tests/test_validate_perf_changelog.py
@@ -5,6 +5,7 @@
 import pytest
 import yaml
 
+import validate_perf_changelog as validator
 from validate_perf_changelog import (
     ChangelogValidationError,
     compare_entries,
@@ -203,7 +204,41 @@ def test_raw_correction_rejects_whitespace_only_history_change() -> None:
         )
 
 
-def test_run_sweep_checks_newline_before_reuse_and_setup() -> None:
+def test_matrix_compatible_check_allows_pr_link_only_correction(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    monkeypatch.setattr(
+        validator,
+        "read_git_file",
+        lambda *_args: b"  pr-link: https://example.com\n",
+    )
+
+    def reject_matrix(*_args: object) -> None:
+        raise ChangelogValidationError("matrix rejected")
+
+    monkeypatch.setattr(validator, "validate_generated_config", reject_matrix)
+    monkeypatch.setattr(
+        validator,
+        "is_pr_link_only_correction",
+        lambda *_args: True,
+    )
+
+    assert not validator.validate_matrix_compatible_change("base", "head", "file")
+
+
+def test_matrix_compatible_check_rejects_pr_1717_conflict_resolution() -> None:
+    with pytest.raises(
+        ChangelogValidationError,
+        match=r"Found deleted line: +pr-link: .*pull/1798",
+    ):
+        validator.validate_matrix_compatible_change(
+            "add33814cce15d0b71e3c98eca4bb2f7ad8aba96",
+            "60bf726a7f324a01e8850d228c8f0f7a6f203dbd",
+            "perf-changelog.yaml",
+        )
+
+
+def test_run_sweep_checks_changelog_before_reuse_and_setup() -> None:
     repo_root = Path(__file__).resolve().parents[2]
     workflow = yaml.load(
         (repo_root / ".github/workflows/run-sweep.yml").read_text(),
@@ -212,8 +247,8 @@ def test_run_sweep_checks_newline_before_reuse_and_setup() -> None:
     jobs = workflow["jobs"]
     pull_request_types = workflow["on"]["pull_request"]["types"]
 
-    assert "check-changelog" not in jobs
-    assert "check-newline" in jobs
+    assert "check-changelog" in jobs
+    assert "check-newline" not in jobs
     # opened/reopened are intentionally excluded so opening or reopening a PR
     # that already carries a sweep label does not start a sweep.
     assert {"synchronize", "labeled", "unlabeled", "ready_for_review"}.issubset(
@@ -225,20 +260,24 @@ def test_run_sweep_checks_newline_before_reuse_and_setup() -> None:
         for step in jobs["setup"]["steps"]
     ]
     assert "Reject conflicting sweep labels" in setup_step_names
-    assert "needs" not in jobs["check-newline"]
-    assert jobs["reuse-sweep-gate"]["needs"] == "check-newline"
+    assert "needs" not in jobs["check-changelog"]
+    assert jobs["reuse-sweep-gate"]["needs"] == "check-changelog"
     assert jobs["setup"]["needs"] == [
-        "check-newline",
+        "check-changelog",
         "reuse-sweep-gate",
     ]
     assert (
-        "needs.check-newline.result == 'success'"
+        "needs.check-changelog.result == 'success'"
         in jobs["reuse-sweep-gate"]["if"]
     )
-    assert "needs.check-newline.result == 'success'" in jobs["setup"]["if"]
-    assert "needs.check-newline.result == 'skipped'" in jobs["setup"]["if"]
-    assert "needs.check-changelog" not in jobs["reuse-sweep-gate"]["if"]
-    assert "needs.check-changelog" not in jobs["setup"]["if"]
+    assert "needs.check-changelog.result == 'success'" in jobs["setup"]["if"]
+    assert "needs.check-changelog.result == 'skipped'" in jobs["setup"]["if"]
+    check_script = "\n".join(
+        step.get("run", "")
+        for step in jobs["check-changelog"]["steps"]
+    )
+    assert "validate_perf_changelog.py" in check_script
+    assert "--matrix-compatible" in check_script
 
 
 def test_merge_helper_waits_for_pr_checks_before_merge() -> None:
diff --git a/utils/validate_perf_changelog.py b/utils/validate_perf_changelog.py
index d1d8c6bfc..56cf3dee4 100644
--- a/utils/validate_perf_changelog.py
+++ b/utils/validate_perf_changelog.py
@@ -1,5 +1,5 @@
 #!/usr/bin/env python3
-"""Validate append-only perf-changelog.yaml changes."""
+"""Validate perf-changelog.yaml changes."""
 
 from __future__ import annotations
 
@@ -343,6 +343,63 @@ def validate_generated_config(base_ref: str, head_ref: str, path: str) -> None:
         ) from exc
 
 
+def is_pr_link_only_correction(
+    base_ref: str,
+    head_ref: str,
+    path: str,
+) -> bool:
+    """Return whether every substantive changed line is a pr-link replacement."""
+    diff = run_git(
+        "diff",
+        "--unified=0",
+        base_ref,
+        head_ref,
+        "--",
+        path,
+    ).stdout
+    removed: list[str] = []
+    added: list[str] = []
+
+    for line in diff.splitlines():
+        if line.startswith("---") or line.startswith("+++"):
+            continue
+        if line.startswith("-") and line[1:].strip():
+            removed.append(line[1:])
+        elif line.startswith("+") and line[1:].strip():
+            added.append(line[1:])
+
+    return (
+        bool(removed)
+        and bool(added)
+        and len(removed) == len(added)
+        and all(line.startswith("  pr-link:") for line in [*removed, *added])
+    )
+
+
+def validate_matrix_compatible_change(
+    base_ref: str,
+    head_ref: str,
+    path: str,
+) -> bool:
+    """Validate the diff accepted by sweep setup, or a pr-link-only correction.
+
+    Returns whether the change generated a sweep matrix.
+    """
+    head_raw = read_git_file(head_ref, path)
+    if not head_raw.endswith(b"\n"):
+        raise ChangelogValidationError(
+            f"{path} at {head_ref} does not end with a newline"
+        )
+
+    try:
+        validate_generated_config(base_ref, head_ref, path)
+    except ChangelogValidationError:
+        if is_pr_link_only_correction(base_ref, head_ref, path):
+            return False
+        raise
+    return True
+
+
 def validate_changelog(
     base_ref: str,
     head_ref: str,
@@ -419,6 +476,14 @@ def main() -> int:
     parser.add_argument("--head-ref", required=True)
     parser.add_argument("--changelog-file", default="perf-changelog.yaml")
     parser.add_argument("--pr-number", type=int)
+    parser.add_argument(
+        "--matrix-compatible",
+        action="store_true",
+        help=(
+            "run the same matrix validation as sweep setup, while allowing "
+            "pr-link-only corrections that do not produce a matrix"
+        ),
+    )
     parser.add_argument(
         "--github-output",
         default=os.environ.get("GITHUB_OUTPUT"),
@@ -426,6 +491,20 @@ def main() -> int:
     args = parser.parse_args()
 
     try:
+        if args.matrix_compatible:
+            generated_matrix = validate_matrix_compatible_change(
+                args.base_ref,
+                args.head_ref,
+                args.changelog_file,
+            )
+            detail = (
+                "matrix generated"
+                if generated_matrix
+                else "pr-link-only correction; no matrix required"
+            )
+            print(f"Validated {args.changelog_file}: {detail}")
+            return 0
+
         additions, corrections = validate_changelog(
             args.base_ref,
             args.head_ref,

From 3ff26c740dabe13a38c1a128e202af822e36eef0 Mon Sep 17 00:00:00 2001
From: Oseltamivir <58582368+Oseltamivir@users.noreply.github.com>
Date: Fri, 19 Jun 2026 12:14:19 +0800
Subject: [PATCH 4/6] ci: require changelog matrix generation

---
 .../test_validate_perf_changelog.py           | 25 +++++---
 utils/validate_perf_changelog.py              | 62 +++----------------
 2 files changed, 26 insertions(+), 61 deletions(-)

diff --git a/utils/changelog_gate_tests/test_validate_perf_changelog.py b/utils/changelog_gate_tests/test_validate_perf_changelog.py
index ffdf520c1..5a9798908 100644
--- a/utils/changelog_gate_tests/test_validate_perf_changelog.py
+++ b/utils/changelog_gate_tests/test_validate_perf_changelog.py
@@ -204,26 +204,35 @@ def test_raw_correction_rejects_whitespace_only_history_change() -> None:
         )
 
 
-def test_matrix_compatible_check_allows_pr_link_only_correction(
+def test_matrix_compatible_check_rejects_missing_final_newline(
     monkeypatch: pytest.MonkeyPatch,
 ) -> None:
     monkeypatch.setattr(
         validator,
         "read_git_file",
-        lambda *_args: b"  pr-link: https://example.com\n",
+        lambda *_args: b"- config-keys: []",
     )
 
-    def reject_matrix(*_args: object) -> None:
-        raise ChangelogValidationError("matrix rejected")
+    with pytest.raises(ChangelogValidationError, match="end with a newline"):
+        validator.validate_matrix_compatible_change("base", "head", "file")
 
-    monkeypatch.setattr(validator, "validate_generated_config", reject_matrix)
+
+def test_matrix_compatible_check_propagates_matrix_rejection(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
     monkeypatch.setattr(
         validator,
-        "is_pr_link_only_correction",
-        lambda *_args: True,
+        "read_git_file",
+        lambda *_args: b"- config-keys: []\n",
     )
 
-    assert not validator.validate_matrix_compatible_change("base", "head", "file")
+    def reject_matrix(*_args: object) -> None:
+        raise ChangelogValidationError("matrix rejected")
+
+    monkeypatch.setattr(validator, "validate_generated_config", reject_matrix)
+
+    with pytest.raises(ChangelogValidationError, match="matrix rejected"):
+        validator.validate_matrix_compatible_change("base", "head", "file")
 
 
 def test_matrix_compatible_check_rejects_pr_1717_conflict_resolution() -> None:
diff --git a/utils/validate_perf_changelog.py b/utils/validate_perf_changelog.py
index 56cf3dee4..fc1df5a21 100644
--- a/utils/validate_perf_changelog.py
+++ b/utils/validate_perf_changelog.py
@@ -343,61 +343,19 @@ def validate_generated_config(base_ref: str, head_ref: str, path: str) -> None:
         ) from exc
 
 
-def is_pr_link_only_correction(
-    base_ref: str,
-    head_ref: str,
-    path: str,
-) -> bool:
-    """Return whether every substantive changed line is a pr-link replacement."""
-    diff = run_git(
-        "diff",
-        "--unified=0",
-        base_ref,
-        head_ref,
-        "--",
-        path,
-    ).stdout
-    removed: list[str] = []
-    added: list[str] = []
-
-    for line in diff.splitlines():
-        if line.startswith("---") or line.startswith("+++"):
-            continue
-        if line.startswith("-") and line[1:].strip():
-            removed.append(line[1:])
-        elif line.startswith("+") and line[1:].strip():
-            added.append(line[1:])
-
-    return (
-        bool(removed)
-        and bool(added)
-        and len(removed) == len(added)
-        and all(line.startswith("  pr-link:") for line in [*removed, *added])
-    )
-
-
 def validate_matrix_compatible_change(
     base_ref: str,
     head_ref: str,
     path: str,
-) -> bool:
-    """Validate the diff accepted by sweep setup, or a pr-link-only correction.
-
-    Returns whether the change generated a sweep matrix.
-    """
+) -> None:
+    """Validate the final newline and the diff accepted by sweep setup."""
     head_raw = read_git_file(head_ref, path)
     if not head_raw.endswith(b"\n"):
         raise ChangelogValidationError(
             f"{path} at {head_ref} does not end with a newline"
         )
 
-    try:
-        validate_generated_config(base_ref, head_ref, path)
-    except ChangelogValidationError:
-        if is_pr_link_only_correction(base_ref, head_ref, path):
-            return False
-        raise
-    return True
+    validate_generated_config(base_ref, head_ref, path)
 
 
 def validate_changelog(
@@ -480,8 +438,8 @@ def main() -> int:
         "--matrix-compatible",
         action="store_true",
         help=(
-            "run the same matrix validation as sweep setup, while allowing "
-            "pr-link-only corrections that do not produce a matrix"
+            "check the final newline and run the same matrix validation as "
+            "sweep setup"
         ),
     )
     parser.add_argument(
@@ -492,17 +450,15 @@ def main() -> int:
 
     try:
         if args.matrix_compatible:
-            generated_matrix = validate_matrix_compatible_change(
+            validate_matrix_compatible_change(
                 args.base_ref,
                 args.head_ref,
                 args.changelog_file,
             )
-            detail = (
-                "matrix generated"
-                if generated_matrix
-                else "pr-link-only correction; no matrix required"
+            print(
+                f"Validated {args.changelog_file}: "
+                "final newline present and matrix generated"
             )
-            print(f"Validated {args.changelog_file}: {detail}")
             return 0
 
         additions, corrections = validate_changelog(

From 60928c8637a5f3c665634f0f5a43cc35d0e251a8 Mon Sep 17 00:00:00 2001
From: Oseltamivir <58582368+Oseltamivir@users.noreply.github.com>
Date: Fri, 19 Jun 2026 12:16:23 +0800
Subject: [PATCH 5/6] ci: remove obsolete strict changelog validation

---
 .github/workflows/run-sweep.yml               |   1 -
 .github/workflows/test-changelog-gate.yml     |  33 -----
 .../test_validate_perf_changelog.py           |   3 +-
 utils/validate_perf_changelog.py              | 118 +-----------------
 4 files changed, 4 insertions(+), 151 deletions(-)

diff --git a/.github/workflows/run-sweep.yml b/.github/workflows/run-sweep.yml
index 77c0f7623..82b8eaf47 100644
--- a/.github/workflows/run-sweep.yml
+++ b/.github/workflows/run-sweep.yml
@@ -57,7 +57,6 @@ jobs:
               run: |
                   pip install pydantic pyyaml
                   python3 utils/validate_perf_changelog.py \
-                    --matrix-compatible \
                     --changelog-file perf-changelog.yaml \
                     --base-ref "origin/${{ github.base_ref }}" \
                     --head-ref "${{ github.event.pull_request.head.sha }}"
diff --git a/.github/workflows/test-changelog-gate.yml b/.github/workflows/test-changelog-gate.yml
index 484b9c982..f5d1d27eb 100644
--- a/.github/workflows/test-changelog-gate.yml
+++ b/.github/workflows/test-changelog-gate.yml
@@ -63,36 +63,3 @@ jobs:
             utils/test_validate_reusable_sweep_artifacts.py \
             utils/changelog_gate_tests/test_run_sweep_gating.py \
             -v
-
-      - name: Test historical push validation
-        run: |
-          expect_rejected() {
-              local label="$1"
-              shift
-              local output
-              if output="$("$@" 2>&1)"; then
-                  echo "::error::${label} was unexpectedly accepted"
-                  return 1
-              fi
-              echo "${label} was rejected as expected"
-              printf '%s\n' "$output"
-          }
-
-          python utils/validate_perf_changelog.py \
-            --changelog-file perf-changelog.yaml \
-            --base-ref d99c824b1c4f0b1b007631191657e458ef2a332c^ \
-            --head-ref d99c824b1c4f0b1b007631191657e458ef2a332c
-
-          expect_rejected "PR #1767 malformed merge state" \
-            python utils/validate_perf_changelog.py \
-              --changelog-file perf-changelog.yaml \
-              --base-ref 7b9843d3a6e1fe7a2d92d327e25aae57ed3506c5^ \
-              --head-ref 7b9843d3a6e1fe7a2d92d327e25aae57ed3506c5 \
-              --pr-number 1767
-
-          expect_rejected "PR #1798 invalid merge state" \
-            python utils/validate_perf_changelog.py \
-              --changelog-file perf-changelog.yaml \
-              --base-ref 8aaff9fbb645ae9df9ba7593fa63273f839b62fb^1 \
-              --head-ref 8aaff9fbb645ae9df9ba7593fa63273f839b62fb \
-              --pr-number 1798
diff --git a/utils/changelog_gate_tests/test_validate_perf_changelog.py b/utils/changelog_gate_tests/test_validate_perf_changelog.py
index 5a9798908..d8bf314b1 100644
--- a/utils/changelog_gate_tests/test_validate_perf_changelog.py
+++ b/utils/changelog_gate_tests/test_validate_perf_changelog.py
@@ -286,7 +286,8 @@ def test_run_sweep_checks_changelog_before_reuse_and_setup() -> None:
         for step in jobs["check-changelog"]["steps"]
     )
     assert "validate_perf_changelog.py" in check_script
-    assert "--matrix-compatible" in check_script
+    assert "--base-ref" in check_script
+    assert "--head-ref" in check_script
 
 
 def test_merge_helper_waits_for_pr_checks_before_merge() -> None:
diff --git a/utils/validate_perf_changelog.py b/utils/validate_perf_changelog.py
index fc1df5a21..204687965 100644
--- a/utils/validate_perf_changelog.py
+++ b/utils/validate_perf_changelog.py
@@ -5,7 +5,6 @@
 
 import argparse
 import json
-import os
 import re
 import subprocess
 import sys
@@ -71,21 +70,6 @@ def construct_unique_mapping(
 )
 
 
-def run_git(*args: str, check: bool = True) -> subprocess.CompletedProcess[str]:
-    """Run git and return captured text output."""
-    result = subprocess.run(
-        ["git", *args],
-        capture_output=True,
-        text=True,
-    )
-    if check and result.returncode != 0:
-        detail = result.stderr.strip() or result.stdout.strip()
-        raise ChangelogValidationError(
-            f"git {' '.join(args)} failed: {detail}"
-        )
-    return result
-
-
 def read_git_file(ref: str, path: str) -> bytes:
     """Read a repository file exactly as stored at a git ref."""
     result = subprocess.run(
@@ -358,114 +342,19 @@ def validate_matrix_compatible_change(
     validate_generated_config(base_ref, head_ref, path)
 
 
-def validate_changelog(
-    base_ref: str,
-    head_ref: str,
-    path: str,
-    pr_number: int | None,
-) -> tuple[int, int]:
-    """Validate the complete head file and its change from base to head."""
-    diff_check = run_git(
-        "diff",
-        "--check",
-        base_ref,
-        head_ref,
-        "--",
-        path,
-        check=False,
-    )
-    if diff_check.returncode != 0:
-        detail = diff_check.stdout.strip() or diff_check.stderr.strip()
-        raise ChangelogValidationError(
-            f"git diff --check failed for {path}:\n{detail}"
-        )
-
-    base_raw = read_git_file(base_ref, path)
-    head_raw = read_git_file(head_ref, path)
-    base_entries = parse_changelog(
-        base_raw,
-        f"{path} at {base_ref}",
-    )
-    head_entries = parse_changelog(
-        head_raw,
-        f"{path} at {head_ref}",
-    )
-    additions, corrections = compare_entries(
-        base_entries,
-        head_entries,
-        pr_number,
-    )
-    validate_raw_change(
-        base_raw,
-        head_raw,
-        len(additions),
-        corrections,
-    )
-
-    if additions:
-        validate_generated_config(base_ref, head_ref, path)
-    elif not corrections:
-        raise ChangelogValidationError(f"{path} has no changes")
-
-    return len(additions), corrections
-
-
-def write_github_outputs(
-    path: str | None,
-    additions: int,
-    corrections: int,
-) -> None:
-    """Expose changelog change type to downstream GitHub Actions jobs."""
-    if not path:
-        return
-    with open(path, "a") as handle:
-        handle.write(f"has-additions={'true' if additions else 'false'}\n")
-        handle.write(
-            f"metadata-only={'true' if corrections and not additions else 'false'}\n"
-        )
-        handle.write(f"addition-count={additions}\n")
-        handle.write(f"correction-count={corrections}\n")
-
-
 def main() -> int:
     """CLI entry point."""
     parser = argparse.ArgumentParser()
     parser.add_argument("--base-ref", required=True)
     parser.add_argument("--head-ref", required=True)
     parser.add_argument("--changelog-file", default="perf-changelog.yaml")
-    parser.add_argument("--pr-number", type=int)
-    parser.add_argument(
-        "--matrix-compatible",
-        action="store_true",
-        help=(
-            "check the final newline and run the same matrix validation as "
-            "sweep setup"
-        ),
-    )
-    parser.add_argument(
-        "--github-output",
-        default=os.environ.get("GITHUB_OUTPUT"),
-    )
     args = parser.parse_args()
 
     try:
-        if args.matrix_compatible:
-            validate_matrix_compatible_change(
-                args.base_ref,
-                args.head_ref,
-                args.changelog_file,
-            )
-            print(
-                f"Validated {args.changelog_file}: "
-                "final newline present and matrix generated"
-            )
-            return 0
-
-        additions, corrections = validate_changelog(
+        validate_matrix_compatible_change(
             args.base_ref,
             args.head_ref,
             args.changelog_file,
-            args.pr_number,
         )
     except ChangelogValidationError as exc:
         print(f"ERROR: {exc}", file=sys.stderr)
@@ -473,11 +362,8 @@ def main() -> int:
 
     print(
         f"Validated {args.changelog_file}: "
-        f"{additions} appended entr{'y' if additions == 1 else 'ies'}, "
-        f"{corrections} pr-link correction"
-        f"{'' if corrections == 1 else 's'}"
+        "final newline present and matrix generated"
     )
-    write_github_outputs(args.github_output, additions, corrections)
     return 0
 
 

From 11f5456251da26df00a5cb40f7e55363209d69dd Mon Sep 17 00:00:00 2001
From: Oseltamivir <58582368+Oseltamivir@users.noreply.github.com>
Date: Fri, 19 Jun 2026 12:22:37 +0800
Subject: [PATCH 6/6] fix: preserve sweep gate invariants

---
 .github/workflows/run-sweep.yml               | 45 +++++++++----------
 .../test_run_sweep_gating.py                  | 13 +++++-
 .../test_validate_perf_changelog.py           | 35 ++++++++-------
 utils/merge_with_reuse.sh                     | 37 +++++++++++++++
 4 files changed, 91 insertions(+), 39 deletions(-)

diff --git a/.github/workflows/run-sweep.yml b/.github/workflows/run-sweep.yml
index 82b8eaf47..00798aece 100644
--- a/.github/workflows/run-sweep.yml
+++ b/.github/workflows/run-sweep.yml
@@ -48,6 +48,28 @@ jobs:
               github.event.label.name == 'full-sweep-fail-fast-no-canary'
             )
         steps:
+            - name: Reject conflicting sweep labels
+              env:
+                  SWEEP_LABELS: ${{ toJson(github.event.pull_request.labels.*.name) }}
+              run: |
+                  count=$(jq '
+                    [
+                      .[] |
+                      select(
+                        . == "sweep-enabled" or
+                        . == "full-sweep-enabled" or
+                        . == "non-canary-full-sweep-enabled" or
+                        . == "full-sweep-fail-fast" or
+                        . == "full-sweep-fail-fast-no-canary"
+                      )
+                    ] |
+                    length
+                  ' <<<"$SWEEP_LABELS")
+                  if [ "$count" -gt 1 ]; then
+                      echo "::error::PR has multiple conflicting sweep labels. Pick exactly one."
+                      exit 1
+                  fi
+
             - name: Checkout code
               uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
               with:
@@ -150,29 +172,6 @@ jobs:
             reuse-source-pr-number: ${{ steps.setup.outputs.reuse-source-pr-number }}
             reuse-source-head-sha: ${{ steps.setup.outputs.reuse-source-head-sha }}
         steps:
-            - name: Reject conflicting sweep labels
-              if: github.event_name == 'pull_request'
-              env:
-                  SWEEP_LABELS: ${{ toJson(github.event.pull_request.labels.*.name) }}
-              run: |
-                  count=$(jq '
-                    [
-                      .[] |
-                      select(
-                        . == "sweep-enabled" or
-                        . == "full-sweep-enabled" or
-                        . == "non-canary-full-sweep-enabled" or
-                        . == "full-sweep-fail-fast" or
-                        . == "full-sweep-fail-fast-no-canary"
-                      )
-                    ] |
-                    length
-                  ' <<<"$SWEEP_LABELS")
-                  if [ "$count" -gt 1 ]; then
-                      echo "::error::PR has multiple conflicting sweep labels. Pick exactly one."
-                      exit 1
-                  fi
-
             - name: Checkout code
               uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
               with:
diff --git a/utils/changelog_gate_tests/test_run_sweep_gating.py b/utils/changelog_gate_tests/test_run_sweep_gating.py
index 9ce38ba42..ea0aae528 100644
--- a/utils/changelog_gate_tests/test_run_sweep_gating.py
+++ b/utils/changelog_gate_tests/test_run_sweep_gating.py
@@ -203,6 +203,8 @@ def run_dag(sc: dict) -> tuple[str, str, str]:
 
     if not _eval(CHECK_IF, ctx):
         check_result = "skipped"
+    elif len(set(sc.get("labels", [])) & SWEEP_LABELS) > 1:
+        check_result = "failure"
     else:
         check_result = sc.get("check", "success")
     ctx["needs.check-changelog.result"] = check_result
@@ -229,6 +231,10 @@ def run_dag(sc: dict) -> tuple[str, str, str]:
     ("PR-sync-full-reuse-authorized",
      {**_PR, "action": "synchronize", "labels": ["full-sweep-enabled"],
       "reuse_auth": True}, ("success", "success", "SKIP")),
+    ("PR-sync-conflicting-labels-reuse-authorized",
+     {**_PR, "action": "synchronize",
+      "labels": ["full-sweep-enabled", "full-sweep-fail-fast"],
+      "reuse_auth": True}, ("failure", "skipped", "SKIP")),
     ("PR-sync-full-changelog-failure",
      {**_PR, "action": "synchronize", "labels": ["full-sweep-enabled"],
       "check": "failure"}, ("failure", "skipped", "SKIP")),
@@ -319,7 +325,12 @@ def reference_gate(sc: dict) -> tuple[str, str, str]:
             or sc.get("label_name") in SWEEP_LABELS
         )
     )
-    check = sc.get("check", "success") if check_runs else "skipped"
+    if not check_runs:
+        check = "skipped"
+    elif len(labels & SWEEP_LABELS) > 1:
+        check = "failure"
+    else:
+        check = sc.get("check", "success")
 
     gate_runs = (
         check == "success"
diff --git a/utils/changelog_gate_tests/test_validate_perf_changelog.py b/utils/changelog_gate_tests/test_validate_perf_changelog.py
index d8bf314b1..8b31d8f94 100644
--- a/utils/changelog_gate_tests/test_validate_perf_changelog.py
+++ b/utils/changelog_gate_tests/test_validate_perf_changelog.py
@@ -5,11 +5,11 @@
 import pytest
 import yaml
 
-import validate_perf_changelog as validator
 from validate_perf_changelog import (
     ChangelogValidationError,
     compare_entries,
     parse_changelog,
+    validate_matrix_compatible_change,
     validate_raw_change,
 )
 
@@ -208,31 +208,32 @@ def test_matrix_compatible_check_rejects_missing_final_newline(
     monkeypatch: pytest.MonkeyPatch,
 ) -> None:
     monkeypatch.setattr(
-        validator,
-        "read_git_file",
+        "validate_perf_changelog.read_git_file",
         lambda *_args: b"- config-keys: []",
     )
 
     with pytest.raises(ChangelogValidationError, match="end with a newline"):
-        validator.validate_matrix_compatible_change("base", "head", "file")
+        validate_matrix_compatible_change("base", "head", "file")
 
 
 def test_matrix_compatible_check_propagates_matrix_rejection(
     monkeypatch: pytest.MonkeyPatch,
 ) -> None:
     monkeypatch.setattr(
-        validator,
-        "read_git_file",
+        "validate_perf_changelog.read_git_file",
         lambda *_args: b"- config-keys: []\n",
     )
 
     def reject_matrix(*_args: object) -> None:
         raise ChangelogValidationError("matrix rejected")
 
-    monkeypatch.setattr(validator, "validate_generated_config", reject_matrix)
+    monkeypatch.setattr(
+        "validate_perf_changelog.validate_generated_config",
+        reject_matrix,
+    )
 
     with pytest.raises(ChangelogValidationError, match="matrix rejected"):
-        validator.validate_matrix_compatible_change("base", "head", "file")
+        validate_matrix_compatible_change("base", "head", "file")
 
 
 def test_matrix_compatible_check_rejects_pr_1717_conflict_resolution() -> None:
@@ -240,7 +241,7 @@ def test_matrix_compatible_check_rejects_pr_1717_conflict_resolution() -> None:
         ChangelogValidationError,
         match=r"Found deleted line: +pr-link: .*pull/1798",
     ):
-        validator.validate_matrix_compatible_change(
+        validate_matrix_compatible_change(
             "add33814cce15d0b71e3c98eca4bb2f7ad8aba96",
             "60bf726a7f324a01e8850d228c8f0f7a6f203dbd",
             "perf-changelog.yaml",
@@ -264,11 +265,13 @@ def test_run_sweep_checks_changelog_before_reuse_and_setup() -> None:
         set(pull_request_types)
     )
     assert {"opened", "reopened"}.isdisjoint(set(pull_request_types))
-    setup_step_names = [
+    check_step_names = [
         step.get("name")
-        for step in jobs["setup"]["steps"]
+        for step in jobs["check-changelog"]["steps"]
     ]
-    assert "Reject conflicting sweep labels" in setup_step_names
+    setup_step_names = [step.get("name") for step in jobs["setup"]["steps"]]
+    assert "Reject conflicting sweep labels" in check_step_names
+    assert "Reject conflicting sweep labels" not in setup_step_names
     assert "needs" not in jobs["check-changelog"]
     assert jobs["reuse-sweep-gate"]["needs"] == "check-changelog"
     assert jobs["setup"]["needs"] == [
@@ -295,6 +298,9 @@ def test_merge_helper_waits_for_pr_checks_before_merge() -> None:
     script = (repo_root / "utils/merge_with_reuse.sh").read_text()
 
     push_index = script.index('git push origin "${LOCAL_BRANCH}:${HEAD_BRANCH}"')
+    wait_index = script.index(
+        'wait_for_check "$POST_MERGE" "check-changelog"'
+    )
     checks_index = script.index(
         'gh pr checks "$PR" --repo "$REPO" --watch --fail-fast'
     )
@@ -302,9 +308,8 @@ def test_merge_helper_waits_for_pr_checks_before_merge() -> None:
         'gh pr merge "$PR" --repo "$REPO" --squash --admin'
     )
 
-    assert push_index < checks_index < merge_index
-    assert "wait_for_check" not in script
-    assert "check-changelog" not in script
+    assert push_index < wait_index < checks_index < merge_index
+    assert "CHECK_TIMEOUT_SECONDS" in script
     assert "prepare_perf_changelog_merge.py" in script
     assert "git commit --allow-empty" in script
     assert script.count('CURRENT_HEAD="$(gh pr view') == 2
diff --git a/utils/merge_with_reuse.sh b/utils/merge_with_reuse.sh
index a29004640..1655746b5 100755
--- a/utils/merge_with_reuse.sh
+++ b/utils/merge_with_reuse.sh
@@ -13,11 +13,13 @@
 #
 # Usage: utils/merge_with_reuse.sh <pr-number>
 # Env:   REPO (default SemiAnalysisAI/InferenceX)
+#        CHECK_TIMEOUT_SECONDS (default 900)
 
 set -euo pipefail
 
 REPO="${REPO:-SemiAnalysisAI/InferenceX}"
 CHANGELOG="perf-changelog.yaml"
+CHECK_TIMEOUT_SECONDS="${CHECK_TIMEOUT_SECONDS:-900}"
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 
 if [ $# -ne 1 ] || ! [[ "$1" =~ ^[0-9]+$ ]]; then
@@ -32,6 +34,38 @@ die() { printf '\033[1;31m✗\033[0m %s\n' "$*" >&2; exit 1; }
 
 [ -z "$(git status --porcelain)" ] || die "Working tree is not clean"
 
+wait_for_check() {
+    local sha="$1"
+    local check_name="$2"
+    local deadline=$((SECONDS + CHECK_TIMEOUT_SECONDS))
+
+    log "Waiting for ${check_name} on ${sha:0:8}"
+    while ((SECONDS < deadline)); do
+        local checks check status conclusion details
+        checks="$(gh api "repos/${REPO}/commits/${sha}/check-runs?per_page=100")"
+        check="$(jq -c --arg name "$check_name" '
+            [.check_runs[] | select(.name == $name)]
+            | sort_by(.started_at)
+            | last // {}
+        ' <<<"$checks")"
+        status="$(jq -r '.status // ""' <<<"$check")"
+        conclusion="$(jq -r '.conclusion // ""' <<<"$check")"
+        details="$(jq -r '.details_url // ""' <<<"$check")"
+
+        if [ "$status" = "completed" ]; then
+            if [ "$conclusion" = "success" ]; then
+                ok "${check_name} passed${details:+ - ${details}}"
+                return 0
+            fi
+            die "${check_name} concluded ${conclusion:-unknown}${details:+ - ${details}}"
+        fi
+
+        sleep 5
+    done
+
+    die "Timed out after ${CHECK_TIMEOUT_SECONDS}s waiting for ${check_name} on ${sha}"
+}
+
 ORIGINAL_BRANCH="$(git symbolic-ref --quiet --short HEAD || git rev-parse HEAD)"
 LOCAL_BRANCH=""
 cleanup() {
@@ -176,6 +210,9 @@ CURRENT_HEAD="$(gh pr view "$PR" --repo "$REPO" --json headRefOid --jq '.headRef
 [ "$CURRENT_HEAD" = "$POST_MERGE" ] \
     || die "PR head changed to ${CURRENT_HEAD:0:8}; expected ${POST_MERGE:0:8}"
 
+# `gh pr checks --watch` fails if GitHub has not registered any checks yet.
+wait_for_check "$POST_MERGE" "check-changelog"
+
 log "Waiting for all PR checks"
 gh pr checks "$PR" --repo "$REPO" --watch --fail-fast
 ok "All PR checks passed"