diff --git a/.github/workflows/pr-review-fix-scheduler.yml b/.github/workflows/pr-review-fix-scheduler.yml
index 92ec0674..f59db584 100644
--- a/.github/workflows/pr-review-fix-scheduler.yml
+++ b/.github/workflows/pr-review-fix-scheduler.yml
@@ -88,7 +88,7 @@ on:
 
 concurrency:
   group: central-pr-review-fix-scheduler-${{ inputs.target_repository || vars.PR_REVIEW_FIX_TARGET_REPOSITORY || github.repository }}
-  cancel-in-progress: false
+  cancel-in-progress: true
 
 jobs:
   dispatch-review-fixes:
diff --git a/.github/workflows/pr-review-merge-scheduler.yml b/.github/workflows/pr-review-merge-scheduler.yml
index 3810c021..b11e2cd5 100644
--- a/.github/workflows/pr-review-merge-scheduler.yml
+++ b/.github/workflows/pr-review-merge-scheduler.yml
@@ -129,7 +129,14 @@ concurrency:
 
 jobs:
   scan-pr-queue:
-    if: github.event_name != 'workflow_run' || github.event.workflow_run.conclusion != 'cancelled'
+    # workflow_dispatch review runs do not reliably carry pull_requests metadata.
+    # Without this guard, one completed central review can wake a repo-wide scan.
+    if: >-
+      github.event_name != 'workflow_run' ||
+      (
+        github.event.workflow_run.conclusion != 'cancelled' &&
+        github.event.workflow_run.pull_requests[0].number
+      )
     runs-on: ubuntu-latest
     permissions:
       actions: write
diff --git a/tests/test_required_workflow_queue_contract.py b/tests/test_required_workflow_queue_contract.py
index 19e443e0..78e6d768 100644
--- a/tests/test_required_workflow_queue_contract.py
+++ b/tests/test_required_workflow_queue_contract.py
@@ -36,3 +36,16 @@ def test_cancelled_review_workflow_runs_do_not_spawn_more_queue_work() -> None:
         workflow = workflow_text(filename)
 
         assert "github.event.workflow_run.conclusion != 'cancelled'" in workflow
+
+
+def test_unassociated_review_workflow_runs_do_not_scan_the_whole_pr_queue() -> None:
+    workflow = workflow_text("pr-review-merge-scheduler.yml")
+
+    assert "github.event.workflow_run.pull_requests[0].number" in workflow
+
+
+def test_fix_scheduler_cancels_superseded_cron_runs() -> None:
+    workflow = workflow_text("pr-review-fix-scheduler.yml")
+
+    assert "central-pr-review-fix-scheduler-" in workflow
+    assert "cancel-in-progress: true" in workflow