diff --git a/.github/workflows/benchmark.yml b/.github/workflows/benchmark.yml
index 43284c6d..7fc5144a 100644
--- a/.github/workflows/benchmark.yml
+++ b/.github/workflows/benchmark.yml
@@ -17,9 +17,10 @@ on:
     - cron: "0 6 * * 1"  # weekly, Monday 06:00 UTC
   workflow_dispatch:
 
-# Cancel superseded runs only for pull requests; runs on main are never cancelled.
+# Cancel superseded runs only for pull requests. Other runs are grouped per commit
+# so a newer queued run on main cannot replace an older commit's queued run.
 concurrency:
-  group: benchmark-${{ github.event_name }}-${{ github.ref }}
+  group: benchmark-${{ github.event_name }}-${{ github.event_name == 'pull_request' && github.ref || github.sha }}
   cancel-in-progress: ${{ github.event_name == 'pull_request' }}
 
 permissions:
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index dcf8d177..8170c24d 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -8,11 +8,13 @@ on:
     - cron: "0 3 * * *"
   workflow_dispatch:
 
-# Only a newer push to the same PR cancels an in-progress run. On main, each
-# merge, the nightly schedule and manual dispatches get their own group and are
-# never cancelled, so every merged commit keeps a complete result.
+# Only a newer push to the same PR cancels its superseded run. Every other run
+# (each merge to main, the nightly schedule, manual dispatches) is grouped by
+# commit: a group keeps at most one queued run and a newer queued run replaces
+# it even without cancel-in-progress, so a per-ref group still dropped the CI of
+# back-to-back merges. Per-commit groups keep a complete result on every commit.
 concurrency:
-  group: ci-${{ github.event_name }}-${{ github.ref }}
+  group: ci-${{ github.event_name }}-${{ github.event_name == 'pull_request' && github.ref || github.sha }}
   cancel-in-progress: ${{ github.event_name == 'pull_request' }}
 
 # Least privilege by default; jobs that need more (nightly alert issue,
diff --git a/.github/workflows/notebooks.yml b/.github/workflows/notebooks.yml
index e35aafd5..74a132f1 100644
--- a/.github/workflows/notebooks.yml
+++ b/.github/workflows/notebooks.yml
@@ -16,9 +16,11 @@ on:
       - ".github/workflows/notebooks.yml"
   workflow_dispatch:
 
+# Cancel superseded runs only for pull requests; runs on main are grouped per
+# commit so back-to-back merges each keep their notebook smoke result.
 concurrency:
-  group: notebooks-${{ github.ref }}
-  cancel-in-progress: true
+  group: notebooks-${{ github.event_name }}-${{ github.event_name == 'pull_request' && github.ref || github.sha }}
+  cancel-in-progress: ${{ github.event_name == 'pull_request' }}
 
 permissions:
   contents: read
diff --git a/.github/workflows/perf-regression.yml b/.github/workflows/perf-regression.yml
index 9789d3d5..39fb04a2 100644
--- a/.github/workflows/perf-regression.yml
+++ b/.github/workflows/perf-regression.yml
@@ -29,10 +29,10 @@ on:
         type: boolean
         default: false
 
-# Cancel superseded runs only for pull requests; scheduled and manual runs on
-# main never cancel each other.
+# Cancel superseded runs only for pull requests. Scheduled and manual runs are
+# grouped per commit so they never cancel or replace each other's queued runs.
 concurrency:
-  group: perf-regression-${{ github.event_name }}-${{ github.ref }}
+  group: perf-regression-${{ github.event_name }}-${{ github.event_name == 'pull_request' && github.ref || github.sha }}
   cancel-in-progress: ${{ github.event_name == 'pull_request' }}
 
 permissions: