diff --git a/.github/workflows/agent-mention-noema-dispatch.yml b/.github/workflows/agent-mention-noema-dispatch.yml
index 5bed3e8963..ad8abc7b25 100644
--- a/.github/workflows/agent-mention-noema-dispatch.yml
+++ b/.github/workflows/agent-mention-noema-dispatch.yml
@@ -8,15 +8,26 @@ on:
   repository_dispatch:
     types: [agent-mention-noema]
 
+concurrency:
+  # Workflow-level admission, for the same reason strix.yml, noema-review.yml,
+  # opencode-review.yml and opencode-review-dispatch.yml carry theirs at this level:
+  # a job-level group is never evaluated while the whole run waits behind the
+  # organization job ceiling, so a superseded mention keeps its queue slot until a
+  # runner frees up and only then cancels. At workflow level the older run is
+  # coalesced while both are still queued, which is where the slot is actually held.
+  # This workflow has a single job, so the group lives here and nowhere else --
+  # every workflow in this repository that carries a group at both levels
+  # (strix.yml, opencode-review-dispatch.yml) gives the two levels DIFFERENT names,
+  # because a job requesting the group its own run already holds would wait on itself.
+  group: agent-mention-noema-${{ github.event.client_payload.target_repository }}-${{ github.event.client_payload.pr_number || github.run_id }}
+  cancel-in-progress: true
+
 permissions:
   contents: read
 
 jobs:
   validate-and-forward:
     if: github.repository == 'ContextualWisdomLab/.github'
-    concurrency:
-      group: agent-mention-noema-${{ github.event.client_payload.target_repository }}-${{ github.event.client_payload.pr_number || github.run_id }}
-      cancel-in-progress: true
     runs-on: ubuntu-24.04
     timeout-minutes: 5
     permissions:
diff --git a/.github/workflows/agent-mention-opencode-dispatch.yml b/.github/workflows/agent-mention-opencode-dispatch.yml
index b27062ae37..05461c9551 100644
--- a/.github/workflows/agent-mention-opencode-dispatch.yml
+++ b/.github/workflows/agent-mention-opencode-dispatch.yml
@@ -8,15 +8,26 @@ on:
   repository_dispatch:
     types: [agent-mention-opencode]
 
+concurrency:
+  # Workflow-level admission, for the same reason strix.yml, noema-review.yml,
+  # opencode-review.yml and opencode-review-dispatch.yml carry theirs at this level:
+  # a job-level group is never evaluated while the whole run waits behind the
+  # organization job ceiling, so a superseded mention keeps its queue slot until a
+  # runner frees up and only then cancels. At workflow level the older run is
+  # coalesced while both are still queued, which is where the slot is actually held.
+  # This workflow has a single job, so the group lives here and nowhere else --
+  # every workflow in this repository that carries a group at both levels
+  # (strix.yml, opencode-review-dispatch.yml) gives the two levels DIFFERENT names,
+  # because a job requesting the group its own run already holds would wait on itself.
+  group: agent-mention-opencode-${{ github.event.client_payload.target_repository }}-${{ github.event.client_payload.pr_number || github.run_id }}
+  cancel-in-progress: true
+
 permissions:
   contents: read
 
 jobs:
   validate-and-forward:
     if: github.repository == 'ContextualWisdomLab/.github'
-    concurrency:
-      group: agent-mention-opencode-${{ github.event.client_payload.target_repository }}-${{ github.event.client_payload.pr_number || github.run_id }}
-      cancel-in-progress: true
     runs-on: ubuntu-24.04
     timeout-minutes: 5
     permissions:
diff --git a/tests/test_agent_mention_downstream_idempotency.py b/tests/test_agent_mention_downstream_idempotency.py
index c9b6ab86ea..85974a5719 100644
--- a/tests/test_agent_mention_downstream_idempotency.py
+++ b/tests/test_agent_mention_downstream_idempotency.py
@@ -33,10 +33,19 @@ def test_downstream_workflows_claim_artifacts_and_coalesce_by_pull_request() ->
     ):
         header = text.split("\npermissions:\n", 1)[0]
         job = text.split("  validate-and-forward:\n", 1)[1]
-        concurrency = job.split("    concurrency:\n", 1)[1].split(
-            "\n    runs-on:", 1
-        )[0]
-        assert "concurrency:" not in header
+        concurrency = header.split("\nconcurrency:\n", 1)[1]
+        # 109d79b7 ("replace unsupported queue concurrency") deleted a
+        # workflow-level block that used ``queue: max``, a key GitHub Actions
+        # does not support, and parked the group on the job while it was at it.
+        # What that commit pins is the absence of ``queue:``, not the level: the
+        # group is back at workflow level because a job-level group is never
+        # evaluated while the run waits behind the organization job ceiling, so a
+        # superseded mention held its queue slot until a runner freed up. Every
+        # other queue-bearing workflow here (strix.yml, noema-review.yml,
+        # opencode-review.yml, codeql-scan-dispatch.yml,
+        # opencode-review-dispatch.yml) keys its group at workflow level too.
+        assert "queue:" not in header
+        assert "    concurrency:" not in job
         assert "github.event.client_payload.agent_invocation_key" in text
         assert "cwl-agent-invocation:" in text
         assert "source_comment_id" in text
diff --git a/tests/test_required_workflow_queue_contract.py b/tests/test_required_workflow_queue_contract.py
index 9724d67ea7..4055bb5b9d 100644
--- a/tests/test_required_workflow_queue_contract.py
+++ b/tests/test_required_workflow_queue_contract.py
@@ -280,6 +280,75 @@ def test_privileged_review_dispatch_coalesces_superseded_runs_before_admission()
     assert re.search(r"(?m)^    concurrency:", workflow)
 
 
+@pytest.mark.parametrize(
+    ("workflow_name", "group_prefix"),
+    (
+        ("agent-mention-opencode-dispatch.yml", "agent-mention-opencode-"),
+        ("agent-mention-noema-dispatch.yml", "agent-mention-noema-"),
+    ),
+)
+def test_agent_mention_dispatch_coalesces_while_queued(
+    workflow_name: str, group_prefix: str
+) -> None:
+    """A superseded agent mention must be discarded before it holds a queue slot.
+
+    Both mention dispatchers carried the same defect
+    ``opencode-review-dispatch.yml`` carried before #1958: the group sat on the
+    single ``validate-and-forward`` job, and a job-level group is not evaluated
+    while the run waits behind the organization job ceiling. Measured on the
+    review dispatcher over the 39.7 hours ending 2026-09-06T12:41Z, 23 pairs of
+    runs for one pull request overlapped -- the older run was still open when its
+    successor arrived -- and none was coalesced; the five that ended
+    ``cancelled`` were cancelled between 0.7 and 2.9 hours after the newer run
+    was created, which is a sweep, not concurrency.
+
+    The group moves to workflow level and is not duplicated on the job. Every
+    workflow here that keys a group at both levels (``strix.yml``,
+    ``opencode-review-dispatch.yml``) gives the two levels different names,
+    because a job that requests the group its own run already holds waits on
+    itself.
+    """
+    workflow = workflow_text(workflow_name)
+    header = workflow.split("permissions:", 1)[0]
+    group = workflow_level_concurrency_group(workflow)
+
+    assert re.search(r"(?m)^concurrency:", header)
+    # Read the group's value, not the block: the comment above these keys quotes
+    # the very expressions asserted here, so a raw-block assertion would survive
+    # the key being collapsed. That is the hole #1970 closed.
+    assert group.strip().startswith(group_prefix)
+    assert "github.event.client_payload.target_repository" in group
+    assert "github.event.client_payload.pr_number || github.run_id" in group
+    # ``cancel-in-progress`` is a sibling key, so it is outside the group value.
+    # Anchor it to its own line at the block's indent; a comment starts with
+    # ``#`` and cannot satisfy this.
+    assert re.search(r"(?m)^  cancel-in-progress: true$", header)
+    # ``\s`` also matches the newline before a column-0 key, so anchor the
+    # job-level search on horizontal whitespace only.
+    assert not re.search(r"(?m)^[ \t]+concurrency:", workflow)
+
+
+def test_agent_mention_router_keeps_its_two_distinct_job_groups() -> None:
+    """The router must not be hoisted: its two jobs need different groups.
+
+    ``agent-mention-router.yml`` runs a per-issue local route that supersedes
+    itself and an organization-wide sweep that must never be cancelled midway.
+    A workflow carries at most one workflow-level group, so hoisting either one
+    would silently give the sweep the route's ``cancel-in-progress: true`` and
+    let a later comment kill a sweep that is part way through the organization.
+    """
+    workflow = workflow_text("agent-mention-router.yml")
+
+    assert not re.search(r"(?m)^concurrency:", workflow)
+    assert (
+        "group: review-agent-mention-router-local-${{ github.repository }}"
+        in workflow
+    )
+    assert "group: review-agent-mention-router-sweep-${{ github.repository }}" in workflow
+
+    sweep = workflow.split("sweep-organization-agent-mentions:", 1)[1]
+    assert "cancel-in-progress: false" in sweep.split("steps:", 1)[0]
+
 def test_concurrency_group_slice_ignores_the_comment_that_documents_it() -> None:
     """A comment quoting the key must not satisfy an assertion about the key.