Missing concurrency group on PR workflow
========================================

.. list-table::
   :stub-columns: 1
   :widths: 20 80

   * - Rule ID
     - ``missing_concurrency``
   * - Category
     - reliability
   * - Severity
     - medium

PR-triggered workflow has no concurrency group. Multiple pushes to the same PR will queue redundant runs instead of cancelling the previous one.

Detection
---------

``static_analysis`` — Checks field presence or value in the workflow YAML.

Examples
--------

**Non-compliant:**

.. code-block:: yaml

   on:
     pull_request:
   jobs:
     test:
       runs-on: ubuntu-latest
       steps:
         - run: npm test

**Compliant:**

.. code-block:: yaml

   on:
     pull_request:
   concurrency:
     group: ${{ github.workflow }}-${{ github.ref }}
     cancel-in-progress: true
   jobs:
     test:
       runs-on: ubuntu-latest
       steps:
         - run: npm test

**Fix**: Add a top-level concurrency block with a group key that includes github.ref and set cancel-in-progress: true to cancel superseded runs automatically.