Bug: Using kubernetes-novolume mode breaks composite actions — runner cannot find action.yml under RUNNER_WORKSPACE

Summary

After migrating our GitHub Actions Runner Scale Set from containerMode: kubernetes (with kubernetesModeWorkVolumeClaim) to the new containerMode: kubernetes-novolume implementation, composite actions can no longer resolve their local paths.

We receive the following error:
Can't find 'action.yml', 'action.yaml' or 'Dockerfile' under '/home/runner/_work/cloudburst/cloudburst/.github/workflows/playwright-test'. Did you forget to run actions/checkout before running your local action?

✔ Previous (Working) Configuration — kubernetes mode (with PVC)

RunnerScaleSet values:

runner-e2e:
  containerMode:
    type: "kubernetes"
    kubernetesModeWorkVolumeClaim:
      accessModes: ["ReadWriteOnce"]
      storageClassName: "github-runners-sc"
      resources:
        requests:
          storage: 10Gi
  template:
    spec:
      containers:
      - name: runner
        env:
        - name: ACTIONS_RUNNER_CONTAINER_HOOK_TEMPLATE
          value: /home/runner/pod-templates/default.yaml
      volumes:
      - name: hook-extension
        configMap:
          name: runner-e2e-hook-extension

Hook extension (ConfigMap):

data:
  default.yaml: |
    apiVersion: v1
    kind: PodTemplate
    spec:
      serviceAccountName: runner-e2e
      resources:
        requests:
          memory: "8Gi"
          cpu: "3000m"
      containers:
      - name: "$job"
        imagePullPolicy: Always

➡ This configuration works.
Local composite actions are found under:
/home/runner/_work///.github/...

❌ New (Failing) Configuration — kubernetes-novolume mode

runner-e2e:
  containerMode:
    type: "kubernetes-novolume"
  template:
    metadata:
      labels:
        pod-type: runner
    spec:
      containers:
      - name: runner
        env:
        - name: ACTIONS_RUNNER_CONTAINER_HOOKS
          value: /home/runner/k8s-novolume/index.js
        - name: ACTIONS_RUNNER_CONTAINER_HOOK_TEMPLATE
          value: /home/runner/k8s-novolume/pod-templates/default.yaml
        volumeMounts:
        - name: hook-extension
          mountPath: /home/runner/k8s-novolume/pod-templates

Hook extension (ConfigMap):

data:
  default.yaml: |
    apiVersion: v1
    kind: PodTemplate
    spec:
      serviceAccountName: runner-e2e
      nodeSelector:
        karpenter.sh/nodepool: github-arc
      containers:
      - name: "$job"
        env:
        - name: RUNNER_WORKSPACE
          value: /__w
        - name: GITHUB_WORKSPACE
          value: /__w/cloudburst

❗ Observed Behavior

The job container tries to locate composite action files under:

/home/runner/_work/cloudburst/cloudburst/.github/workflows/playwright-test

But with kubernetes-novolume, the actual workspace appears to be:

/__w/cloudburst/cloudburst

Additionally, /home/runner/_work does not exist at all inside the job container.

This mismatch causes composite actions to fail with:

Can't find 'action.yml', 'action.yaml' or 'Dockerfile'

Start by tracing the kubernetes-novolume hook at /home/runner/k8s-novolume/index.js and the mounted pod-templates/default.yaml. Compare how RUNNER_WORKSPACE and GITHUB_WORKSPACE are set against the working kubernetes configuration and the observed /home/runner/_work versus /__w paths. Done means local composite actions resolve their action.yml, action.yaml, or Dockerfile paths in the job container.