feat(provisioner): add optional PVC support for sandbox volumes (#2020)

* feat(provisioner): add optional PVC support for sandbox volumes (#1978)

  Add SKILLS_PVC_NAME and USERDATA_PVC_NAME env vars to allow sandbox
  Pods to use PersistentVolumeClaims instead of hostPath volumes. This
  prevents data loss in production when pods are rescheduled across nodes.

  When USERDATA_PVC_NAME is set, a subPath of threads/{thread_id}/user-data
  is used so a single PVC can serve multiple threads. Falls back to hostPath
  when the new env vars are not set, preserving backward compatibility.

* add unit test for provisioner pvc volumes

* refactor: extract shared provisioner_module fixture to conftest.py

Agent-Logs-Url: https://github.com/bytedance/deer-flow/sessions/e7ccf708-c6ba-40e4-844a-b526bdb249dd

Co-authored-by: WillemJiang <219644+WillemJiang@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: JeffJiang <for-eleven@hotmail.com>

docker/docker-compose-dev.yaml

@@ -36,6 +36,11 @@ services:
       #   export DEER_FLOW_ROOT=/absolute/path/to/deer-flow
       - SKILLS_HOST_PATH=${DEER_FLOW_ROOT}/skills
       - THREADS_HOST_PATH=${DEER_FLOW_ROOT}/backend/.deer-flow/threads
+      # Production: use PVC instead of hostPath to avoid data loss on node failure.
+      # When set, hostPath vars above are ignored for the corresponding volume.
+      # USERDATA_PVC_NAME uses subPath (threads/{thread_id}/user-data) automatically.
+      # - SKILLS_PVC_NAME=deer-flow-skills-pvc
+      # - USERDATA_PVC_NAME=deer-flow-userdata-pvc
       - KUBECONFIG_PATH=/root/.kube/config
       - NODE_HOST=host.docker.internal
       # Override K8S API server URL since kubeconfig uses 127.0.0.1