docs/e2e: privileged SCC grant for openshell-sandbox may be obsolete after SCC-aware UID resolution #4808

User Story

As an operator deploying OpenShell on OpenShift, I want the sandbox service account to run with the minimum privileges required, so that the deployment does not grant unnecessary privileged SCC access.

Problem Statement

The public debugging skill (skills/debug-openshell-cluster/SKILL.md) and the e2e helper (e2e/with-kube-gateway.sh) both state that the openshell-sandbox service account requires the privileged SCC on OpenShift, and the helper applies that grant on every run. Since #3110 (plus the annotation fix in #4054), the Kubernetes driver resolves the sandbox UID from the namespace's sa.scc.uid-range annotation, so a sandbox pod should satisfy the restricted-v2 SCC without any grant.

Impact / Why This Matters

• Least privilege: a service account with privileged SCC is unnecessary attack surface if the driver already resolves a compliant identity.
• Documentation accuracy: the skill is the public debugging guide — telling operators the SA "needs" privileged when it does not induces unnecessary privilege grants in real clusters.
• Operational cost: the e2e helper grants and revokes the SCC on every OpenShift run, adding a side effect that is avoidable if the SCC-aware resolution is sufficient.

Acceptance Criteria

• e2e:kubernetes passes on OpenShift without the privileged SCC grant to openshell-sandbox
• The grant/revoke pair is removed from e2e/with-kube-gateway.sh if confirmed unnecessary
• The skill row is rewritten to document the SCC-aware UID resolution as the primary path, with the explicit grant noted only as a fallback
• Any workload fixture that genuinely requires a fixed UID (e.g. e2e/python/Dockerfile.workload with user 1000) is identified and either uses sandbox_uid explicitly or documents the need

Reproduction

Deployed a gateway on an OpenShift cluster using the Helm chart with the values-openshift-scc.yaml overlay. No SCC grants were applied — the deploy only uses the chart's own overlay that nulls the hardcoded runAsUser/fsGroup so restricted-v2 can inject the namespace-assigned range.

The sandbox pods run successfully under the default restricted-v2 profile:

• The namespace's sa.scc.uid-range annotation resolves to 1001150000/10000
• Sandbox pods are created with runAsUser: 1001150000 (the first UID from the namespace range) under the openshell-sandbox service account
• oc get scc privileged -o jsonpath='{.users}' returns no entry for openshell-sandbox — zero privileged grants exist
• Sandbox create, exec, and delete all complete normally
• An SELinux audit confirms sandbox processes run under the expected container_t label

This matches the SCC-aware UID resolution in resolve_sandbox_uid (crates/openshell-driver-kubernetes/src/config.rs): the driver reads the sa.scc.uid-range annotation and picks a UID from that range, so the pod satisfies restricted-v2 admission without any grant.

Additional Context

Timeline — the guidance appears to predate the fix by approximately three weeks:

• feat(e2e): make e2e:kubernetes work transparently on OpenShift #3183 (Sep 8) added the privileged grant to the helper and the skill row
• refactor(auth): separate sandbox identity from TLS #3110 (Oct 1) introduced resolve_sandbox_uid with namespace-range resolution
• fix(kubernetes): wait for OpenShift SCC annotations #4054 (Oct 5) fixed waiting for the OpenShift SCC annotations

One edge case worth deciding with data: workload fixtures that depend on a fixed UID. For example, e2e/python/Dockerfile.workload builds a sandbox user with UID 1000 and files owned by it. Under namespace-range resolution the process runs with a different UID; if such a workload needs to write to UID-1000-owned paths, an explicit sandbox_uid or the grant may still be required for that specific case.