Supervisor ConnectSupervisor and RelayStream RPCs rejected when OIDC is enabled without mTLS #1470

Summary

When the gateway is configured with OIDC authentication and TLS disabled (disable_tls = true), the supervisor's ConnectSupervisor and RelayStream gRPC calls are rejected because they are not listed in SANDBOX_METHODS and the supervisor does not (by design) send an OIDC Bearer token.

This makes sandbox connect and any SSH relay fail with:

supervisor relay failed: status: Unavailable, message: "supervisor session not connected"

Root Cause

In crates/openshell-server/src/auth/oidc.rs, SANDBOX_METHODS exempts sandbox-to-gateway RPCs from OIDC Bearer validation:

const SANDBOX_METHODS: &[&str] = &[
    "/openshell.v1.OpenShell/ReportPolicyStatus",
    "/openshell.v1.OpenShell/PushSandboxLogs",
    "/openshell.v1.OpenShell/GetSandboxProviderEnvironment",
    "/openshell.v1.OpenShell/SubmitPolicyAnalysis",
    "/openshell.sandbox.v1.SandboxService/GetSandboxConfig",
    "/openshell.inference.v1.Inference/GetInferenceBundle",
];

ConnectSupervisor and RelayStream are missing from this list.

In crates/openshell-sandbox/src/grpc_client.rs (line 88-91), the supervisor explicitly documents that it does not present a Bearer token:

Sandboxes authenticate to the gateway via the mTLS client certificate configured by connect_channel. They do not present an OIDC Bearer token; the gateway recognises sandbox-class callers by absence of a Bearer header on the request.

In crates/openshell-server/src/multiplex.rs (line 339), when mTLS is the only auth mode (oidc_cache.is_none() && has_client_ca), all requests pass because the TLS handshake is sufficient. But when OIDC is configured, non-exempt methods without a Bearer token are rejected (line 367-374).

Reproduction

1. Deploy gateway with OIDC enabled and TLS disabled (Kubernetes driver):

   [openshell.gateway]
   disable_tls = true
   
   [openshell.gateway.oidc]
   issuer = "http://keycloak.example.com/realms/openshell"
   audience = "openshell-cli"

2. Create a sandbox:

   openshell sandbox create --name test --no-auto-providers -- echo hello

3. Observe: sandbox reaches Ready phase, supervisor connects repeatedly (each ConnectSupervisor returns HTTP 200 but the gRPC stream is rejected), SSH relay never establishes.

Environment

• Gateway: 0.0.44 (Helm chart, Kubernetes driver, OpenShift cluster)
• Supervisor: 0.0.44
• CLI: 0.0.43-dev
• Auth: OIDC (Keycloak), TLS disabled, LoadBalancer service (no proxy)

Proposed Fix

Add ConnectSupervisor and RelayStream to SANDBOX_METHODS:

const SANDBOX_METHODS: &[&str] = &[
    "/openshell.v1.OpenShell/ReportPolicyStatus",
    "/openshell.v1.OpenShell/PushSandboxLogs",
    "/openshell.v1.OpenShell/GetSandboxProviderEnvironment",
    "/openshell.v1.OpenShell/SubmitPolicyAnalysis",
    "/openshell.sandbox.v1.SandboxService/GetSandboxConfig",
    "/openshell.inference.v1.Inference/GetInferenceBundle",
    "/openshell.v1.OpenShell/ConnectSupervisor",  // supervisor session relay
    "/openshell.v1.OpenShell/RelayStream",         // SSH data plane
];

Alternatively, these could be DUAL_AUTH_METHODS if CLI users also call them with Bearer tokens.