feat(BA-5738): add session_v2 single-node GraphQL query with RBAC (#11124)

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Co-authored-by: octodog <mu001@lablup.com>

Author: 3 people

changes/11124.feature.md

@@ -0,0 +1 @@
+Add `session_v2(id)` GraphQL single-node query with RBAC-enforced single-session reads across GraphQL, REST v2, SDK, and CLI.

docs/manager/graphql-reference/supergraph.graphql

@@ -13078,6 +13078,11 @@ type Query
   """
   projectSessionsV2(scope: ProjectSessionV2Scope!, filter: SessionV2Filter = null, orderBy: [SessionV2OrderBy!] = null, before: String = null, after: String = null, first: Int = null, last: Int = null, limit: Int = null, offset: Int = null): SessionV2Connection! @join__field(graph: STRAWBERRY)
 
+  """
+  Added in UNRELEASED. Query a single session by ID. Returns an error if not found.
+  """
+  sessionV2(id: UUID!): SessionV2 @join__field(graph: STRAWBERRY)
+
   """Added in 25.19.0. List deployments within a specific project."""
   projectDeployments(scope: ProjectDeploymentScope!, filter: DeploymentFilter = null, orderBy: [DeploymentOrderBy!] = null, before: String = null, after: String = null, first: Int = null, last: Int = null, limit: Int = null, offset: Int = null): ModelDeploymentConnection @join__field(graph: STRAWBERRY)
 

docs/manager/graphql-reference/v2-schema.graphql

@@ -8283,6 +8283,11 @@ type Query {
   """
   projectSessionsV2(scope: ProjectSessionV2Scope!, filter: SessionV2Filter = null, orderBy: [SessionV2OrderBy!] = null, before: String = null, after: String = null, first: Int = null, last: Int = null, limit: Int = null, offset: Int = null): SessionV2Connection!
 
+  """
+  Added in UNRELEASED. Query a single session by ID. Returns an error if not found.
+  """
+  sessionV2(id: UUID!): SessionV2
+
   """Added in 25.19.0. List deployments within a specific project."""
   projectDeployments(scope: ProjectDeploymentScope!, filter: DeploymentFilter = null, orderBy: [DeploymentOrderBy!] = null, before: String = null, after: String = null, first: Int = null, last: Int = null, limit: Int = null, offset: Int = null): ModelDeploymentConnection
 

src/ai/backend/manager/api/gql/schema.py

@@ -382,6 +382,7 @@
     admin_sessions_v2,
     enqueue_session,
     project_sessions_v2,
+    session_v2,
     terminate_project_sessions_v2,
 )
 from .storage_host import my_storage_host_permissions
@@ -499,6 +500,7 @@ class Query:
     admin_login_history_v2 = admin_login_history_v2
     admin_sessions_v2 = admin_sessions_v2
     project_sessions_v2 = project_sessions_v2
+    session_v2 = session_v2
     project_deployments = project_deployments
     my_deployments = my_deployments
     resource_slot_type = resource_slot_type

src/ai/backend/manager/api/gql/session/resolver/__init__.py

@@ -4,12 +4,14 @@
     admin_sessions_v2,
     enqueue_session,
     project_sessions_v2,
+    session_v2,
     terminate_project_sessions_v2,
 )
 
 __all__ = [
     "admin_sessions_v2",
     "enqueue_session",
     "project_sessions_v2",
+    "session_v2",
     "terminate_project_sessions_v2",
 ]

src/ai/backend/manager/api/gql/session/resolver/session.py

@@ -10,6 +10,8 @@
     AdminSearchSessionsInput,
     TerminateSessionsInProjectInput,
 )
+from ai.backend.common.meta.meta import NEXT_RELEASE_VERSION
+from ai.backend.common.types import SessionId
 from ai.backend.manager.api.gql.base import encode_cursor
 from ai.backend.manager.api.gql.decorators import (
     BackendAIGQLMeta,
@@ -32,6 +34,20 @@
 from ai.backend.manager.errors.user import UserNotFound
 
 
+@gql_root_field(
+    BackendAIGQLMeta(
+        added_version=NEXT_RELEASE_VERSION,
+        description="Query a single session by ID. Returns an error if not found.",
+    )
+)  # type: ignore[misc]
+async def session_v2(
+    info: Info[StrawberryGQLContext],
+    id: UUID,
+) -> SessionV2GQL | None:
+    payload = await info.context.adapters.session.get(SessionId(id))
+    return SessionV2GQL.from_pydantic(payload)
+
+
 @gql_root_field(
     BackendAIGQLMeta(
         added_version="26.3.0",