Chat: select deployments by active replica traffic status via nested replica filter (FR-3303 follow-up)

[agatha197]

Background

Follow-up to FR-3303. That bug fixed the Playground Chat endpoint selector hiding a deployment while a new revision rolls out (a prior revision's replica is still serving). The interim fix filters the legacy endpoint_list connection by endpoint-level lifecycle_stage (lifecycle_stage != "destroyed" & lifecycle_stage != "destroying"), which is a proxy signal — it keeps non-terminated deployments visible but does not truly check whether a replica is serving traffic.

Per the originating discussion, the clean signal is the replica traffic status: a deployment should be chat-selectable when it has at least one replica whose traffic status is ACTIVE. This was blocked on the endpoint/deployment connection lacking nested filters.

That backend capability is now available: backend.ai #12805 (BA-6849) "support nested replica deployment filters" (manager 26.8.0). It adds DeploymentFilter.replicas: ReplicaNestedFilter { some | every | none: ReplicaFilter }, and ReplicaFilter.trafficStatus: TrafficStatusFilter with enum TrafficStatus { ACTIVE, INACTIVE }.

Goal

Replace the interim lifecycle_stage-based filtering in the Chat endpoint selection with the nested replica traffic-status filter, so a deployment is selectable precisely when a replica is actively serving.

Target filter (on the myDeployments connection):

filter: { replicas: { some: { trafficStatus: { equals: ACTIVE } } } }

Scope

• react/src/pages/ChatPage.tsx — useDefaultEndpointId (currently queries endpoint_list with a string lifecycle_stage filter).
• react/src/components/Chat/EndpointSelect.tsx — the Chat endpoint dropdown (currently queries endpoint_list with a string lifecycle_stage filter).

Both carry a TODO(FR-3303) marker pointing at this work.

Implementation notes

• The nested replicas filter lives on the structured DeploymentFilter input of the deployments connections (myDeployments / projectDeployments / adminDeployments), not on the legacy endpoint_list string-filter field. So this requires migrating the two Chat queries from endpoint_list to myDeployments (user-scoped), following the existing BAIDeploymentSelect / DeploymentListPage patterns.
• DeploymentFilter.replicas ships in manager 26.8.0, so it must be version-gated (isManagerVersionCompatibleWith('26.8.0')). On older managers, fall back to the interim behavior (exclude terminated deployments) so nothing regresses.
• Requires syncing data/schema.graphql to include input ReplicaNestedFilter and DeploymentFilter.replicas, then pnpm relay.

Verification

• bash scripts/verify.sh (Relay + Lint + Format + TypeScript).
• Live verification against a 26.8.0 manager is pending the manager release; until then the change ships behind the version gate.

JIRA Issue: FR-3332