kandev/docs/plans/message-queue-merge/task-02-backend-service-handler.md

id, title, status, wave, depends_on, plan, spec

id	title	status	wave	depends_on	plan	spec
message-queue-merge-02	Backend service and WS handler	completed	2	message-queue-merge-01	plan.md	../../specs/ui/message-queue-merge.md

Task 02: Backend service and WS handler

Acceptance

1. ActionMessageQueueMerge = "message.queue.merge" exists in pkg/websocket/actions.go and Service.MergeIntoAbove delegates to the repository (with the same logger pattern as RemoveEntry).
2. QueueHandlers registers message.queue.merge, validates session_id / entry_id, rejects reserved user_id, defaults user_id to QueuedByUser, and maps ErrEntryNotFound → entry_not_found / ErrNoMergeTarget → validation, publishing message.queue.status_changed on success.
3. Handler tests cover the happy path, missing fields, head/mismatch → validation, reserved user_id rejection, and drained source → entry_not_found.

Verification

• cd apps/backend && go test -race ./internal/orchestrator/handlers/... ./internal/orchestrator/messagequeue/...

Files

• apps/backend/pkg/websocket/actions.go
• apps/backend/internal/orchestrator/messagequeue/service.go
• apps/backend/internal/orchestrator/handlers/queue_handlers.go
• apps/backend/internal/orchestrator/handlers/queue_handlers_merge_test.go
• apps/backend/internal/orchestrator/messagequeue/service_test.go

Inputs

• Spec sections: API surface, Failure modes, Permissions.
• Plan sections: Backend → Contract, Backend → WS handler, Tests (service
  • handler rows).
• Patterns to mirror: wsUpdateMessage validation/error mapping (queue_handlers.go:243), wsRemoveEntry shape (queue_handlers.go:332), publishStatus.

Risks

• Any other QueueService implementor in the codebase must gain the new MergeIntoAbove method — grep for QueueService implementations (e.g. mocks in tests) and update them.