SubmitQueue service layout:

• gateway/ — Gateway service: entry point for Ping, Land, Cancel, request-summary, request-history, and queue-listing RPCs. It also consumes request-log events and maintains the public request projections.
• orchestrator/ — Orchestrator service: coordinates validation, dependency analysis, speculation, builds, landing, cancellation, conclusion, hooks, and DLQ reconciliation.
• extension/ — SubmitQueue-specific extension contracts and implementations, including storage, queue configuration, change providers, validation, conflict analysis, speculation, and build runners.
• entity/ — SubmitQueue-specific domain entities.
• core/ — Infrastructure shared across SubmitQueue's own services, including request and batch lifecycle helpers, change-set resolution, and internal topic keys.

Cross-domain building blocks live outside this directory: shared entities in platform/base/, shared extensions in platform/extension/, and cross-domain infrastructure such as the consumer framework in platform/.