Context And Boundaries

External Context

_{Figure source: ../assets/infographics/architecture/01-context-and-boundaries.infographic}

Boundary Rules

• ran_cu_cp, ran_cu_up, and ran_du_high may coordinate through ran_core services, but they must not directly manage native timing loops.
• ran_du_high only speaks canonical IR through ran_fapi_core.
• ran_fapi_core owns contract translation, profile selection, and capability negotiation.
• fapi_rt_gateway owns backend-specific transport and process supervision outside the BEAM scheduler.
• Skills never apply shell-level mutations directly when ranctl can express the action.

Southbound Profiles

• stub_fapi_profile: local test and contract validation.
• local_fapi_profile: native local DU-low adapter owned by this repository.
• aerial_fapi_profile: profile for future NVIDIA Aerial integration without leaking vendor-specific details into core apps.

Data Ownership

• CU-CP owns control-plane session and association state.
• CU-UP owns user-plane tunnel lifecycle state.
• DU-high owns scheduling intent, cell-group runtime state, and DU-local orchestration.
• ran_action_gateway owns operational change state and approval flow.
• ran_observability owns artifact routing, telemetry naming, and incident snapshots.

Assumptions

• A single cell_group is the minimum scheduling and change-application scope for MVP.
• UE state remains partitionable under a cell-group supervisor subtree.
• A backend gateway process can be drained and replaced without requiring a global node restart.