// SPDX-FileCopyrightText: 2026 Bruno Meilick
// SPDX-License-Identifier: LicenseRef-Nereid-FreeUse-NoCopy-NoDerivatives
//
// All rights reserved.
//
// This file is part of Nereid and is proprietary software.
// Unauthorized copying, modification, or distribution is prohibited.
//! Read-only derived views over diagrams and session xrefs.
//!
//! Flow reachability/paths/cycles, sequence message search and traces, and session-wide
//! `ObjectRef` routes (structure edges plus cross-diagram xrefs) for MCP query tools and TUI
//! navigation. Pure: never mutates session content or revisions.