Modernization / Migration Roadmap Diagram

**Description**

Develop a Modernization / Migration Roadmap Diagram that visually illustrates the transition from the current-state architecture to the future-state architecture. The diagram will identify key modernization phases, migration waves, dependencies, milestones, and transition states, providing a clear view of the modernization journey.
This artifact will help executives, program managers, architects, and transformation teams align on the modernization strategy, sequencing, priorities, and associated risks.

Business Value
A modernization roadmap bridges the gap between the current state and future state by providing a structured view of how transformation will occur over time. It enables strategic planning, helps manage modernization risks, supports stakeholder alignment, and provides a framework for prioritizing initiatives and investment decisions.

Audience

- Executives
- Leadership
- Business Team
- Product Owners
- Architect
- Development team
- Modernization teams

**Key Questions Addressed**

How will we move from the current state to the future state?
What are the major phases of modernization?
What systems, capabilities, or platforms will be modernized, replaced, or retired?
What dependencies influence migration sequencing?
What transition states or interim architectures may be required?
What are the major risks and considerations throughout the transformation journey?

**Scope**

Document and visualize:

- [ ] Current-state architecture baseline
- [ ] Future-state architecture target
- [ ] Modernization phases or migration waves
- [ ] Major transformation initiatives
- [ ] Interim or transition states
- [ ] Dependencies and sequencing considerations
- [ ] Key milestones and decision points
- [ ] System retirements and replacements
- [ ] Major capability transitions
- [ ] High-level risks and constraints (where applicable)

The issue names no repository file, test, or entry point. Start by identifying the current-state and future-state architecture inputs, then define the diagram format and map phases, migration waves, dependencies, milestones, transitions, retirements, replacements, and risks. Done means the roadmap covers the listed scope and communicates sequencing to the stated audiences.

Written by the indexing model from the issue text.