Step 03 of 10 8-12 weeks· advanced
Step 3: Target Architecture Design
Design the modern target — not just the tech stack, but the architectural approach (monolith vs microservices, sync vs event-driven, batch vs online, cloud vs hybrid).
Recommended prompts
Use one of these to do the work in your IDE
Open the template to read it in full. Click Copy prompt to grab it (with your stack values pre-filled where they apply) — then paste into Claude Code, Cursor, or wherever you build.
Recommended skills
Drop these into Claude Code for this phase
Skills auto-trigger on the right kind of request. Install once; they apply to every prompt that fits.
Recommended MCP configs
Wire these tools into Claude Code first
MCP servers give Claude Code direct access to external systems (Jira, browsers, databases). Configure once.
When you're done
Verify these in your own work before moving on
This is a checklist for you to mentally tick off in your repo and IDE — the site doesn't track it, you do.
- Target architecture documented end-to-end
- Monolith vs microservice decision made with rationale
- Sync vs async decision per major capability
- Database strategy decided
- Batch architecture decided (Spring Batch / Step Functions / Airflow / etc.)
- Online architecture decided (REST / GraphQL / event-driven)
- Auth approach decided
- Cloud / hybrid decision made
- 10-15 ADRs documenting the key decisions
- Operational model defined (who runs what, with which skills)
Common pitfalls
What goes wrong at this step
- Premature microservices — COBOL monoliths often work because of transaction integrity; splitting too early creates distributed-system pain
- Ignoring batch — online apps get all the architecture attention; batch gets shoehorned in later
- Skipping the ops model — modern stack with no one to run it = ops nightmare
- All-in on bleeding-edge tech — COBOL stack was stable for decades; new stack should also bias toward stability