Step 06 of 10 4-6 months for the first slice· advanced
Step 6: Migrate the First Capability (Vertical Slice)
Ship one complete capability through the new stack. For RPG specifically, slice 1 should be read-only or low-stakes with limited 5250 redesign — exercise the infrastructure, not the riskiest UX.
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.
- Slice 1 implementation complete (frontend + API + DB)
- Parity tests pass against extracted rules
- Shadow mode running, comparing to IBM i
- Performance meets targets
- Internal validation passed
- Canary rollout to a small user set successful
- Stop conditions clear; rollback procedure tested
Common pitfalls
What goes wrong at this step
- Slice 1 too big — should fail safely
- Skipping shadow mode — catches bugs that tests miss
- Replicating 5250 patterns in web — use slice 1 to establish modern UX patterns
- Performance neglect — ORM-based access can be slower than RPG native I/O on hot paths