We retire mainframes onto Kora CBA — one bounded domain at a time.
A productized mainframe-modernization service for US community and mid-cap regional banks running COBOL on z/OS. This console is the engineering surface where the full pipeline — discovery, ingestion, transform, reconciliation, statement parity — runs end-to-end against AWS's open-source CardDemo COBOL codebase.
How a design-partner walkthrough flows
Four swimlanes — presenter, console, backend services, audit trail — across seven steps. The hero column (★) is L5 statement parity: mainframe-generated golden vs. CBA-regenerated, three-line numeric content compare.
Click the image to view full resolution (3200×2160) · source: docs/diagrams/07-demo-flow.svg
Live MVP · no mocks below the mainframe
End-to-end pipeline
Six Go services + a Kotlin parser sidecar + a Next.js console, all on Cloud Run.
- 10 CardDemo entity slices reconcile end-to-end against the mock CBA target — accounts, customers, disclosure_groups, transactions, tcatbal, tran_types, tran_categories, users, cards, card_xref.
- L1 + L2 count + sum-of-numeric per entity, zero monetary tolerance.
- L5 statement parity for 5 demo accounts — three-line numeric content compare.
Auditor-walkable evidence
The trust signal beyond green totals.
- M12 evidence chain aggregates every artifact + every user action with provenance metadata (run_id, timestamps, sha256, mapping name).
- Append-only audit.events table — who approved each run, when, from where. Routes to CBA audit-service when Phase 2 lands.
- CI gate on every push to main — full bench re-runs against this URL; PRs turn red on any regression.
The non-negotiables
Eight principles in docs/02-architecture.md §1; here are the four a prospect's migration lead will want to see first.
One domain at a time, both stacks live in parallel until the mainframe is empty. Never big-bang.
Monetary movements reconcile to CBA's General Ledger — not to mid-stream artifacts.
Every ingest / transform / replay / cutover step is re-runnable without duplicates.
Engagement data stays in customer-controlled GCP projects. Shared Kora infra is tooling only.
For prospects
If you're a US bank evaluating migration partners.
We're signing design partners. The ask: one hour of your migration lead's time walking through this demo together. In return: right of first refusal on the production engagement at below-market design-partner pricing, plus co-authorship on the public methodology document.
Contact: bisi@korastratum.com
For engineers
If you're reading the code.
Repo: github.com/badedokun/mfmodern (private during design-partner stage)
Six Go services + a Kotlin gRPC parser sidecar + a Next.js console, all on Cloud Run. One shared Postgres for engagement data. Mapping specs are YAML. Money is decimal.Decimal end-to-end. CardDemo runs in CI on every push.
Reference docs: requirements · architecture · design · implementation · roadmap · methodology · deployment · architecture-conformance review.