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Sprint 01 Ledger Foundation
Tiana_ edited this page May 30, 2026
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First sprint after documentation phase completes. Goal: ship the v0.1.0 release. Duration: 6 weeks (May 12 - June 23, 2026) Outcome: tag v0.1.0, public launch.
Ship a working, tested, documented ledger service with sandbox bank, observability, and quickstart that gets a developer from git clone to "I posted my first transaction" in under 5 minutes.
git clone https://github.com/tiana-code/fincore-engine
cd fincore-engine
docker compose up -d # wait ~30 seconds
./scripts/demo.sh # creates accounts, posts transaction, verifies balance
# Output should show:
# x Postgres ready
# x Redpanda ready
# x Keycloak ready
# x Ledger Service ready
# x Account A created (acc_01HX...)
# x Account B created (acc_01HX...)
# x Transaction posted (tx_01HX...)
# x Account A balance: -100.00 EUR
# x Account B balance: 100.00 EUR
# x Time-travel balance at T-5s: 0.00 EUR (before posting)
# x Reverse transaction: succeeded
# x Final balances: 0.00 EUR each
# x Idempotency check (post twice with same key): 1 transaction in DB
#
# Demo complete. Visit:
# - Swagger UI: http://localhost:8080/swagger-ui.html
# - Grafana: http://localhost:3000 (admin/admin)
# - Keycloak: http://localhost:8081 (admin/admin)If this doesn't run cleanly on a fresh machine, the sprint is incomplete.
Theme: Get the repo bootable. Domain layer ready.
| Day | Task | Owner |
|---|---|---|
| Mon | Repo skeleton: settings.gradle.kts, build.gradle.kts, gradle/libs.versions.toml, gradle wrapper
|
Maintainer |
| Mon |
libs/fincore-core module: Money, Currency, AccountId, etc. |
Maintainer |
| Tue |
libs/fincore-events module: EventEnvelope, OutboxEvent
|
Maintainer |
| Tue |
services/ledger module skeleton (Spring Boot 3.5 hello-world starts) |
Maintainer |
| Wed | Liquibase changelog: schemas, base extensions | Maintainer |
| Wed | Liquibase changelog: ledger.accounts table |
Maintainer |
| Thu | Domain layer: Account, Transaction, Entry classes with invariants | Maintainer |
| Thu | Domain unit tests | Maintainer |
| Fri | Liquibase: transactions, entries tables + indexes |
Maintainer |
| Fri | The deferred trigger for SUM=0 invariant | Maintainer |
| Sat | Verify trigger works against direct JDBC inserts | Maintainer |
End-of-week milestone: Postgres up + ledger schema applied + domain tests green.
Theme: First real API call works.
| Day | Task |
|---|---|
| Mon | JPA entities (AccountEntity, etc.) + repositories |
| Mon | KSP + MapStruct mappers |
| Tue |
AccountServiceImpl (create, get, update) |
| Tue | Account integration tests via Testcontainers |
| Wed |
account_balances materialized view + refresh |
| Wed |
BalanceServiceImpl + time-travel implementation |
| Thu | TransactionServiceImpl.post |
| Thu | First end-to-end test: post a transaction, verify balance |
| Fri | TransactionServiceImpl.reverse |
| Fri | Integration test for reverse |
End-of-week milestone: post + reverse work end-to-end, balances correct.
Theme: Externally callable API.
| Day | Task |
|---|---|
| Mon | DTO classes + Bean Validation |
| Mon |
AccountController (POST, GET, GET balance, GET entries, PATCH) |
| Tue |
TransactionController (POST, GET, POST reverse) |
| Tue |
GlobalExceptionHandler + RFC 7807 |
| Wed |
IdempotencyService + IdempotencyFilter
|
| Wed | Idempotency integration tests (same key = same response) |
| Thu | Idempotency concurrency test (100 threads, same key) |
| Thu | Spring Security + Keycloak JWT validation |
| Fri | Springdoc OpenAPI annotations matching api/openapi.yaml
|
| Fri | OpenAPI conformance test |
End-of-week milestone: full REST API works, secured, idempotent.
Theme: Eventing in place. Metrics flowing.
| Day | Task |
|---|---|
| Mon |
outbox_events table + OutboxEventPublisher
|
| Mon | Outbox dispatcher worker (SELECT FOR UPDATE SKIP LOCKED) |
| Tue | Kafka producer setup (Redpanda) |
| Tue | Outbox integration test (publish on commit) |
| Wed | Crash recovery test (kill dispatcher mid-batch) |
| Wed | Logback structured JSON + MDC |
| Thu | Micrometer + Prometheus exporter |
| Thu | Custom business metrics (ledger.transactions.posted.total etc.) |
| Fri | OpenTelemetry tracing + auto-instrumentation |
| Fri | Grafana dashboard JSON (Ledger overview) |
End-of-week milestone: events flow to Kafka, metrics + traces visible in Grafana.
Theme: Hardening. Confidence under chaos.
| Day | Task |
|---|---|
| Mon |
SandboxBankAdapter (success/fail/delay scenarios) |
| Mon | Seed data script |
| Tue | Property test: invariant holds for any sequence of valid posts |
| Tue | Property test: invalid posts always rejected |
| Wed | Concurrency test: 100 posters × 50 transactions |
| Wed | Performance test: 1000 tx/sec sustained |
| Thu | Chaos test setup (Toxiproxy injection) |
| Thu | Chaos test: bank timeouts, DB slow queries, Postgres restart mid-tx |
| Fri | Bug fixes from chaos / property test findings |
| Fri | Final coverage check (>= 90% domain, >= 70% overall) |
End-of-week milestone: invariants verified under random and concurrent inputs.
Theme: Ship.
| Day | Task |
|---|---|
| Mon |
Dockerfile (multi-stage, distroless) |
| Mon | Build + push image to GHCR (test) |
| Tue | Helm chart deploy/helm/fincore-engine/
|
| Tue |
helm lint + helm template clean |
| Wed | Health probes (liveness, readiness) |
| Wed | Graceful shutdown + outbox drain |
| Thu |
scripts/demo.sh polish - must run cleanly |
| Thu | README polish + quickstart |
| Fri | Final integration smoke (docker compose up && demo.sh) |
| Fri | Tag v0.1.0, release CI runs (Docker, Helm, GitHub Release) |
| Sat | Hacker News post: "Show HN: FinCore Engine - open-source fintech core" |
- Code merged to
mainvia PR - Code review passed (self-review + 24h cooling period)
- CI green: build, test, lint, security scans
- Code coverage targets met
- Documentation updated (Wiki page + Code-Rules link)
- OpenAPI spec updated if API changed
- Integration test if user-facing
- Property test if invariant-related
- No new deps without ADR
- SPDX header on new files
- No PII in logs
- Performance regression checked
- All week 1-6 milestones met
-
docker compose up && ./scripts/demo.shworks on fresh laptop - Tag
v0.1.0published - CI release pipeline green (Docker pushed, Helm packaged)
- Hacker News post submitted
- Demo video recorded (optional, stretch goal)
| Risk | Mitigation |
|---|---|
| Underestimated time on infrastructure (KSP, MapStruct, Testcontainers wiring) | Skip Week 5 stretch goals if behind |
| Trigger deferred constraint behaves differently than expected | Prove out in Week 1 deliberately |
| Property tests too slow for CI | Reduce iterations to 100 in PR mode, full 1000 nightly |
| Chaos tests reveal real bugs | Schedule fix time in Week 5; scope-cut Week 6 if critical |
| Solo burnout | Strict 40h/week ceiling; weekend off mandatory |
- Cool-down: 1 week (no new features, only critical fixes)
- Sprint 02 starts July 1 - Epic-02 Payments + Epic-03 Event Bus + Epic-05 Decision Engine
This sprint maps to GitHub Project "FinCore Engine Roadmap" with:
-
Milestone:
v0.1.0 - Ledger Foundation -
Iteration field:
Sprint 01(May 12 - Jun 23, 2026) -
Tasks: each line above = GitHub Issue with
effort(XS/S/M/L),priority(P0/P1/P2),area(ledger/infra/docs/sandbox/obs) - Views: Backlog, Current Sprint, By Component, Roadmap
See Dev-Guides§3 for git flow.
- Epic-01-Ledger - full task breakdown
- Roadmap - broader release plan
- User-Flows - what flows we're implementing
- Code-Rules - implementation conventions
- Testing-Strategy - what tests we write
- Overview
- Services
- Data Model
- Domain Model
- Event Flow
- Security
- Observability
- Resilience
- SLA / SLI / SLO