# Roadmap

Current release: **v1.0.0**. Stable SemVer for the public API frozen in 0.12.

## Done in 0.1.0

- Mongo-backed immutable event log
- Bounded fetch + leases + ACK
- Crash/redelivery + stale lease fencing
- Competing consumers
- Independent consumer groups
- Historical query
- Idiomatic `Rheo.Consumer`
- Bounded demand (`max_demand`)
- Demo + docs/tutorials
- Livebook demo (`notebooks/rheo_demo.livemd`)

## Done in 0.2.0

- Named multi-instance Rheo + opaque backend handles
- Local `Rheo.Group` runtime (demand, concurrency, renew, drain)
- Portable `Rheo.Query`; Event codec moved to Mongo
- Explicit persistence-error telemetry / settle semantics
- Migration guide + Article 9

## Done in 0.3.0

- `Rheo.Backend.ETS` (ephemeral, per-instance tables)
- Backend capabilities map
- Shared conformance suite (ETS always; Mongo tagged)
- Docker-free demo / Livebook path
- ADRs 011, 012, 014 + Article 10

## Done in 0.4.0

- Query sequence bounds, `query_page` / `stream_query`
- Replay / `reset_group` (no event copies); `create_group` start cursors
- `Rheo.Event.Lineage` conventions
- ADR 015 + Article 11 + [0.3 → 0.4 migration](https://github.com/thanos/rheo/blob/main/docs/migrations/0.3-to-0.4.md)

## Done in 0.4.1

- Hex README links use HexDocs / GitHub absolutes (relative `docs/` paths 404 on hex.pm)

## Done in 0.5.0

- Configurable partitions + `:erlang.phash2/2` key routing
- Per-partition sequences; ordered consume within a partition only
- Contiguous ACK frontier + `Rheo.lag/3`
- Static Group/Consumer `:partitions` assignment (no auto-rebalance)
- Partition-scoped `replay` / `reset_group`
- ADR 016 + Article 12 + [0.4 → 0.5 migration](https://github.com/thanos/rheo/blob/main/docs/migrations/0.4-to-0.5.md)
- Docs/Livebook/CHANGELOG links use absolute HexDocs or GitHub URLs for hex.pm

## Done in 0.6.0

- `Rheo.Backend.Ecto` on host-owned Repo (PostgreSQL + SQLite)
- SQL migrations + `mix rheo.ecto.gen_migration`
- Postgres `FOR UPDATE SKIP LOCKED`; optional `NOTIFY`
- SQLite durable single-node path; `distributed: false`
- ADR 017 + Article 13 + [0.5 → 0.6 migration](https://github.com/thanos/rheo/blob/main/docs/migrations/0.5-to-0.6.md)

## Done in 0.7.0

- `Rheo.Producer` — GenStage producer emitting `%Rheo.Lease{}` (demand → fetch,
  inflight renewal, idle poll, backoff, drain)
- `Rheo.Broadway.transform/2` + `Rheo.Broadway.Acknowledger` (ack / nack / reject)
- `Rheo.Producer.confirm/2` so settled leases stop renewing and free demand
- `Rheo.Consumer` / `Rheo.Group` unchanged — the producer is an alternative surface
- ADR 018 + Article 14 + [0.6 → 0.7 migration](https://github.com/thanos/rheo/blob/main/docs/migrations/0.6-to-0.7.md)

## Done in 0.7.1

- HexDocs sidebar groups for guides, design, and migrations (later slimmed in
  v0.11 to current docs only; archive stays on GitHub)
- Mermaid diagrams render on HexDocs
- Livebook Broadway demo aligned with the published v0.7 API

## Done in 0.8.0

- Architectural reset (ADR 019): read-only handler context and one Group owner
  per `{rheo, stream, group}` (ADR 022); lease `receipt` (ADR 021); typed
  capabilities (ADR 023); semantic backend contract and settlement vocabulary
  (ADR 024); `Rheo.Inflight` / `Rheo.Backoff` shared by Group and Producer
- `Rheo.Producer.ack/3`, `nack/4`, `reject/4` — one-call settle and release
- Conformance suite grouped by guarantee, run by ETS, Mongo, Ecto, and a
  native-stream double; failure-injection and property tests on ETS
- Optional integrations with compile-time guards and a core-only build check; Flow and Redis readiness spikes
- ADRs 019–025; Article 15; [0.7 → 0.8 migration](https://github.com/thanos/rheo/blob/main/docs/migrations/0.7-to-0.8.md)

## Done in 0.9.0

- `Rheo.Backend.Redis` on optional `redix` (ADR 026) — Model C sequences +
  native receipts, fenced `XACK`, reclaim, replay
- Wakeup contract implemented (ADR 025): reader Task + `wait/2`; polling remains
  fallback
- Conformance suite tagged `:redis`; docker-compose Redis 7 service
- [0.8 → 0.9 migration](https://github.com/thanos/rheo/blob/main/docs/migrations/0.8-to-0.9.md); Redis guide
- Article 16 (portable sequence, native PEL)

## Done in 0.10.0

- Ops surface (ADR 027): DLQ listing, stream/group inventory, group health,
  telemetry metrics helpers, optional LiveDashboard, Mix inspect tasks,
  formalized benchmarks
- [0.9 → 0.10 migration](https://hexdocs.pm/rheo/0-9-to-0-10.html)

## Done in 0.11.0

- `Rheo.Backend.Mnesia` — durable ETS-shaped OTP `:mnesia` store, single-node
  `disc_copies` (`durable: true`, `distributed: false`) (ADR 028)
- Multi-node backend comparison documented (Redis / Postgres yes; ETS / SQLite /
  Mnesia v0.11 no)
- [0.10 → 0.11 migration](https://hexdocs.pm/rheo/0-10-to-0-11.html)

## Done in 0.11.1

- Composite `query_page` cursors, single Group poll timer, Registry group names
- Shared ETS/Mnesia table engine with indexes; stream-first fetch errors
- [0.11 → 0.11.1 migration](https://hexdocs.pm/rheo/0-11-to-0-11-1.html)

## Done in 0.12.0

- API freeze candidate (ADR 029): HexDocs publishes Facade / Consume / Values /
  Backend / Runtime / Ops; internal modules filtered
- Public API guide; unavailable-handle contract case; Metrics coverage
- [0.11.1 → 0.12 migration](https://hexdocs.pm/rheo/0-11-1-to-0-12.html)

## Done in 1.0.0

- SemVer baseline for the frozen surface (ADR 030)
- [0.12 → 1.0 migration](https://hexdocs.pm/rheo/0-12-to-1-0.html) — no intended
  breaks from 0.12.0

## Next (post-1.0)

- Multi-node Mnesia table copies (backend arbitration only — not a Rheo cluster)
- Article candidate: Rheo + Flow settlement narrative

## Explicitly deferred

- Distributed Rheo cluster coordination (beyond durable backend arbitration)
- Automatic partition rebalancing
- Cross-region replication
- Exactly-once claims
- Transactional consume-and-produce
- Schema registry
- Custom wire protocol
- Administrative web UI
- Kubernetes operator
- AuthN/AuthZ frameworks
- Multi-tenancy
- Retention tiers
- Standalone Rheo server
- `mongodb_ecto` as a Rheo backend path