# Quickstart: Multi-Raft (Static → Split → Move)

## Prerequisites
- Nix or Rust toolchain per repo.
- PD stub runs inline (tests use in-memory).

## Run tests (recommended)
```bash
nix develop -c cargo test -q rdb-server::tests::test_multi_region
nix develop -c cargo test -q rdb-server::tests::test_split
nix develop -c cargo test -q rdb-server::tests::test_confchange_move
```
Or full suite:
```bash
nix develop -c cargo test -q
```

## Manual smoke (single node, two regions)
1. Launch PD stub (or ensure `pdpb` gRPC reachable).
2. Start server:
   ```bash
   nix develop -c cargo run -p rdb-server -- --pd-endpoint http://127.0.0.1:50051
   ```
3. Verify routing:
   - Put key `b"a"` → Region1
   - Put key `b"z"` → Region2

## Trigger split (dev)
1. Run `test_split` or fill a region with writes.
2. Observe log: `ApplyCommand::Split` and new region registered.

## Move (rebalance) flow (simplified)
1. Source store handles region; target store starts with PD meta.
2. PD issues `MoveRegion(region_id, from=src, to=dst)`.
3. Source adds replica on target (ConfChange Add); target catches up; source can later remove itself (ConfChange Remove).
4. Verify data on target:
   ```bash
   nix develop -c cargo test -q move_region_replica_carries_data -- --nocapture
   ```

## Notes
- Key ranges must not overlap; nodes validate PD meta.
- Raft logs and hard-state are prefixed by `region_id` to isolate shards.
- Pending eventual writes are forwarded to leaders; local queue persists to disk to survive restart.