ClusterNode hosts a BTreeMap<ShardId, Arc<ShardReplica>>: writes hash-route
to the owning shard leader, reads scatter over shard groups. In-group
shard==region preserved so the engine and tidal-net are untouched; S=1 stays
byte-for-byte (today's cluster is a 1-shard × RF=N group). Topology grows
shard-group awareness; membership, election, forward, reseed, and join_boot
thread ShardId through.
Proven by an in-process 2×2 RF=2 gRPC test plus S=1 parity, incl. tier-3
real-OS-process failover. clippy/fmt clean.
Kind-3 term markers in the WAL stream, STREAM-relative vote frontiers,
heartbeat-only divergence detection + quarantine, and fenced promote.
Elections converge in 0.6–1.0s; zero acked-write loss across all kill points.
Closes G5 (leaderless recovery) from the v0.9 wave.
m11p1 — decoupled ack/ship path: staged writes (seqno+WAL+relay-push,
microseconds) separate from group-commit fsync; ShipQueue batches+windows
outbound segments; receiver coalesces inbound chunks before applying.
Adds first tidaldb_cluster_* metrics.
m11p2 — leader WAL is now THE replicated log: fsynced batches feed a
bounded WalShipFeed and ship byte-identical to followers; WAL seqnos
survive restarts (relay-reset hazard gone). Item metadata and embeddings
journal kind-1/2 blob records on the same stream as signals; the m8p10
HTTP broadcast is deleted. StreamSegments catch-up is follower-pulled via
server-streaming RPC, triggered on gap detection, follower boot, and
leader heal nudge. Promote carries a stream baseline so peers skip
pre-stream history.
Splits monolithic cluster.rs into tidal-server/src/cluster/ modules. Adds redeliver-missed
relay, bounded HLC drift, lag tracking, and reconcile idempotence. Five new tier-3 test suites
(chaos, lifecycle, multiproc, region, routes, runbook) all green. Docs, CHANGELOG, and ROADMAP
updated with G4/G5/G6 known gaps.
