Durable `leader_acked` frontier in `ShardReplica` tracks the highest seqno
acked under `ack=leader` (journal-only, un-replicated); `decide_join` now
quarantines on THIS node's own frontier rather than comparing stream numbers
across stream boundaries — eliminates false-quarantine churn on rolling
restarts. `SHUTDOWN_HANDOFF_WAIT` (3s) drains the leader's tail to quorum
before step-down so the next leader inherits a clean prefix. New
`load_leader_acked`/`persist_leader_acked` helpers; `cluster_reseed.rs` gains
the divergence-fix regression suite; `replication_ops.rs` threads the signal.
Soak-eval: `tidal_stress::soak_eval` + `soak-eval` binary implement the
30-night streak (ledger.tsv × restarts.tsv → streak.tsv); monitor and nightly
CronJob k8s YAMLs updated; phase-9 doc clarifies the dual-stream streak
definition (ledger PASS AND zero pod restarts in window). `run-reliability.sh`
gates the election-divergence suite before any k8s push.
Release tooling: `docker/release/` multi-stage Dockerfile + DR image;
`scripts/build-release.sh` single repeatable cross-compile+buildx path.
