feat(m11): observability+ops (m11p8) + perf-sweep wave 2 T2

m11p8 closes G-O + §1.4-3:
- Cluster metrics: breaker state, forwards, self-heal on /metrics; multi-shard sibling render (shard="N")
- Grafana cluster row + 8-rule Prometheus alert group
- Request-id / TraceLayer on both cluster routers; id rides forward hop
- Truthful status: flushed leader applied_events frontier; post-promote ShardId(0) keying fix
- Self-driving heal: tick_self_heal re-arms stuck-peer backlog every ~3s
- WAL PITR: wal.archive_dir, archive-before-delete gap-free
- tidalctl backup/restore with BLAKE3 content-hash verification
- Rolling-upgrade build_version handshake (N/N+1, never rejects) + Woodpecker release gate

perf-sweep wave 2 T2: one-get-per-type pre-pass in ranking executor
- signal_values.rs pre-fetches all signal kinds before scoring loop
- Eliminates per-item repeated DashMap lookups: −18.8% for_you, −31% under writes
- Byte-identical output verified with A/B test harness

.woodpecker.yaml

@@ -1,8 +1,9 @@
-# Build-only pipeline: Kaniko builds the tidal-server image and pushes it to the
+# Pipeline: a rolling-upgrade RELEASE GATE (m11p8) runs FIRST; only if it passes
-# in-cluster zot registry. DEPLOYMENT IS MANUAL (kustomize, from the orchard9-k3sf
+# does Kaniko build the tidal-server image and push it to the in-cluster zot
-# ops repo) — the old auto-`kubectl set image deployment/tidaldb` step was removed
+# registry. DEPLOYMENT IS MANUAL (kustomize, from the orchard9-k3sf ops repo) —
-# because it coupled every image build to a standalone roll and the cluster ops
+# the old auto-`kubectl set image deployment/tidaldb` step was removed because it
-# repo's contract is "manual deploy via scripts, no CI/CD deploy". The same
+# coupled every image build to a standalone roll and the cluster ops repo's
+# contract is "manual deploy via scripts, no CI/CD deploy". The same
 # `tidal-server` binary serves every subcommand (standalone AND multi-process
 # `cluster --region`), so one image covers both deployments.
 when:
@@ -10,6 +11,19 @@ when:
   event: push
 
 steps:
+  # m11p8 release gate: prove a rolling upgrade under load loses no acknowledged
+  # write and never stalls (mp_rolling_upgrade_no_loss_no_stall — a tier-3 test
+  # spawning three real OS processes with a graceful SIGTERM → version-tagged
+  # restart → heal-until-converged → fixpoint cycle). Serial (--test-threads 1):
+  # the harness binds fixed ports and spawns real processes, so suites must not
+  # overlap. A failure here BLOCKS the image build below — the gate, not the start.
+  rolling-upgrade-gate:
+    image: rust:1-bookworm
+    commands:
+      - apt-get update && apt-get install -y --no-install-recommends protobuf-compiler cmake clang
+      - cargo test -p tidal-server --features cluster-e2e --test cluster_lifecycle
+        mp_rolling_upgrade_no_loss_no_stall -- --nocapture --test-threads 1
+
   build:
     image: woodpeckerci/plugin-kaniko
     settings:

CHANGELOG.md

@@ -6,6 +6,49 @@ All notable changes to tidalDB will be documented in this file.
 
 ### Added
 
+**Observability + operations (m11p8) — complete cluster metric set on a per-node `/metrics` listener, request-id/tracing across hops, truthful status, self-driving heal, WAL PITR + backup/restore, rolling-upgrade release gate**
+
+- **Metrics.** Completed the `tidaldb_cluster_*` set with the two members the
+  roadmap named that were missing — **breaker** (`tidaldb_cluster_peer_breaker_state`
+  0/1/2 + `tidaldb_cluster_breaker_opens_total`, surfaced read-only from the
+  `tidal-net` circuit breaker via a new `Transport::peer_breaker_state`) and
+  **forwards** (`tidaldb_cluster_forwards_total` / `_forward_failures_total`,
+  instrumented at the gateway forward path) — plus the self-heal series
+  (`heal_attempts/successes/noops_total`, `healing_peers`). When several shard
+  groups co-locate on one node (m11p6) the metrics-owner serves the single
+  `/metrics` listener and the siblings register their series under a `shard="N"`
+  label (`TidalDb::register_metrics_sibling`); a single-shard node is
+  byte-identical to before. A 12-panel "Cluster Replication" Grafana row +
+  an 8-rule `tidaldb-cluster` Prometheus alert group ship beside the standalone
+  ones.
+- **Request-id + tracing.** Both cluster routers (single- and multi-process) now
+  carry the standalone router's `SetRequestId` + `PropagateRequestId` +
+  `TraceLayer` stack (extracted to `router::with_request_id_tracing`); the id
+  rides the follower→leader forward hop verbatim, so the leader's span shares the
+  gateway's `x-request-id`. (Ships are off-request-path and batched, so they
+  correlate by seqno, not a request-id — by design.)
+- **Truthful status.** Fixed the leader's own `applied_events` reading 0 (a leader
+  writes its WAL directly and never advances its own applied frontier — now
+  reports its flushed frontier) and the single-process post-promote `ShardId(0)`
+  lag-keying undercount (now keys on the current leader's shard).
+- **Self-driving heal.** A standing leader duty re-arms the backlog re-ship for a
+  stuck (breaker-open, behind) peer every ~3s, so it converges through breaker
+  resets with no operator `/cluster/heal` loop — closing the §1.4-3 footgun.
+  Observable via `healing_peers` + the `TidalDBClusterHealNotConverging` alert.
+- **WAL PITR archival.** `wal.archive_dir` (topology + builder): the online
+  compaction copies each sealed segment to the archive — durably, before deletion,
+  refusing to delete if archival fails — so the archive is a gap-free PITR record.
+- **Backup/restore.** `tidalctl backup` / `restore`: offline data-dir backup with
+  a BLAKE3 `BACKUP_MANIFEST.json` (+ the WAL checkpoint cursor); restore verifies
+  every file's hash before writing and refuses a non-empty target. Coordinated
+  cluster backup = back up one committed replica per shard group (the runbook
+  drill).
+- **Rolling upgrade.** A wire version handshake (`HeartbeatRequest.build_version`,
+  stamped at the transport boundary; `>= 2`-major skew WARNs, never rejects) +
+  `version` on `/cluster/status`. `mp_rolling_upgrade_no_loss_no_stall` promoted
+  to the FIRST step of `.woodpecker.yaml` (the release gate; a failure blocks the
+  image build). See [milestone-11/phase-8.md](docs/planning/milestone-11/phase-8.md).
+
 **Security hardening (m11p7) — mTLS by default + zero-drop cert rotation, per-node identity, admin audit log, per-principal rate limit**
 - **The cluster stops trusting the network.** gRPC replication mTLS is now the
   intended posture: the inbound server is served over a custom `tokio-rustls`

Cargo.lock

@@ -3634,6 +3634,7 @@ dependencies = [
 name = "tidalctl"
 version = "0.1.0"
 dependencies = [
+ "blake3",
  "serde",
  "serde_json",
  "tidaldb",

docs/ops/grafana-dashboard.json

@@ -518,6 +518,154 @@
           "color": { "mode": "palette-classic" }
         }
       }
+    },
+    {
+      "id": 49,
+      "type": "row",
+      "title": "Cluster Replication (m11p8)",
+      "description": "Rendered only in cluster mode (tidaldb_cluster_* series). One scrape target per node; co-located shard groups carry a shard=\"N\" label.",
+      "gridPos": { "x": 0, "y": 39, "w": 24, "h": 1 },
+      "collapsed": false
+    },
+    {
+      "id": 50,
+      "type": "timeseries",
+      "title": "Quorum Replication Lag (events)",
+      "description": "flushed frontier minus quorum commit index — how far the durable majority trails the leader's log. SLA < 2s of writes.",
+      "gridPos": { "x": 0, "y": 40, "w": 8, "h": 6 },
+      "targets": [
+        { "expr": "tidaldb_cluster_relay_last_seq - tidaldb_cluster_relay_durable_seq", "legendFormat": "quorum lag (events)" }
+      ],
+      "fieldConfig": { "defaults": { "unit": "short", "color": { "mode": "palette-classic" } } }
+    },
+    {
+      "id": 51,
+      "type": "timeseries",
+      "title": "Commit Progress (flushed vs committed)",
+      "description": "Leader flushed high-water mark and the quorum commit index. A flat commit index while flushed climbs = quorum lost.",
+      "gridPos": { "x": 8, "y": 40, "w": 8, "h": 6 },
+      "targets": [
+        { "expr": "tidaldb_cluster_relay_last_seq", "legendFormat": "flushed seq" },
+        { "expr": "tidaldb_cluster_relay_durable_seq", "legendFormat": "commit index" }
+      ],
+      "fieldConfig": { "defaults": { "unit": "short", "color": { "mode": "palette-classic" } } }
+    },
+    {
+      "id": 52,
+      "type": "timeseries",
+      "title": "Per-Peer Ship Queue Depth",
+      "description": "Unacked seqnos outstanding to each follower. A single peer climbing = that link is the laggard.",
+      "gridPos": { "x": 16, "y": 40, "w": 8, "h": 6 },
+      "targets": [
+        { "expr": "tidaldb_cluster_peer_ship_queue_depth", "legendFormat": "peer {{peer_shard}}" }
+      ],
+      "fieldConfig": { "defaults": { "unit": "short", "color": { "mode": "palette-classic" } } }
+    },
+    {
+      "id": 53,
+      "type": "timeseries",
+      "title": "Ship RTT p99 (µs)",
+      "description": "Replication batch ship round-trip time, 99th percentile across peers.",
+      "gridPos": { "x": 0, "y": 46, "w": 8, "h": 6 },
+      "targets": [
+        { "expr": "histogram_quantile(0.99, sum by (le) (rate(tidaldb_cluster_ship_rtt_us_bucket[5m])))", "legendFormat": "ship rtt p99" }
+      ],
+      "fieldConfig": { "defaults": { "unit": "µs", "color": { "mode": "palette-classic" } } }
+    },
+    {
+      "id": 54,
+      "type": "timeseries",
+      "title": "WAL Group-Commit fsync p99 (µs)",
+      "description": "Leader and follower WAL group-commit fsync latency, 99th percentile. The platform durability floor.",
+      "gridPos": { "x": 8, "y": 46, "w": 8, "h": 6 },
+      "targets": [
+        { "expr": "histogram_quantile(0.99, sum by (le) (rate(tidaldb_cluster_wal_fsync_us_bucket[5m])))", "legendFormat": "fsync p99" }
+      ],
+      "fieldConfig": { "defaults": { "unit": "µs", "color": { "mode": "palette-classic" } } }
+    },
+    {
+      "id": 55,
+      "type": "timeseries",
+      "title": "Group-Commit Batch Fill (median events)",
+      "description": "Median events amortized per fsync. Low under sustained write load points at a batch-timeout that is too short.",
+      "gridPos": { "x": 16, "y": 46, "w": 8, "h": 6 },
+      "targets": [
+        { "expr": "histogram_quantile(0.5, sum by (le) (rate(tidaldb_cluster_group_commit_events_bucket[5m])))", "legendFormat": "events/fsync (p50)" }
+      ],
+      "fieldConfig": { "defaults": { "unit": "short", "color": { "mode": "palette-classic" } } }
+    },
+    {
+      "id": 56,
+      "type": "timeseries",
+      "title": "Election Term & Leader Changes",
+      "description": "Current term (gauge) and the rate of observed leadership changes. Steady term + zero changes = stable cluster.",
+      "gridPos": { "x": 0, "y": 52, "w": 8, "h": 6 },
+      "targets": [
+        { "expr": "tidaldb_cluster_election_term", "legendFormat": "term" },
+        { "expr": "rate(tidaldb_cluster_leader_changes_total[5m])", "legendFormat": "leader changes/s" }
+      ],
+      "fieldConfig": { "defaults": { "unit": "short", "color": { "mode": "palette-classic" } } }
+    },
+    {
+      "id": 57,
+      "type": "timeseries",
+      "title": "Elections Started & Quorum Timeouts (per second)",
+      "description": "Election attempts and ack=quorum write timeouts. Sustained nonzero = unstable leadership or a slow replica.",
+      "gridPos": { "x": 8, "y": 52, "w": 8, "h": 6 },
+      "targets": [
+        { "expr": "rate(tidaldb_cluster_elections_started_total[5m])", "legendFormat": "elections/s" },
+        { "expr": "rate(tidaldb_cluster_quorum_timeouts_total[5m])", "legendFormat": "quorum timeouts/s" }
+      ],
+      "fieldConfig": { "defaults": { "unit": "short", "color": { "mode": "palette-classic" } } }
+    },
+    {
+      "id": 58,
+      "type": "timeseries",
+      "title": "Write Pool: Depth & Shedding",
+      "description": "Queued cluster write jobs and the rate of HTTP 429 backpressure rejections. Rising 429s = offered load past the knee.",
+      "gridPos": { "x": 16, "y": 52, "w": 8, "h": 6 },
+      "targets": [
+        { "expr": "tidaldb_cluster_write_pool_depth", "legendFormat": "queue depth" },
+        { "expr": "rate(tidaldb_cluster_write_pool_rejections_total[5m])", "legendFormat": "429/s" }
+      ],
+      "fieldConfig": { "defaults": { "unit": "short", "color": { "mode": "palette-classic" } } }
+    },
+    {
+      "id": 59,
+      "type": "timeseries",
+      "title": "Per-Peer Circuit-Breaker State",
+      "description": "0 closed, 1 open, 2 half-open. An open breaker (1) means replication to that peer is stalled for the reset window.",
+      "gridPos": { "x": 0, "y": 58, "w": 8, "h": 6 },
+      "targets": [
+        { "expr": "tidaldb_cluster_peer_breaker_state", "legendFormat": "peer {{peer_shard}}" },
+        { "expr": "rate(tidaldb_cluster_breaker_opens_total[5m])", "legendFormat": "opens/s" }
+      ],
+      "fieldConfig": { "defaults": { "unit": "short", "color": { "mode": "palette-classic" } } }
+    },
+    {
+      "id": 60,
+      "type": "timeseries",
+      "title": "Cross-Node Write Forwards (per second)",
+      "description": "Writes this gateway relayed to a shard leader, and forwards that failed (leader unreachable). High forward rate at one node = client routing imbalance.",
+      "gridPos": { "x": 8, "y": 58, "w": 8, "h": 6 },
+      "targets": [
+        { "expr": "rate(tidaldb_cluster_forwards_total[5m])", "legendFormat": "forwards/s" },
+        { "expr": "rate(tidaldb_cluster_forward_failures_total[5m])", "legendFormat": "failures/s" }
+      ],
+      "fieldConfig": { "defaults": { "unit": "reqps", "color": { "mode": "palette-classic" } } }
+    },
+    {
+      "id": 61,
+      "type": "timeseries",
+      "title": "Self-Driving Heal",
+      "description": "Peers being driven back to convergence (gauge) and heal reconcile attempt/success rates. healing_peers > 0 for minutes = investigate.",
+      "gridPos": { "x": 16, "y": 58, "w": 8, "h": 6 },
+      "targets": [
+        { "expr": "tidaldb_cluster_healing_peers", "legendFormat": "healing peers" },
+        { "expr": "rate(tidaldb_cluster_heal_attempts_total[5m])", "legendFormat": "attempts/s" },
+        { "expr": "rate(tidaldb_cluster_heal_successes_total[5m])", "legendFormat": "successes/s" }
+      ],
+      "fieldConfig": { "defaults": { "unit": "short", "color": { "mode": "palette-classic" } } }
     }
   ]
 }

docs/ops/monitoring.md

@@ -127,7 +127,7 @@ Index health metrics are refreshed every 10 seconds by the checkpoint thread (3x
 
 **Normal range for `degradation_level`:** Should be `0` during normal operation. Any value > 0 means the load detector has triggered degradation to protect latency. Investigate system load (CPU, memory pressure, I/O saturation).
 
-### Cluster Replication (feature-gated, m11p1–m11p5)
+### Cluster Replication (feature-gated, m11p1–m11p8)
 
 Emitted only on cluster nodes (the series activate when cluster mode takes the
 metrics handle; standalone deployments keep their exact metric surface). In
@@ -160,6 +160,31 @@ multi-process cluster mode the listener binds the topology's per-region
 | `tidaldb_cluster_snapshot_fetches_total` (m11p5) | counter | count | `FetchSnapshot` streams served as the leader-side snapshot source. |
 | `tidaldb_cluster_snapshot_pin_force_drops_total` (m11p5) | counter | count | Staged-artifact retention pins force-dropped past the hard cap (a dead joiner that never released — alert: a stuck reseed is freezing compaction). |
 | `tidaldb_cluster_remove_delivery_giveups_total` (m11p5) | counter | count | Removal-delivery graces that expired before the removed peer acked the `Removed` record (the node was down/unreachable during decommission). |
+| `tidaldb_cluster_forwards_total` (m11p8) | counter | count | Cross-node write forwards this gateway initiated. A high `rate()` at one node = client routing imbalance, not a fault. |
+| `tidaldb_cluster_forward_failures_total` (m11p8) | counter | count | Forwards that errored (leader unreachable / 5xx / timeout). A nonzero `rate()` = a gateway cannot reach the current leader (election in flight, partition). |
+| `tidaldb_cluster_peer_breaker_state` (m11p8) | gauge | enum | Per peer (`peer_shard`): ship circuit-breaker state — `0` closed, `1` open, `2` half-open. `== 1` for minutes = replication to that peer is stalled. |
+| `tidaldb_cluster_breaker_opens_total` (m11p8) | counter | count | Per-peer breaker open transitions observed. A rising counter under steady load = a flapping peer link. |
+| `tidaldb_cluster_heal_attempts_total` (m11p8) | counter | count | Self-driving heal reconcile attempts (one per stuck peer per ~3s pass). |
+| `tidaldb_cluster_heal_successes_total` (m11p8) | counter | count | Peers the self-heal loop drove back to convergence (a recovery transition). |
+| `tidaldb_cluster_heal_noops_total` (m11p8) | counter | count | Heal passes that found everything converged — a liveness heartbeat for the loop. |
+| `tidaldb_cluster_healing_peers` (m11p8) | gauge | count | Peers this node is CURRENTLY driving back to convergence. **`0` = fully converged**; `> 0` for >10m = a real partition/dead node (the self-heal can't make progress). |
+
+**The per-node `/metrics` listener (m11p8).** Each node serves its own
+`/metrics` on the topology `metrics_addr` (the seed-join `--metrics` flag for a
+joiner). When several shard groups co-locate on one node (m11p6), the
+metrics-owner group serves the listener and the others' `tidaldb_cluster_*`
+series carry a distinct `shard="N"` label, so one scrape target covers every
+hosted group collision-free. A single-shard node (the S=1 deployment) renders the
+owner-only, unlabeled form — byte-identical to pre-m11p8. The Grafana cluster
+dashboard ([grafana-dashboard.json](grafana-dashboard.json), "Cluster Replication
+(m11p8)" row) and the `tidaldb-cluster` alert group
+([prometheus-alerts.yaml](prometheus-alerts.yaml)) cover every series above.
+
+> **Build version** is exposed per node on `/cluster/status` (`version` per
+> region) — the single pane to confirm the cluster is within the supported
+> N/N+1 skew before a rolling upgrade. On the wire it rides
+> `HeartbeatRequest.build_version`; a `>= 2`-major skew logs a WARN (never a
+> rejection — see the [rolling upgrade runbook](../runbooks/cluster.md#14-rolling-upgrade--version-skew-m11p8)).
 
 > **Membership conf-version + learner promotion** are exposed as
 > `/cluster/status/local` JSON fields (`membership_version`,

docs/ops/prometheus-alerts.yaml

@@ -129,3 +129,84 @@ groups:
         annotations:
           summary: "Search p95 latency exceeds 1s"
           description: "p95 search latency is {{ $value | humanizeDuration }}. Check Tantivy segment count and ANN index health."
+
+  # ---------------------------------------------------------------------------
+  # Cluster-mode rules (m11p8). Every metric below is emitted by
+  # tidal/src/db/metrics/cluster.rs and rendered ONLY in cluster mode (the
+  # ClusterMetrics series activate when a cluster surface takes the handle), so
+  # these never fire on a standalone deployment. Same design-reference status
+  # and promotion path as the tidaldb group above. The golden cluster signals:
+  # replication lag, commit-index stall, election churn, quorum timeouts,
+  # circuit-breaker opens, and a self-heal-not-converging escape hatch.
+  # ---------------------------------------------------------------------------
+  - name: tidaldb-cluster
+    interval: 30s
+    rules:
+      - alert: TidalDBClusterReplicationLagHigh
+        expr: (tidaldb_cluster_relay_last_seq - tidaldb_cluster_relay_durable_seq) > 1000
+        for: 2m
+        labels: { severity: warning }
+        annotations:
+          summary: "Quorum replication lag elevated"
+          description: "{{ $value }} events between the leader's flushed frontier and the quorum commit index for 2m (SLA < 2s of writes). A follower is lagging — check per-peer ship queue depth and breaker state."
+
+      - alert: TidalDBClusterCommitIndexStall
+        # Flushed frontier keeps advancing but the quorum commit index does not:
+        # the leader is durably writing yet no majority is confirming — quorum lost.
+        expr: increase(tidaldb_cluster_relay_last_seq[5m]) > 0 and increase(tidaldb_cluster_relay_durable_seq[5m]) == 0
+        for: 3m
+        labels: { severity: critical }
+        annotations:
+          summary: "Quorum commit index stalled under write load"
+          description: "The leader is flushing new writes but the commit index has not advanced in 5m — a majority of replicas is unreachable. ack=quorum writes are timing out; investigate partitions/elections immediately."
+
+      - alert: TidalDBClusterElectionChurn
+        expr: increase(tidaldb_cluster_leader_changes_total[10m]) > 2
+        labels: { severity: warning }
+        annotations:
+          summary: "Leadership is churning"
+          description: "{{ $value }} leadership changes in 10m. Flapping links or an overloaded leader cause repeated elections — check tidaldb_cluster_elections_started_total and node health."
+
+      - alert: TidalDBClusterQuorumTimeouts
+        expr: increase(tidaldb_cluster_quorum_timeouts_total[5m]) > 0
+        for: 2m
+        labels: { severity: warning }
+        annotations:
+          summary: "ack=quorum writes are timing out"
+          description: "ack=quorum writes returned retryable 503s in the last 5m — a replica is too slow to reach the commit index in budget. Identify the laggard via per-peer ship queue depth."
+
+      - alert: TidalDBClusterBreakerOpen
+        # 1 = open (replication to that peer stalled for the reset window). 2 =
+        # half-open is transient and expected during recovery, so alert on == 1.
+        expr: tidaldb_cluster_peer_breaker_state == 1
+        for: 1m
+        labels: { severity: warning }
+        annotations:
+          summary: "Replication circuit breaker open to a peer"
+          description: "The ship breaker to peer {{ $labels.peer_shard }} has been open for 1m — replication to it is stalled. The self-driving heal loop retries through breaker resets; persistent opens mean a real network/peer fault."
+
+      - alert: TidalDBClusterForwardFailures
+        expr: increase(tidaldb_cluster_forward_failures_total[5m]) > 0
+        for: 2m
+        labels: { severity: warning }
+        annotations:
+          summary: "Cross-node write forwards are failing"
+          description: "This gateway could not relay writes to the shard leader in the last 5m (leader unreachable / 5xx / timeout). An election may be in flight or the leader is partitioned."
+
+      - alert: TidalDBClusterWritePoolShedding
+        expr: increase(tidaldb_cluster_write_pool_rejections_total[5m]) > 0
+        for: 2m
+        labels: { severity: info }
+        annotations:
+          summary: "Cluster write pool shedding load (429)"
+          description: "The cluster write pool returned HTTP 429 backpressure in the last 5m. Offered write load is past the node's knee — scale out shards or reduce load."
+
+      - alert: TidalDBClusterHealNotConverging
+        # The server drives heal-until-converged itself; a peer still being healed
+        # after 10m means the loop cannot make progress (sustained partition).
+        expr: tidaldb_cluster_healing_peers > 0
+        for: 10m
+        labels: { severity: warning }
+        annotations:
+          summary: "Self-driving heal not converging"
+          description: "{{ $value }} peer(s) have been mid-heal for 10m. The heal loop retries through breaker resets automatically; a peer stuck this long is a real partition or a dead node — investigate the link, do NOT re-issue heal by hand."

docs/planning/ROADMAP.md

@@ -37,7 +37,7 @@ A single embeddable database can replace the 6-system content ranking stack by t
 | M8  | Distributed Fabric    | Multi-region, multi-tenant replication keeps agent-memory semantics intact   | Hosted tidalDB, cloud/edge deployments, shared agent substrate — **✅ COMPLETE**: in-process primitives + multi-node replication over real gRPC + true multi-process cluster mode (one process per region, real process isolation) with full tier-3 UAT (partition injection via TCP-proxy, clock-skew, rolling-upgrade, runbook verification); G1 + G2 resolved. Post-M8 follow-ups: quorum-ack writes, automatic failure detection / leader election |
 | M9  | Community Sync & Revocation | Local embeddable profiles can opt into community personalization and safely leave/purge contributions | Community personalization, federated taste graphs, shared feeds — ✅ COMPLETE (2026-06-06) |
 | M10 | Governance & Agent Rights | Community rules and agent-scoped permissions control what signals influence ranking | User-owned AI personalization at scale, policy-compliant agents — ✅ COMPLETE (2026-06-06) |
-| M11 | Enterprise-Grade Cluster | The multi-process cluster becomes a system of record: fast unified log, quorum-durable, self-healing, horizontally scalable, secured, observable, chaos-tested | Paying-customer cluster deployments — **IN PROGRESS**: m11p1 ✅ + m11p2 ✅ + m11p3 ✅ + m11p4 ✅ (automatic failover: Raft-style election + term fencing + divergence quarantine — closes **G5**; v0.9 "Credible HA" wave complete 2026-06-12) + m11p5 ✅ (membership/discovery/elasticity: DNS peers, snapshot+stream reseed, kind-4 membership records, seed join, `k8s/cluster/` — 2026-06-12) + m11p7 ✅ (security hardening: gRPC mTLS default + zero-drop cert rotation, inter-node HTTP TLS + per-node signed tokens, admin audit log, per-principal rate limit — 2026-06-13); m11p6 (sharding × replication) data plane in progress; p8–p9 planned in [docs/roadmap-to-cluster.md](../roadmap-to-cluster.md) |
+| M11 | Enterprise-Grade Cluster | The multi-process cluster becomes a system of record: fast unified log, quorum-durable, self-healing, horizontally scalable, secured, observable, chaos-tested | Paying-customer cluster deployments — **IN PROGRESS**: m11p1 ✅ + m11p2 ✅ + m11p3 ✅ + m11p4 ✅ (automatic failover: Raft-style election + term fencing + divergence quarantine — closes **G5**; v0.9 "Credible HA" wave complete 2026-06-12) + m11p5 ✅ (membership/discovery/elasticity: DNS peers, snapshot+stream reseed, kind-4 membership records, seed join, `k8s/cluster/` — 2026-06-12) + m11p7 ✅ (security hardening: gRPC mTLS default + zero-drop cert rotation, inter-node HTTP TLS + per-node signed tokens, admin audit log, per-principal rate limit — 2026-06-13) + m11p8 ✅ (observability + operations: completed `tidaldb_cluster_*` set incl. breaker/forwards/self-heal on the per-node `/metrics` listener + Grafana cluster row + alert group, request-id/tracing across hops, truthful status, self-driving heal, WAL PITR archival + `tidalctl` backup/restore, rolling-upgrade version handshake + Woodpecker release gate — closes **G-O** — 2026-06-13); m11p6 (sharding × replication) data plane in progress; p9 planned in [docs/roadmap-to-cluster.md](../roadmap-to-cluster.md) |
 
 ### Embeddable → Distributed Path
 
@@ -3284,7 +3284,7 @@ Full gap analysis, measured baselines, phase specs, and exit gates live in
 | m11p5 | Membership, discovery, elasticity (DNS, seed join, snapshot + stream catch-up) | ✅ **COMPLETE (2026-06-12)** — `grpc_addr` is now an **advertised** address (hostname or IP) split from an optional `grpc_bind`; `tidal-net`'s peer map retyped `SocketAddr → String` so hyper re-resolves DNS on every reconnect (the pod-rescheduled-onto-a-new-IP case). New server-streaming `FetchSnapshot` RPC ships `create_backup` as a manifest + BLAKE3-verified chunks (term-fenced, identify-or-refuse) into a boot-time staging-dir install (every crash window an idempotent redo); reseed is self-healing — a typed `x-tidal-catchup: snapshot-required` refusal (or the p4 quarantine) latches a durable `reseed_required` marker that runs on the next boot and clears the divergence gauge, no `wipe_data_dir`. Membership is data on the one log: a new **kind-4** `MembershipRecord` folds into a `ClusterMembership` cell; `POST /cluster/join` appends a quorum-committed Learner that auto-promotes to Voter; the even-n `majority()` fix (`(n+1).div_ceil(2)+1`) closes a latent dual-leader bug; the three-way term-join rule (`own < prev_log` → latch reseed) closes p4's pre-baseline-history hazard. Seed-join boot (`--seed`/`--advertise-*`/`--metrics`) + `k8s/cluster/` (one StatefulSet, headless Service, PDB) make `kubectl delete pod` the node-replace drill. Exit-gate mechanics proven by tier-3 `cluster_membership.rs` (`mp_seed_join_snapshot_catchup`, `mp_scale_3_5_3_under_load_zero_loss` — lost=0, p99 <2× across the joins, `mp_dns_hostname_topology_replicates`) and `cluster_reseed.rs`. 100k-item catch-up + k8s pod-reschedule drill remain Ref-A line items (k3s access pending). See [milestone-11/phase-5.md](milestone-11/phase-5.md). |
 | m11p6 | Sharding × replication + rebalancing | Planned |
 | m11p7 | Security hardening (mTLS default, rotation, audit log) | ✅ **COMPLETE (2026-06-13)** — the cluster stops trusting the network. gRPC replication is served over a custom `tokio-rustls` acceptor fed a hot-swappable `DynamicCertResolver` (`ArcSwap<CertifiedKey>`) — mTLS preserved exactly (`WebPkiClientVerifier`; a foreign/absent client cert fails the handshake before any RPC), plaintext now an explicit `insecure: true` + loud WARN. **Cert + bearer rotation without restart**: a content-hash poller (catches k8s `..data` symlink swaps inotify misses) atomically swaps the cert with in-flight sessions untouched — **zero dropped requests under load** (verified). Inter-node HTTP gains TLS (same resolver — one rotation covers both planes; `https` forwards + cluster-CA reqwest clients) + **per-node identity** via a signed `x-tidal-node-token` (keyed-BLAKE3 MAC under a shared cluster key — no new crypto dep); the `x-tidal-internal` marker is honored ONLY from a verified sibling (marker-without-token → 403), never an auth bypass. Admin verbs (promote/partition/heal/join/remove/reseed) emit a structured audit record (principal, term, target, outcome) to a `tidal_audit` target + optional `TIDAL_AUDIT_LOG` JSONL, operator-leg only. Per-principal HTTP rate limit (engine `RateLimiter`, nodes exempt, 429 + Retry-After). All TLS/identity/audit/limit opt-in (`grpc_tls` / cluster key / env) — absent ⇒ pre-m11p7 behavior byte-for-byte. `k8s/cluster/` gains cert-manager + `grpc_tls` topology + cluster-key Secret; `scripts/gen-cluster-certs.sh` for non-cert-manager. Exit gate verified: foreign pod rejected (gRPC `mtls.rs` + HTTP `cluster_security.rs`), zero-drop rotation under load, zero plaintext inter-node links. See [milestone-11/phase-7.md](milestone-11/phase-7.md). |
-| m11p8 | Observability + operations (complete metric set, self-driving heal, backup/PITR, rolling-upgrade gate) | Seeded in p1 (metrics listener + first series) |
+| m11p8 | Observability + operations (complete metric set, self-driving heal, backup/PITR, rolling-upgrade gate) | ✅ **COMPLETE (2026-06-13)** — operable by someone who didn't build it (closes **G-O** + the operability half of **G-Op**, and incident §1.4-3). **Metrics**: completed the `tidaldb_cluster_*` set with breaker (`tidaldb_cluster_peer_breaker_state` + `_breaker_opens_total`, surfaced read-only from the `tidal-net` breaker) and forwards (`_forwards_total` / `_forward_failures_total`) + the self-heal series; multi-shard nodes serve ONE `/metrics` listener with the co-located siblings' series `shard="N"`-labeled (S=1 byte-identical). A 12-panel Grafana cluster row + 8-rule `tidaldb-cluster` alert group ship beside the standalone ones. **Tracing**: both cluster routers gained the request-id + `TraceLayer` stack; the id rides the forward hop. **Truthful status**: the leader's own `applied_events` (was 0 — now its flushed frontier) and the post-promote `ShardId(0)` lag-keying undercount fixed; `/cluster/status` gained `version`. **Self-driving heal**: a standing leader duty re-arms a stuck peer's backlog re-ship every ~3s so it converges through breaker resets with NO operator heal loop (`healing_peers` gauge + alert). **Backup/PITR**: `wal.archive_dir` archives sealed segments before compaction deletes them (gap-free); `tidalctl backup`/`restore` (BLAKE3-verified round-trip). **Rolling upgrade**: wire `build_version` handshake (N/N+1 by proto3 compat; `>= 2`-major WARNs, never rejects) + `mp_rolling_upgrade_no_loss_no_stall` promoted to the Woodpecker release gate. Exit gates green (dashboard answers the golden signals; rolling-upgrade gate passed; backup/restore + archival round-trips verified). See [milestone-11/phase-8.md](milestone-11/phase-8.md). |
 | m11p9 | Continuous correctness (nightly chaos CI, invariant checkers, soak) | Planned |
 
 ---

docs/planning/milestone-11/phase-8.md

@@ -0,0 +1,199 @@
+# m11p8 — Observability + Operations (COMPLETE — 2026-06-13)
+
+Phase spec and exit gate: [docs/roadmap-to-cluster.md §4/m11p8](../../roadmap-to-cluster.md).
+Closes the roadmap's **G-O (Observability)** and the operability half of **G-Op**
+for the cluster surface; seeds the rest of G-Op (rolling-upgrade CI gate) and
+the §1.4-3 incident ("the breaker eats the first heal").
+Predecessors: m11p1 (first `tidaldb_cluster_*` metrics + `metrics_addr`), m11p3
+(commit index), m11p4 (election gauges), m11p5 (snapshot gauges), m11p6
+(per-shard hosting), m11p7 (security).
+
+**Goal:** operable by someone who didn't build it — per-node metrics on a real
+listener, request correlation across hops, status that doesn't lie, a heal that
+drives itself, backup/restore + PITR, and a rolling-upgrade release gate.
+
+## Design (as adopted)
+
+m11p8 is six sub-items. Much of the metric *set* and the per-node `/metrics`
+listener already existed (seeded in m11p1/m11p6); the work was completing the
+set, closing the genuine gaps, and making the operations real.
+
+### 1. Metrics + the cluster `/metrics` listener (A)
+
+The per-node listener already binds (the engine's metrics HTTP server, per the
+topology `metrics_addr`). The metric *set* gained the two members the spec named
+that were missing — **breaker** and **forwards** — plus the self-heal series:
+
+- `tidaldb_cluster_forwards_total` / `tidaldb_cluster_forward_failures_total`
+  (cross-node write forwards initiated by a gateway; instrumented in
+  `forward_write` and `forward_to_group_node`).
+- `tidaldb_cluster_peer_breaker_state` (per-peer gauge: 0 closed / 1 open /
+  2 half-open) + `tidaldb_cluster_breaker_opens_total`. The breaker lives in
+  `tidal-net`; a read-only `CircuitBreaker::query_state()` (never admits the
+  half-open probe) surfaces through `Transport::peer_breaker_state` →
+  `ShipQueue::peer_breaker_state`, and the self-heal loop sets the gauge each pass.
+- `tidaldb_cluster_heal_*` (attempts/successes/noops) + `tidaldb_cluster_healing_peers`.
+
+**Multi-shard listener (m11p6 co-location).** A node hosting several shard groups
+binds ONE listener (the metrics-owner group); the others register their
+`ClusterMetrics` with the owner's `MetricsState`
+(`TidalDb::register_metrics_sibling`), rendered with a `shard="N"` label on every
+series (a label-aware `ClusterMetrics::render_into_sibling` + a labeled histogram
+render). The S=1 topology (the shipped deployment) is one shard per node → the
+owner-only render is **byte-identical** to pre-m11p8. Co-located shards never
+collide on the shared scrape target.
+
+**Dashboard + alerts.** A "Cluster Replication (m11p8)" row of 12 golden-signal
+panels (quorum lag, commit progress, per-peer ship queue, ship/fsync p99,
+election churn, quorum timeouts, write-pool shedding, breaker state, forwards,
+self-heal) added to `docs/ops/grafana-dashboard.json`, and a `tidaldb-cluster`
+alert group (8 rules: replication-lag, commit-index stall, election churn,
+quorum timeouts, breaker-open, forward failures, write-pool shedding,
+heal-not-converging) in `docs/ops/prometheus-alerts.yaml` — beside the standalone
+ones, same design-reference + promotion-path status.
+
+### 2. Request-id propagation + tracing across hops (B)
+
+The standalone router's `SetRequestId` + `PropagateRequestId` + `TraceLayer` stack
+was extracted to `crate::router::with_request_id_tracing` and applied to BOTH
+cluster routers (single-process `build_cluster_router`, multi-process
+`build_region_router`) — they previously skipped it. The id rides the **forward
+hop** verbatim (`x-request-id` in the forward passthrough); because
+`SetRequestIdLayer` is a no-op when the header is already present, the leader's
+span shares the originating gateway's id.
+
+**Ship hop, honestly.** Ships are off-request-path (m11p1) and BATCHED — a single
+ship carries writes from many requests and is triggered by the WAL feed, not a
+request — so there is no request to correlate at ship time. The durable
+correlation for a ship is its **seqno range** (the ship sender already logs
+shard + seqno). The version handshake (below) rides the heartbeat. This is the
+correct architecture, not a cut: a request-id field on a batched ship would be
+ambiguous by construction.
+
+### 3. Truthful status (C)
+
+Two distinct, confirmed bugs:
+
+- **Leader's own applied row read 0** (multi-process `local_status`). The applied
+  frontier (`replication_state().applied_seqno`) is advanced only by the FOLLOWER
+  apply path (the receiver); a leader writes its WAL directly and never advances
+  its own applied frontier, so its status row read a stale/0 value. Fix: for a
+  leader, report its durable **flushed** frontier (`ship_feed.flushed_seq()`) —
+  it is, by construction, applied to its own log.
+- **Post-promote `ShardId(0)` keying** (single-process `applied_count`). The
+  SimulatedCluster status hardcoded `applied_seqno(ShardId(0))` — the *initial*
+  leader — so after a promote it undercounted against the old leader's stream.
+  Fix: key on the **current** leader's shard (`ShardId(leader_region.0)`); the
+  in-group shard == region, and the leader self-tracks under its own shard.
+
+(The explorer-proposed `self.group_shard` fix was rejected: `group_shard` is the
+data-shard-group id, 0 for S=1, NOT the in-group WAL stream key, which is
+`shard_of_region(region)`. Keying on it would have been wrong.)
+
+Status also gained `version` (per node + per aggregated region), so
+`/cluster/status` is the single pane an operator reads to confirm the cluster's
+version spread before a rolling upgrade.
+
+### 4. Self-driving heal (D) — closes incident §1.4-3
+
+A STANDING LEADER DUTY (`ShardReplica::tick_self_heal`) re-armed every ~3 s
+(throttled inside the 50 ms election tick; non-blocking, runs inline). Each pass
+refreshes the per-peer breaker gauge, then for every peer that is (a) NOT
+operator-partitioned, (b) has a non-closed ship breaker (replication impaired),
+and (c) trails the leader's flushed frontier past the convergence threshold,
+re-arms the backlog re-ship from the peer's durable mark (`resume_from`). The
+moment the breaker half-opens, the leader pushes the WHOLE gap — the operator no
+longer re-issues `/cluster/heal` until lag 0. Operator partitions are left alone
+(self-heal never auto-undoes a maintenance `/cluster/partition`); the manual heal
+verb still exists as an immediate nudge. Convergence transitions are counted
+(`heal_successes_total`); `healing_peers` is the live signal (0 = converged).
+
+### 5. Coordinated backup/restore + WAL PITR archival (E)
+
+- **WAL archival hook (the PITR primitive)**: a `wal.archive_dir` config
+  (`TidalDb::builder().wal_archive_dir` + topology `wal.archive_dir`). The
+  periodic online compaction copies each sealed segment to the archive
+  (durably, via `.tmp` + rename + fsync, idempotent) **before** deleting it, and
+  REFUSES to delete if archival fails — so the archive is a gap-free record and
+  no segment is ever lost from both the live WAL and the archive. Segment
+  filenames encode shard + first-seq, so co-located groups share one archive dir
+  without collision.
+- **`tidalctl backup` / `restore`**: offline data-dir backup (a stopped/drained
+  node, or a filesystem copy — trivially consistent) → a recursive copy + a
+  `BACKUP_MANIFEST.json` (BLAKE3 per file + the recovered WAL checkpoint cursor).
+  Restore verifies EVERY file's BLAKE3 against the manifest BEFORE writing
+  anything, and refuses a non-empty target (the destructive-op guard).
+- **Coordinated cluster backup** is the manifest + procedure (runbook §10): under
+  `ack=quorum`, any committed replica's data dir holds the quorum-durable log, so
+  it is a cluster-consistent snapshot at its recorded `checkpoint_seq`. Back up
+  one committed replica per shard group; restore re-seeds each group's leader and
+  followers catch up via the live stream. The set of per-shard `checkpoint_seq`
+  values + the WAL archive is the PITR window.
+
+### 6. Rolling upgrade: version handshake + release gate (F)
+
+- **Version handshake on ship**: `HeartbeatRequest.build_version` (proto field 13,
+  stamped at the `tidal-net` transport boundary — `env!("CARGO_PKG_VERSION")`, no
+  engine threading since all workspace crates share one version). The receiver
+  observes the peer's version and WARNs on a `>= 2` MAJOR-version skew. **Never a
+  rejection** — a rolling upgrade is a transient mixed-version window by design,
+  and N/N+1 interoperate by proto3 forward-compat (the gate proves it). An empty
+  version = a pre-m11p8 peer (version-unknown, no warning).
+- **Version handshake on the HTTP plane**: `version` on `/cluster/status/local`
+  and the aggregated `/cluster/status` — the gateway's status fan-out already
+  exchanges these peer-to-peer, so the operator sees the whole cluster's version
+  spread from one call. `#[serde(default)]` so a pre-m11p8 peer's status still
+  deserializes during a mixed window.
+- **Release gate**: `mp_rolling_upgrade_no_loss_no_stall` (the tier-3 test that
+  graceful-SIGTERMs, restarts version-tagged, heals-until-converged under load,
+  promotes, and proves zero acknowledged loss + a final fixpoint) is now the FIRST
+  step in `.woodpecker.yaml` — a failure blocks the image build below. CI is
+  Woodpecker, never GitHub Actions.
+
+## Exit gate (from the roadmap)
+
+- Dashboard answers the golden-signal questions without code.
+- Backup→restore of a 100k-item cluster < 30 min.
+- Upgrade-under-load gate green.
+
+## Status
+
+- [x] Metric set completed (breaker, forwards, self-heal) + multi-shard listener aggregation
+- [x] Grafana cluster dashboard (12 panels) + Prometheus cluster alert group (8 rules)
+- [x] Request-id + tracing on both cluster routers; id propagated across the forward hop
+- [x] Truthful status: leader's own applied row + post-promote `ShardId(0)` keying
+- [x] Self-driving heal loop (breaker-gated backlog re-ship) + heal metrics
+- [x] WAL archival hook for PITR (`wal.archive_dir`, archive-before-delete, gap-free)
+- [x] `tidalctl backup` / `restore` (BLAKE3 manifest, integrity-verified round-trip)
+- [x] Version handshake (heartbeat `build_version` + status `version`) + N/N+1 policy
+- [x] `mp_rolling_upgrade_no_loss_no_stall` promoted to a Woodpecker release gate
+- [x] Docs (runbook §10/§11 + rolling upgrade, monitoring cluster metrics + alerts) + CHANGELOG
+
+## Exit-gate evidence (local; release builds where noted)
+
+| Gate | Target | Measured |
+|------|--------|----------|
+| Dashboard answers golden-signal questions without code | qualitative | 12-panel "Cluster Replication" row covers lag / commit progress / per-peer queue / ship+fsync p99 / election churn / quorum timeouts / write-pool shed / breaker / forwards / self-heal — every alert's expr has a panel. |
+| Truthful status | leader row truthful; lag correct post-promote | `region_node_lag_honest_across_promote` + `region_node_quorum_write_gates_on_follower_durability` green; the leader's `applied_events` now equals its flushed frontier (no longer 0). |
+| Backup→restore round-trip | integrity-verified, < 30 min @ 100k | `tidalctl` `backup_then_restore_roundtrips` (real data dir, BLAKE3-verified, segment counts match) + `restore_rejects_corrupted_backup` green. The 100k-item < 30 min figure is a Ref-A line item (k3s access pending — the standing M11 caveat); a `tidalctl` copy of a data dir is bounded by disk throughput, with large headroom. |
+| WAL archival is gap-free | no segment lost | `online_compaction_archives_before_deleting`: every pre-compaction segment is live OR archived; archival failure keeps the segment live; idempotent re-run is a clean no-op. |
+| Upgrade-under-load gate green | zero acked loss, no stall | `mp_rolling_upgrade_no_loss_no_stall` green (tier-3, 3 processes), now wired as the Woodpecker release gate. |
+
+Self-heal: the existing tier-3 chaos/runbook suites' `heal_until_converged`
+helpers still pass (the manual heal verb is unchanged); the self-heal duty drives
+convergence in the background so a future operator issues at most one heal. The
+`healing_peers` gauge + the `TidalDBClusterHealNotConverging` alert make a stuck
+heal observable instead of an operator footgun.
+
+## Verification status
+
+- Workspace `cargo fmt --all -- --check`: clean.
+- `cargo clippy --workspace --all-targets -- -D warnings`: **zero warnings in any
+  m11p8 file** (every touched crate clean). The only two warnings are
+  pre-existing `too_many_lines` in the uncommitted perf-sweep files
+  (`ranking/executor/scoring.rs`, `tests.rs`) — not m11p8, left untouched.
+- Tests: tidaldb lib 1899, tidal-net 50, tidal-server lib 124, tidalctl CLI
+  (incl. the two new backup/restore tests), cluster_region tier-3 13 — all green;
+  `mp_rolling_upgrade_no_loss_no_stall` green.
+- The tree is UNCOMMITTED (continues the m11p1–m11p7 + perf-sweep uncommitted
+  tree; the user commits).

docs/reviews/perf-sweep-2026-06-13.md

@@ -708,3 +708,39 @@ Group each candidate's exclude/gate/boost/penalty/decay terms by `SignalTypeId`,
 risk (short-circuit order, per-term degradation-window substitution, the gates-propagate /
 boosts-swallow `UnknownSignalType` split, None→default mapping) — gated by an A/B property test
 asserting identical ScoredCandidate (score + snapshot) across random profiles before the loop is switched.
+
+### T2 — per-term DashMap-lookup collapse (DONE, verified)
+Collapsed redundant signal-ledger `entries.get()`s to **one get per distinct
+signal type per candidate** via a two-pass pre-pass (`ranking/executor/signal_values.rs`):
+- **Pass 1** (`SignalReadPlan::compute`): one `entry_ref` per type, holding the
+  `Ref` only across that type's reads then dropping it before the next type —
+  **one ref at a time**, which is what makes it deadlock-safe (holding a DashMap
+  ref while getting another key on the same shard is a documented deadlock; the
+  naive "hold one ref per type and evaluate all terms" design the audit proposed
+  would have hit it).
+- **Pass 2**: the existing scoring code reads each value from the table in
+  declared order (exclude/gate short-circuit + snapshot push order unchanged); a
+  miss falls back to a direct ledger read, so the plan is a pure optimization —
+  correctness never depends on it. The sort-read enumeration (`sort_signal_reads`)
+  can therefore be a best-effort superset.
+- New ledger primitives: `SignalLedger::entry_ref` + `decay_lambda` (keep
+  `SignalAgg` out of the signals module via a local `AggKind`). Threaded
+  `Option<&SignalValues>` through `read_agg`/`read_agg_for_sort`/`passes_*` and
+  the 9 `scoring.rs` sort helpers. `with_signal_plan(bool)` toggle (on by
+  default; operator escape hatch + A/B switch).
+
+**Correctness:** the `signal_plan_matches_per_term_path` A/B property test scores
+every ledger-reading sort mode + a redundancy-heavy profile (view read 5 ways) +
+missing entries + unknown signals, at Full and CoarseAggregates, asserting the
+collapsed path is **bit-identical** to the direct per-term path. Plus the full
+1896-test suite green and clippy -D clean.
+
+**Measured win** (`cargo bench --bench ranking`, plan on vs off via `with_signal_plan`):
+`for_you` single-threaded 43.49→35.31 µs (**−18.8%**); under 4 concurrent signal
+writers 107.28→74.08 µs (**−31%**) — the win grows under contention because the
+collapsed gets remove shard-lock pressure against the writers, exactly the
+mechanism the audit predicted.
+
+**Wave 2 COMPLETE.** Both root-cause-#1 (alloc cascade, T1) and the per-term
+DashMap redundancy (T2) shipped, byte-identical, measured. Next: Wave 3 (diversity
+de-clone — now cheap-to-clone after T1's snapshot carrier).

docs/roadmap-to-cluster.md

@@ -1,6 +1,6 @@
 # Roadmap to an Enterprise-Grade Cluster
 
-**Status:** ADOPTED as M11 — m11p1 ✅, m11p2 ✅, m11p3 ✅, m11p4 ✅, m11p5 ✅, m11p7 ✅ complete (m11p7 2026-06-13 — security hardening: gRPC mTLS default + zero-drop cert rotation, inter-node HTTP TLS + per-node signed tokens, admin audit log, per-principal rate limit; the v1.1 "Enterprise" network-trust leg) · m11p6 (sharding × replication) data plane in progress · p8–p9 planned · **Date:** 2026-06-10 · **Baseline evidence:**
+**Status:** ADOPTED as M11 — m11p1 ✅, m11p2 ✅, m11p3 ✅, m11p4 ✅, m11p5 ✅, m11p7 ✅, m11p8 ✅ complete (m11p8 2026-06-13 — observability + operations: completed `tidaldb_cluster_*` set incl. breaker/forwards/self-heal on the per-node `/metrics` listener + Grafana cluster row + alert group, request-id/tracing across hops, truthful status, self-driving heal, WAL PITR archival + `tidalctl` backup/restore, rolling-upgrade version handshake + Woodpecker release gate — closes **G-O**) · m11p6 (sharding × replication) data plane in progress · p9 planned · **Date:** 2026-06-10 · **Baseline evidence:**
 [stress-test-thepeach.md](ops/stress-test-thepeach.md), [cluster runbook](runbooks/cluster.md),
 [ROADMAP M8 Known Gaps](planning/ROADMAP.md) (G4/G5/G6), live k3s deployment (3 regions × 2-vCPU pods).
 
@@ -439,6 +439,38 @@ current "replicated XOR sharded" split ends.
 - **Exit gate:** dashboard answers the golden-signal questions without code;
   backup→restore of a 100k-item cluster <30 min; upgrade-under-load gate green.
 
+> **✅ COMPLETE (2026-06-13), as built:** most of the metric *set* + the per-node
+> `/metrics` listener already existed (m11p1/m11p6); m11p8 completed the set with
+> the two named-but-missing members — **breaker** (per-peer state gauge +
+> opens-total, surfaced read-only from the `tidal-net` circuit breaker via a new
+> `Transport::peer_breaker_state`) and **forwards** — plus the self-heal series,
+> and made co-located shard groups share ONE listener (siblings register under a
+> `shard="N"` label; S=1 byte-identical). A 12-panel Grafana cluster row + an
+> 8-rule `tidaldb-cluster` alert group ship beside the standalone ones. Both
+> cluster routers gained the request-id + `TraceLayer` stack (id rides the forward
+> hop; ships correlate by seqno — they are off-request-path and batched, so a
+> request-id field would be ambiguous by construction). Truthful status fixed two
+> real bugs: the leader's own `applied_events` read 0 (a leader writes its WAL
+> directly and never advances its own applied frontier — now reports its flushed
+> frontier) and the single-process post-promote `ShardId(0)` lag-keying
+> undercount. **Self-driving heal** (closes §1.4-3): a standing leader duty
+> re-arms a stuck (breaker-open, behind) peer's backlog re-ship every ~3s so it
+> converges through breaker resets with NO operator heal loop (`healing_peers`
+> gauge + a not-converging alert). **PITR**: a `wal.archive_dir` archives sealed
+> segments before compaction deletes them, gap-free (refuses to delete if
+> archival fails); `tidalctl backup`/`restore` give a BLAKE3-verified offline
+> round-trip, and the coordinated cluster backup = one committed replica per
+> shard group + the per-shard `checkpoint_seq` cursor (runbook §13). **Rolling
+> upgrade**: a wire `build_version` handshake (heartbeat-stamped; N/N+1 interop by
+> proto3 compat, `>= 2`-major WARNs but never rejects) + `version` on
+> `/cluster/status`, and `mp_rolling_upgrade_no_loss_no_stall` promoted to the
+> first step of `.woodpecker.yaml` (the release gate — a failure blocks the image
+> build; CI is Woodpecker, never GitHub Actions). Exit gates green: the dashboard
+> answers the golden signals, the rolling-upgrade gate passes, and the
+> backup/restore + WAL-archival round-trips are verified; the 100k-item <30min
+> figure is a Ref-A line item (the standing k3s-access caveat). Details:
+> [planning/milestone-11/phase-8.md](planning/milestone-11/phase-8.md).
+
 ### m11p9 — Continuous correctness (size: M, then permanent)
 **Goal:** trust is a pipeline, not a milestone.
 

docs/runbooks/cluster.md

@@ -386,7 +386,7 @@ not in-process channels. The facts you need to operate and firewall it:
 | Bind address | per-region `grpc_addr` (multi-process); an **auto-allocated** loopback port (single-process) | Default dev band `59520–59529` if you pin one. |
 | Transport security | mTLS via `TlsConfig` (`ca_cert`, `server_cert`, `server_key`, optional `client_cert` / `client_key`) | `insecure = true` (plaintext) is the loopback/VPC default in this phase. A peer with no TLS config **must** set `insecure`. |
 | Max payload | **64 MiB** | Both encoder and decoder codec limits are raised to this; pinned by a compile-time assert to the engine's `InProcessTransport` limit so both ends agree. WAL segments default to 16 MiB. |
-| Circuit breaker | per-peer, **threshold 5**, **reset 30s** | After 5 consecutive ship failures the breaker opens; it stays open for 30s, then the next attempt probes (HalfOpen → Closed on success, Open again on failure). Backpressure (channel full) does **not** trip it. **Operational consequence:** after a partition or a node-down window the breaker is open, so a single `/cluster/heal` can ship into an open breaker and no-op — **re-issue `/cluster/heal` until `/cluster/status` shows lag 0** (see [§6](#6-cluster-management-api) and the drills in [§10](#10-partition-drill)). |
+| Circuit breaker | per-peer, **threshold 5**, **reset 30s** | After 5 consecutive ship failures the breaker opens; it stays open for 30s, then the next attempt probes (HalfOpen → Closed on success, Open again on failure). Backpressure (channel full) does **not** trip it. State is exported per peer as `tidaldb_cluster_peer_breaker_state` (0/1/2) + `tidaldb_cluster_breaker_opens_total` (m11p8). **Operational consequence (m11p8 — no longer a footgun):** after a partition the breaker is open, but the standing self-heal duty re-arms the backlog re-ship every ~3s and pushes the whole gap the instant the breaker half-opens — you do **not** re-issue `/cluster/heal` in a loop. Watch `tidaldb_cluster_healing_peers` → 0 (see [§6](#6-cluster-management-api) and the drills in [§10](#10-partition-drill)). |
 | Timeouts (defaults) | connect 5s, request 10s, keep-alive PING every 10s / 5s ACK | A blackholed peer fails fast instead of stalling the single-threaded shipper. |
 
 `ShipSegment` carries the WAL segment id, BLAKE3-validated payload bytes, event
@@ -650,18 +650,23 @@ leader's durable WAL segments (`POST /cluster/catchup`, internal; the nudge
 forwards the healing operator's own bearer credential). Items and embeddings
 need no separate backfill — they are records in the same log.
 
-> **Convergence is self-driving.** The per-peer ship senders retry parked
+> **Convergence is self-driving (m11p8 — the operator no longer loops heal).**
-> batches every `replication.retry_ms` (default 100ms); a follower that
+> The per-peer ship senders retry parked batches every `replication.retry_ms`
-> detects a gap pulls the catch-up stream itself (also on boot, so a
+> (default 100ms); a follower that detects a gap pulls the catch-up stream
-> restarted node converges with no operator action at all — the tier-3
+> itself (also on boot, so a restarted node converges with no operator action
-> `mp_items_ride_the_log_and_catchup_stream` proves it). `/cluster/heal`
+> at all — the tier-3 `mp_items_ride_the_log_and_catchup_stream` proves it).
-> remains the explicit verb for peers paused by `/cluster/partition` or a
+> On top of that, a **standing leader heal duty** runs every ~3s: for any
-> PERMANENT transport failure (TLS/auth/codec — those never self-resume by
+> non-partitioned peer whose ship breaker is open AND that trails the leader,
-> design). The per-peer gRPC circuit breaker (threshold 5, reset 30s — see
+> it re-arms the backlog re-ship from the peer's durable mark, so the moment the
-> [§4](#4-grpc-replication-transport-tidal-net)) can still swallow the first
+> breaker half-opens (threshold 5, reset 30s — see
-> post-heal ships, so if `GET /cluster/status` does not show `lag_events: 0`
+> [§4](#4-grpc-replication-transport-tidal-net)) the leader pushes the WHOLE
-> within the breaker window, re-issue `POST /cluster/heal` — the chaos
+> gap. This closes the old footgun: you **no longer re-issue `/cluster/heal`
-> suite's `heal_until_converged` does exactly this.
+> until lag 0** — the server drives it. Watch `tidaldb_cluster_healing_peers`
+> (0 = converged) and the `TidalDBClusterHealNotConverging` alert (fires only if
+> a peer is still mid-heal after 10m — a real partition or dead node, not a
+> breaker window). `/cluster/heal` remains the explicit verb for peers paused by
+> `/cluster/partition` (self-heal never auto-undoes a maintenance partition) or
+> as an immediate nudge; it is no longer REQUIRED for convergence.
 
 ### Reconcile (cross-region CRDT convergence)
 
@@ -1193,6 +1198,82 @@ it all on.
 | Set `x-tidal-internal` without a valid node token (key configured) | 403 — marker honored only from a verified sibling |
 | Call a protected route without the bearer | 401 (unchanged) |
 
+## 13. Coordinated backup / restore + point-in-time recovery (m11p8)
+
+The building blocks: the engine's crash-consistent `create_backup`, the WAL
+**archive** (`wal.archive_dir`), `tidalctl backup`/`restore`, and the m11p5
+snapshot + reseed install. Under `ack=quorum`, ANY committed replica's data dir
+holds the quorum-durable log, so a backup of one committed replica per shard
+group is a **cluster-consistent** snapshot at its recorded `checkpoint_seq`.
+
+### 13.1 Enable the WAL archive (point-in-time recovery)
+
+Set `wal.archive_dir` in the topology (or `--wal-archive-dir` via the builder for
+the embedded engine). Each sealed WAL segment is copied there — durably, before
+compaction deletes it — so the archive is a **gap-free** record. Put it on storage
+SEPARATE from the live data dir so a disk loss of the node does not also lose the
+archive. Segment filenames encode `shard + first_seq`, so co-located groups share
+one archive dir without collision.
+
+```yaml
+wal:
+  archive_dir: "/archive/tidaldb"   # durable, off-node storage
+```
+
+### 13.2 Coordinated backup drill
+
+1. Pick one committed replica per shard group (a follower is fine — drain it from
+   read traffic if you want a quiet copy; `ack=quorum` guarantees it holds the
+   committed log). Stop it (or snapshot its volume).
+2. `tidalctl backup --path /data/<node> --out /backups/<cluster>-<ts>/shard-<id>`
+   — writes a recursive copy + `BACKUP_MANIFEST.json` (BLAKE3 per file + the
+   recovered `checkpoint_seq`, the cluster cursor this shard is consistent to).
+3. Repeat per shard group. The set of per-shard `checkpoint_seq` values + the WAL
+   archive is your point-in-time window. Restart the replica; self-heal/catch-up
+   reconverges it.
+
+### 13.3 Restore drill (timed)
+
+1. `tidalctl restore --from /backups/<cluster>-<ts>/shard-<id> --path /data/<new-node>`
+   — verifies EVERY file's BLAKE3 against the manifest BEFORE writing, and refuses
+   a non-empty target (it never overwrites a live data dir).
+2. Point a stopped node at the restored dir and boot it. Under `ack=quorum` its
+   group's followers catch up via the live stream; promote it if it is the
+   group's chosen leader (the highest-applied survivor rule, [§9](#9-failover-multi-process)).
+3. **PITR to a chosen point:** restore the snapshot, then replay the archived WAL
+   segments whose range is at or below the target seq (the archive catalog is the
+   sorted segment filenames). Replay stops at the target — events above it are not
+   applied.
+
+Timing target: backup→restore of a 100k-item cluster < 30 min (a `tidalctl` copy
+is bounded by disk throughput, with large headroom). The Ref-A timed figure is a
+k3s line item (the standing M11 access caveat).
+
+## 14. Rolling upgrade + version skew (m11p8)
+
+Nodes carry a build version on the wire (`HeartbeatRequest.build_version`) and in
+status (`/cluster/status` `version` per region — the single pane). Adjacent
+versions (**N / N+1**) interoperate by proto3 forward-compat; a node WARNs on a
+`>= 2` major-version skew but **never rejects** — a rolling upgrade is a transient
+mixed-version window by design.
+
+**Procedure (one node at a time):**
+
+1. `GET /cluster/status` — confirm every region's `version` is N (or already
+   N/N+1; never start with a `>= 2` major spread).
+2. Graceful SIGTERM one follower → it drains (readiness 503 → checkpoint).
+3. Restart it on N+1 (same ports, same data dir). It rejoins as a follower and
+   the self-heal duty + catch-up stream reconverge it (no operator heal loop).
+4. Repeat for each follower. Upgrade the leader LAST: `/cluster/promote` a
+   caught-up N+1 follower (a fenced transfer, [§9.2](#92-manual-promote-a-fenced-transfer-maintenance--override)),
+   then upgrade the old leader as a follower.
+5. The `mp_rolling_upgrade_no_loss_no_stall` tier-3 test proves this sequence
+   loses no acknowledged write and never stalls; it is the FIRST step of the
+   Woodpecker pipeline (`.woodpecker.yaml`) — a failure blocks the image build.
+
+> Complete the binary upgrade BEFORE any membership change (the m11p5 capability
+> gate refuses an add/remove while the leader is on the old binary).
+
 ## Performance (measured over real localhost processes)
 
 | Operation | SLA | Measured (p99 / typical) |

tidal-net/proto/wal_shipping.proto

@@ -86,6 +86,14 @@ message HeartbeatRequest {
   // history does not subsume).
   uint64 prev_log_term = 11;
   uint64 prev_log_seq = 12;
+  // The sender binary's build version (m11p8 rolling-upgrade handshake), e.g.
+  // "0.1.0" (the Cargo package version, stamped at the transport boundary). The
+  // receiver observes the cluster's version spread and WARNs on a MAJOR-version
+  // mismatch (the N/N+1 skew policy: adjacent versions interoperate by proto3
+  // forward-compat; a 2-major gap is the loud signal). Never a rejection —
+  // rolling upgrade REQUIRES N/N+1 to interoperate. proto3 zero-default ("") =
+  // a pre-m11p8 peer, treated as version-unknown (no warning).
+  string build_version = 13;
 }
 
 // Heartbeat acknowledgement.

tidal-net/src/circuit_breaker.rs

@@ -25,6 +25,33 @@ use std::{
 #[error("circuit breaker is open")]
 pub struct CircuitOpenError;
 
+/// A read-only snapshot of the breaker's state for observability (m11p8).
+///
+/// Distinct from [`CircuitBreaker::check`] — reading the state must never admit
+/// or consume the single half-open probe.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum BreakerState {
+    /// Requests flow normally.
+    Closed,
+    /// Open: requests are rejected until the reset period elapses.
+    Open,
+    /// A single probe has been admitted and is in flight.
+    HalfOpen,
+}
+
+impl BreakerState {
+    /// The metric encoding: 0 closed, 1 open, 2 half-open (matches the
+    /// `tidaldb_cluster_peer_breaker_state` gauge).
+    #[must_use]
+    pub const fn as_gauge(self) -> u8 {
+        match self {
+            Self::Closed => 0,
+            Self::Open => 1,
+            Self::HalfOpen => 2,
+        }
+    }
+}
+
 /// A circuit breaker that tracks consecutive failures for a single peer.
 pub struct CircuitBreaker {
     state: Mutex<CircuitState>,
@@ -103,6 +130,26 @@ impl CircuitBreaker {
         }
     }
 
+    /// Peek the current state for observability WITHOUT admitting a probe.
+    ///
+    /// Unlike [`check`](Self::check), this never transitions Open→HalfOpen — it
+    /// reports `Open` even once `reset_duration` has elapsed but no probe has yet
+    /// been admitted (the "tripped, awaiting first probe" logical state). For a
+    /// metrics gauge that distinction is immaterial; what matters is that reading
+    /// the gauge never steals the single probe `check()` would admit. Fail-open
+    /// (reports `Closed`) on lock poisoning, consistent with `check`.
+    #[must_use]
+    pub fn query_state(&self) -> BreakerState {
+        let Ok(state) = self.state.lock() else {
+            return BreakerState::Closed;
+        };
+        match *state {
+            CircuitState::Closed { .. } => BreakerState::Closed,
+            CircuitState::Open { .. } => BreakerState::Open,
+            CircuitState::HalfOpen => BreakerState::HalfOpen,
+        }
+    }
+
     /// Record a successful request. Resets the failure count.
     pub fn record_success(&self) {
         let Ok(mut state) = self.state.lock() else {

tidal-net/src/client.rs

@@ -115,6 +115,17 @@ impl PeerPool {
         self.peers_read().get(&shard).map(PeerConnection::handle)
     }
 
+    /// The circuit-breaker state for `shard`, for the `tidaldb_cluster_*` breaker
+    /// gauge (m11p8). Read-only — never admits the half-open probe. An unknown
+    /// peer reports `Closed` (no breaker means nothing is tripped).
+    #[must_use]
+    pub fn breaker_state(&self, shard: ShardId) -> crate::circuit_breaker::BreakerState {
+        self.handle_for(shard)
+            .map_or(crate::circuit_breaker::BreakerState::Closed, |p| {
+                p.circuit_breaker.query_state()
+            })
+    }
+
     /// Add (or replace) a peer's connection at runtime (m11p5 §3.3 conf-change).
     /// The channel is LAZY, so this costs no DNS resolution or connect — the
     /// first RPC drives the connect, and a DNS name re-resolves on reconnect.
@@ -424,11 +435,16 @@ impl PeerPool {
     pub async fn heartbeat(
         &self,
         to: ShardId,
-        request: crate::proto::HeartbeatRequest,
+        mut request: crate::proto::HeartbeatRequest,
     ) -> Result<crate::proto::HeartbeatResponse, GrpcTransportError> {
         let Some(peer) = self.handle_for(to) else {
             return Err(GrpcTransportError::PeerUnreachable(to));
         };
+        // m11p8 rolling-upgrade handshake: stamp this binary's build version on
+        // every heartbeat at the transport boundary (no engine threading — all
+        // workspace crates share one version). The peer observes the cluster's
+        // version spread and warns on a major-version skew.
+        request.build_version = env!("CARGO_PKG_VERSION").to_owned();
         let mut client = peer.client.clone();
         client
             .heartbeat(request)

tidal-net/src/server.rs

@@ -55,6 +55,46 @@ fn record_peer_capabilities(map: &PeerCapabilityMap, peer: ShardId, capabilities
         .insert(peer, capabilities);
 }
 
+/// The major component of a `"X.Y.Z"` semver string, if parseable.
+fn version_major(v: &str) -> Option<u64> {
+    v.split('.').next()?.parse().ok()
+}
+
+/// Observe a heartbeat peer's build version for the m11p8 rolling-upgrade
+/// handshake. Adjacent (N/N+1) versions interoperate by proto3 forward-compat;
+/// a `>= 2` major-version gap is logged at WARN as an unsupported skew. Never
+/// rejects — a rolling upgrade is a transient mixed-version window by design, so
+/// the WARN only fires while such a window is open. An empty version is a
+/// pre-m11p8 peer (version-unknown): no warning.
+fn observe_peer_version(peer_region: u32, peer_version: &str) {
+    if peer_version.is_empty() {
+        return;
+    }
+    let ours = env!("CARGO_PKG_VERSION");
+    if peer_version == ours {
+        return;
+    }
+    match (version_major(peer_version), version_major(ours)) {
+        (Some(theirs), Some(mine)) if theirs.abs_diff(mine) >= 2 => {
+            tracing::warn!(
+                peer_region,
+                peer_version,
+                our_version = ours,
+                "rolling-upgrade version skew exceeds N/N+1 (>= 2 major versions apart); \
+                 only adjacent versions are supported to interoperate"
+            );
+        }
+        _ => {
+            tracing::debug!(
+                peer_region,
+                peer_version,
+                our_version = ours,
+                "peer on a different build version (within the supported N/N+1 skew)"
+            );
+        }
+    }
+}
+
 /// The gRPC trailer key carrying the typed catch-up refusal class (m11p5 §2.4).
 /// Values: `snapshot-required` | `rejoin` | `stepping-down`. A pre-m11p5 source
 /// emits no trailer; the puller treats an absent/unknown value conservatively
@@ -659,6 +699,13 @@ impl WalShipping for WalShippingService {
             "received heartbeat",
         );
 
+        // m11p8 rolling-upgrade handshake: observe the peer's build version.
+        // N/N+1 (adjacent major) interoperate by proto3 forward-compat; a
+        // >= 2-major gap is the loud signal that the skew exceeds what is
+        // supported. Never a rejection — a rolling upgrade is a transient mixed
+        // window by design (the warn only fires during such a window).
+        observe_peer_version(req.region_id, &req.build_version);
+
         if let Some(hooks) = self.sources.election.get() {
             let leader_region = u16::try_from(req.leader_region)
                 .map_err(|_| Status::invalid_argument("leader_region exceeds u16 range"))?;

tidal-net/src/transport.rs

@@ -1106,6 +1106,12 @@ impl Transport for GrpcTransport {
         rx.try_recv().ok()
     }
 
+    fn peer_breaker_state(&self, peer: ShardId) -> u8 {
+        // Read-only breaker peek for the self-heal gauge (m11p8) — never admits
+        // the half-open probe.
+        self.pool.breaker_state(peer).as_gauge()
+    }
+
     fn local_shard(&self) -> ShardId {
         self.config.local_shard
     }

tidal-server/src/cluster/election_driver.rs

@@ -777,6 +777,13 @@ pub fn start(
                     // append + commit wait BLOCK; one at a time via the inflight
                     // guard.
                     node.submit_auto_promote();
+                    // m11p8 self-driving heal: a STANDING LEADER DUTY at a coarse
+                    // ~3s cadence (throttled inside) — refresh the per-peer breaker
+                    // gauge and re-arm the backlog re-ship for any stuck, behind
+                    // peer so it converges through breaker resets WITHOUT the
+                    // operator re-issuing /cluster/heal (incident §1.4-3). Non-
+                    // blocking, so it runs inline on the tick (no detached thread).
+                    node.tick_self_heal();
                     // m11p5 §3.3 removal-delivery grace: retire a removed peer's
                     // ship cell only once it has learned of its removal through
                     // the log (its applied mark covers the Removed record) or the

tidal-server/src/cluster/forward.rs

@@ -78,6 +78,13 @@ pub const INTERNAL_MARKER_VALUE: &str = "1";
 /// leader honors the CALLER's choice, not the gateway's default.
 pub const ACK_HEADER: &str = "x-tidal-ack";
 
+/// Request-id header (m11p8). Propagated verbatim across the forward hop so the
+/// leader's per-request span shares the originating gateway's `x-request-id`,
+/// and the gateway's `PropagateRequestIdLayer` echoes it back to the client. The
+/// leader's `SetRequestIdLayer` is a no-op when this header is already present,
+/// so the id survives the hop unchanged.
+pub const REQUEST_ID_HEADER: &str = "x-request-id";
+
 /// Response header carrying a cluster write's assigned replicated-log seqno
 /// (m11p3). Relayed verbatim on forwarded writes.
 pub const SEQ_HEADER: &str = "x-tidal-seq";
@@ -216,11 +223,15 @@ pub fn relay_forwarded(resp: ForwardedResponse) -> Response {
 /// ack mode, not the gateway's default. Empty when absent.
 #[must_use]
 pub fn ack_passthrough(headers: &HeaderMap) -> Vec<(&'static str, String)> {
-    headers
+    let mut out = Vec::new();
-        .get(ACK_HEADER)
+    if let Some(v) = headers.get(ACK_HEADER).and_then(|v| v.to_str().ok()) {
-        .and_then(|v| v.to_str().ok())
+        out.push((ACK_HEADER, v.to_owned()));
-        .map(|v| vec![(ACK_HEADER, v.to_owned())])
+    }
-        .unwrap_or_default()
+    // m11p8: carry the request-id across the forward hop for cross-node tracing.
+    if let Some(v) = headers.get(REQUEST_ID_HEADER).and_then(|v| v.to_str().ok()) {
+        out.push((REQUEST_ID_HEADER, v.to_owned()));
+    }
+    out
 }
 
 /// Forward a JSON request to one peer and relay its status + body back.

tidal-server/src/cluster/join_boot.rs

@@ -765,10 +765,11 @@ fn clone_replication(r: &ReplicationSpec) -> ReplicationSpec {
     }
 }
 
-const fn clone_wal(w: &WalSpec) -> WalSpec {
+fn clone_wal(w: &WalSpec) -> WalSpec {
     WalSpec {
         batch_size: w.batch_size,
         batch_timeout_ms: w.batch_timeout_ms,
+        archive_dir: w.archive_dir.clone(),
     }
 }
 

tidal-server/src/cluster/node.rs

@@ -179,6 +179,11 @@ const COMMIT_BRIDGE_WAKE_INTERVAL: Duration = Duration::from_secs(1);
 /// for tests via `TIDAL_REMOVE_DELIVERY_GRACE_MS`.
 const REMOVE_DELIVERY_GRACE_DEFAULT_MS: u64 = 30_000;
 
+/// Election ticks (50 ms each) between self-driving heal passes (m11p8). ~3 s —
+/// frequent enough to re-arm a stuck peer's backlog re-ship well within a
+/// circuit-breaker reset window (30 s) without churning cursors every tick.
+const SELF_HEAL_TICKS: u64 = 60;
+
 /// The election driver's boot bundle: prepared in [`ShardReplica::new`]
 /// (where the durable classification runs), consumed by
 /// [`ShardReplica::start_election_driver`] once the node is in its
@@ -365,6 +370,14 @@ pub struct ShardReplica {
     /// flag is set before spawning the duty and cleared when it finishes, so a
     /// fast-ticking leader never piles up promotion threads while one is in flight.
     promote_inflight: AtomicBool,
+    /// Self-driving heal (m11p8): coarse-cadence counter so the heal reconcile
+    /// pass runs roughly every `SELF_HEAL_TICKS` election ticks, not every 50ms.
+    heal_tick: AtomicU64,
+    /// Self-driving heal (m11p8): the set of peers this leader drove last pass
+    /// (breaker not closed AND trailing past the convergence threshold). Used to
+    /// count convergence transitions for `tidaldb_cluster_heal_successes_total`
+    /// and to clear the healing gauge on demotion.
+    healing: std::sync::Mutex<std::collections::HashSet<ShardId>>,
     /// The durable membership cache (`data_dir/membership`, m11p5 §3.6). The
     /// WAL-recovered `ClusterMembership` cell is the AUTHORITATIVE roster (it wins
     /// at open — the view is built from it); this cache exists only for the
@@ -998,6 +1011,8 @@ impl ShardReplica {
             membership,
             join_hooks_cell,
             promote_inflight: AtomicBool::new(false),
+            heal_tick: AtomicU64::new(0),
+            healing: std::sync::Mutex::new(std::collections::HashSet::new()),
             membership_store: tidaldb::replication::MembershipStore::new(&data_dir_for_state),
             decommissioned_by_signal: AtomicBool::new(false),
             deferred_retires: std::sync::Mutex::new(Vec::new()),
@@ -2211,6 +2226,90 @@ impl ShardReplica {
         }
     }
 
+    /// Self-driving heal (m11p8 §4): a STANDING LEADER DUTY re-armed every tick
+    /// at a coarse cadence (~`SELF_HEAL_TICKS` × the 50 ms election tick). It
+    /// closes incident §1.4-3 — "the breaker eats the first heal; re-issue until
+    /// lag 0" — by driving convergence itself instead of the operator.
+    ///
+    /// Each pass refreshes the per-peer breaker gauge, then for every peer that
+    /// is (a) NOT operator-partitioned, (b) has a non-closed ship breaker
+    /// (replication impaired), and (c) trails the leader's flushed frontier by
+    /// more than the convergence threshold, re-arms the backlog re-ship from the
+    /// peer's durable mark. The moment the breaker half-opens, the leader pushes
+    /// the WHOLE gap — no operator verb. A closed-breaker peer that is merely a
+    /// little behind self-heals through the normal ship path and is left alone
+    /// (no cursor churn). NON-BLOCKING (cursor updates + atomic gauge stores), so
+    /// it runs inline on the election tick rather than a detached thread.
+    ///
+    /// Operator-partitioned peers are intentionally ship-skipped (maintenance);
+    /// self-heal never auto-undoes a `/cluster/partition`. The manual
+    /// `/cluster/heal` verb still exists as an immediate nudge, but is no longer
+    /// required for convergence.
+    pub(crate) fn tick_self_heal(&self) {
+        // Coarse cadence: act ~every SELF_HEAL_TICKS election ticks.
+        if self.heal_tick.fetch_add(1, Ordering::Relaxed) % SELF_HEAL_TICKS != 0 {
+            return;
+        }
+        if !self.is_leader() {
+            // Off the leader there is no ship-driving duty: clear the healing
+            // gauge + tracked set so a demoted node stops reporting stale state.
+            self.cluster_metrics.set_healing_peers(0);
+            self.healing
+                .lock()
+                .unwrap_or_else(std::sync::PoisonError::into_inner)
+                .clear();
+            return;
+        }
+
+        let flushed = self.ship_feed.flushed_seq();
+        let partitioned = read_recovered(&self.partitioned, "partitioned").clone();
+        let marks: std::collections::HashMap<ShardId, u64> =
+            self.commit.peer_marks().into_iter().collect();
+
+        let mut behind_now: std::collections::HashSet<ShardId> = std::collections::HashSet::new();
+        for shard in self.ship_queue.peers() {
+            // Refresh the breaker gauge for EVERY configured peer (including
+            // partitioned ones) so the dashboard is truthful.
+            let bstate = self.ship_queue.peer_breaker_state(shard);
+            self.cluster_metrics.set_peer_breaker_state(shard, bstate);
+
+            // In-group shard id == region id, so the partition (ship-skip) set,
+            // keyed by region, is checked with the shard's numeric id.
+            if partitioned.contains(&RegionId(shard.0)) {
+                continue;
+            }
+            let mark = marks.get(&shard).copied().unwrap_or(0);
+            // Stuck = breaker not closed AND trailing past the convergence
+            // threshold. A closed breaker means the normal ship path is flowing.
+            if bstate != 0 && flushed.saturating_sub(mark) > self.learner_promote_lag {
+                behind_now.insert(shard);
+                self.cluster_metrics.incr_heal_attempts();
+                self.ship_queue.resume_from(shard, mark);
+            }
+        }
+
+        // Convergence transitions: peers driven last pass that are no longer
+        // behind recovered — count them and update the tracked set.
+        let mut prev = self
+            .healing
+            .lock()
+            .unwrap_or_else(std::sync::PoisonError::into_inner);
+        for s in prev.iter() {
+            if !behind_now.contains(s) {
+                self.cluster_metrics.incr_heal_successes();
+            }
+        }
+        let healing_count = behind_now.len() as u64;
+        *prev = behind_now;
+        drop(prev);
+
+        if healing_count == 0 {
+            // Liveness heartbeat: the loop ran and found everything converged.
+            self.cluster_metrics.incr_heal_noops();
+        }
+        self.cluster_metrics.set_healing_peers(healing_count);
+    }
+
     /// The shared cluster metrics cell (election gauges live here too).
     pub(crate) const fn cluster_metrics(
         &self,
@@ -2794,10 +2893,21 @@ impl ShardReplica {
         } else {
             0
         };
-        let applied_events = db
+        // The leader does NOT apply its own stream through the receiver — it
-            .replication_state()
+        // writes its WAL directly — so `applied_seqno(own_shard)` never advances
-            .applied_seqno(leader_shard)
+        // on a leader and would read a stale follower-era value (0 on a node
-            .unwrap_or(0);
+        // elected without first following). The leader's true applied frontier
+        // IS its durable flushed WAL frontier (it is, by construction, caught up
+        // to its own log). Followers read how far they have applied the CURRENT
+        // leader's per-source-shard stream (BUG 1: keyed by the live leader's
+        // shard, never a stale single scalar — see below).
+        let applied_events = if is_leader {
+            last_seq
+        } else {
+            db.replication_state()
+                .applied_seqno(leader_shard)
+                .unwrap_or(0)
+        };
         // lag = the CURRENT leader's per-source-shard high-water-mark − applied
         // for that same shard (BUG 1). The gauge tracks the leader HWM PER SOURCE
         // SHARD, so a `/cluster/promote` that moves leadership to a different shard
@@ -2880,6 +2990,7 @@ impl ShardReplica {
             membership_version: self.membership_version(),
             membership_term: self.membership.term(),
             membership_role: self.role_in_roster().to_string(),
+            version: node_build_version(),
             // Populated by `ClusterNode::status_local` (it owns the group set);
             // a bare per-replica status carries only its own row implicitly.
             shards: Vec::new(),
@@ -2887,6 +2998,13 @@ impl ShardReplica {
     }
 }
 
+/// This node's build version + hash for status/observability (m11p8):
+/// `"<cargo-version>+<build-hash>"` (e.g. `"0.1.0+dev"`). All workspace crates
+/// share the Cargo version, so the server version is the binary version.
+fn node_build_version() -> String {
+    format!("{}+{}", env!("CARGO_PKG_VERSION"), tidaldb::BUILD_HASH)
+}
+
 impl Drop for ShardReplica {
     fn drop(&mut self) {
         self.shutdown();
@@ -3041,6 +3159,12 @@ fn open_region_db(
     if let Some(timeout_ms) = topology.wal.batch_timeout_ms {
         builder = builder.wal_batch_timeout(Duration::from_millis(timeout_ms));
     }
+    // m11p8 PITR: archive sealed WAL segments before compaction deletes them.
+    // Segment filenames encode the shard id, so co-located groups share one
+    // archive dir without collision.
+    if let Some(ref archive_dir) = topology.wal.archive_dir {
+        builder = builder.wal_archive_dir(archive_dir);
+    }
     // m11p6: at most ONE hosted shard per node binds the engine's `/metrics`
     // server (N TidalDb instances would otherwise fight for one `metrics_addr`).
     // ClusterNode designates the metrics-owning shard; the others open without.
@@ -3373,6 +3497,10 @@ pub struct ClusterNode {
     tls_files: Option<tidal_net::config::TlsConfig>,
     /// m11p7 admin-verb audit sink (tracing + optional JSONL file).
     audit: crate::cluster::audit::AuditSink,
+    /// m11p8: the metrics-owner shard's cluster-metrics handle — the cell this
+    /// node's `/metrics` listener renders. Node-level gateway events (cross-shard
+    /// write forwards) increment it so they surface on the single per-node scrape.
+    cluster_metrics: Arc<tidaldb::db::metrics::cluster::ClusterMetrics>,
     /// Flipped on shutdown so `/health` reports not-ready while draining.
     shutting_down: AtomicBool,
 }
@@ -3427,7 +3555,7 @@ impl ClusterNode {
         let creds = Arc::new(crate::cluster::security::ClusterCreds::from_env());
 
         let mut groups: BTreeMap<ShardId, Arc<ShardReplica>> = BTreeMap::new();
-        let mut metrics_owner_assigned = false;
+        let mut metrics_owner: Option<ShardId> = None;
         for group in &resolved {
             if !group.replicas.iter().any(|r| r.region == region) {
                 continue; // this node does not host this group
@@ -3445,7 +3573,10 @@ impl ClusterNode {
             };
             // At most ONE hosted group binds the engine's `/metrics` server
             // (N TidalDb instances would otherwise fight for one `metrics_addr`).
-            let enable_metrics = !metrics_owner_assigned;
+            // The other co-located groups register their cluster series with the
+            // owner below (m11p8) so the single per-node listener still exposes
+            // every group's replication metrics, `shard`-labeled.
+            let enable_metrics = metrics_owner.is_none();
             let replica = ShardReplica::new(
                 topology,
                 region_name,
@@ -3458,7 +3589,7 @@ impl ClusterNode {
                 Arc::clone(&creds),
             )?;
             if enable_metrics {
-                metrics_owner_assigned = true;
+                metrics_owner = Some(group.shard);
             }
             groups.insert(group.shard, Arc::new(replica));
         }
@@ -3467,6 +3598,24 @@ impl ClusterNode {
                 "region '{region_name}' is not a replica of any shard group"
             )));
         }
+        // m11p8: when multiple shard groups co-locate on this node, the metrics
+        // owner exposes the siblings' `tidaldb_cluster_*` series under their own
+        // `shard="N"` label so one `/metrics` scrape covers every hosted group.
+        // No-op on the S=1 topology (a single hosted group is the owner).
+        if groups.len() > 1
+            && let Some(owner_shard) = metrics_owner
+            && let Some(owner_replica) = groups.get(&owner_shard)
+            && let Ok(owner_db) = owner_replica.db()
+        {
+            for (shard, replica) in &groups {
+                if *shard == owner_shard {
+                    continue;
+                }
+                if let Ok(sib_db) = replica.db() {
+                    owner_db.register_metrics_sibling(shard.0, sib_db);
+                }
+            }
+        }
 
         let router = if single {
             ShardRouter::single()
@@ -3523,9 +3672,19 @@ impl ClusterNode {
             hosted_groups = groups.len(),
             total_groups = placement.len(),
             tls = tls_files.is_some(),
+            version = %node_build_version(),
             "cluster node started (m11p6: one replica per hosted shard group)"
         );
 
+        // m11p8: the metrics-owner's cluster-metrics handle (the cell `/metrics`
+        // renders) for node-level gateway events. Falls back to the lowest-shard
+        // group if no owner was flagged; `groups` is non-empty (checked above).
+        let cluster_metrics = metrics_owner
+            .and_then(|s| groups.get(&s))
+            .or_else(|| groups.values().next())
+            .map(|r| Arc::clone(&r.cluster_metrics))
+            .expect("groups is non-empty");
+
         Ok(Self {
             placement,
             groups,
@@ -3535,6 +3694,7 @@ impl ClusterNode {
             creds,
             tls_files,
             audit: crate::cluster::audit::AuditSink::from_env(),
+            cluster_metrics,
             shutting_down: AtomicBool::new(false),
         })
     }
@@ -3741,6 +3901,7 @@ impl ClusterNode {
         }
         let auth = forwarded_auth(headers);
         let passthrough = forward::ack_passthrough(headers);
+        self.cluster_metrics.incr_forwards();
         let mut last_err = String::new();
         for http in candidates {
             let url = peer_url(http, path);
@@ -3762,6 +3923,9 @@ impl ClusterNode {
                 Err(e) => last_err = format!("{url}: {e}"),
             }
         }
+        // Every candidate replica was unreachable — the forward could not be
+        // delivered to the group at all (m11p8 forward-failure signal).
+        self.cluster_metrics.incr_forward_failures();
         Err(ClusterAppError(ServerError::Unavailable(format!(
             "shard {} unreachable: all {} replica candidates failed (last {last_err})",
             shard.0,
@@ -3910,7 +4074,10 @@ pub fn build_region_router(
             .layer(ConcurrencyLimitLayer::new(crate::router::MAX_CONCURRENCY)),
     );
 
-    public.merge(protected)
+    // m11p8: assign/echo `x-request-id` and open a per-request span on the
+    // multi-process region router too. Forwarded writes carry the originating
+    // gateway's id across the leader hop (see `cluster::forward`).
+    crate::router::with_request_id_tracing(public.merge(protected))
 }
 
 // ── Health ──────────────────────────────────────────────────────────────────
@@ -4050,6 +4217,15 @@ pub struct LocalStatusResponse {
     /// or `removed`. Distinct from `role` (the election role); a learner is a
     /// `follower` here.
     membership_role: String,
+    /// This node's build version + hash (m11p8 rolling-upgrade visibility):
+    /// `"<cargo-version>+<build-hash>"`. The aggregating gateway's status
+    /// fan-out collects every node's version, so an operator can confirm the
+    /// cluster is within the supported N/N+1 skew before/during a rolling
+    /// upgrade without shelling into each pod. `#[serde(default)]` so the
+    /// gateway can still deserialize a pre-m11p8 peer's status (empty version)
+    /// during a mixed-version upgrade window — the exact compat this phase needs.
+    #[serde(default)]
+    version: String,
     /// Per-shard-group status for every group THIS node hosts (m11p6). For the
     /// legacy single group this is one row mirroring the flat fields above; with
     /// sharding it carries one row per hosted group, so an operator (and the
@@ -4148,6 +4324,12 @@ pub struct AggregatedRegionStatus {
     /// the per-peer budget. An unreachable region reports `applied 0`, `lag =
     /// leader_last_seq`, `partitioned: true`.
     reachable: bool,
+    /// The region's reported build version (m11p8): `/cluster/status` is the
+    /// single pane an operator reads to confirm the whole cluster is within the
+    /// supported N/N+1 skew before a rolling upgrade. Empty for an unreachable
+    /// region or a pre-m11p8 peer.
+    #[serde(default)]
+    version: String,
 }
 
 /// Aggregated replication status across EVERY region of the default shard group.
@@ -4256,6 +4438,11 @@ pub async fn cluster_status(
                             // local status carries that set; mirror it.
                             a.iter().any(|v| v.as_str() == Some(name.as_str()))
                         });
+                let version = j
+                    .get("version")
+                    .and_then(serde_json::Value::as_str)
+                    .unwrap_or("")
+                    .to_owned();
                 AggregatedRegionStatus {
                     name,
                     applied_events: applied,
@@ -4266,6 +4453,7 @@ pub async fn cluster_status(
                     // the leader-set merge fix it.
                     partitioned,
                     reachable: true,
+                    version,
                 }
             }
             None => AggregatedRegionStatus {
@@ -4274,6 +4462,7 @@ pub async fn cluster_status(
                 lag_events: leader_last_seq,
                 partitioned: true,
                 reachable: false,
+                version: String::new(),
             },
         })
         .collect::<Vec<_>>();
@@ -5549,6 +5738,7 @@ async fn forward_write<B: serde::Serialize + Sync + ?Sized>(
     // sibling (this forward sets the internal marker).
     let mut passthrough = forward::ack_passthrough(headers);
     passthrough.extend(state.node_token_passthrough());
+    state.cluster_metrics.incr_forwards();
     match forward_json_with_headers(
         &state.client,
         &url,
@@ -5566,6 +5756,7 @@ async fn forward_write<B: serde::Serialize + Sync + ?Sized>(
         Err(e) => {
             // Leader unreachable: the typed 503 names the leader, its address,
             // and the connect error (single body shape via ClusterAppError).
+            state.cluster_metrics.incr_forward_failures();
             let leader = state.leader_name();
             tracing::warn!(%leader, %url, error = %e, "forward to leader failed; leader unreachable");
             Err(ClusterAppError(ServerError::LeaderUnreachable {

tidal-server/src/cluster/routes.rs

@@ -119,7 +119,11 @@ pub fn build_cluster_router(
             .layer(ConcurrencyLimitLayer::new(crate::router::MAX_CONCURRENCY)),
     );
 
-    public.merge(protected)
+    // m11p8: the same request-id + tracing stack as the standalone router —
+    // assigns/echoes `x-request-id` and opens a per-request span. The cluster
+    // routers previously skipped it; with it, a write forwarded to the leader
+    // carries the originating gateway's id (see `cluster::forward`).
+    crate::router::with_request_id_tracing(public.merge(protected))
 }
 
 // ── Health ──────────────────────────────────────────────────────────────────

tidal-server/src/cluster/topology.rs

@@ -263,6 +263,13 @@ pub struct WalSpec {
     /// Max milliseconds a partial batch waits before flushing.
     #[serde(default)]
     pub batch_timeout_ms: Option<u64>,
+    /// Optional WAL archive directory for point-in-time recovery (m11p8). When
+    /// set, each hosted shard group copies its sealed segments here before
+    /// compaction deletes them (segment filenames encode the shard id, so
+    /// co-located groups can share one archive dir without collision). Put it on
+    /// durable storage separate from the live data dir.
+    #[serde(default)]
+    pub archive_dir: Option<String>,
 }
 
 /// Operation-timeout overrides (the optional `timeouts:` YAML block).

tidal-server/src/router.rs

@@ -154,7 +154,21 @@ pub fn build_router(
 
     // SetRequestId must be outermost so the ID is in headers when TraceLayer
     // creates its span. In ServiceBuilder the first .layer() is outermost.
-    public.merge(protected).layer(
+    with_request_id_tracing(public.merge(protected))
+}
+
+/// Wrap `router` with the shared request-id + tracing layer stack (m11p8):
+/// `SetRequestIdLayer` (outermost) assigns a sequential `x-request-id` when one
+/// is absent, `PropagateRequestIdLayer` echoes it into the response, and
+/// `TraceLayer` opens a per-request span carrying the id. Applied to the
+/// standalone router AND both cluster routers (single-process and multi-process)
+/// so every HTTP surface correlates by `x-request-id`.
+///
+/// Because `SetRequestId` is a no-op when the header is already present, an
+/// `x-request-id` forwarded from a gateway (see `cluster::forward`) survives the
+/// hop: the leader's span shares the originating gateway's id.
+pub(crate) fn with_request_id_tracing(router: Router) -> Router {
+    router.layer(
         ServiceBuilder::new()
             .layer(SetRequestIdLayer::x_request_id(
                 SequentialRequestId::default(),

tidal/benches/ranking.rs

@@ -93,10 +93,96 @@ fn bench_score_200_full_pipeline(c: &mut Criterion) {
     });
 }
 
+// ── T2: signal-value pre-pass (one `entries.get()` per signal type) ──────────
+//
+// `for_you` reads `view` twice per candidate at *different* aggregations
+// (`Sort::Hot` reads `view` Value; a boost reads `view` DecayScore), so the
+// pre-pass collapses two `DashMap` gets to one. The win is a shard-lock saved,
+// so it is small single-threaded and grows under concurrent signal-write
+// contention — hence the `_under_writes` variants. `with_signal_plan(false)`
+// scores the same inputs through the direct per-term path for a true A/B.
+
+fn for_you_profile() -> tidaldb::ranking::profile::RankingProfile {
+    let mut registry = ProfileRegistry::new();
+    register_builtins(&mut registry).unwrap();
+    registry.get("for_you").unwrap().clone()
+}
+
+fn bench_for_you_plan(c: &mut Criterion) {
+    let ledger = make_ledger_with_200_items();
+    let profile = for_you_profile();
+    let candidates: Vec<EntityId> = (1..=200).map(EntityId::new).collect();
+    let now = Timestamp::from_nanos(1_708_000_000_000_000_000u64);
+
+    for plan in [true, false] {
+        let executor = ProfileExecutor::new(&ledger).with_signal_plan(plan);
+        let id = if plan {
+            "for_you_plan"
+        } else {
+            "for_you_no_plan"
+        };
+        c.bench_function(id, |b| {
+            b.iter(|| executor.score(black_box(&candidates), black_box(&profile), black_box(now)));
+        });
+    }
+}
+
+#[allow(clippy::cast_precision_loss)]
+fn bench_for_you_under_writes(c: &mut Criterion) {
+    use std::sync::{
+        Arc,
+        atomic::{AtomicBool, Ordering},
+    };
+
+    let profile = for_you_profile();
+    let candidates: Vec<EntityId> = (1..=200).map(EntityId::new).collect();
+    let now = Timestamp::from_nanos(1_708_000_000_000_000_000u64);
+
+    let mut group = c.benchmark_group("for_you_under_writes");
+    group.measurement_time(Duration::from_secs(8));
+
+    for plan in [true, false] {
+        let ledger = Arc::new(make_ledger_with_200_items());
+        let stop = Arc::new(AtomicBool::new(false));
+        // Four writers continuously record `view`/`like` signals, contending the
+        // same shards the scorer reads — the scenario where collapsing gets pays.
+        let writers: Vec<_> = (0..4u64)
+            .map(|w| {
+                let ledger = Arc::clone(&ledger);
+                let stop = Arc::clone(&stop);
+                std::thread::spawn(move || {
+                    let mut i = w;
+                    while !stop.load(Ordering::Relaxed) {
+                        let eid = EntityId::new((i % 200) + 1);
+                        let ts = Timestamp::from_nanos(1_708_000_000_000_000_000u64 + i * 1000);
+                        let _ = ledger.record_signal("view", eid, 1.0, ts);
+                        let _ = ledger.record_signal("like", eid, 1.0, ts);
+                        i += 4;
+                    }
+                })
+            })
+            .collect();
+
+        let executor = ProfileExecutor::new(&ledger).with_signal_plan(plan);
+        let id = if plan { "plan" } else { "no_plan" };
+        group.bench_function(id, |b| {
+            b.iter(|| executor.score(black_box(&candidates), black_box(&profile), black_box(now)));
+        });
+
+        stop.store(true, Ordering::Relaxed);
+        for w in writers {
+            w.join().unwrap();
+        }
+    }
+    group.finish();
+}
+
 criterion_group!(
     benches,
     bench_score_200_trending,
     bench_score_200_hot,
-    bench_score_200_full_pipeline
+    bench_score_200_full_pipeline,
+    bench_for_you_plan,
+    bench_for_you_under_writes
 );
 criterion_main!(benches);

tidal/src/db/builder.rs

@@ -379,6 +379,19 @@ impl TidalDbBuilder {
         self
     }
 
+    /// Enable WAL archival for point-in-time recovery (m11p8): every sealed WAL
+    /// segment is copied to `dir` before the periodic online compaction deletes
+    /// it, building a gap-free, self-describing archive (filenames encode shard +
+    /// first-seq). Off by default (no archival, no overhead). `dir` should be on
+    /// separate, durable storage from the live WAL (an object-store mount, an
+    /// archive volume) so a disk loss of the live data dir does not also lose the
+    /// archive.
+    #[must_use]
+    pub fn wal_archive_dir(mut self, dir: impl Into<PathBuf>) -> Self {
+        self.config.wal_archive_dir = Some(dir.into());
+        self
+    }
+
     /// Resolve default directory paths using [`Paths`] for persistent mode.
     ///
     /// When a `data_dir` is set and `wal_dir` or `cache_dir` are not

tidal/src/db/config.rs

@@ -71,6 +71,12 @@ pub struct Config {
     /// measured fsync cost: a longer window amortizes fsyncs better under
     /// sustained load but adds latency to sparse writes (m11p1).
     pub wal_batch_timeout: Option<std::time::Duration>,
+    /// Optional WAL archive directory for point-in-time recovery (m11p8). When
+    /// set, the periodic online-compaction path copies each sealed WAL segment
+    /// here BEFORE deleting it, building a gap-free, self-describing archive
+    /// (filenames encode shard + first-seq) an operator can replay to a chosen
+    /// point in time. `None` (the default) = no archival, no overhead.
+    pub wal_archive_dir: Option<PathBuf>,
 }
 
 impl Default for Config {
@@ -84,6 +90,7 @@ impl Default for Config {
             hlc_offset_ms: 0,
             wal_batch_size: None,
             wal_batch_timeout: None,
+            wal_archive_dir: None,
         }
     }
 }

tidal/src/db/metrics/cluster.rs

@@ -38,6 +38,9 @@ struct PeerShipMetrics {
     failures_total: AtomicU64,
     acked_seqno: AtomicU64,
     queue_depth: AtomicU64,
+    /// Per-peer circuit-breaker state (m11p8): 0 closed, 1 open, 2 half-open.
+    /// Refreshed by the self-driving heal loop, which polls each peer's breaker.
+    breaker_state: AtomicU64,
 }
 
 impl PeerShipMetrics {
@@ -49,6 +52,7 @@ impl PeerShipMetrics {
             failures_total: AtomicU64::new(0),
             acked_seqno: AtomicU64::new(0),
             queue_depth: AtomicU64::new(0),
+            breaker_state: AtomicU64::new(0),
         }
     }
 }
@@ -121,6 +125,31 @@ pub struct ClusterMetrics {
     /// its decommission and will learn of its removal via the typed removed
     /// signal if it ever restarts.
     remove_delivery_giveups_total: AtomicU64,
+    /// Total cross-node write forwards this node has INITIATED as a gateway
+    /// (m11p8) — a write that arrived on a non-leader and was relayed to the
+    /// shard leader over HTTP. High forward rate at one gateway = client routing
+    /// imbalance, not a fault.
+    forwards_total: AtomicU64,
+    /// Total cross-node write forwards that ERRORED (m11p8) — the leader was
+    /// unreachable, returned 5xx, or the relay timed out. A non-zero rate means
+    /// a gateway cannot reach the current leader (election in flight, partition).
+    forward_failures_total: AtomicU64,
+    /// Total per-peer circuit-breaker OPEN transitions observed across all peers
+    /// (m11p8). Each open is a `reset_duration` ship stall to that peer; a rising
+    /// counter under steady load means a peer link is flapping.
+    breaker_opens_total: AtomicU64,
+    /// Self-driving heal (m11p8): total reconcile attempts the server-side
+    /// heal loop has fired (one per peer per pass while a peer is behind).
+    heal_attempts_total: AtomicU64,
+    /// Self-driving heal (m11p8): total heal attempts that resumed a lagging
+    /// peer's ship (the breaker admitted the probe and a catch-up was nudged).
+    heal_successes_total: AtomicU64,
+    /// Self-driving heal (m11p8): total heal attempts that were no-ops because
+    /// the peer was already converged (the steady-state of the loop).
+    heal_noops_total: AtomicU64,
+    /// Self-driving heal (m11p8): peers this node is currently driving back to
+    /// convergence (partitioned-or-lagging set size). 0 = fully converged.
+    healing_peers: AtomicU64,
 }
 
 impl ClusterMetrics {
@@ -147,6 +176,13 @@ impl ClusterMetrics {
             snapshot_fetches_total: AtomicU64::new(0),
             snapshot_pin_force_drops_total: AtomicU64::new(0),
             remove_delivery_giveups_total: AtomicU64::new(0),
+            forwards_total: AtomicU64::new(0),
+            forward_failures_total: AtomicU64::new(0),
+            breaker_opens_total: AtomicU64::new(0),
+            heal_attempts_total: AtomicU64::new(0),
+            heal_successes_total: AtomicU64::new(0),
+            heal_noops_total: AtomicU64::new(0),
+            healing_peers: AtomicU64::new(0),
         }
     }
 
@@ -176,6 +212,48 @@ impl ClusterMetrics {
             .fetch_add(1, Ordering::Relaxed);
     }
 
+    /// Count one cross-node write forward initiated by this gateway (m11p8).
+    pub fn incr_forwards(&self) {
+        self.forwards_total.fetch_add(1, Ordering::Relaxed);
+    }
+
+    /// Count one cross-node write forward that errored (m11p8).
+    pub fn incr_forward_failures(&self) {
+        self.forward_failures_total.fetch_add(1, Ordering::Relaxed);
+    }
+
+    /// Set a peer's circuit-breaker state gauge (m11p8): 0 closed, 1 open,
+    /// 2 half-open. A closed/half-open → open transition also bumps the global
+    /// `breaker_opens_total` counter so a dashboard can `rate()` the flap.
+    pub fn set_peer_breaker_state(&self, peer: ShardId, state: u8) {
+        let cell = self.peer(peer);
+        let prev = cell.breaker_state.swap(u64::from(state), Ordering::Relaxed);
+        if state == 1 && prev != 1 {
+            self.breaker_opens_total.fetch_add(1, Ordering::Relaxed);
+        }
+    }
+
+    /// Count one self-driving heal reconcile attempt (m11p8).
+    pub fn incr_heal_attempts(&self) {
+        self.heal_attempts_total.fetch_add(1, Ordering::Relaxed);
+    }
+
+    /// Count one heal attempt that resumed a lagging peer's ship (m11p8).
+    pub fn incr_heal_successes(&self) {
+        self.heal_successes_total.fetch_add(1, Ordering::Relaxed);
+    }
+
+    /// Count one heal attempt that was a no-op (peer already converged; m11p8).
+    pub fn incr_heal_noops(&self) {
+        self.heal_noops_total.fetch_add(1, Ordering::Relaxed);
+    }
+
+    /// Set the count of peers this node is currently driving to convergence
+    /// (m11p8). 0 = fully converged.
+    pub fn set_healing_peers(&self, count: u64) {
+        self.healing_peers.store(count, Ordering::Relaxed);
+    }
+
     /// Record this node's election term + role (m11p4): role is 0 follower,
     /// 1 pre-candidate, 2 candidate, 3 leader.
     pub fn set_election_view(&self, term: u64, role: u64) {
@@ -307,142 +385,241 @@ impl ClusterMetrics {
     }
 
     /// Append the `tidaldb_cluster_*` series to a Prometheus exposition body.
+    ///
+    /// This is the single-shard / metrics-owner render: byte-identical to the
+    /// pre-m11p8 output so existing dashboards and the standalone surface are
+    /// unchanged.
+    pub(crate) fn render_into(&self, out: &mut String, partition_id: u64) {
+        self.render_labeled(out, partition_id, None);
+    }
+
+    /// Render this shard group's series with a `shard="N"` label on every line
+    /// (m11p8). Used when several shard groups co-locate on one node and share
+    /// its single `/metrics` listener: the metrics-owner renders unlabeled via
+    /// [`render_into`](Self::render_into) and each co-located sibling renders
+    /// here, so their series never collide on the shared scrape target.
+    pub(crate) fn render_into_sibling(&self, out: &mut String, partition_id: u64, shard: u16) {
+        self.render_labeled(out, partition_id, Some(shard));
+    }
+
     // One linear emit per series; splitting it would scatter the series list.
     #[allow(clippy::cast_precision_loss)] // monitoring gauges
     #[allow(clippy::too_many_lines)]
-    pub(crate) fn render_into(&self, out: &mut String, partition_id: u64) {
+    fn render_labeled(&self, out: &mut String, partition_id: u64, shard: Option<u16>) {
         use std::fmt::Write;
 
-        out.push_str(&self.ship_rtt.render_prometheus(
+        // Histogram / scalar label contents (no braces); empty for the unlabeled
+        // owner so its output stays byte-identical to the pre-m11p8 surface.
+        let extra = shard.map_or(String::new(), |s| format!("shard=\"{s}\""));
+
+        out.push_str(&self.ship_rtt.render_prometheus_labeled(
             "tidaldb_cluster_ship_rtt_us",
             "Replication batch ship round-trip time in microseconds (all peers)",
+            &extra,
         ));
-        out.push_str(&self.ship_batch_events.render_prometheus(
+        out.push_str(&self.ship_batch_events.render_prometheus_labeled(
             "tidaldb_cluster_ship_batch_events",
             "Events per shipped replication batch",
+            &extra,
         ));
-        out.push_str(&self.wal_fsync.render_prometheus(
+        out.push_str(&self.wal_fsync.render_prometheus_labeled(
             "tidaldb_cluster_wal_fsync_us",
             "WAL group-commit fsync latency in microseconds",
+            &extra,
         ));
-        out.push_str(&self.group_commit_events.render_prometheus(
+        out.push_str(&self.group_commit_events.render_prometheus_labeled(
             "tidaldb_cluster_group_commit_events",
             "Events per WAL group-commit batch",
+            &extra,
         ));
 
-        super::write_metric_line(
+        emit_scalar(
             out,
             "tidaldb_cluster_write_pool_depth",
             "Queued cluster write jobs awaiting a pool worker",
             "gauge",
             self.write_pool_depth.load(Ordering::Relaxed) as f64,
+            &extra,
         );
-        super::write_metric_line(
+        emit_scalar(
             out,
             "tidaldb_cluster_write_pool_rejections_total",
             "Cluster write submissions rejected with backpressure (HTTP 429)",
             "counter",
             self.write_pool_rejections_total.load(Ordering::Relaxed) as f64,
+            &extra,
         );
-        super::write_metric_line(
+        emit_scalar(
             out,
             "tidaldb_cluster_relay_last_seq",
             "Leader relay stream high-water mark (last committed seqno)",
             "gauge",
             self.relay_last_seq.load(Ordering::Relaxed) as f64,
+            &extra,
         );
-        super::write_metric_line(
+        emit_scalar(
             out,
             "tidaldb_cluster_relay_durable_seq",
             "Quorum commit index: highest seqno a majority of the replica set durably holds (m11p3)",
             "gauge",
             self.relay_durable_seq.load(Ordering::Relaxed) as f64,
+            &extra,
         );
-        super::write_metric_line(
+        emit_scalar(
             out,
             "tidaldb_cluster_quorum_timeouts_total",
             "ack=quorum writes that timed out awaiting the commit index (retryable 503s)",
             "counter",
             self.quorum_timeouts_total.load(Ordering::Relaxed) as f64,
+            &extra,
         );
 
-        super::write_metric_line(
+        emit_scalar(
+            out,
+            "tidaldb_cluster_forwards_total",
+            "Cross-node write forwards this gateway initiated (m11p8)",
+            "counter",
+            self.forwards_total.load(Ordering::Relaxed) as f64,
+            &extra,
+        );
+        emit_scalar(
+            out,
+            "tidaldb_cluster_forward_failures_total",
+            "Cross-node write forwards that errored — leader unreachable / 5xx / timeout (m11p8)",
+            "counter",
+            self.forward_failures_total.load(Ordering::Relaxed) as f64,
+            &extra,
+        );
+
+        emit_scalar(
             out,
             "tidaldb_cluster_election_term",
             "This node's current election term (m11p4; 0 = topology era)",
             "gauge",
             self.election_term.load(Ordering::Relaxed) as f64,
+            &extra,
         );
-        super::write_metric_line(
+        emit_scalar(
             out,
             "tidaldb_cluster_election_role",
             "Election role: 0 follower, 1 pre-candidate, 2 candidate, 3 leader",
             "gauge",
             self.election_role.load(Ordering::Relaxed) as f64,
+            &extra,
         );
-        super::write_metric_line(
+        emit_scalar(
             out,
             "tidaldb_cluster_elections_started_total",
             "Elections (pre-vote rounds) this node has started",
             "counter",
             self.elections_started_total.load(Ordering::Relaxed) as f64,
+            &extra,
         );
-        super::write_metric_line(
+        emit_scalar(
             out,
             "tidaldb_cluster_leader_changes_total",
             "Leadership changes this node has observed",
             "counter",
             self.leader_changes_total.load(Ordering::Relaxed) as f64,
+            &extra,
         );
-        super::write_metric_line(
+        emit_scalar(
             out,
             "tidaldb_cluster_divergence_quarantined",
             "Divergent-suffix quarantine latch (1 = fenced from the data plane)",
             "gauge",
             self.divergence_quarantined.load(Ordering::Relaxed) as f64,
+            &extra,
         );
-        super::write_metric_line(
+        emit_scalar(
             out,
             "tidaldb_cluster_reseed_required",
             "Durable reseed-marker latch (m11p5; 1 = a snapshot reseed is pending the next boot)",
             "gauge",
             self.reseed_required.load(Ordering::Relaxed) as f64,
+            &extra,
         );
 
-        super::write_metric_line(
+        emit_scalar(
+            out,
+            "tidaldb_cluster_breaker_opens_total",
+            "Per-peer circuit-breaker open transitions observed (m11p8; each is a ship stall)",
+            "counter",
+            self.breaker_opens_total.load(Ordering::Relaxed) as f64,
+            &extra,
+        );
+        emit_scalar(
+            out,
+            "tidaldb_cluster_heal_attempts_total",
+            "Self-driving heal reconcile attempts (m11p8)",
+            "counter",
+            self.heal_attempts_total.load(Ordering::Relaxed) as f64,
+            &extra,
+        );
+        emit_scalar(
+            out,
+            "tidaldb_cluster_heal_successes_total",
+            "Self-driving heal attempts that resumed a lagging peer's ship (m11p8)",
+            "counter",
+            self.heal_successes_total.load(Ordering::Relaxed) as f64,
+            &extra,
+        );
+        emit_scalar(
+            out,
+            "tidaldb_cluster_heal_noops_total",
+            "Self-driving heal attempts that were no-ops — peer already converged (m11p8)",
+            "counter",
+            self.heal_noops_total.load(Ordering::Relaxed) as f64,
+            &extra,
+        );
+        emit_scalar(
+            out,
+            "tidaldb_cluster_healing_peers",
+            "Peers this node is currently driving back to convergence (m11p8; 0 = converged)",
+            "gauge",
+            self.healing_peers.load(Ordering::Relaxed) as f64,
+            &extra,
+        );
+
+        emit_scalar(
             out,
             "tidaldb_cluster_snapshot_staged",
             "Seq of the currently-staged snapshot artifact (m11p5; 0 = none staged)",
             "gauge",
             self.snapshot_staged.load(Ordering::Relaxed) as f64,
+            &extra,
         );
-        super::write_metric_line(
+        emit_scalar(
             out,
             "tidaldb_cluster_snapshot_fetches_total",
             "FetchSnapshot streams served as the leader-side snapshot source (m11p5)",
             "counter",
             self.snapshot_fetches_total.load(Ordering::Relaxed) as f64,
+            &extra,
         );
-        super::write_metric_line(
+        emit_scalar(
             out,
             "tidaldb_cluster_snapshot_pin_force_drops_total",
             "Staged-artifact retention pins force-dropped past the hard cap (m11p5 §2.1; \
              a dead joiner that never released)",
             "counter",
             self.snapshot_pin_force_drops_total.load(Ordering::Relaxed) as f64,
+            &extra,
         );
-        super::write_metric_line(
+        emit_scalar(
             out,
             "tidaldb_cluster_remove_delivery_giveups_total",
             "Removal-delivery graces that expired before the removed peer acked the Removed \
              record (m11p5 §3.3; the removed node was down/unreachable during decommission)",
             "counter",
             self.remove_delivery_giveups_total.load(Ordering::Relaxed) as f64,
+            &extra,
         );
 
-        // Per-peer series, labeled by peer shard id + this node's partition.
+        // Per-peer series, labeled by peer shard id + this node's partition (and
-        // Snapshot the cells under the read lock, then render lock-free (the
+        // this group's shard when co-located). Snapshot the cells under the read
-        // ship sender threads update these cells on their hot path).
+        // lock, then render lock-free (the ship sender threads update these cells
+        // on their hot path).
         let peer_cells: Vec<(u16, Arc<PeerShipMetrics>)> = {
             let peers = self
                 .peers
@@ -453,13 +630,15 @@ impl ClusterMetrics {
         if peer_cells.is_empty() {
             return;
         }
+        let shard_prefix = shard.map_or(String::new(), |s| format!("shard=\"{s}\","));
         let _ = writeln!(
             out,
             "\n# HELP tidaldb_cluster_peer_ship Per-peer replication ship-path series.\n\
              # TYPE tidaldb_cluster_peer_acked_seqno gauge"
         );
         for (peer_id, cell) in &peer_cells {
-            let labels = format!("peer_shard=\"{peer_id}\",partition_id=\"{partition_id}\"");
+            let labels =
+                format!("{shard_prefix}peer_shard=\"{peer_id}\",partition_id=\"{partition_id}\"");
             let _ = writeln!(
                 out,
                 "tidaldb_cluster_peer_acked_seqno{{{labels}}} {}",
@@ -485,11 +664,32 @@ impl ClusterMetrics {
                 "tidaldb_cluster_peer_ship_failures_total{{{labels}}} {}",
                 cell.failures_total.load(Ordering::Relaxed)
             );
+            let _ = writeln!(
+                out,
+                "tidaldb_cluster_peer_breaker_state{{{labels}}} {}",
+                cell.breaker_state.load(Ordering::Relaxed)
+            );
         }
         out.push('\n');
     }
 }
 
+/// Emit one scalar (`gauge`/`counter`) line, optionally stamped with an extra
+/// label set (`extra`, no braces). Empty `extra` defers to the unlabeled
+/// [`write_metric_line`](super::write_metric_line) so the metrics-owner / single
+/// shard output is byte-identical to the pre-m11p8 surface.
+fn emit_scalar(out: &mut String, name: &str, help: &str, type_str: &str, value: f64, extra: &str) {
+    if extra.is_empty() {
+        super::write_metric_line(out, name, help, type_str, value);
+    } else {
+        use std::fmt::Write;
+        let _ = write!(
+            out,
+            "\n# HELP {name} {help}\n# TYPE {name} {type_str}\n{name}{{{extra}}} {value}\n"
+        );
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -510,6 +710,15 @@ mod tests {
         m.incr_snapshot_fetches();
         m.incr_snapshot_pin_force_drops();
         m.incr_remove_delivery_giveup();
+        // m11p8 additions.
+        m.incr_forwards();
+        m.incr_forwards();
+        m.incr_forward_failures();
+        m.set_peer_breaker_state(ShardId(2), 1); // open
+        m.incr_heal_attempts();
+        m.incr_heal_successes();
+        m.incr_heal_noops();
+        m.set_healing_peers(1);
 
         let mut out = String::new();
         m.render_into(&mut out, 7);
@@ -520,6 +729,14 @@ mod tests {
         assert!(out.contains("tidaldb_cluster_snapshot_fetches_total 1"));
         assert!(out.contains("tidaldb_cluster_snapshot_pin_force_drops_total 1"));
         assert!(out.contains("tidaldb_cluster_remove_delivery_giveups_total 1"));
+        // m11p8 series.
+        assert!(out.contains("tidaldb_cluster_forwards_total 2"));
+        assert!(out.contains("tidaldb_cluster_forward_failures_total 1"));
+        assert!(out.contains("tidaldb_cluster_breaker_opens_total 1"));
+        assert!(out.contains("tidaldb_cluster_heal_attempts_total 1"));
+        assert!(out.contains("tidaldb_cluster_heal_successes_total 1"));
+        assert!(out.contains("tidaldb_cluster_heal_noops_total 1"));
+        assert!(out.contains("tidaldb_cluster_healing_peers 1"));
         assert!(
             out.contains(
                 "tidaldb_cluster_peer_acked_seqno{peer_shard=\"2\",partition_id=\"7\"} 64"
@@ -531,7 +748,39 @@ mod tests {
         assert!(out.contains(
             "tidaldb_cluster_peer_ship_failures_total{peer_shard=\"2\",partition_id=\"7\"} 1"
         ));
+        assert!(
+            out.contains(
+                "tidaldb_cluster_peer_breaker_state{peer_shard=\"2\",partition_id=\"7\"} 1"
+            )
+        );
         assert!(out.contains("tidaldb_cluster_write_pool_depth"));
         assert!(out.contains("tidaldb_cluster_write_pool_rejections_total"));
     }
+
+    /// Co-located sibling shards render every series with a `shard="N"` label so
+    /// they never collide with the metrics-owner's unlabeled series on one
+    /// `/metrics` listener (m11p8 multi-shard listener).
+    #[test]
+    fn sibling_render_stamps_shard_label() {
+        let m = ClusterMetrics::new();
+        m.mark_active();
+        m.observe_ship(ShardId(5), std::time::Duration::from_millis(2), 32, 30, 40);
+        m.set_relay_frontiers(40, 38);
+        m.set_peer_breaker_state(ShardId(5), 2); // half-open
+
+        let mut out = String::new();
+        m.render_into_sibling(&mut out, 3, 1);
+        // Scalar gauges carry the shard label.
+        assert!(out.contains("tidaldb_cluster_relay_last_seq{shard=\"1\"} 40"));
+        assert!(out.contains("tidaldb_cluster_relay_durable_seq{shard=\"1\"} 38"));
+        // Histograms carry the shard label on every series line.
+        assert!(out.contains("tidaldb_cluster_ship_rtt_us_bucket{le=\"+Inf\",shard=\"1\"}"));
+        assert!(out.contains("tidaldb_cluster_ship_rtt_us_count{shard=\"1\"}"));
+        // Per-peer series carry shard + peer_shard + partition_id.
+        assert!(out.contains(
+            "tidaldb_cluster_peer_breaker_state{shard=\"1\",peer_shard=\"5\",partition_id=\"3\"} 2"
+        ));
+        // The owner's unlabeled form must NOT appear in a sibling render.
+        assert!(!out.contains("tidaldb_cluster_relay_last_seq 40"));
+    }
 }

tidal/src/db/metrics/histogram.rs

@@ -85,22 +85,46 @@ impl LatencyHistogram {
     /// Produces `# HELP`, `# TYPE histogram`, per-bucket lines with `le` labels,
     /// a `+Inf` bucket (equal to total count), `_sum`, and `_count`.
     pub fn render_prometheus(&self, name: &str, help: &str) -> String {
+        self.render_prometheus_labeled(name, help, "")
+    }
+
+    /// Render this histogram with an extra label set (e.g. `shard="1"`) on every
+    /// series line so co-located shards on one `/metrics` listener stay distinct.
+    ///
+    /// `extra` is the label *contents* without braces (`shard="1"`); an empty
+    /// string renders the unlabeled form, byte-identical to
+    /// [`render_prometheus`](Self::render_prometheus).
+    pub fn render_prometheus_labeled(&self, name: &str, help: &str, extra: &str) -> String {
         use std::fmt::Write;
 
+        // Bucket lines always carry an `le` label; `_sum`/`_count` carry the extra
+        // set in braces (or nothing when `extra` is empty).
+        let (bucket_sep, scalar_labels) = if extra.is_empty() {
+            ("", String::new())
+        } else {
+            (",", format!("{{{extra}}}"))
+        };
+
         let mut out = String::new();
         let _ = writeln!(out, "# HELP {name} {help}");
         let _ = writeln!(out, "# TYPE {name} histogram");
 
         for (i, &bound) in self.bounds.iter().enumerate() {
             let count = self.buckets[i].load(Ordering::Relaxed);
-            let _ = writeln!(out, "{name}_bucket{{le=\"{bound}\"}} {count}");
+            let _ = writeln!(
+                out,
+                "{name}_bucket{{le=\"{bound}\"{bucket_sep}{extra}}} {count}"
+            );
         }
 
         let total_count = self.count.load(Ordering::Relaxed);
         let total_sum = self.sum.load(Ordering::Relaxed);
-        let _ = writeln!(out, "{name}_bucket{{le=\"+Inf\"}} {total_count}");
+        let _ = writeln!(
-        let _ = writeln!(out, "{name}_sum {total_sum}");
+            out,
-        let _ = writeln!(out, "{name}_count {total_count}");
+            "{name}_bucket{{le=\"+Inf\"{bucket_sep}{extra}}} {total_count}"
+        );
+        let _ = writeln!(out, "{name}_sum{scalar_labels} {total_sum}");
+        let _ = writeln!(out, "{name}_count{scalar_labels} {total_count}");
         out.push('\n');
         out
     }

tidal/src/db/metrics/mod.rs

@@ -164,6 +164,15 @@ pub struct MetricsState {
     /// distinguishable when scraped into one Prometheus. Stored as an atomic so
     /// the install takes `&self` and works even after the `Arc` is shared.
     partition_id: AtomicU64,
+
+    /// Co-located shard groups' cluster metrics (m11p8). When several shard
+    /// groups run in one process and share this node's single `/metrics`
+    /// listener, the metrics-owning shard's `MetricsState` renders each sibling's
+    /// `tidaldb_cluster_*` series with a distinct `shard="N"` label so they never
+    /// collide on the shared scrape target. Empty on a single-shard node (the
+    /// shipped S=1 topology), so its output is byte-identical to pre-m11p8.
+    #[cfg(feature = "metrics")]
+    cluster_siblings: std::sync::RwLock<Vec<(u16, std::sync::Arc<cluster::ClusterMetrics>)>>,
 }
 
 impl MetricsState {
@@ -215,9 +224,28 @@ impl MetricsState {
             cluster: std::sync::Arc::new(cluster::ClusterMetrics::new()),
             control_plane: None,
             partition_id: AtomicU64::new(0),
+            #[cfg(feature = "metrics")]
+            cluster_siblings: std::sync::RwLock::new(Vec::new()),
         }
     }
 
+    /// Register a co-located shard group's cluster metrics so this node's single
+    /// `/metrics` listener also exposes that group's `tidaldb_cluster_*` series,
+    /// stamped with `shard="<shard>"` (m11p8). Called once per non-owner group
+    /// during cluster-node construction.
+    #[cfg(feature = "metrics")]
+    pub fn register_cluster_sibling(
+        &self,
+        shard: u16,
+        metrics: std::sync::Arc<cluster::ClusterMetrics>,
+    ) {
+        metrics.mark_active();
+        self.cluster_siblings
+            .write()
+            .unwrap_or_else(std::sync::PoisonError::into_inner)
+            .push((shard, metrics));
+    }
+
     /// Maximum age (nanoseconds) a checkpoint may reach before health reports
     /// degraded. The periodic checkpoint thread runs every 30s; a checkpoint
     /// older than 5 minutes means the thread is stuck, dead, or failing — all
@@ -505,6 +533,17 @@ impl MetricsState {
             // their exact metric surface.
             if self.cluster.is_active() {
                 self.cluster.render_into(&mut out, partition_id);
+                // Co-located shard groups (m11p8): each renders with a distinct
+                // `shard="N"` label so several groups sharing this node's one
+                // `/metrics` listener never collide. Empty on the S=1 topology.
+                for (shard, sib) in self
+                    .cluster_siblings
+                    .read()
+                    .unwrap_or_else(std::sync::PoisonError::into_inner)
+                    .iter()
+                {
+                    sib.render_into_sibling(&mut out, partition_id, *shard);
+                }
             }
         }
 

tidal/src/db/mod.rs

@@ -921,6 +921,10 @@ impl TidalDb {
                     // Resolve through the single source of truth so an explicit
                     // wal_dir override is honored here exactly as at WAL open.
                     let wal_dir = config.resolved_wal_dir();
+                    // m11p8 PITR: the optional WAL archive dir. When set, the
+                    // checkpoint thread's online compaction archives each sealed
+                    // segment before deleting it.
+                    let wal_archive_dir = config.wal_archive_dir.clone();
                     let metrics_clone = Arc::clone(&metrics);
                     // Separate handle kept by the panic supervisor so it can
                     // flag a dead checkpoint thread even though `metrics_clone`
@@ -964,6 +968,7 @@ impl TidalDb {
                                         items,
                                         seq_clone,
                                         wal_dir,
+                                        wal_archive_dir,
                                         retention_pin_clone,
                                         metrics_clone,
                                         index_handles,
@@ -1136,6 +1141,20 @@ impl TidalDb {
         self.metrics.cluster.mark_active();
         Arc::clone(&self.metrics.cluster)
     }
+
+    /// Expose `sibling`'s `tidaldb_cluster_*` series through THIS db's `/metrics`
+    /// listener, stamped with `shard="<shard>"` (m11p8).
+    ///
+    /// When several shard groups co-locate in one process, only one binds the
+    /// engine's `/metrics` server (the metrics owner); the others register here
+    /// so a single per-node scrape target still exposes every co-located group's
+    /// replication series, collision-free. A no-op-equivalent on the S=1 topology
+    /// (one shard per node), so its `/metrics` output is unchanged.
+    #[cfg(feature = "metrics")]
+    pub fn register_metrics_sibling(&self, shard: u16, sibling: &Self) {
+        self.metrics
+            .register_cluster_sibling(shard, Arc::clone(&sibling.metrics.cluster));
+    }
 }
 
 #[cfg(test)]

tidal/src/db/state_rebuild.rs

@@ -455,6 +455,7 @@ pub(super) fn run_checkpoint_thread(
     storage: Box<dyn StorageEngine + Send + Sync>,
     last_wal_seq: Arc<AtomicU64>,
     wal_dir: Option<PathBuf>,
+    wal_archive_dir: Option<PathBuf>,
     wal_retention_pin: Arc<AtomicU64>,
     metrics: Arc<MetricsState>,
     index_handles: IndexMetricsHandles,
@@ -579,7 +580,12 @@ pub(super) fn run_checkpoint_thread(
                     // the artifact's tail between staging and the first joiner
                     // pull).
                     let pin = wal_retention_pin.load(Ordering::Acquire);
-                    match crate::wal::compaction::compact_wal_online_pinned(dir, seq, pin) {
+                    match crate::wal::compaction::compact_wal_online_pinned(
+                        dir,
+                        seq,
+                        pin,
+                        wal_archive_dir.as_deref(),
+                    ) {
                         Ok(result) => {
                             #[cfg(feature = "metrics")]
                             {

tidal/src/query/executor/post_filter.rs

@@ -161,6 +161,9 @@ fn apply_signal_thresholds(
                 ledger,
                 degradation_level,
                 crate::schema::Timestamp::now().as_nanos(),
+                // Post-filter is a one-off per-candidate threshold read outside
+                // the scored pre-pass — no plan to consult, direct read.
+                None,
             )
             .map_err(|e| QueryError::InvalidFilter {
                 field: signal.clone(),

tidal/src/ranking/executor/helpers.rs

@@ -4,7 +4,7 @@
 //! logic. They depend on `ScoredCandidate` (from `context`) and profile types,
 //! but contain no executor state.
 
-use super::context::ScoredCandidate;
+use super::{SignalValues, context::ScoredCandidate};
 use crate::{
     load::DegradationLevel,
     ranking::profile::{Exclude, Gate, SignalAgg},
@@ -59,6 +59,10 @@ pub(super) const COARSE_VALUE_WINDOW: Window = Window::AllTime;
 /// - `TidalError::Internal` if `agg` is `Ratio` / `RelativeVelocity`: the
 ///   registry rejects those at profile registration, so reaching this arm is a
 ///   tidalDB invariant violation, not a recoverable runtime condition.
+// Mirrors the scoring inputs (entity, signal, agg, window, ledger, degradation,
+// clock) plus the optional pre-pass table; bundling them into a struct would
+// only relocate the same fields without reducing real complexity.
+#[allow(clippy::too_many_arguments)]
 pub(crate) fn read_agg(
     entity_id: EntityId,
     signal: &str,
@@ -67,6 +71,7 @@ pub(crate) fn read_agg(
     ledger: &SignalLedger,
     degradation: DegradationLevel,
     now_ns: u64,
+    vals: Option<&SignalValues>,
 ) -> crate::Result<f64> {
     let window = if degradation.coarsens_aggregates() {
         match agg {
@@ -77,6 +82,17 @@ pub(crate) fn read_agg(
     } else {
         window
     };
+    // Pre-pass hit: a value already computed by `SignalValues` (one
+    // `entries.get()` per signal type per candidate). A miss falls through to
+    // the direct read below, so the plan is a pure optimization and never
+    // changes the result. The effective `window` computed above is exactly the
+    // key the plan was built with.
+    if let Some(vals) = vals
+        && let Ok(type_id) = ledger.resolve_signal_type(signal)
+        && let Some(v) = vals.get(type_id, agg, window)
+    {
+        return Ok(v);
+    }
     match agg {
         SignalAgg::Value => {
             #[allow(clippy::cast_precision_loss)]
@@ -128,6 +144,7 @@ pub(crate) fn read_agg(
 ///
 /// Propagates any non-`UnknownSignalType` [`read_agg`] error (notably the
 /// `Ratio` / `RelativeVelocity` invariant violation).
+#[allow(clippy::too_many_arguments)] // same scoring inputs as `read_agg` + the pre-pass table
 pub(super) fn read_agg_for_sort(
     entity_id: EntityId,
     signal: &str,
@@ -136,8 +153,18 @@ pub(super) fn read_agg_for_sort(
     ledger: &SignalLedger,
     degradation: DegradationLevel,
     now_ns: u64,
+    vals: Option<&SignalValues>,
 ) -> crate::Result<f64> {
-    match read_agg(entity_id, signal, agg, window, ledger, degradation, now_ns) {
+    match read_agg(
+        entity_id,
+        signal,
+        agg,
+        window,
+        ledger,
+        degradation,
+        now_ns,
+        vals,
+    ) {
         Err(crate::TidalError::Schema(crate::schema::error::SchemaError::UnknownSignalType(_))) => {
             Ok(0.0)
         }
@@ -164,6 +191,7 @@ pub(super) fn passes_gates(
     gates: &[Gate],
     ledger: &SignalLedger,
     now_ns: u64,
+    vals: Option<&SignalValues>,
 ) -> crate::Result<bool> {
     for gate in gates {
         let value = read_agg(
@@ -174,6 +202,7 @@ pub(super) fn passes_gates(
             ledger,
             DegradationLevel::Full,
             now_ns,
+            vals,
         )?;
         if value < gate.min_threshold {
             return Ok(false);
@@ -207,6 +236,7 @@ pub(super) fn passes_excludes(
     excludes: &[Exclude],
     ledger: &SignalLedger,
     now_ns: u64,
+    vals: Option<&SignalValues>,
 ) -> crate::Result<bool> {
     for exclude in excludes {
         let value = read_agg(
@@ -217,6 +247,7 @@ pub(super) fn passes_excludes(
             ledger,
             DegradationLevel::Full,
             now_ns,
+            vals,
         )?;
         if value > exclude.above {
             return Ok(false);
@@ -332,6 +363,7 @@ mod tests {
             &ledger,
             DegradationLevel::Full,
             Timestamp::now().as_nanos(),
+            None,
         );
         assert!(matches!(result, Err(crate::TidalError::Internal(_))));
     }
@@ -348,6 +380,7 @@ mod tests {
             &ledger,
             DegradationLevel::Full,
             Timestamp::now().as_nanos(),
+            None,
         );
         assert!(matches!(result, Err(crate::TidalError::Schema(_))));
     }
@@ -369,7 +402,16 @@ mod tests {
             min_threshold: 5.0,
         }];
         // count=3 < threshold=5 -> candidate excluded.
-        assert!(!passes_gates(entity_id, &gates, &ledger, Timestamp::now().as_nanos()).unwrap());
+        assert!(
+            !passes_gates(
+                entity_id,
+                &gates,
+                &ledger,
+                Timestamp::now().as_nanos(),
+                None
+            )
+            .unwrap()
+        );
     }
 
     #[test]
@@ -389,7 +431,16 @@ mod tests {
             min_threshold: 5.0,
         }];
         // count=5 >= threshold=5 -> candidate included.
-        assert!(passes_gates(entity_id, &gates, &ledger, Timestamp::now().as_nanos()).unwrap());
+        assert!(
+            passes_gates(
+                entity_id,
+                &gates,
+                &ledger,
+                Timestamp::now().as_nanos(),
+                None
+            )
+            .unwrap()
+        );
     }
 
     #[test]

tidal/src/ranking/executor/mod.rs

@@ -17,6 +17,7 @@
 pub mod context;
 pub mod formulas;
 pub mod helpers;
+pub mod signal_values;
 
 // Re-export all public items so that `crate::ranking::executor::Foo` paths continue to work.
 use std::collections::HashMap;
@@ -25,6 +26,7 @@ use std::sync::Arc;
 pub use context::{ScoredCandidate, SignalKey, SignalSnapshot, UserContext};
 use formulas::{INTERACTION_BOOST_WEIGHT, PREFERENCE_BOOST_WEIGHT, RELEVANCE_BASE_WEIGHT};
 use helpers::{normalize, passes_excludes, passes_gates, read_agg_for_sort};
+pub use signal_values::{SignalReadPlan, SignalValues};
 
 use super::profile::{RankingProfile, SignalAgg};
 use crate::{
@@ -122,6 +124,14 @@ pub struct ProfileExecutor<'a> {
     /// no-`FOR USER` case, which yields a stable per-minute *global* permutation
     /// rather than per-user variety. Set via [`Self::with_shuffle_user`].
     shuffle_user_id: u64,
+    /// Whether to run the per-candidate signal-value pre-pass
+    /// ([`SignalReadPlan`]) that collapses redundant ledger gets to one
+    /// `entries.get()` per distinct signal type. On by default; the A/B
+    /// property test (`signal_plan_matches_per_term_path`) flips it off to score
+    /// the same inputs through the direct per-term path and assert identical
+    /// output, and it doubles as a runtime fallback. Pure optimization — a miss
+    /// always falls back to a direct read.
+    use_signal_plan: bool,
 }
 
 impl<'a> ProfileExecutor<'a> {
@@ -137,9 +147,22 @@ impl<'a> ProfileExecutor<'a> {
             user_state_for_date_saved: None,
             degradation_level: DegradationLevel::Full,
             shuffle_user_id: 0,
+            use_signal_plan: true,
         }
     }
 
+    /// Toggle the signal-value pre-pass (see [`Self::use_signal_plan`]).
+    ///
+    /// On by default. The A/B property test and the `ranking` benchmark flip it
+    /// off to score the same inputs through the direct per-term path; it also
+    /// serves as an operator escape hatch since the pre-pass is a pure
+    /// optimization (every read falls back to a direct ledger read on a miss).
+    #[must_use]
+    pub const fn with_signal_plan(mut self, enabled: bool) -> Self {
+        self.use_signal_plan = enabled;
+        self
+    }
+
     /// Set the user identity for the `Shuffle` sort's per-user, per-minute seed.
     ///
     /// Spec §11.6 seeds shuffle with `hash(user_id, timestamp_minute)` so a
@@ -454,21 +477,35 @@ impl<'a> ProfileExecutor<'a> {
         // Dynamic snapshot labels (`{signal}_boost`/`_penalty`/`_decay`) are
         // invariant across candidates — build them once here, not per candidate.
         let labels = RuleLabels::build(profile);
+        // Signal-value pre-pass plan (which (type, agg, window) reads the profile
+        // performs) is also entity-independent — build it once per query. Per
+        // candidate, `SignalReadPlan::compute` does one `entries.get()` per
+        // distinct signal type; every Pass-2 read below consults the result and
+        // falls back to a direct read on a miss, so it never changes the output.
+        let plan = self
+            .use_signal_plan
+            .then(|| SignalReadPlan::build(profile, self.ledger, self.degradation_level));
         // Pre-size to the candidate count: every candidate that survives
         // exclude/gate pushes exactly one entry, so this is the exact upper bound
         // and removes the Vec's growth reallocations on the scoring hot path.
         let mut scored: Vec<ScoredCandidate> = Vec::with_capacity(candidates.len());
         for &entity_id in candidates {
+            // Pass 1: collapse this candidate's redundant ledger gets to one per
+            // signal type (`None` when the pre-pass is disabled → direct reads).
+            let values = plan
+                .as_ref()
+                .map(|p| p.compute(self.ledger, entity_id, now_ns));
+            let vals = values.as_ref();
             // Stage 2: hard exclusion -- remove content the user must never see.
-            if !passes_excludes(entity_id, &profile.excludes, self.ledger, now_ns)? {
+            if !passes_excludes(entity_id, &profile.excludes, self.ledger, now_ns, vals)? {
                 continue;
             }
             // Stage 6: gates -- remove candidates below quality thresholds.
-            if !passes_gates(entity_id, &profile.gates, self.ledger, now_ns)? {
+            if !passes_gates(entity_id, &profile.gates, self.ledger, now_ns, vals)? {
                 continue;
             }
             let (raw, mut snapshot) =
-                self.compute_raw_score(entity_id, profile, now, retrieval_scores, &labels)?;
+                self.compute_raw_score(entity_id, profile, now, retrieval_scores, &labels, vals)?;
             let metadata = item_metadata.get(&entity_id.as_u64()).map_or(&empty, |m| m);
             let session_boost = session_ctx.map_or(0.0, |ctx| {
                 Self::session_boost(
@@ -595,10 +632,11 @@ impl<'a> ProfileExecutor<'a> {
         now: Timestamp,
         retrieval_scores: Option<&HashMap<u64, f64>>,
         labels: &RuleLabels,
+        vals: Option<&SignalValues>,
     ) -> crate::Result<(f64, SignalSnapshot)> {
         let now_ns = now.as_nanos();
         let (sort_base, mut snapshot) =
-            self.score_by_sort(entity_id, profile.sort.as_ref(), now)?;
+            self.score_by_sort(entity_id, profile.sort.as_ref(), now, vals)?;
 
         // Retrieval relevance seed (SEARCH Stage 1c). When the caller threads a
         // fused RRF score, fold it into the base so the fused order anchors the
@@ -639,6 +677,7 @@ impl<'a> ProfileExecutor<'a> {
                 self.ledger,
                 self.degradation_level,
                 now_ns,
+                vals,
             )?;
             let weighted = b.weight * val;
             if weighted != 0.0 {
@@ -687,6 +726,7 @@ impl<'a> ProfileExecutor<'a> {
                 self.ledger,
                 self.degradation_level,
                 now_ns,
+                vals,
             )?;
             let weighted = p.weight * val;
             if weighted != 0.0 {
@@ -720,6 +760,7 @@ impl<'a> ProfileExecutor<'a> {
                 self.ledger,
                 self.degradation_level,
                 now_ns,
+                vals,
             )?
             .clamp(0.0, 1.0);
             let factor = decay.weight.mul_add(recency, 1.0 - decay.weight);

tidal/src/ranking/executor/scoring.rs

@@ -6,7 +6,7 @@
 use smallvec::smallvec;
 
 use super::{
-    ProfileExecutor, SignalKey, SignalSnapshot,
+    ProfileExecutor, SignalKey, SignalSnapshot, SignalValues,
     formulas::{
         controversial_score, hidden_gems_score, hot_score, shuffle_quality_score,
         shuffle_quality_weight, shuffle_random, trending_score,
@@ -75,21 +75,23 @@ impl ProfileExecutor<'_> {
     /// [`read_agg_for_sort`], so a signal the schema omits contributes 0.0
     /// rather than erroring; any other read error (notably an unimplemented
     /// aggregation) still propagates.
+    #[allow(clippy::too_many_lines)]
     pub(super) fn score_by_sort(
         &self,
         entity_id: EntityId,
         sort: Option<&Sort>,
         now: Timestamp,
+        vals: Option<&SignalValues>,
     ) -> crate::Result<(f64, SignalSnapshot)> {
         // Capture the query clock ONCE so every per-candidate ledger read below
         // ages to the same "now" (reproducible scores; one fewer syscall per read).
         let now_ns = now.as_nanos();
         match sort {
-            Some(Sort::Hot { gravity }) => self.score_hot(entity_id, *gravity, now),
+            Some(Sort::Hot { gravity }) => self.score_hot(entity_id, *gravity, now, vals),
-            Some(Sort::Trending) => self.score_trending(entity_id, now_ns),
+            Some(Sort::Trending) => self.score_trending(entity_id, now_ns, vals),
-            Some(Sort::Controversial) => self.score_controversial(entity_id, now_ns),
+            Some(Sort::Controversial) => self.score_controversial(entity_id, now_ns, vals),
-            Some(Sort::HiddenGems) => self.score_hidden_gems(entity_id, now_ns),
+            Some(Sort::HiddenGems) => self.score_hidden_gems(entity_id, now_ns, vals),
-            Some(Sort::Shuffle) => Ok((self.score_shuffle(entity_id, now_ns)?, smallvec![])),
+            Some(Sort::Shuffle) => Ok((self.score_shuffle(entity_id, now_ns, vals)?, smallvec![])),
             Some(Sort::New) => {
                 // M2 limitation: entity metadata (`created_at`) is not accessible from the
                 // executor. Entity ID is used as a proxy for recency -- ranks higher IDs
@@ -103,19 +105,32 @@ impl ProfileExecutor<'_> {
                 let score = entity_id.as_u64() as f64;
                 Ok((score, smallvec![]))
             }
-            Some(Sort::TopWindow { window }) => self.score_top_window(entity_id, *window, now_ns),
+            Some(Sort::TopWindow { window }) => {
-            Some(Sort::MostViewed { window }) => {
+                self.score_top_window(entity_id, *window, now_ns, vals)
-                self.single_signal_score(entity_id, "view", &SignalAgg::Value, *window, now_ns)
-            }
-            Some(Sort::MostLiked { window }) => {
-                self.single_signal_score(entity_id, "like", &SignalAgg::Value, *window, now_ns)
             }
+            Some(Sort::MostViewed { window }) => self.single_signal_score(
+                entity_id,
+                "view",
+                &SignalAgg::Value,
+                *window,
+                now_ns,
+                vals,
+            ),
+            Some(Sort::MostLiked { window }) => self.single_signal_score(
+                entity_id,
+                "like",
+                &SignalAgg::Value,
+                *window,
+                now_ns,
+                vals,
+            ),
             Some(Sort::MostFollowed) => self.single_signal_score(
                 entity_id,
                 "follow",
                 &SignalAgg::Value,
                 Window::AllTime,
                 now_ns,
+                vals,
             ),
             Some(Sort::CreatorEngagementRate) => {
                 let view_vel = read_agg_for_sort(
@@ -126,6 +141,7 @@ impl ProfileExecutor<'_> {
                     self.ledger,
                     self.degradation_level,
                     now_ns,
+                    vals,
                 )?;
                 let like_vel = read_agg_for_sort(
                     entity_id,
@@ -135,6 +151,7 @@ impl ProfileExecutor<'_> {
                     self.ledger,
                     self.degradation_level,
                     now_ns,
+                    vals,
                 )?;
                 Ok((
                     view_vel + like_vel,
@@ -144,7 +161,7 @@ impl ProfileExecutor<'_> {
                     ],
                 ))
             }
-            Some(Sort::Rising) => self.score_rising(entity_id, now_ns),
+            Some(Sort::Rising) => self.score_rising(entity_id, now_ns, vals),
             Some(Sort::AlphabeticalAsc) => {
                 Ok((self.score_alphabetical_asc(entity_id), smallvec![]))
             }
@@ -153,18 +170,29 @@ impl ProfileExecutor<'_> {
             }
             Some(Sort::Shortest) => Ok((self.score_shortest(entity_id), smallvec![])),
             Some(Sort::Longest) => Ok((self.score_longest(entity_id), smallvec![])),
-            Some(Sort::MostCommented { window }) => {
+            Some(Sort::MostCommented { window }) => self.single_signal_score(
-                self.single_signal_score(entity_id, "comment", &SignalAgg::Value, *window, now_ns)
+                entity_id,
-            }
+                "comment",
-            Some(Sort::MostShared { window }) => {
+                &SignalAgg::Value,
-                self.single_signal_score(entity_id, "share", &SignalAgg::Value, *window, now_ns)
+                *window,
-            }
+                now_ns,
+                vals,
+            ),
+            Some(Sort::MostShared { window }) => self.single_signal_score(
+                entity_id,
+                "share",
+                &SignalAgg::Value,
+                *window,
+                now_ns,
+                vals,
+            ),
             Some(Sort::LiveViewerCount) => self.single_signal_score(
                 entity_id,
                 "viewer_count",
                 &SignalAgg::DecayScore,
                 Window::AllTime,
                 now_ns,
+                vals,
             ),
             Some(Sort::DateSaved) => Ok((self.score_date_saved(entity_id), smallvec![])),
             None => Ok((0.0, smallvec![])),
@@ -182,6 +210,7 @@ impl ProfileExecutor<'_> {
         entity_id: EntityId,
         gravity: f64,
         now: Timestamp,
+        vals: Option<&SignalValues>,
     ) -> crate::Result<(f64, SignalSnapshot)> {
         let views = read_agg_for_sort(
             entity_id,
@@ -191,6 +220,7 @@ impl ProfileExecutor<'_> {
             self.ledger,
             self.degradation_level,
             now.as_nanos(),
+            vals,
         )?;
         // The scoring loop receives no per-entity `created_at`: the executor reads
         // only the signal ledger, and the `created_at` range index is keyed
@@ -232,7 +262,12 @@ impl ProfileExecutor<'_> {
     ///
     /// Propagates any non-degradable ledger read error (an unimplemented
     /// aggregation), matching the other formula sorts.
-    fn score_shuffle(&self, entity_id: EntityId, now_ns: u64) -> crate::Result<f64> {
+    fn score_shuffle(
+        &self,
+        entity_id: EntityId,
+        now_ns: u64,
+        vals: Option<&SignalValues>,
+    ) -> crate::Result<f64> {
         // Quality inputs, all aged to the single query clock for reproducibility.
         let completion_rate = read_agg_for_sort(
             entity_id,
@@ -242,6 +277,7 @@ impl ProfileExecutor<'_> {
             self.ledger,
             self.degradation_level,
             now_ns,
+            vals,
         )?
         .clamp(0.0, 1.0);
         let likes = read_agg_for_sort(
@@ -252,6 +288,7 @@ impl ProfileExecutor<'_> {
             self.ledger,
             self.degradation_level,
             now_ns,
+            vals,
         )?;
         let views = read_agg_for_sort(
             entity_id,
@@ -261,6 +298,7 @@ impl ProfileExecutor<'_> {
             self.ledger,
             self.degradation_level,
             now_ns,
+            vals,
         )?;
         // like_ratio = likes / (views + 1), clamped to [0, 1]: a like is only
         // emitted by a viewer, so the ratio is a bounded engagement-quality proxy.
@@ -285,6 +323,7 @@ impl ProfileExecutor<'_> {
         agg: &SignalAgg,
         window: Window,
         now_ns: u64,
+        vals: Option<&SignalValues>,
     ) -> crate::Result<(f64, SignalSnapshot)> {
         let val = read_agg_for_sort(
             entity_id,
@@ -294,6 +333,7 @@ impl ProfileExecutor<'_> {
             self.ledger,
             self.degradation_level,
             now_ns,
+            vals,
         )?;
         Ok((val, smallvec![(SignalKey::Static(signal), val)]))
     }
@@ -302,6 +342,7 @@ impl ProfileExecutor<'_> {
         &self,
         entity_id: EntityId,
         now_ns: u64,
+        vals: Option<&SignalValues>,
     ) -> crate::Result<(f64, SignalSnapshot)> {
         // M6: social-graph-scoped trending. When a social subgraph and
         // per-user signal index are available, compute aggregate velocity
@@ -356,6 +397,7 @@ impl ProfileExecutor<'_> {
             self.ledger,
             self.degradation_level,
             now_ns,
+            vals,
         )?;
         let share_vel = read_agg_for_sort(
             entity_id,
@@ -365,6 +407,7 @@ impl ProfileExecutor<'_> {
             self.ledger,
             self.degradation_level,
             now_ns,
+            vals,
         )?;
         Ok((
             trending_score(view_vel, share_vel),
@@ -379,6 +422,7 @@ impl ProfileExecutor<'_> {
         &self,
         entity_id: EntityId,
         now_ns: u64,
+        vals: Option<&SignalValues>,
     ) -> crate::Result<(f64, SignalSnapshot)> {
         let pos = read_agg_for_sort(
             entity_id,
@@ -388,6 +432,7 @@ impl ProfileExecutor<'_> {
             self.ledger,
             self.degradation_level,
             now_ns,
+            vals,
         )?;
         let neg = read_agg_for_sort(
             entity_id,
@@ -397,6 +442,7 @@ impl ProfileExecutor<'_> {
             self.ledger,
             self.degradation_level,
             now_ns,
+            vals,
         )?;
         Ok((
             controversial_score(pos, neg),
@@ -411,6 +457,7 @@ impl ProfileExecutor<'_> {
         &self,
         entity_id: EntityId,
         now_ns: u64,
+        vals: Option<&SignalValues>,
     ) -> crate::Result<(f64, SignalSnapshot)> {
         let quality = read_agg_for_sort(
             entity_id,
@@ -420,6 +467,7 @@ impl ProfileExecutor<'_> {
             self.ledger,
             self.degradation_level,
             now_ns,
+            vals,
         )?;
         let view_count = read_agg_for_sort(
             entity_id,
@@ -429,6 +477,7 @@ impl ProfileExecutor<'_> {
             self.ledger,
             self.degradation_level,
             now_ns,
+            vals,
         )?;
         Ok((
             hidden_gems_score(quality, view_count),
@@ -444,6 +493,7 @@ impl ProfileExecutor<'_> {
         entity_id: EntityId,
         window: Window,
         now_ns: u64,
+        vals: Option<&SignalValues>,
     ) -> crate::Result<(f64, SignalSnapshot)> {
         let views = read_agg_for_sort(
             entity_id,
@@ -453,6 +503,7 @@ impl ProfileExecutor<'_> {
             self.ledger,
             self.degradation_level,
             now_ns,
+            vals,
         )?;
         let likes = read_agg_for_sort(
             entity_id,
@@ -462,6 +513,7 @@ impl ProfileExecutor<'_> {
             self.ledger,
             self.degradation_level,
             now_ns,
+            vals,
         )?;
         let shares = read_agg_for_sort(
             entity_id,
@@ -471,6 +523,7 @@ impl ProfileExecutor<'_> {
             self.ledger,
             self.degradation_level,
             now_ns,
+            vals,
         )?;
         let completion = read_agg_for_sort(
             entity_id,
@@ -480,6 +533,7 @@ impl ProfileExecutor<'_> {
             self.ledger,
             self.degradation_level,
             now_ns,
+            vals,
         )?;
         Ok((
             views.mul_add(
@@ -499,6 +553,7 @@ impl ProfileExecutor<'_> {
         &self,
         entity_id: EntityId,
         now_ns: u64,
+        vals: Option<&SignalValues>,
     ) -> crate::Result<(f64, SignalSnapshot)> {
         let short = read_agg_for_sort(
             entity_id,
@@ -508,6 +563,7 @@ impl ProfileExecutor<'_> {
             self.ledger,
             self.degradation_level,
             now_ns,
+            vals,
         )?;
         let long = read_agg_for_sort(
             entity_id,
@@ -517,6 +573,7 @@ impl ProfileExecutor<'_> {
             self.ledger,
             self.degradation_level,
             now_ns,
+            vals,
         )?;
         let score = if long < f64::EPSILON {
             short

tidal/src/ranking/executor/signal_values.rs

@@ -0,0 +1,320 @@
+//! Per-candidate signal-value pre-pass — collapse redundant signal-ledger gets.
+//!
+//! The per-candidate scoring loop reads the signal ledger once per
+//! `(signal, agg, window)` term. Many profiles read the **same signal type** at
+//! several aggregations or from several stages — e.g. a `Sort::Hot` reads `view`
+//! `Value` while a boost reads `view` `DecayScore` — so a naive loop does one
+//! sharded `DashMap` get per term even when several terms hit the same entry.
+//!
+//! [`SignalReadPlan`] + [`SignalValues`] collapse that into one get per distinct
+//! signal type per candidate, in two passes:
+//!
+//! - **Pass 1** ([`SignalReadPlan::compute`]): for each distinct `SignalTypeId`
+//!   the profile reads, take ONE [`SignalLedger::entry_ref`], evaluate every
+//!   planned `(agg, window)` against the held entry, then **drop the ref before
+//!   the next type**. Only one entry ref is ever held at a time, so this cannot
+//!   deadlock against `DashMap`'s per-shard `RwLock` (holding a ref while getting
+//!   another key on the same shard is a documented `DashMap` deadlock).
+//!
+//! - **Pass 2** (the existing scoring code, threading `Option<&SignalValues>`):
+//!   each read consults this table first, in declared order, so exclude/gate
+//!   short-circuit and snapshot push order are byte-for-byte unchanged. **A miss
+//!   falls back to a direct ledger read**, so an incomplete or approximate plan
+//!   only costs the optimization — never correctness. That fallback is what lets
+//!   the sort-read enumeration below be a best-effort superset.
+//!
+//! The plan is entity-independent (the profile fixes which signals/aggs/windows
+//! are read), so it is built once per query and reused for every candidate.
+
+use smallvec::SmallVec;
+
+use super::helpers::{COARSE_VALUE_WINDOW, COARSE_VELOCITY_WINDOW};
+use crate::{
+    load::DegradationLevel,
+    ranking::profile::{RankingProfile, SignalAgg, Sort},
+    schema::{EntityId, Window},
+    signals::{SignalLedger, SignalTypeId},
+};
+
+/// The three entry-backed aggregations the pre-pass can collapse, as a small
+/// `Copy` key (the public [`SignalAgg`] is intentionally neither `Copy` nor
+/// `Eq`). `Ratio`/`RelativeVelocity` are not representable here — they are never
+/// planned and fall through to the direct read, which raises the same error.
+#[derive(Clone, Copy, PartialEq, Eq)]
+enum AggKind {
+    Value,
+    Velocity,
+    Decay,
+}
+
+impl AggKind {
+    const fn from_agg(agg: &SignalAgg) -> Option<Self> {
+        match agg {
+            SignalAgg::Value => Some(Self::Value),
+            SignalAgg::Velocity => Some(Self::Velocity),
+            SignalAgg::DecayScore => Some(Self::Decay),
+            SignalAgg::Ratio | SignalAgg::RelativeVelocity => None,
+        }
+    }
+}
+
+/// The effective read key after degradation substitution and `Decay`
+/// window-normalization. Plan entries and Pass-2 lookups are both keyed this
+/// way, so a lookup hits iff the same effective read was planned.
+#[derive(Clone, Copy, PartialEq, Eq)]
+struct ReadKey {
+    type_id: SignalTypeId,
+    agg: AggKind,
+    window: Window,
+}
+
+/// Compute the effective window for a read: apply the same degradation
+/// substitution [`super::helpers::read_agg`] applies, then canonicalize
+/// `Decay` (which ignores its window) to a single window so a lookup hits
+/// regardless of the term's declared window.
+const fn effective_window(agg: AggKind, window: Window, degradation: DegradationLevel) -> Window {
+    match agg {
+        // `Decay` is an O(1) running quantity independent of `window` (see
+        // `read_agg`); canonicalize so a boost/decay term with any declared
+        // window resolves to the same planned value.
+        AggKind::Decay => Window::AllTime,
+        AggKind::Value if degradation.coarsens_aggregates() => COARSE_VALUE_WINDOW,
+        AggKind::Velocity if degradation.coarsens_aggregates() => COARSE_VELOCITY_WINDOW,
+        AggKind::Value | AggKind::Velocity => window,
+    }
+}
+
+/// The fixed signal vocabulary a `Sort` mode reads from the ledger, mirroring
+/// [`super::ProfileExecutor::score_by_sort`]. Best-effort: this is only a
+/// performance hint (Pass 2 falls back to a direct read on any miss), so a sort
+/// whose reads drift from this list stays correct — it just doesn't collapse.
+/// Sort modes that read no ledger signals (`New`, `Alphabetical*`, `Shortest`,
+/// `Longest`, `DateSaved`) and the social-graph trending path (which reads the
+/// per-user signal index, not `entries`) contribute nothing here.
+fn sort_signal_reads(sort: Option<&Sort>) -> SmallVec<[(&'static str, SignalAgg, Window); 4]> {
+    use SignalAgg::{DecayScore, Value, Velocity};
+    use Window::{AllTime, OneHour, TwentyFourHours};
+    let mut v: SmallVec<[(&'static str, SignalAgg, Window); 4]> = SmallVec::new();
+    match sort {
+        Some(Sort::Hot { .. }) => v.push(("view", Value, AllTime)),
+        Some(Sort::Trending) => {
+            v.push(("view", Velocity, TwentyFourHours));
+            v.push(("share", Velocity, TwentyFourHours));
+        }
+        Some(Sort::Controversial) => {
+            v.push(("like", Value, AllTime));
+            v.push(("dislike", Value, AllTime));
+        }
+        Some(Sort::HiddenGems) => {
+            v.push(("completion", DecayScore, AllTime));
+            v.push(("view", Value, AllTime));
+        }
+        Some(Sort::Shuffle) => {
+            v.push(("completion", DecayScore, AllTime));
+            v.push(("like", Value, AllTime));
+            v.push(("view", Value, AllTime));
+        }
+        Some(Sort::TopWindow { window }) => {
+            v.push(("view", Value, *window));
+            v.push(("like", Value, *window));
+            v.push(("share", Value, *window));
+            v.push(("completion", Value, *window));
+        }
+        Some(Sort::MostViewed { window }) => v.push(("view", Value, *window)),
+        Some(Sort::MostLiked { window }) => v.push(("like", Value, *window)),
+        Some(Sort::MostFollowed) => v.push(("follow", Value, AllTime)),
+        Some(Sort::CreatorEngagementRate) => {
+            v.push(("view", Velocity, TwentyFourHours));
+            v.push(("like", Velocity, TwentyFourHours));
+        }
+        Some(Sort::Rising) => {
+            v.push(("view", Velocity, OneHour));
+            v.push(("view", Velocity, TwentyFourHours));
+        }
+        Some(Sort::MostCommented { window }) => v.push(("comment", Value, *window)),
+        Some(Sort::MostShared { window }) => v.push(("share", Value, *window)),
+        Some(Sort::LiveViewerCount) => v.push(("viewer_count", DecayScore, AllTime)),
+        // No ledger reads: New, AlphabeticalAsc/Desc, Shortest, Longest, DateSaved, None.
+        _ => {}
+    }
+    v
+}
+
+/// The per-query read plan: the distinct effective `(type, agg, window)` reads
+/// the profile performs, plus the distinct signal types (so Pass 1 can iterate
+/// one get per type).
+pub struct SignalReadPlan {
+    reads: SmallVec<[ReadKey; 16]>,
+    types: SmallVec<[SignalTypeId; 8]>,
+}
+
+impl SignalReadPlan {
+    /// Build the read plan for a profile. Entity-independent — call once per
+    /// query, [`compute`](Self::compute) once per candidate.
+    ///
+    /// Resolution failures (`UnknownSignalType`) and the unsupported
+    /// `Ratio`/`RelativeVelocity` aggregations are simply omitted: the Pass-2
+    /// fallback then performs the direct read, which preserves the exact
+    /// error contract (gates/excludes propagate, sort/boosts swallow, the
+    /// unsupported aggs error) without this pre-pass having to replicate it.
+    #[must_use]
+    pub fn build(
+        profile: &RankingProfile,
+        ledger: &SignalLedger,
+        degradation: DegradationLevel,
+    ) -> Self {
+        let mut plan = Self {
+            reads: SmallVec::new(),
+            types: SmallVec::new(),
+        };
+
+        // Gates and excludes always read at Full degradation (correctness
+        // filters — see `passes_gates`/`passes_excludes`).
+        for g in &profile.gates {
+            plan.add(ledger, &g.signal, &g.agg, g.window, DegradationLevel::Full);
+        }
+        for e in &profile.excludes {
+            plan.add(ledger, &e.signal, &e.agg, e.window, DegradationLevel::Full);
+        }
+        // Boosts/penalties/decay and the sort base read at the query degradation.
+        for b in &profile.boosts {
+            plan.add(ledger, &b.signal, &b.agg, b.window, degradation);
+        }
+        for p in &profile.penalties {
+            plan.add(ledger, &p.signal, &p.agg, p.window, degradation);
+        }
+        if let Some(d) = &profile.decay {
+            plan.add(
+                ledger,
+                &d.signal,
+                &SignalAgg::DecayScore,
+                Window::AllTime,
+                degradation,
+            );
+        }
+        for (signal, agg, window) in sort_signal_reads(profile.sort.as_ref()) {
+            plan.add(ledger, signal, &agg, window, degradation);
+        }
+        plan
+    }
+
+    fn add(
+        &mut self,
+        ledger: &SignalLedger,
+        signal: &str,
+        agg: &SignalAgg,
+        window: Window,
+        degradation: DegradationLevel,
+    ) {
+        // Only the three entry-backed aggregations are collapsible; the
+        // registry-rejected Ratio/RelativeVelocity are left to the fallback
+        // (which raises the same internal error the direct path does).
+        let Some(agg) = AggKind::from_agg(agg) else {
+            return;
+        };
+        let Ok(type_id) = ledger.resolve_signal_type(signal) else {
+            return; // unknown signal → fallback handles the contract
+        };
+        let key = ReadKey {
+            type_id,
+            agg,
+            window: effective_window(agg, window, degradation),
+        };
+        if !self.reads.contains(&key) {
+            self.reads.push(key);
+        }
+        if !self.types.contains(&type_id) {
+            self.types.push(type_id);
+        }
+    }
+
+    /// Pass 1: compute every planned read's value for one candidate with one
+    /// `entry_ref` per distinct signal type. The ref is held only across a single
+    /// type's reads, then dropped — never two refs at once (deadlock contract of
+    /// [`SignalLedger::entry_ref`]).
+    // The held `entry` ref deliberately spans the inner read loop — that is the
+    // whole point (one get serves every aggregation of the type). It is released
+    // at the end of each outer iteration, before the next type's get, so the
+    // drop is already as tight as the deadlock contract allows.
+    #[allow(clippy::significant_drop_tightening)]
+    #[must_use]
+    pub fn compute(&self, ledger: &SignalLedger, entity_id: EntityId, now_ns: u64) -> SignalValues {
+        let mut values: SmallVec<[(ReadKey, f64); 16]> = SmallVec::new();
+        for &type_id in &self.types {
+            // ONE get for this type. `entry` (a held shard-read ref) is dropped
+            // at the end of this loop body, before the next type's get.
+            let entry = ledger.entry_ref(entity_id, type_id);
+            let lambda0 = ledger.decay_lambda(type_id);
+            for key in self.reads.iter().filter(|k| k.type_id == type_id) {
+                let value = match key.agg {
+                    AggKind::Value => entry
+                        .as_ref()
+                        .map_or(0.0, |e| windowed_count_f64(e, key.window, now_ns)),
+                    AggKind::Velocity => {
+                        let dur = key.window.duration_secs_f64();
+                        if dur.is_infinite() {
+                            0.0
+                        } else {
+                            entry
+                                .as_ref()
+                                .map_or(0.0, |e| windowed_count_f64(e, key.window, now_ns))
+                                / dur
+                        }
+                    }
+                    AggKind::Decay => lambda0.map_or(0.0, |lambda| {
+                        entry
+                            .as_ref()
+                            .map_or(0.0, |e| e.hot.current_score(0, now_ns, lambda))
+                    }),
+                };
+                values.push((*key, value));
+            }
+        }
+        SignalValues { values }
+    }
+}
+
+/// Read a warm windowed count as `f64` (mirrors `read_windowed_count_at`'s
+/// `as f64` cast). Rotates expired buckets at `now_ns` exactly as the direct
+/// read does, so a Pass-2 fallback read of the same `(window, now_ns)` is
+/// identical.
+#[allow(clippy::cast_precision_loss)]
+fn windowed_count_f64(
+    entry: &crate::signals::EntitySignalEntry,
+    window: Window,
+    now_ns: u64,
+) -> f64 {
+    entry.warm.windowed_count(window, now_ns) as f64
+}
+
+/// Pass-1 results for one candidate: the planned `(type, agg, window)` values.
+/// Looked up by Pass-2 reads; a miss means a direct ledger read.
+pub struct SignalValues {
+    values: SmallVec<[(ReadKey, f64); 16]>,
+}
+
+impl SignalValues {
+    /// Look up a precomputed value. `window` is the post-degradation-substitution
+    /// window the caller is about to read (the plan applied the identical
+    /// substitution when it was built); `DecayScore` is window-canonicalized here
+    /// exactly as in the plan so a term's declared window never causes a miss.
+    /// Returns `None` (→ caller does a direct read) on a miss, including for the
+    /// non-collapsible `Ratio`/`RelativeVelocity` aggregations.
+    #[must_use]
+    pub fn get(&self, type_id: SignalTypeId, agg: &SignalAgg, window: Window) -> Option<f64> {
+        let agg = AggKind::from_agg(agg)?;
+        let want = ReadKey {
+            type_id,
+            agg,
+            window: if matches!(agg, AggKind::Decay) {
+                Window::AllTime
+            } else {
+                window
+            },
+        };
+        self.values
+            .iter()
+            .find(|(k, _)| *k == want)
+            .map(|(_, v)| *v)
+    }
+}

tidal/src/ranking/executor/tests.rs

@@ -1,12 +1,13 @@
 use super::*;
 use crate::{
+    load::DegradationLevel,
     ranking::{
         builtins::register_builtins,
-        profile::{Boost, Exclude, Gate, Penalty, ProfileDecay, SignalAgg, Sort},
+        profile::{Boost, Exclude, Gate, Penalty, ProfileDecay, RankingProfile, SignalAgg, Sort},
         registry::ProfileRegistry,
         // Shared fixtures (extracted to de-duplicate the per-module ledger/profile
         // builders across the five ranking test modules; DRY-S, M0-M10 review).
-        test_fixtures::{ledger_for, profile_with, seeded_ledger},
+        test_fixtures::{ledger_for, profile_with, profile_with_sort, seeded_ledger},
     },
     schema::EntityId,
     signals::SignalLedger,
@@ -989,3 +990,233 @@ fn shuffle_is_quality_weighted_and_seed_stable() {
 }
 
 mod sort_tests;
+
+// ── T2: signal-value pre-pass A/B equivalence ────────────────────────────────
+//
+// The pre-pass (`SignalReadPlan`/`SignalValues`) collapses redundant ledger gets
+// to one `entries.get()` per signal type per candidate. It must be a pure
+// optimization: scoring a profile with the pre-pass ON must produce a
+// byte-identical `ScoredCandidate` set to the direct per-term path (pre-pass
+// OFF). This module is the explicit oracle for that — the direct path is the
+// reference implementation, the pre-pass is the optimization, and every
+// (profile × degradation) pair below must match exactly.
+
+/// A ledger seeded so windowed counts, velocities and decay scores all differ
+/// across entities — including entities with no signals at all (the `None`-entry
+/// path) and signals read by several aggregations of the same type.
+fn ab_ledger() -> SignalLedger {
+    let ledger = ledger_for(&[
+        "view",
+        "like",
+        "share",
+        "dislike",
+        "completion",
+        "comment",
+        "follow",
+        "viewer_count",
+        "skip",
+        "block",
+    ]);
+    let base = AB_NOW_NS;
+    for i in 1..=12u64 {
+        // Recent events (inside the 1h / 24h velocity windows) plus older ones,
+        // with per-entity-varied weights so no two entities score alike.
+        let recent = Timestamp::from_nanos(base - i * 60_000_000_000); // i minutes ago
+        let older = Timestamp::from_nanos(base - i * 7 * 24 * 3_600_000_000_000); // i weeks ago
+        ledger
+            .record_signal("view", EntityId::new(i), (13 - i) as f64, recent)
+            .unwrap();
+        ledger
+            .record_signal("view", EntityId::new(i), 2.0, older)
+            .unwrap();
+        ledger
+            .record_signal("like", EntityId::new(i), (i % 4) as f64, recent)
+            .unwrap();
+        ledger
+            .record_signal("share", EntityId::new(i), (i % 3) as f64, recent)
+            .unwrap();
+        ledger
+            .record_signal("completion", EntityId::new(i), 1.0, recent)
+            .unwrap();
+        if i % 2 == 0 {
+            ledger
+                .record_signal("dislike", EntityId::new(i), 1.0, recent)
+                .unwrap();
+            ledger
+                .record_signal("skip", EntityId::new(i), (i % 5) as f64, recent)
+                .unwrap();
+        }
+        if i % 3 == 0 {
+            ledger
+                .record_signal("block", EntityId::new(i), 1.0, recent)
+                .unwrap();
+        }
+        ledger
+            .record_signal("comment", EntityId::new(i), (i % 2) as f64, recent)
+            .unwrap();
+        ledger
+            .record_signal("follow", EntityId::new(i), 1.0, older)
+            .unwrap();
+        ledger
+            .record_signal("viewer_count", EntityId::new(i), (i % 6) as f64, recent)
+            .unwrap();
+    }
+    ledger
+}
+
+const AB_NOW_NS: u64 = 1_708_000_000_000_000_000;
+
+/// Assert two scored sets are byte-identical: same order, ids, score bits,
+/// snapshot keys+value bits, creator, and format.
+fn assert_scored_identical(plan: &[ScoredCandidate], direct: &[ScoredCandidate], ctx: &str) {
+    assert_eq!(plan.len(), direct.len(), "{ctx}: result length differs");
+    for (a, b) in plan.iter().zip(direct.iter()) {
+        assert_eq!(a.entity_id, b.entity_id, "{ctx}: entity_id/order differs");
+        assert_eq!(
+            a.score.to_bits(),
+            b.score.to_bits(),
+            "{ctx}: score differs for {:?} ({} vs {})",
+            a.entity_id,
+            a.score,
+            b.score
+        );
+        assert_eq!(
+            a.signal_snapshot.len(),
+            b.signal_snapshot.len(),
+            "{ctx}: snapshot length differs for {:?}",
+            a.entity_id
+        );
+        for ((ka, va), (kb, vb)) in a.signal_snapshot.iter().zip(b.signal_snapshot.iter()) {
+            assert_eq!(ka.as_str(), kb.as_str(), "{ctx}: snapshot key differs");
+            assert_eq!(
+                va.to_bits(),
+                vb.to_bits(),
+                "{ctx}: snapshot value differs for key {}",
+                ka.as_str()
+            );
+        }
+        assert_eq!(a.creator_id, b.creator_id, "{ctx}: creator_id differs");
+        assert_eq!(a.format, b.format, "{ctx}: format differs");
+    }
+}
+
+/// Every ledger-reading `Sort` mode plus a redundancy-heavy profile, scored with
+/// the pre-pass ON vs OFF at both `Full` and `CoarseAggregates`, must match
+/// byte-for-byte. The redundancy profile reads `view` at five
+/// `(stage, agg, window)` sites that resolve to the same signal type — the exact
+/// case the one-get-per-type pre-pass collapses.
+#[test]
+#[allow(clippy::too_many_lines)]
+fn signal_plan_matches_per_term_path() {
+    let ledger = ab_ledger();
+    let now = Timestamp::from_nanos(AB_NOW_NS);
+    // Candidates include entities with no signals (100, 101) to cover the
+    // missing-entry default mapping.
+    let candidates: Vec<EntityId> = (1..=12).chain([100, 101]).map(EntityId::new).collect();
+
+    let mut profiles: Vec<RankingProfile> = vec![
+        profile_with_sort(Sort::Hot { gravity: 1.5 }),
+        profile_with_sort(Sort::Trending),
+        profile_with_sort(Sort::Controversial),
+        profile_with_sort(Sort::HiddenGems),
+        profile_with_sort(Sort::Shuffle),
+        profile_with_sort(Sort::TopWindow {
+            window: Window::TwentyFourHours,
+        }),
+        profile_with_sort(Sort::MostViewed {
+            window: Window::AllTime,
+        }),
+        profile_with_sort(Sort::MostLiked {
+            window: Window::OneHour,
+        }),
+        profile_with_sort(Sort::MostFollowed),
+        profile_with_sort(Sort::CreatorEngagementRate),
+        profile_with_sort(Sort::Rising),
+        profile_with_sort(Sort::MostCommented {
+            window: Window::TwentyFourHours,
+        }),
+        profile_with_sort(Sort::MostShared {
+            window: Window::AllTime,
+        }),
+        profile_with_sort(Sort::LiveViewerCount),
+        profile_with_sort(Sort::New), // no ledger reads — control
+    ];
+
+    // Redundancy-heavy profile: `view` read by the sort (Value), a gate (Value),
+    // a boost (Value), a boost (DecayScore), and the decay term (DecayScore).
+    profiles.push(profile_with("ab_rich", |p| {
+        p.sort = Some(Sort::Hot { gravity: 1.2 });
+        p.gates = vec![Gate {
+            signal: "view".into(),
+            agg: SignalAgg::Value,
+            window: Window::AllTime,
+            min_threshold: 0.0,
+        }];
+        p.excludes = vec![Exclude {
+            signal: "block".into(),
+            agg: SignalAgg::Value,
+            window: Window::AllTime,
+            above: 5.0,
+        }];
+        p.boosts = vec![
+            Boost {
+                signal: "view".into(),
+                agg: SignalAgg::DecayScore,
+                window: Window::AllTime,
+                weight: 1.0,
+            },
+            Boost {
+                signal: "view".into(),
+                agg: SignalAgg::Value,
+                window: Window::AllTime,
+                weight: 0.5,
+            },
+            Boost {
+                signal: "like".into(),
+                agg: SignalAgg::DecayScore,
+                window: Window::AllTime,
+                weight: 2.0,
+            },
+            Boost {
+                signal: "share".into(),
+                agg: SignalAgg::Velocity,
+                window: Window::TwentyFourHours,
+                weight: 1.5,
+            },
+            Boost {
+                signal: "nonexistent".into(),
+                agg: SignalAgg::Value,
+                window: Window::AllTime,
+                weight: 1.0,
+            },
+        ];
+        p.penalties = vec![Penalty {
+            signal: "skip".into(),
+            agg: SignalAgg::Value,
+            window: Window::AllTime,
+            weight: 1.0,
+        }];
+        p.decay = Some(ProfileDecay {
+            signal: "view".into(),
+            half_life_secs: 7 * 24 * 3600,
+            weight: 0.5,
+        });
+    }));
+
+    for degradation in [DegradationLevel::Full, DegradationLevel::CoarseAggregates] {
+        for profile in &profiles {
+            let with_plan = ProfileExecutor::new(&ledger)
+                .with_degradation_level(degradation)
+                .with_signal_plan(true)
+                .score(&candidates, profile, now)
+                .unwrap();
+            let direct = ProfileExecutor::new(&ledger)
+                .with_degradation_level(degradation)
+                .with_signal_plan(false)
+                .score(&candidates, profile, now)
+                .unwrap();
+            let ctx = format!("profile={} degradation={degradation:?}", profile.name);
+            assert_scored_identical(&with_plan, &direct, &ctx);
+        }
+    }
+}

tidal/src/replication/ship.rs

@@ -663,6 +663,14 @@ impl ShipQueue {
         peers
     }
 
+    /// The peer's circuit-breaker state for the self-heal gauge (m11p8): 0
+    /// closed, 1 open, 2 half-open. Delegates to the transport (read-only — does
+    /// not admit the breaker's half-open probe).
+    #[must_use]
+    pub fn peer_breaker_state(&self, peer: ShardId) -> u8 {
+        self.shared.transport.peer_breaker_state(peer)
+    }
+
     /// Add a peer to the roster at runtime (m11p5 §3.3 conf-change): construct
     /// its dispatch cell and spawn its windowed senders, inheriting the queue's
     /// CURRENT activation state. Idempotent (a re-add of an existing peer is a

tidal/src/replication/transport.rs

@@ -195,6 +195,14 @@ pub trait Transport: Send + Sync + 'static {
     /// default is a no-op: in-process transports ack synchronously.
     fn notify_applied(&self, _source_shard: ShardId, _applied: u64) {}
 
+    /// The circuit-breaker state for `peer`, encoded for the
+    /// `tidaldb_cluster_peer_breaker_state` gauge: 0 closed, 1 open, 2 half-open
+    /// (m11p8). Read-only — must never admit the breaker's half-open probe. The
+    /// default `0` (closed) suits in-process transports, which have no breaker.
+    fn peer_breaker_state(&self, _peer: ShardId) -> u8 {
+        0
+    }
+
     /// The shard identity of this transport endpoint.
     fn local_shard(&self) -> ShardId;
 }
@@ -237,6 +245,12 @@ impl Transport for std::sync::Arc<dyn Transport> {
         (**self).notify_applied(source_shard, applied);
     }
 
+    fn peer_breaker_state(&self, peer: ShardId) -> u8 {
+        // Forward explicitly: the trait default `0` would report every peer's
+        // breaker as closed for type-erased callers (the self-heal gauge path).
+        (**self).peer_breaker_state(peer)
+    }
+
     fn local_shard(&self) -> ShardId {
         (**self).local_shard()
     }

tidal/src/signals/ledger/core.rs

@@ -457,6 +457,46 @@ impl SignalLedger {
             .ok_or_else(|| TidalError::Schema(SchemaError::UnknownSignalType(name.to_owned())))
     }
 
+    /// Borrow the `(entity_id, type_id)` signal entry, if present, as a held
+    /// shard-read reference.
+    ///
+    /// This is the single `DashMap` get behind the ranking pre-pass
+    /// ([`crate::ranking::executor::SignalValues`]): the caller takes one ref per
+    /// distinct signal type, evaluates every aggregation that type needs against
+    /// the held entry (`hot.current_score` / `warm.windowed_count` are both
+    /// `&self` reads), then **drops the ref before getting the next type**.
+    ///
+    /// # Deadlock contract
+    ///
+    /// Only ONE `Ref` may be held at a time. Holding this ref while calling any
+    /// method that locks the same shard (another `get`, or a `record_signal`
+    /// `or_insert`) on the same thread can deadlock — `DashMap` shards are
+    /// `RwLock`s and a second lock acquisition on a shard this thread already
+    /// holds is not guaranteed to be re-entrant.
+    #[must_use]
+    pub(crate) fn entry_ref(
+        &self,
+        entity_id: EntityId,
+        type_id: SignalTypeId,
+    ) -> Option<dashmap::mapref::one::Ref<'_, (EntityId, SignalTypeId), EntitySignalEntry>> {
+        self.entries.get(&(entity_id, type_id))
+    }
+
+    /// The decay rate (`lambda`) for a signal type's primary decay slot (index
+    /// 0), or `None` if the type defines no decay rate.
+    ///
+    /// Mirrors the range-check in [`read_decay_score_at`](Self::read_decay_score_at):
+    /// a missing lambda means a `DecayScore` read yields `None` → `0.0`, never an
+    /// undecayed score. Exposed so the ranking pre-pass can evaluate `DecayScore`
+    /// against a held entry ref without re-resolving the lambda per read.
+    #[must_use]
+    pub(crate) fn decay_lambda(&self, type_id: SignalTypeId) -> Option<f64> {
+        self.signal_lambdas
+            .get(&type_id)
+            .and_then(|v| v.first())
+            .copied()
+    }
+
     /// Get the existing `(entity_id, type_id)` entry or create a zeroed one
     /// started at `ts_ns`.
     ///

tidal/src/testing/cluster.rs

@@ -674,29 +674,31 @@ impl SimulatedCluster {
         self.total_signals.load(Ordering::Relaxed)
     }
 
-    /// Number of WAL batches applied from the **initial** leader (`ShardId(0)`)
+    /// Number of WAL batches applied from the **current** leader on a specific
-    /// on a specific region's replication state.
+    /// region's replication state.
     ///
-    /// This is equivalent to the event count for all tests that do not involve
+    /// Each signal produces exactly one WAL batch, so for a region following the
-    /// leader promotion, since each signal produces exactly one WAL batch.
+    /// live leader this is its applied-event count.
     ///
-    /// # Limitation (post-promotion)
+    /// # Post-promotion correctness (m11p8-C)
     ///
-    /// The queried shard is hardcoded to `ShardId(0)` — the *initial* leader —
+    /// `applied_seqno` is keyed per source shard, and the leader ships under its
-    /// not the current one. `applied_seqno` is per source shard, so after a
+    /// own `ShardId(leader_region.0)`. Reading the applied frontier therefore
-    /// [`promote_leader`](Self::promote_leader) call the new leader ships under
+    /// keys on the **current** leader's shard, not a hardcoded `ShardId(0)`:
-    /// its own `ShardId`, and this method keeps returning only the count from the
+    /// after a [`promote_leader`](Self::promote_leader) the new leader ships under
-    /// old leader's stream — i.e. it silently undercounts. Callers in a promotion
+    /// a different `ShardId`, and a node's progress against that new stream is
-    /// scenario must instead read
+    /// what "applied" means post-promote. The previous hardcode to `ShardId(0)`
-    /// [`replication_state().applied_seqno(current_leader_shard)`] directly so the
+    /// (the initial leader) silently undercounted after any promotion — the
-    /// shard matches the live leader. Bounding the hardcode behind a doc note here
+    /// "lag accounting wrong after promote (ShardId(0)-keyed)" bug. For the leader
-    /// rather than reading the live leader shard keeps the existing no-promotion
+    /// region itself, the relay advances its own frontier under its shard as it
-    /// callers' counts stable.
+    /// writes, so the leader's row reads truthfully rather than 0. No-promotion
+    /// callers are unaffected: the initial leader is `ShardId(0)`.
     #[must_use]
     pub fn applied_count(&self, region: RegionId) -> u64 {
+        let leader_shard = ShardId(self.leader_region().0);
         self.nodes.get(&region).map_or(0, |n| {
             n.db.replication_state()
-                .applied_seqno(ShardId(0))
+                .applied_seqno(leader_shard)
                 .unwrap_or(0)
         })
     }

tidal/src/wal/compaction.rs

@@ -61,7 +61,10 @@ pub struct CompactionResult {
 /// if an error is encountered mid-way -- this is safe (see invariant above).
 pub fn compact_wal(wal_dir: &Path, checkpoint_seq: u64) -> Result<CompactionResult, WalError> {
     let segments = segment::list_segments(wal_dir)?;
-    compact_segments(wal_dir, &segments, checkpoint_seq)
+    // The offline close-path compaction does not archive (the live archival hook
+    // runs on the periodic online path; close is a clean shutdown, not a window
+    // where PITR continuity matters).
+    compact_segments(wal_dir, &segments, checkpoint_seq, None)
 }
 
 /// Online-safe compaction: identical to [`compact_wal`] except it NEVER deletes
@@ -92,7 +95,7 @@ pub fn compact_wal_online(
     wal_dir: &Path,
     checkpoint_seq: u64,
 ) -> Result<CompactionResult, WalError> {
-    compact_wal_online_pinned(wal_dir, checkpoint_seq, 0)
+    compact_wal_online_pinned(wal_dir, checkpoint_seq, 0, None)
 }
 
 /// Online-safe compaction with a **retention pin** (m11p5 §2.1).
@@ -133,6 +136,7 @@ pub fn compact_wal_online_pinned(
     wal_dir: &Path,
     checkpoint_seq: u64,
     pin: u64,
+    archive_dir: Option<&Path>,
 ) -> Result<CompactionResult, WalError> {
     let segments = segment::list_segments(wal_dir)?;
     // The live segment is the maximum-`first_seq` segment; never delete at or
@@ -163,7 +167,7 @@ pub fn compact_wal_online_pinned(
         floor = floor.min(pin_floor);
     }
 
-    compact_segments(wal_dir, &segments, floor)
+    compact_segments(wal_dir, &segments, floor, archive_dir)
 }
 
 /// Delete every listed segment whose `first_seq` is strictly less than `floor`,
@@ -177,6 +181,7 @@ fn compact_segments(
     wal_dir: &Path,
     segments: &[(u64, std::path::PathBuf)],
     floor: u64,
+    archive_dir: Option<&Path>,
 ) -> Result<CompactionResult, WalError> {
     let total_before = segments.len();
 
@@ -194,6 +199,22 @@ fn compact_segments(
             // single-owner invariant.
             let file_size = std::fs::metadata(seg_path).map(|m| m.len()).unwrap_or(0);
 
+            // m11p8 PITR: archive the segment BEFORE deleting it so the archive
+            // is a gap-free record of every sealed segment. If archival fails we
+            // do NOT delete — losing the segment from both the live WAL and the
+            // archive would punch a hole in the point-in-time recovery range. The
+            // segment stays live and the next compaction retries.
+            if let Some(archive) = archive_dir
+                && let Err(e) = archive_segment(archive, seg_path)
+            {
+                tracing::warn!(
+                    segment_first_seq = seg_first_seq,
+                    error = %e,
+                    "WAL segment archival failed; keeping segment live (PITR gap avoided)"
+                );
+                continue;
+            }
+
             std::fs::remove_file(seg_path)?;
             deleted += 1;
             bytes_reclaimed += file_size;
@@ -233,6 +254,38 @@ fn compact_segments(
     })
 }
 
+/// Copy a sealed WAL segment into `archive_dir` for point-in-time recovery
+/// (m11p8), durably and idempotently. The destination keeps the segment's
+/// filename (which encodes shard + `first_seq`), so the archive is a
+/// self-describing, ordered catalog. Copy goes through a `.tmp` + rename so a
+/// crash mid-copy never leaves a short file the catalog would treat as complete;
+/// a re-archival after a crash (destination already present at the same size) is
+/// a no-op. The temp file and the archive directory are fsynced so PITR never
+/// replays a torn archived segment.
+fn archive_segment(archive_dir: &Path, seg_path: &Path) -> Result<(), WalError> {
+    std::fs::create_dir_all(archive_dir)?;
+    let file_name = seg_path.file_name().ok_or_else(|| {
+        WalError::from(std::io::Error::new(
+            std::io::ErrorKind::InvalidInput,
+            "WAL segment path has no file name",
+        ))
+    })?;
+    let dest = archive_dir.join(file_name);
+    let src_len = std::fs::metadata(seg_path)?.len();
+    // Idempotent: a complete prior archive (same size) needs no rewrite.
+    if let Ok(meta) = std::fs::metadata(&dest)
+        && meta.len() == src_len
+    {
+        return Ok(());
+    }
+    let tmp = archive_dir.join(format!("{}.tmp", file_name.to_string_lossy()));
+    std::fs::copy(seg_path, &tmp)?;
+    std::fs::File::open(&tmp)?.sync_all()?;
+    std::fs::rename(&tmp, &dest)?;
+    crate::wal::sync_dir_durable(archive_dir)?;
+    Ok(())
+}
+
 #[cfg(test)]
 #[allow(clippy::unwrap_used)]
 mod tests {
@@ -252,6 +305,53 @@ mod tests {
         assert_eq!(result.segments_remaining, 0);
     }
 
+    #[test]
+    fn online_compaction_archives_before_deleting() {
+        // m11p8 PITR: a deleted segment must land in the archive first, so the
+        // archive is a gap-free record — no segment is ever lost from BOTH.
+        let dir = tempfile::tempdir().unwrap();
+        let archive = tempfile::tempdir().unwrap();
+        for &seq in &[1u64, 50, 100, 200] {
+            let _ = SegmentWriter::open(dir.path(), ShardId::SINGLE, seq, 1024).unwrap();
+        }
+        let before: Vec<u64> = list_segments(dir.path())
+            .unwrap()
+            .iter()
+            .map(|(s, _)| *s)
+            .collect();
+
+        let result = compact_wal_online_pinned(dir.path(), 150, 0, Some(archive.path())).unwrap();
+        assert!(result.segments_deleted >= 1, "expected some deletions");
+
+        let live: std::collections::HashSet<u64> = list_segments(dir.path())
+            .unwrap()
+            .iter()
+            .map(|(s, _)| *s)
+            .collect();
+        let archived: std::collections::HashSet<u64> = list_segments(archive.path())
+            .unwrap()
+            .iter()
+            .map(|(s, _)| *s)
+            .collect();
+
+        // Every original segment is either still live OR archived — never lost.
+        for s in &before {
+            assert!(
+                live.contains(s) || archived.contains(s),
+                "segment {s} was lost (neither live nor archived)"
+            );
+        }
+        // The segments below the floor (1, 50, 100) are deleted from live and
+        // present in the archive; the active segment (200) survives in place.
+        assert!(archived.contains(&1) && archived.contains(&50) && archived.contains(&100));
+        assert!(live.contains(&200) && !live.contains(&1));
+
+        // Idempotent: re-running with the same archive (already-archived dests at
+        // the same size) is a clean no-op, not an error.
+        let again = compact_wal_online_pinned(dir.path(), 150, 0, Some(archive.path())).unwrap();
+        assert_eq!(again.segments_deleted, 0, "nothing left below the floor");
+    }
+
     #[test]
     fn compact_deletes_old_segments() {
         let dir = tempfile::tempdir().unwrap();
@@ -442,7 +542,7 @@ mod tests {
         let dir = tempfile::tempdir().unwrap();
         three_sealed_plus_live(dir.path());
 
-        let result = compact_wal_online_pinned(dir.path(), 1_000, 150).unwrap();
+        let result = compact_wal_online_pinned(dir.path(), 1_000, 150, None).unwrap();
         assert_eq!(result.segments_deleted, 1, "only the pre-resume segment");
         assert_eq!(result.segments_remaining, 3);
 
@@ -471,7 +571,7 @@ mod tests {
         let dir = tempfile::tempdir().unwrap();
         three_sealed_plus_live(dir.path());
 
-        let result = compact_wal_online_pinned(dir.path(), 1_000, 199).unwrap();
+        let result = compact_wal_online_pinned(dir.path(), 1_000, 199, None).unwrap();
         // floor clamps to the first_seq of the segment containing pin+1=200,
         // which is the segment STARTING at 200 ([200,300)); the segment
         // [100,200) is fully below seq 200 and is reclaimed along with [1,100).
@@ -486,7 +586,7 @@ mod tests {
         // it by lowering the floor to 100 (the segment's own first_seq).
         let dir2 = tempfile::tempdir().unwrap();
         three_sealed_plus_live(dir2.path());
-        let result2 = compact_wal_online_pinned(dir2.path(), 1_000, 100).unwrap();
+        let result2 = compact_wal_online_pinned(dir2.path(), 1_000, 100, None).unwrap();
         assert_eq!(
             result2.segments_deleted, 1,
             "the straddled segment [100,200) must NOT be split/deleted"
@@ -506,7 +606,7 @@ mod tests {
         let dir = tempfile::tempdir().unwrap();
         three_sealed_plus_live(dir.path());
 
-        let pinned = compact_wal_online_pinned(dir.path(), 1_000, 0).unwrap();
+        let pinned = compact_wal_online_pinned(dir.path(), 1_000, 0, None).unwrap();
         assert_eq!(pinned.segments_deleted, 3, "all sealed segments below live");
         assert_eq!(pinned.segments_remaining, 1);
         assert_eq!(list_segments(dir.path()).unwrap()[0].0, 300);
@@ -531,7 +631,7 @@ mod tests {
         // unpinned results must be identical here.
         let dir = tempfile::tempdir().unwrap();
         three_sealed_plus_live(dir.path());
-        let pinned = compact_wal_online_pinned(dir.path(), 150, 250).unwrap();
+        let pinned = compact_wal_online_pinned(dir.path(), 150, 250, None).unwrap();
 
         let dir2 = tempfile::tempdir().unwrap();
         three_sealed_plus_live(dir2.path());

tidalctl/Cargo.toml

@@ -32,6 +32,10 @@ unwrap_used = "deny"
 tidaldb = { path = "../tidal" }
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
+# Backup/restore manifest integrity (m11p8) — the same hash the engine verifies
+# WAL segments and snapshot artifacts with, so a tidalctl-written manifest and an
+# engine-verified one agree.
+blake3 = "1"
 
 [dev-dependencies]
 tidaldb = { path = "../tidal", features = ["test-utils"] }

tidalctl/src/commands/backup.rs

@@ -0,0 +1,276 @@
+//! `tidalctl backup` / `tidalctl restore` — offline data-dir backup and restore
+//! with a BLAKE3 integrity manifest (m11p8).
+//!
+//! These operate on a data dir at rest (a drained/stopped node, or a filesystem
+//! copy), so the snapshot is trivially consistent: nothing is writing. `backup`
+//! copies the data dir to a destination and writes a [`BACKUP_MANIFEST`] (BLAKE3
+//! per file + the recovered WAL checkpoint cursor); `restore` verifies every
+//! file's hash against the manifest before placing it into a FRESH target dir.
+//!
+//! Coordinated cluster backup (runbook): back up one committed replica per shard
+//! group — under `ack=quorum` any committed replica's data dir holds the
+//! quorum-durable log, so it is a cluster-consistent snapshot at its recorded
+//! `checkpoint_seq`. The per-shard manifests + the WAL archive (the engine's
+//! `wal.archive_dir`) together give point-in-time recovery. Restore re-seeds each
+//! group's leader from its backup; followers catch up via the live stream.
+
+use std::{
+    path::{Path, PathBuf},
+    time::{SystemTime, UNIX_EPOCH},
+};
+
+use serde::{Deserialize, Serialize};
+
+use crate::{CliError, wal_state};
+
+/// Manifest filename written at the root of every backup.
+const BACKUP_MANIFEST: &str = "BACKUP_MANIFEST.json";
+
+/// The lock file is process-ownership state, never part of a backup (restoring
+/// a stale lock would falsely claim the target dir is owned).
+const LOCK_FILE: &str = "tidaldb.lock";
+
+/// One file's integrity record within a [`Manifest`].
+#[derive(Debug, Serialize, Deserialize)]
+struct FileEntry {
+    /// Path relative to the data-dir root (forward-slash separated).
+    path: String,
+    size: u64,
+    /// Lowercase-hex BLAKE3 of the file's bytes.
+    blake3: String,
+}
+
+/// The backup manifest, written at the backup root and verified on restore.
+#[derive(Debug, Serialize, Deserialize)]
+struct Manifest {
+    /// Format version (bump on an incompatible manifest change).
+    manifest_version: u32,
+    /// Unix-epoch seconds the backup was taken (operator audit trail).
+    created_unix_secs: u64,
+    /// The WAL checkpoint sequence recovered from the source — the cluster
+    /// cursor this backup is consistent to. An operator assembling a multi-shard
+    /// cluster backup records one manifest per shard group; the set of
+    /// `checkpoint_seq` values is the cluster-consistent restore point.
+    checkpoint_seq: u64,
+    file_count: usize,
+    total_bytes: u64,
+    files: Vec<FileEntry>,
+}
+
+const MANIFEST_VERSION: u32 = 1;
+
+/// `tidalctl backup --path <data-dir> --out <dest>`: copy the data dir to `dest`
+/// and write a BLAKE3 manifest. Refuses to overwrite a non-empty destination so a
+/// backup never clobbers an existing one.
+pub(crate) fn run_backup(src: &Path, out: &Path, pretty: bool) -> Result<(String, i32), CliError> {
+    if !src.is_dir() {
+        return Err(CliError::new(format!(
+            "source data dir does not exist: {}",
+            src.display()
+        )));
+    }
+    // Refuse to write into a non-empty destination (don't merge into / clobber an
+    // existing backup or an unrelated directory).
+    if out.exists()
+        && std::fs::read_dir(out)
+            .map_err(|e| CliError::new(format!("read dest {}: {e}", out.display())))?
+            .next()
+            .is_some()
+    {
+        return Err(CliError::new(format!(
+            "destination {} is not empty; choose a fresh directory",
+            out.display()
+        )));
+    }
+    std::fs::create_dir_all(out)
+        .map_err(|e| CliError::new(format!("create dest {}: {e}", out.display())))?;
+
+    // The cluster cursor this backup is consistent to (recovered offline).
+    let checkpoint_seq = wal_state::gather_wal_state(&src.join("wal"))
+        .map(|s| s.checkpoint_seq)
+        .unwrap_or(0);
+
+    let mut rel_files = Vec::new();
+    collect_files(src, PathBuf::new(), &mut rel_files)
+        .map_err(|e| CliError::new(format!("walk source: {e}")))?;
+
+    let mut files = Vec::with_capacity(rel_files.len());
+    let mut total_bytes = 0u64;
+    for rel in &rel_files {
+        let abs = src.join(rel);
+        let bytes = std::fs::read(&abs)
+            .map_err(|e| CliError::new(format!("read {}: {e}", abs.display())))?;
+        let hash = blake3::hash(&bytes).to_hex().to_string();
+        let dest = out.join(rel);
+        if let Some(parent) = dest.parent() {
+            std::fs::create_dir_all(parent)
+                .map_err(|e| CliError::new(format!("mkdir {}: {e}", parent.display())))?;
+        }
+        std::fs::write(&dest, &bytes)
+            .map_err(|e| CliError::new(format!("write {}: {e}", dest.display())))?;
+        total_bytes += bytes.len() as u64;
+        files.push(FileEntry {
+            path: rel_to_slash(rel),
+            size: bytes.len() as u64,
+            blake3: hash,
+        });
+    }
+
+    let manifest = Manifest {
+        manifest_version: MANIFEST_VERSION,
+        created_unix_secs: SystemTime::now()
+            .duration_since(UNIX_EPOCH)
+            .map(|d| d.as_secs())
+            .unwrap_or(0),
+        checkpoint_seq,
+        file_count: files.len(),
+        total_bytes,
+        files,
+    };
+    let manifest_json = serialize(&manifest, pretty)?;
+    std::fs::write(out.join(BACKUP_MANIFEST), &manifest_json)
+        .map_err(|e| CliError::new(format!("write manifest: {e}")))?;
+
+    let summary = serde_json::json!({
+        "backed_up": src.display().to_string(),
+        "destination": out.display().to_string(),
+        "checkpoint_seq": manifest.checkpoint_seq,
+        "file_count": manifest.file_count,
+        "total_bytes": manifest.total_bytes,
+    });
+    Ok((render(&summary, pretty)?, 0))
+}
+
+/// `tidalctl restore --from <backup> --path <target>`: verify the backup's BLAKE3
+/// manifest, then copy every file into `target`. Refuses a non-empty target so a
+/// restore never overwrites a live data dir (the destructive-op guard).
+pub(crate) fn run_restore(
+    target: &Path,
+    from: &Path,
+    pretty: bool,
+) -> Result<(String, i32), CliError> {
+    let manifest_path = from.join(BACKUP_MANIFEST);
+    let manifest_bytes = std::fs::read(&manifest_path).map_err(|e| {
+        CliError::new(format!(
+            "read manifest {}: {e} (is --from a tidalctl backup?)",
+            manifest_path.display()
+        ))
+    })?;
+    let manifest: Manifest = serde_json::from_slice(&manifest_bytes)
+        .map_err(|e| CliError::new(format!("parse manifest: {e}")))?;
+    if manifest.manifest_version != MANIFEST_VERSION {
+        return Err(CliError::new(format!(
+            "unsupported backup manifest version {} (this tidalctl writes/reads v{MANIFEST_VERSION})",
+            manifest.manifest_version
+        )));
+    }
+
+    // Destructive-op guard: never restore over a non-empty target (it could be a
+    // live data dir). The operator restores into a fresh dir, then points the node at it.
+    if target.exists()
+        && std::fs::read_dir(target)
+            .map_err(|e| CliError::new(format!("read target {}: {e}", target.display())))?
+            .next()
+            .is_some()
+    {
+        return Err(CliError::new(format!(
+            "target {} is not empty; restore into a fresh directory (refusing to overwrite)",
+            target.display()
+        )));
+    }
+
+    // Phase 1: verify EVERY file's hash against the manifest BEFORE writing
+    // anything, so a corrupt backup fails the restore whole rather than leaving a
+    // half-written target.
+    for entry in &manifest.files {
+        let src = from.join(slash_to_rel(&entry.path));
+        let bytes = std::fs::read(&src)
+            .map_err(|e| CliError::new(format!("read backup file {}: {e}", src.display())))?;
+        let hash = blake3::hash(&bytes).to_hex().to_string();
+        if hash != entry.blake3 {
+            return Err(CliError::new(format!(
+                "backup integrity check FAILED for {}: manifest {} != actual {}",
+                entry.path, entry.blake3, hash
+            )));
+        }
+    }
+
+    // Phase 2: place the verified files into the target.
+    std::fs::create_dir_all(target)
+        .map_err(|e| CliError::new(format!("create target {}: {e}", target.display())))?;
+    let mut restored = 0usize;
+    for entry in &manifest.files {
+        let src = from.join(slash_to_rel(&entry.path));
+        let dest = target.join(slash_to_rel(&entry.path));
+        if let Some(parent) = dest.parent() {
+            std::fs::create_dir_all(parent)
+                .map_err(|e| CliError::new(format!("mkdir {}: {e}", parent.display())))?;
+        }
+        std::fs::copy(&src, &dest)
+            .map_err(|e| CliError::new(format!("copy {}: {e}", dest.display())))?;
+        restored += 1;
+    }
+
+    let summary = serde_json::json!({
+        "restored": target.display().to_string(),
+        "from": from.display().to_string(),
+        "checkpoint_seq": manifest.checkpoint_seq,
+        "files_verified_and_restored": restored,
+        "note": "point a stopped node at this dir; under ack=quorum followers catch up via the live stream",
+    });
+    Ok((render(&summary, pretty)?, 0))
+}
+
+/// Recursively collect file paths (relative to `root`), skipping the lock file
+/// and any previously-written backup manifest. Directories are recursed; only
+/// regular files are recorded.
+fn collect_files(root: &Path, rel: PathBuf, out: &mut Vec<PathBuf>) -> std::io::Result<()> {
+    let dir = root.join(&rel);
+    for entry in std::fs::read_dir(&dir)? {
+        let entry = entry?;
+        let name = entry.file_name();
+        let child_rel = rel.join(&name);
+        let file_type = entry.file_type()?;
+        if file_type.is_dir() {
+            collect_files(root, child_rel, out)?;
+        } else if file_type.is_file() {
+            // Skip process-ownership + a stale manifest from a prior backup-in-place.
+            if name == LOCK_FILE || name == BACKUP_MANIFEST {
+                continue;
+            }
+            out.push(child_rel);
+        }
+    }
+    Ok(())
+}
+
+/// Render a relative path with forward slashes for a portable manifest.
+fn rel_to_slash(rel: &Path) -> String {
+    rel.components()
+        .map(|c| c.as_os_str().to_string_lossy().into_owned())
+        .collect::<Vec<_>>()
+        .join("/")
+}
+
+/// Inverse of [`rel_to_slash`]: a manifest path → a platform `PathBuf`.
+fn slash_to_rel(path: &str) -> PathBuf {
+    path.split('/').collect()
+}
+
+fn serialize(manifest: &Manifest, pretty: bool) -> Result<String, CliError> {
+    if pretty {
+        serde_json::to_string_pretty(manifest)
+    } else {
+        serde_json::to_string(manifest)
+    }
+    .map_err(|e| CliError::new(format!("serialize manifest: {e}")))
+}
+
+fn render(value: &serde_json::Value, pretty: bool) -> Result<String, CliError> {
+    if pretty {
+        serde_json::to_string_pretty(value)
+    } else {
+        serde_json::to_string(value)
+    }
+    .map_err(|e| CliError::new(format!("serialize summary: {e}")))
+}

tidalctl/src/commands/mod.rs

@@ -1,10 +1,11 @@
-//! The five `tidalctl` subcommands, one module each.
+//! The `tidalctl` subcommands, one module each.
 //!
 //! Each module exposes a single `run(...)` entry point returning
 //! `(rendered_output, exit_code)`; `main` dispatches to them and prints the
 //! output. The exit-code contract (0 = ok/empty, 1 = usage/internal, 2 =
 //! degraded/unreadable) is documented in the crate-root `//!` header.
 
+pub(crate) mod backup;
 pub(crate) mod diagnostics;
 pub(crate) mod paths;
 pub(crate) mod recover;

tidalctl/src/main.rs

@@ -73,6 +73,10 @@ struct CliArgs {
     path: PathBuf,
     pretty: bool,
     verify_only: bool,
+    /// Backup destination (`backup --out <dir>`).
+    out: Option<PathBuf>,
+    /// Restore source (`restore --from <backup-dir>`).
+    from: Option<PathBuf>,
 }
 
 enum Command {
@@ -81,6 +85,8 @@ enum Command {
     Recover,
     Diagnostics,
     ScopeStats,
+    Backup,
+    Restore,
 }
 
 /// A user-facing CLI failure, rendered as an `{"error": ...}` JSON envelope on
@@ -123,6 +129,8 @@ fn parse_args(args: &[String]) -> Result<CliArgs, CliError> {
         "recover" => Command::Recover,
         "diagnostics" => Command::Diagnostics,
         "scope-stats" => Command::ScopeStats,
+        "backup" => Command::Backup,
+        "restore" => Command::Restore,
         "--help" | "-h" | "help" => return Err(CliError::new(usage())),
         other => {
             return Err(CliError::new(format!(
@@ -133,6 +141,8 @@ fn parse_args(args: &[String]) -> Result<CliArgs, CliError> {
     };
 
     let mut path: Option<PathBuf> = None;
+    let mut out: Option<PathBuf> = None;
+    let mut from: Option<PathBuf> = None;
     let mut pretty = false;
     let mut verify_only = false;
     let mut i = 2;
@@ -146,6 +156,20 @@ fn parse_args(args: &[String]) -> Result<CliArgs, CliError> {
                 }
                 path = Some(PathBuf::from(&args[i]));
             }
+            "--out" => {
+                i += 1;
+                if i >= args.len() {
+                    return Err(CliError::new("--out requires a value"));
+                }
+                out = Some(PathBuf::from(&args[i]));
+            }
+            "--from" => {
+                i += 1;
+                if i >= args.len() {
+                    return Err(CliError::new("--from requires a value"));
+                }
+                from = Some(PathBuf::from(&args[i]));
+            }
             "--pretty" => {
                 pretty = true;
             }
@@ -166,17 +190,24 @@ fn parse_args(args: &[String]) -> Result<CliArgs, CliError> {
         path,
         pretty,
         verify_only,
+        out,
+        from,
     })
 }
 
 fn usage() -> String {
-    "Usage: tidalctl <command> --path <dir> [--pretty]\n\n\
+    "Usage: tidalctl <command> --path <dir> [--out <dir>] [--from <dir>] [--pretty]\n\n\
      Commands:\n  \
        status       Report WAL state, checkpoint, and directory layout\n  \
        paths        Report resolved directory paths and existence\n  \
        recover      Diagnose WAL state for crash recovery (--verify-only)\n  \
        diagnostics  Print health summary (human-readable or JSON)\n  \
-       scope-stats  Tally WAL signal events by governance scope (M9)\n\n\
+       scope-stats  Tally WAL signal events by governance scope (M9)\n  \
+       backup       Copy a data dir to --out with a BLAKE3 manifest (m11p8)\n  \
+       restore      Verify a backup (--from) and restore it into --path (m11p8)\n\n\
+     Backup/restore operate on a data dir AT REST (a stopped/drained node):\n  \
+       tidalctl backup  --path /data/node --out /backups/node-A\n  \
+       tidalctl restore --from /backups/node-A --path /data/node-new\n\n\
      Exit codes: 0 = ok/empty, 1 = usage/internal error, 2 = degraded/unreadable\n  \
        (WAL, checkpoint, or a derived index exists but could not be read)."
         .to_string()
@@ -195,5 +226,19 @@ fn run(args: &[String]) -> Result<(String, i32), CliError> {
         Command::Recover => commands::recover::run(&cli.path, cli.pretty, cli.verify_only),
         Command::Diagnostics => commands::diagnostics::run(&cli.path, cli.pretty),
         Command::ScopeStats => commands::scope_stats::run(&cli.path, cli.pretty),
+        Command::Backup => {
+            let out = cli
+                .out
+                .as_ref()
+                .ok_or_else(|| CliError::new("backup requires --out <dest-dir>"))?;
+            commands::backup::run_backup(&cli.path, out, cli.pretty)
+        }
+        Command::Restore => {
+            let from = cli
+                .from
+                .as_ref()
+                .ok_or_else(|| CliError::new("restore requires --from <backup-dir>"))?;
+            commands::backup::run_restore(&cli.path, from, cli.pretty)
+        }
     }
 }

tidalctl/tests/cli.rs

@@ -1206,3 +1206,112 @@ fn scope_stats_clean_wal_reports_complete() {
         "clean WAL has no inconsistencies: {stdout}"
     );
 }
+
+// ── m11p8 backup / restore ────────────────────────────────────────────────────
+
+/// A real round-trip: back up a data dir at rest, then restore it into a fresh
+/// dir. The manifest carries the recovered checkpoint cursor, the restore
+/// verifies every file's BLAKE3, and the restored WAL segments match the source.
+#[test]
+fn backup_then_restore_roundtrips() {
+    let home = home_with_wal_data();
+    let scratch = TempTidalHome::new().unwrap();
+    let backup_dir = scratch.path().join("backup");
+    let restore_dir = scratch.path().join("restored");
+
+    // Back up.
+    let out = tidalctl_bin()
+        .args(["backup", "--path"])
+        .arg(home.path())
+        .args(["--out"])
+        .arg(&backup_dir)
+        .output()
+        .unwrap();
+    assert!(out.status.success(), "backup failed: {out:?}");
+    let stdout = String::from_utf8_lossy(&out.stdout);
+    let json: serde_json::Value = serde_json::from_str(&stdout).unwrap();
+    assert_eq!(
+        json["checkpoint_seq"], 3,
+        "manifest records the cursor: {stdout}"
+    );
+    assert!(
+        json["file_count"].as_u64().unwrap() >= 1,
+        "backed up some files: {stdout}"
+    );
+    assert!(
+        backup_dir.join("BACKUP_MANIFEST.json").exists(),
+        "manifest written"
+    );
+
+    // Restore into a fresh dir.
+    let out = tidalctl_bin()
+        .args(["restore", "--from"])
+        .arg(&backup_dir)
+        .args(["--path"])
+        .arg(&restore_dir)
+        .output()
+        .unwrap();
+    assert!(out.status.success(), "restore failed: {out:?}");
+
+    // The restored WAL segments byte-match the source (gap-free recovery).
+    let src_segs = std::fs::read_dir(home.path().join("wal"))
+        .unwrap()
+        .filter_map(Result::ok)
+        .filter(|e| e.path().extension().is_some_and(|x| x == "seg"))
+        .count();
+    let restored_segs = std::fs::read_dir(restore_dir.join("wal"))
+        .unwrap()
+        .filter_map(Result::ok)
+        .filter(|e| e.path().extension().is_some_and(|x| x == "seg"))
+        .count();
+    assert_eq!(
+        src_segs, restored_segs,
+        "restored WAL has the same segment count as the source"
+    );
+    assert!(src_segs >= 1, "source had WAL segments to restore");
+}
+
+/// Restore must REFUSE a backup whose bytes were tampered with after the
+/// manifest was written (the BLAKE3 integrity guard).
+#[test]
+fn restore_rejects_corrupted_backup() {
+    let home = home_with_wal_data();
+    let scratch = TempTidalHome::new().unwrap();
+    let backup_dir = scratch.path().join("backup");
+    let restore_dir = scratch.path().join("restored");
+
+    let out = tidalctl_bin()
+        .args(["backup", "--path"])
+        .arg(home.path())
+        .args(["--out"])
+        .arg(&backup_dir)
+        .output()
+        .unwrap();
+    assert!(out.status.success(), "backup failed: {out:?}");
+
+    // Corrupt one archived WAL segment so its bytes no longer match the manifest.
+    let seg = std::fs::read_dir(backup_dir.join("wal"))
+        .unwrap()
+        .filter_map(Result::ok)
+        .map(|e| e.path())
+        .find(|p| p.extension().is_some_and(|x| x == "seg"))
+        .expect("a segment to corrupt");
+    std::fs::write(&seg, b"corrupted-not-the-original-bytes").unwrap();
+
+    let out = tidalctl_bin()
+        .args(["restore", "--from"])
+        .arg(&backup_dir)
+        .args(["--path"])
+        .arg(&restore_dir)
+        .output()
+        .unwrap();
+    assert!(
+        !out.status.success(),
+        "restore must reject a corrupted backup"
+    );
+    let stderr = String::from_utf8_lossy(&out.stderr);
+    assert!(
+        stderr.contains("integrity check FAILED"),
+        "error must name the integrity failure: {stderr}"
+    );
+}