docs(deploy): degraded-apply ack amendment (#601)

Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe
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Joseph Doherty
2026-10-08 17:35:55 -04:00
parent f066fb9c80
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@@ -175,6 +175,8 @@ The checked-in `appsettings*.json` files are deliberately thin: they carry only
**`Grpc` mode: central dials each node, a node posts its ack to central.** `CentralCommunicationActor` fans one `NodeCommandService.Execute` call per node — the target set is every enabled, non-maintenance `ClusterNode` row that carries a `GrpcPort` (dialled at `Host`+`GrpcPort`), rebuilt every `ContactRefreshSeconds`. There is no receptionist and no single fleet-wide (or per-cluster) client object: it is a plain per-node dial. A node posts its `ApplyAck` with `GrpcApplyAckSender`, which walks `CentralGrpcEndpoints` in order and stops at the first success — an availability list, not a fan-out list, so central normally sees one ack per node per dispatch (the walk as a whole is at-least-once on a slow-then-retried endpoint; `ConfigPublishCoordinator.HandleAck` absorbs a duplicate idempotently). Both directions are **fire-and-forget, with no retry**: a failed dispatch is logged (naming the node and the gRPC status) and dropped in the dispatch second — the deploy path's 2-minute apply deadline and a node's boot-time replay (`DriverHostActor.Bootstrap()` re-applying an orphan `Applying` row) are the only recovery mechanisms, exactly as they were under `ClusterClient`.
The ack itself is sent only once the node's address-space apply outcome is known, and carries an additive `degraded` flag (`ApplyAckMessage` fields 6/7; trailing `ApplyAck.Degraded`/`DegradedReason` on DPS) — an old node's ack decodes clean, exactly as before. See [Redundancy.md § "What an `Applied` ack means"](Redundancy.md#what-an-applied-ack-means-the-degraded-apply-amendment-gitea-601) (Gitea #601).
| Key | Type | Default | Meaning |
|---|---|---|---|
| `GrpcPsk` | string? | `null` (unset) | Node-side only, required under `Grpc` on a driver-role node: this node's pre-shared key for its own `Cluster`, presented as the bearer on outbound acks and required on inbound `NodeCommandService` calls. Production form is `${secret:OT-MESH-PSK-<clusterId>}`; supply a literal only on a rig, via `MeshTransport__GrpcPsk` — never commit one. |