ClusterClient→gRPC migration Phase 4 (docs/plans/2026-07-22-clusterclient-to-grpc-plan.md).
Phases 2/3 proved both directions on gRPC; this removes the Akka transport underneath.
Deleted:
- AkkaCentralTransport, AkkaSiteTransport (+ their dedicated tests)
- ISiteClientFactory + DefaultSiteClientFactory; CentralCommunicationActor legacy
ctor + SelectTransport (Host now builds GrpcSiteTransport and injects it)
- ClusterClient creation + both ClusterClientReceptionist.RegisterService calls in
AkkaHostedService; the RegisterCentralClient message + receive block
- CommunicationOptions.CentralContactPoints; the CentralTransport/SiteTransport
coexistence flags; the CentralTransportMode/SiteTransportKind enums
gRPC is now the only site↔central transport (site→central CentralControlService via
GrpcCentralTransport; central→site SiteCommandService via GrpcSiteTransport), both
built unconditionally by the Host. NoOpCentralTransport is the fail-loud null-default
so TestKit command-dispatch suites still construct the site actor without a wired
transport; production always injects GrpcCentralTransport.
Config: CentralGrpcEndpoints is now unconditional — CommunicationOptionsValidator
rejects blank entries (role-agnostic), and StartupValidator requires a Site node to
list >=1 endpoint (fail-fast, mirrors GrpcPsk). Rig configs moved
CentralContactPoints -> CentralGrpcEndpoints (docker x6, docker-env2 x2, Host default,
deploy/wonder-app-vd03). Kept Akka.Cluster.Tools (ClusterSingleton still used).
Tests: build 0/0; Communication.Tests 640, Host.Tests 421 green. Removed the
ClusterClient.Send per-site-routing tests (covered by the transport suites), swapped
the ISiteClientFactory-based ctors to a substitute ISiteCommandTransport, converted
the audit-push integration relay to an in-process bridge transport.
Docs: Component-Communication/Host/StoreAndForward, components/Communication,
topology-guide, grpc_streams (SUPERSEDED note), the frame-size known-issue (retired
amendment), and CLAUDE.md transport decisions.
Not included: the dead IntegrationCallRequest path (#32) is a separate user-owned
behavioral decision — SiteEnvelope routing is transport-agnostic so it still compiles.
Normative first: Component-StoreAndForward.md:83 specified the whole chunked,
ack-confirmed SfBufferSnapshotChunk resync protocol, which Phase 2 deleted. It
is rewritten rather than removed — the failure modes it reasoned about still
exist, they are just bounded differently — and it now states the
duplicate-delivery bound explicitly: a message can be delivered twice only when
the OLD primary delivered it and the status change had not yet replicated when
the gate flipped. One flush interval plus the in-flight ack, and unlike the old
model it does NOT grow with backlog depth or with how long a node was absent.
The N1 directional-authority and N5 orphan-row hazards are recorded as
structurally gone, not merely unguarded.
Frame-size known-issue amended: its 2026-06-26 resolution replaced the
intra-site hop with notify-and-fetch; Phase 2 then deleted notify-and-fetch
itself, so the 128 KB Akka frame constraint no longer applies to that hop in
any form. Successor ceiling recorded (4 MB gRPC cap via MaxBatchSize, which
batches by ROW COUNT), including that the failure mode differs — an oversized
gRPC message is rejected, not silently dropped.
Deployment docs gain the two operational constraints that have no home in code:
a site pair must be stopped and started TOGETHER (the SfBufferSnapshot compat
handler that made a mixed-version pair converge went with the replicator, and a
mixed pair now diverges silently), and a node offline beyond TombstoneRetention
can resurrect deleted rows on rejoin.
Both CLAUDE.md files corrected — each still said Phase 2 was NOT started.
Definition of done closed: build 0 warnings, all 10 suites green (3509 tests,
0 failures, 0 skips). Two DoD items needed amending rather than ticking: the
stale-symbol grep still matches 4 lines, all deliberate comment prose recording
what was deleted (a literal zero would delete the explanations that stop the
old design coming back), and the live gate has 10 evidence items, not the 9 the
checklist claimed.
Deletes the phase2 resume-state scratch doc, which said to delete it on landing.
Claude-Session: https://claude.ai/code/session_01BL2Vu1ESDQ9SCN4gVKkdts
Add explicit dark text color (per-class color + base theme override) to
the store-and-forward mermaid diagram so node/edge labels read clearly
regardless of gitea's page theme.
Swap the store-and-forward Message Lifecycle PNG embed for an inline
mermaid block to verify whether gitea renders mermaid in markdown. If it
does, the standard flow/state/hierarchy diagrams can move to inline
mermaid (text-only, auto-layout) instead of draw.io source + PNG.
Replace ASCII-art diagrams across the README and docs/ with editable
.drawio sources plus exported PNGs, so the diagrams render clearly in
rendered markdown and can be maintained/regenerated instead of being
hand-edited as fragile text art. Non-diagram blocks (code, folder
trees, UI wireframes) were left as text.
The largest themed batch — small mechanical fixes across 11 modules.
API / message hygiene:
- Comm-020: SiteAddressCacheLoaded now carries IReadOnlyDictionary /
IReadOnlyList — Akka messages must be immutable.
- Commons-016: BundleSession.MaxUnlockAttempts named constant replaces
magic 3.
- Commons-018: IOperationTrackingStore + IPartitionMaintenance moved from
Interfaces/ root to Interfaces/Services/ (namespace preserved — 9
consumers exceeded the in-prompt move threshold).
- Commons-023: TrackingStatusSnapshot.SourceNode now consistent with the
trailing-optional-with-default pattern used elsewhere.
- SR-022: AuditingDbCommand.DbConnection.set no longer uses reflection —
exposes AuditingDbConnection.Inner via internal API surface.
Dead code / config cleanup:
- ClusterInfra-011: decorative SectionName constant deleted.
- ClusterInfra-014: dead AddClusterInfrastructureActors method + its
"throws-when-called" test deleted.
- Host-021: Microsoft Logging:LogLevel block deleted from appsettings.json
(dead under Serilog).
Fail-loud over fail-silent:
- DM-021: ResolveSiteIdentifierAsync throws on missing site (was silently
substituting a DB id).
- DM-022: dropped transient Pending write — record now lands directly in
InProgress (no UI flicker, one fewer DB write).
- Host-020: LoggerConfigurationFactory emits a Console.Error warning when
both Serilog:MinimumLevel and ScadaLink:Logging:MinimumLevel are set
(ScadaLink remains truth per Host-011).
- SnF-022: NotifyCachedCallObserverAsync logs Warning on unparseable
TrackedOperationId (was silently dropping).
- SnF-023: empty siteId default replaced with $unknown-site sentinel
+ constructor normalisation.
Correctness:
- SCA-001: SupervisorStrategy XML rewritten to match actual
DefaultDecider/Restart semantics (was claiming Resume).
- SCA-003: OnUpsertAsync now restamps IngestedAtUtc on every upsert.
- SR-021: HandleDeployArtifacts now dispatches an internal
ApplyArtifactDataConnectionsToDcl message after the SQLite write so
system-wide artifact-deploy data-connection changes go live
immediately (was requiring a site restart).
- SnF-020: RetryParkedMessageAsync captures the parked row BEFORE the
local write so a concurrent delete can't skip standby replication.
Sentinels / naming collisions:
- HM-021: CentralSiteId changed from "central" to "$central"
(uncollideable — leading $ is forbidden in real SiteIdentifiers).
Doc / surface cleanups:
- SEL-018: FailedWriteCount promoted to ISiteEventLogger; XML softened
to "Available for future Health Monitoring integration".
- SnF-019: VERIFY outcome — documented parking-after-DefaultMaxRetries
in Component-StoreAndForward.md + DefaultMaxRetries XML (uniform
cap; maxRetries:0 is the unbounded escape hatch).
- SnF-021: Component-StoreAndForward.md no longer claims the tracking
table lives in SnF — it's in SiteRuntime, the interface is in Commons.
- CLI-020: bundle export response parse guarded with try/catch on
JsonException / KeyNotFoundException / FormatException — emits a
clean INVALID_RESPONSE exit instead of a stack trace.
Config:
- ClusterInfra-013: intent comment added to "catastrophic config" test.
- Host-016: appsettings.Site.json second CentralContactPoints entry
removed (was pointing at the SITE's own port); doc-key explains how
to extend.
- Host-018: NodeName added to both shipped per-role configs (was
causing SourceNode to be null on audit rows).
UI:
- CentralUI-029: replaced JS.InvokeAsync<int>("eval", …) with an ES
module import (new wwwroot/js/browser-time.js).
- CentralUI-032: AuditResultsGrid gains a Previous button backed by a
cursor stack.
10+ new regression tests across the affected projects. Build clean;
all suites green. README regenerated: 6 open (was 33).
Session-to-date: 130 of 136 originally-open Theme findings closed.
Organize documentation by moving requirements (HighLevelReqs, Component-*,
lmxproxy_protocol) to docs/requirements/ and test infrastructure docs to
docs/test_infra/. Updates all cross-references in README, CLAUDE.md,
infra/README, component docs, and 23 plan files.
Joseph Doherty