ScadaBridge/docs/plans/2026-07-08-deferred-work-register.md

# Deferred-Work Register (established 2026-07-08, from architecture review 08)

Single tracked list of consciously-deferred work. Rules: every deferral gets a row
(rationale + revisit trigger); fix-now items reference the archreview plan that owns
them and are removed from this table when that plan's task lands.

## Fix-now (owned by archreview plans)

All 7 fix-now items landed via PLAN-04/05/06/07/08 (verified in review 08 round 2, 2026-07-12) — rows removed per the rule above; see the round-2 report §1 for the per-item evidence.

## Deferred (with rationale + revisit trigger)
| # | Item | Where noted | Rationale for deferral | Revisit trigger |
|---|------|-------------|------------------------|-----------------|
| 8 | Hash-chain tamper evidence (T1); CLI verify-chain is a no-op stub | audit-log roadmap :12 | v1.x by locked decision; append-only DB roles are the control | Compliance requirement for cryptographic tamper evidence |
| 9 | Parquet audit archival (T2); endpoint returns 501 | AuditEndpoints.cs:204 | v1.x; 501 + CLI messaging are honest | AuditLog partition volume nears retention ceiling |
| 11 | Central-persisted OPC UA cert-trust audit | m7 follow-ups | Broadcast-to-both-nodes covers HA | Governance/audit requirement for trust decisions |
| 17 | Unified notifications+site-calls outbox page | stillpending :118 | Explicit M9 decision to keep two pages | Operator confusion reports |
| 19 | Bundle signing / cluster-to-cluster pull / differential bundles | transport-design :402 | v1 manifest hash + AES-GCM held sufficient | Non-repudiation requirement across orgs |
| 23 | Live LDAP group-membership re-query for an active session | `docs/requirements/Component-Security.md` :61-69 (+ :78-79) | Blocked on an external package. The mid-session refresh re-maps the **stored** groups against the central DB with **no LDAP call**, so a directory group-membership change lands only at next login. A live re-query needs a passwordless service-account group-search method on the shared `ZB.MOM.WW.Auth.Ldap` library — an external NuGet `PackageReference` (`src/ZB.MOM.WW.ScadaBridge.Security/…csproj:23`) exposing only `AuthenticateAsync(username, password, ct)`. Central role-mapping/scope changes still apply within ~15 min (`RoleRefreshThresholdMinutes`). | `ZB.MOM.WW.Auth.Ldap` gains a standalone group-search API, or a requirement that a directory-side group revocation take effect mid-session rather than at next login |
| 24 | M8 large-bundle performance hardening | `docs/plans/2026-06-15-stillpending-completion-design.md:106` — "Small follow-ups logged (not blocking): … large-bundle/perf hardening" | Logged as a non-blocking follow-up when M8 shipped and never given an artifact: **no plan, no task entry, no perf/load test exists** (`tests/…Transport.Tests/Import/BundleImporterLoadTests.cs` is a `LoadAsync` unit suite despite the name). No measured problem; the only sizing controls in place are the 5-minute CLI transport timeout, `LineDiffer`'s `MaxInputLines`=4000 summary-only cap, and `MaxConcurrentImportSessions`=8. | First real bundle that times out, exhausts memory, or makes the import wizard's diff step unusable |
| 25 | ~~**Phase-8 WP-4 target-scale load test** (10 sites x 500 instances x 75 tags = 37,500 subscriptions/site, 375,000 total)~~ **RESOLVED 2026-08-15 — run, measured, evidenced.** The 107-byte stub is replaced by a real full-scale run: **10 x 500 x 75 = 375,000 live tag subscriptions**, 37,518 tag updates/s achieved against 37,500 nominal (100.0%), **45,021,375 updates offered** over a 20-minute steady-state window on an M4 Pro / 14-core / 48 GB host with the 8-node `docker/` rig still running. Headline numbers: tag update latency **P50 0.88 ms / P99 4.57 ms / max 37.41 ms** end-to-end (DCL boundary to stream subscriber, the emit instant carried verbatim through production code); **0 events dropped** at 100 live subscribers; health report collect+ingest **P99 0.31 ms** with 10/10 sites tracked; debug view snapshot under load **P99 2.19 ms, 0 timeouts**; 500 instances deployed to a site in **2.6 s**; CPU **2.9% of the box**; working-set slope **+8.83 MB/min**. **11 clean passes, 1 pass with a caveat (F1: 20 min with zero gen-2 collections cannot fully settle the leak question — the 1-hour run would), 0 failures.** Harness: `tests/ZB.MOM.WW.ScadaBridge.LoadHarness/` (standalone Exe — the `Category=Performance` trait enables a filter but does NOT exclude by default, so a 20-minute test could not live in `PerformanceTests`) plus a CI-scale smoke `[Fact]` (`PerformanceTests/TargetScale/TargetScaleHarnessSmokeTests.cs`). Real: per-site ActorSystem + LocalDb, the real DCL via the documented `DataConnectionFactory.RegisterAdapter` seam, real `InstanceActor`s, real `SiteStreamManager`, real `StreamRelayActor` + production-capacity bounded channel, real S&F, real health collector/aggregator; only the socket hops are stood in for. **Results: `docs/plans/2026-08-15-target-scale-load-test-results.md`; design + deviations + thresholds: `docs/plans/2026-08-15-target-scale-load-test-design.md`.** | as before | Closed. Residual scope: `[xc-3]` site-event-log retention volume, `[xc-4]` audit-vs-central degradation, `[xc-5]` large-template flattening and `[xc-8]` UI responsiveness are NOT covered by this harness (central-cluster/browser concerns) and remain open WP-4 scope — see results doc SS6. | Closed 2026-08-15. |
| 26 | Ipsen MES MoveIn tail: leak-test (`-LT`) receivers + routing, PLC-output-flag writes, `Z28062` BTDB data completeness | `docs/plans/2026-06-16-ipsen-mes-movein.md:409` ("Out of scope (future)"); design `2026-06-16-ipsen-mes-movein-design.md:58-60, :196-198` | Customer-site scope, not a platform gap. `-LT` routing needs an MES-receiver child + Galaxy reference that do not exist on the reactor template (any `-LT`/unknown suffix returns `WasSuccessful=false` with an "unsupported side/target" message by decision); `MoveInComplete`/`Successful`/`ErrorText` are **PLC-owned** by locked decision, so ScadaBridge deliberately does not write them; `Z28062` completeness is an operational data fix, not code. Note the separate alarm-status path already handles the suffix — `_LT` is stripped before side-scoping (`2026-06-30-mes-alarm-status-api.md:158`). | Ipsen creates the leak-test receiver + Galaxy reference, or asks ScadaBridge to own the PLC-output flags — otherwise a **candidate won't-do** (`[PERM]`) at the next Ipsen scope review |
| 27 | External-system per-system retry config (`MaxRetries`/`RetryDelay`) never reaches sites, and has no CLI/management surface | Found live 2026-08-01 (rig session, #11 gRPC live checks) | Two stacked gaps: (a) `ExternalSystemArtifact` (Commons) carries `TimeoutSeconds` but NOT `MaxRetries`/`RetryDelay`, and the site `external_systems` table has no such columns — so a centrally-configured retry policy is silently ignored on sites; every cached call buffers with the S&F default (`DefaultMaxRetries` 50 × `DefaultRetryInterval` 30s ≈ 25 min to park). (b) `Create/UpdateExternalSystemCommand` don't expose the fields either — the only way to set them today is a direct DB edit of `ExternalSystemDefinitions`. Transport bundles DO carry them (arch-review 05 "ES retry config"), which masks the gap in export/import round-trips. Fix is additive: extend the artifact + site schema + apply path, and add `--max-retries`/`--retry-delay` to the CLI. | First operator who tunes retry policy on an external system and expects site cached calls to honor it |
| 28 | Health-dashboard "Trigger failover" confirm dialog's confirm button is labeled **"Delete"** | Found live 2026-08-01 (rig session, #11 TriggerSiteFailover check) | The DialogService confirmation host's default destructive-action label leaks through — the dialog copy is correct but the red confirm button says "Delete" for a failover. One-line fix: pass an explicit confirm label ("Fail over") at the Health-dashboard call site (and audit other confirm-dialog call sites for the same default). | Next Central UI session |
| 29 | **1-hour sustained run to settle the memory-slope ambiguity (load-test finding F1)** | `docs/plans/2026-08-15-target-scale-load-test-results.md` F1 (Low) | The row-25 20-minute run PASSED the working-set threshold (+8.83 MB/min < 20) but recorded **zero gen-2 collections across 45M events**, so the +19.52 MB/min managed-heap drift on an uncompacted gen-2 is ambiguous — the heap demonstrably sawtooths, but 20 min cannot distinguish "gen-2 not yet collected" from a slow leak. Not a defect finding; an evidence gap. The harness exists (`tests/ZB.MOM.WW.ScadaBridge.LoadHarness/`) and the full 1-hour protocol is one documented command (results doc §7) — deferred only because the measured window was scaled for practicality. | Before production go-live at target scale, or first field report of unexplained site-node memory growth |
| 30 | **WP-4 residual scope: `[xc-3]` site-event-log retention volume, `[xc-4]` audit-load-vs-central degradation, `[xc-5]` large-template flattening time, `[xc-8]` UI responsiveness under load** | `docs/plans/2026-08-15-target-scale-load-test-results.md` §6 + row 25 closure note | The row-25 harness is a site-runtime rig; these four WP-4 sub-criteria are central-cluster/browser concerns it deliberately does not cover. Recorded so the row-25 closure never reads as "WP-4 fully done" — phase-8 WP-4 is closed for the site-runtime data path only. | Before declaring phase-8 WP-4 complete, or production go-live at target scale |
| 31 | **Unpaced-burst absorption is bounded by the shared publish stage, not per-subscriber buffers (load-test finding F3 caveat)** | `docs/plans/2026-08-15-target-scale-load-test-results.md` F3 | Measurement-backed design note, no defect: slow-subscriber isolation is structural and total (a stalled reader loses events only in its own bounded `DropOldest` channel; healthy subscribers delivered 100.00%), but the publish `Source.ActorRef` **upstream** of the `BroadcastHub` is shared, so an unpaced burst degrades every subscriber equally — that stage, not per-subscriber buffering, is the burst ceiling. | First field report of event loss on *healthy* subscribers during a burst, or any redesign of the site stream publish stage |
| 32 | **`QueueDepthGaugeTests` full-suite flake — shared static gauge (load-test finding F4)** | `tests/ZB.MOM.WW.ScadaBridge.StoreAndForward.Tests/QueueDepthGaugeTests.cs`; surfaced by the row-25 verification runs (`docs/plans/2026-08-15-target-scale-load-test-results.md` F4) | Pre-existing, test-only: fails when the full suite runs concurrently, passes in isolation — the gauge under test is process-global static state shared across test classes. Zero `src/` involvement; needs test isolation (per-test meter/collector instance), not a product fix. | Next test-infra session, or the first time it fails a CI/full-suite run that matters |

## Resolved (verified against the code 2026-07-10)
Rows removed from the Deferred table above once confirmed shipped. Kept here for traceability.

| # | Item | Resolution |
|---|------|-----------|
| 10 | Aggregated live alarm stream for Alarm Summary | Shipped 2026-07-10 (`docs/plans/2026-07-10-aggregated-live-alarm-stream-plan.md`): a **transient, in-memory** per-site central live alarm cache (`ISiteAlarmLiveCache`/`SiteAlarmLiveCacheService` + per-site `SiteAlarmAggregatorActor`) fed by a new site-wide, alarm-only `SubscribeSite` gRPC stream (`SiteStreamManager.SubscribeSiteAlarms`), seed-then-stream with dedup + NodeA↔NodeB re-seed + periodic reconcile. Alarm Summary is now live-cache-driven (`AlarmSummaryService.BuildFromLiveAlarms`) with the 15s poll retained as fallback + `NotReporting` authority. Honors the `[PERM]` no-central-store rule — nothing persisted (no EF table/migration). Options on `CommunicationOptions` (eagerly validated) + two `ScadaBridgeTelemetry` signals. |
| 7 | SecuredWrite audit rows leave SourceNode NULL | Resolved (PLAN-07): `ManagementActor.EmitSecuredWriteAuditAsync` routes through `ICentralAuditWriter`, which stamps `SourceNode` (`central-a`/`central-b`) from `INodeIdentityProvider`. |
| 12 (CLI/API) | Native-alarm-source-override CSV import | Shipped 2026-07-10: shared `CsvLineSplitter`, `NativeAlarmSourceOverrideCsvParser`, bulk all-or-nothing `SetInstanceNativeAlarmSourceOverridesCommand` + ManagementActor handler (Deployer-gated), CLI `instance native-alarm-source import --file`, parser/CLI/handler tests. **UI upload affordance shipped 2026-08-01** — second `InputFile` on the `InstanceConfigure` Native Alarm Source Overrides card reusing the shared parser, mirroring the attribute importer's UX and the server's all-or-nothing merge semantics (`InstanceConfigureNativeAlarmCsvImportTests`); row 12 removed from the Deferred table. |
| 13 | WaitForAttribute quality-gated ("Good"-only) mode | Already implemented (Commons `WaitForAttribute.RequireGoodQuality`, enforced in `InstanceActor`, threaded through `ScriptRuntimeContext`, tested in `InstanceActorWaitForAttributeTests`). Stale "planned enhancement" doc line corrected 2026-07-10. |
| 14 | WaitForAttribute in Test-Run sandbox | Shipped 2026-07-10 (full fidelity): sandbox `Attributes.WaitAsync`/`WaitForAsync` (value-equality) route to the bound instance via `ISandboxInstanceGateway.WaitForAttributeAsync` → the existing `CommunicationService.RouteToWaitForAttributeAsync` cross-site route. Additive `RouteToWaitForAttributeRequest.RequireGoodQuality` (honored by the site handler) makes quality-gated waits route too. **Predicate-form waits stay unsupported** (an in-process lambda can't be routed) and throw a labelled `ScriptSandboxException`. Tests: sandbox accessor routing (CentralUI), site-handler quality-flag threading (SiteRuntime). |
| 15 | BrowseNext final-page signal not surfaced | Already surfaced (M7 browse work): `RealOpcUaClient` sets `Truncated=false`/`ContinuationToken=null` on the last page; `BrowseNodeResult` carries both; `TreeRow.razor` renders "Load more" only when a continuation token remains — no wasted BrowseNext. |
| 16 | StubOpcUaClient throws on browse | Already resolved: `StubOpcUaClient` supports browse + address-space search, covered by `StubOpcUaClientBrowseTests`/`StubOpcUaClientSearchTests`. |
| 18 | Folder drag-drop | Closed — **permanently deferred (`[PERM]`)** by the M9 decision (`docs/plans/2026-06-15-stillpending-completion-design.md:122`): menu-based reorder (T23) shipped instead, and the folder-hierarchy design fixed the reorganization UX as "right-click context menus only (no drag-drop)" (`2026-05-11-templates-folder-hierarchy-design.md:27`). Row removed from the Deferred table 2026-08-01 — nothing left to revisit. |
| 20 | Deployment EXPIRED-row purge | Already resolved (PLAN-04): `PendingDeploymentPurgeActor` central singleton (spawned in `AkkaHostedService`) ticks `IDeploymentManagerRepository.PurgeExpiredPendingDeploymentsAsync` every `CommunicationOptions.PendingDeploymentPurgeInterval` (default 1h), options-validated, tested. |
| 21 | SiteAuditBacklogReporter threshold consolidation | Shipped 2026-07-10: `SqliteAuditWriterOptions.BacklogPollIntervalSeconds` (default 30) now drives the reporter's poll cadence; explicit ctor override still wins (tests), non-positive falls back to the 30 s default. Cadence tests added; stale "hard-code / follow-up" class-doc corrected. |
| 22 | KPI history hourly rollups | Shipped 2026-07-10 (`docs/plans/2026-07-10-kpi-history-hourly-rollups-plan.md`, T1–T8): new `KpiRollupHourly` table (migration `20260710153953`) folded by a third recorder tick (`kpi-rollup`, `RollupInterval` default 1h) over a re-folded `RollupLookbackHours` window via an idempotent, failover-self-healing upsert; per-metric gauge-vs-rate aggregation (`KpiMetricAggregationCatalog`); a one-shot backfill of the retention window on start; raw-vs-rollup query routing by `RollupThresholdHours` (default 168h); longer rollup retention (`RollupRetentionDays` default 365 ≥ `RetentionDays`, dual daily purge); and 30 d / 90 d trend windows added to the four surfaces. Options + validator, docs (`Component-KpiHistory.md`), and tests shipped. |

## New deferrals from review 08 (this plan)
| Item | Rationale | Revisit trigger |
|------|-----------|-----------------|
| Communication → HealthMonitoring layering (ICentralHealthAggregator consumed by CentralCommunicationActor.cs:351) | Moving the interface + SiteHealthState to Commons ripples across 5 projects for a cosmetic inversion | Next breaking change to ICentralHealthAggregator |
| docs/components reference docs for ScriptAnalysis, KpiHistory, DelmiaNotifier | Reference docs are substantial (StyleGuide-conformant); README claim scoped instead (PLAN-08 Task 10) | Next doc-writing session touching those components |
| Test-coverage backfill: SiteCallAudit.Tests (31 tests/1.6k LOC), DeploymentManager.Tests | No defect identified; coverage partly lives in ManagementService/Host/Integration suites | First regression escaping either component |
| ~~Failover-timing measurement (the "~25s total failover" envelope)~~ **RESOLVED 2026-08-01** — split out of the combined row and closed. `tests/ZB.MOM.WW.ScadaBridge.PerformanceTests/Failover/FailoverTimingTests.cs` is no longer a skipped placeholder: it runs as a live `[Fact]` (`Category=Performance`) on the real two-node in-process rig (`TwoNodeClusterFixture`, production `BuildHocon`) at production timings — 2s heartbeat / 10s failure-detection threshold / 15s stable-after — hard-killing the younger node and timing the survivor's member REMOVAL with singleton continuity asserted on the oldest. Delivered by **PLAN-R2-01 Task 4** (`archreview/plans/PLAN-R2-01-cluster-host-failover.md:226`). The oldest-crash direction is covered behaviorally by `SbrFailoverTests.AutoDown_HardCrashOfOldestNode_*` and by `docker/failover-drill.sh`. | The 2026-07-08 "PLAN-01 rig landing" trigger had fired unnoticed (NF2); PLAN-R2-01 T4 wired the placeholder to the fixture rig rather than recording a blocker. | Closed. |
| ~~Broader perf envelope — **S&F drain rate + per-subscriber stream backpressure**~~ **RESOLVED 2026-08-15 — absorbed into the row-25 target-scale run, exactly as this row's trigger anticipated.** Both halves measured at full scale. **(a) S&F drain:** 20,000 messages buffered concurrently from 25 origin instances at **15,368 msg/s**, draining at **3,533 msg/s** to depth 0. Reported as two numbers because the naive single number is misleading — a deferred backlog sits for one full `DefaultRetryInterval` (measured 28.9 s) before *anything* drains, since `EnqueueAsync(attemptImmediateDelivery: false)` stamps `LastAttemptAt` and the due-predicate then holds the row for one interval (correct by design; `Notify.Send`'s `deferToSweep: true` leaves it null and skips the wait). Filed as informational finding **F2**. **(b) Slow-subscriber backpressure:** with 5 subscribers on the SAME instance and one reader stalled at 50 ms/event, the four healthy subscribers delivered **100.00% with zero drops** while the stalled one lost 197,028 of 200,000 events **entirely within its own bounded channel**. Isolation is structural and total — `Buffer(DropHead)` never backpressures the `BroadcastHub`, `Sink.ForEach`'s `Tell` never blocks, and `StreamRelayActor.WriteToChannel`'s `TryWrite` on a `DropOldest` channel never blocks — so a slow WAN link degrades only its own feed, visibly (per-stream eviction counter + `RecordSiteStreamEventDropped`). Finding **F3**. Caveat also recorded: an *unpaced* burst costs every subscriber, because the publish `Source.ActorRef` upstream of the hub is shared — that shared stage, not per-subscriber buffering, bounds burst absorption. | Closed by the row-25 run; no defect found in either half. | Closed 2026-08-15 — `docs/plans/2026-08-15-target-scale-load-test-results.md`. |

## Deferred — operational risk (from the initiative tracker, folded in 2026-07-12)
Two live items previously tracked ONLY in `archreview/plans/00-MASTER-TRACKER.md`'s registry are folded in here (NF5) so this register is the single tracking place. The tracker's narrative subsections remain as the historical evidence.

| # | Item | Where noted | Rationale for deferral | Revisit trigger |
|---|------|-------------|------------------------|-----------------|
| SBR | ~~**SBR oldest-crash total-outage gap**~~ **RESOLVED 2026-07-21 (owner decision — availability over partition-safety).** All clusters switched from `keep-oldest` to the `auto-down` downing strategy (Akka `AutoDowning`, `auto-down-unreachable-after` = 15s): a hard crash of EITHER node — active/oldest included — now fails over to the survivor in ~25s with no operator action. Accepted trade: a real network partition produces dual-active until an operator restarts one side. Decision record + evidence (live keep-oldest `DownReachable … including myself` log, Akka.NET 1.5.62 `KeepOldest.OldestDecision` source, rejected alternatives incl. the static-quorum-1 `DownAll` trap): `docs/plans/2026-07-21-auto-down-availability-decision.md`. | `archreview/plans/00-MASTER-TRACKER.md:194` + auto-memory `sbr-keep-oldest-2node-active-crash-gap` (both now historical) | — | Closed. Residual: seed-node boot-alone constraint (unchanged, documented in `Component-ClusterInfrastructure.md`); dual-active recovery is operator-driven. |
| vd03 | **`deploy/wonder-app-vd03/` overlay edits unapplied** — `appsettings.Central.json` needs `AllowSingleNodeCluster: true` + phantom-seed removal + `NodeName: central-a`; `install.ps1` needs `sc.exe failure` recovery actions. The `deploy/wonder-app-vd03/` artifact directory is intentionally untracked (production config out of source control), so the repo cannot ship the fix. | `archreview/plans/00-MASTER-TRACKER.md:198` (PLAN-01 T16/T20/T23) | Needs on-host access; without `NodeName` that deployment's audit rows stamp NULL `SourceNode` — **partially mitigated once PLAN-R2-08 Task 7 lands: the host now FAILS AT BOOT with a key-naming error instead of silently NULLing, so applying the overlay becomes mandatory at the next upgrade.** Owner: whoever maintains the host (user). | Next wonder-app-vd03 deployment/upgrade — **the Task 7 validator makes this row unskippable then.** |