# Arch-Review Remediation — Status & Handoff

**Snapshot:** 2026-07-08 · **Review baseline:** master `9cad9ed0` · this file is the single source of
truth for remediation progress. Update it as work lands.

## Branch topology (all LOCAL — nothing pushed, nothing on master)

| Branch | Head | Contains |
|---|---|---|
| `master` | `9cad9ed0` | untouched baseline |
| `docs/archreview-plans-and-drift-fixes` | `9fadead6` | the 7 domain plans + `00-INDEX.md` + this `STATUS.md` + the two CLAUDE.md doc-drift fixes. **(the plans live ONLY here)** |
| `fix/archreview-crit1-split-brain-resolver` | `a81dea10` | Critical 1 (03/S1) activation + guard test + Redundancy.md |
| `fix/archreview-crit2-vt-timeout` | `7fd44f0f` | Critical 2 (02/U2 + 02/U3) + tests |
| `fix/archreview-crit3-s7-reconnect` | `25c0c6f6` | Critical 3 (05/STAB-1) IS7Plc seam + lazy reconnect + unit guards + live bounce test |

**Decision (user):** one branch per Critical, each off `master`. The plans are only on the docs branch,
so from a critical branch read them via `git show docs/archreview-plans-and-drift-fixes:archreview/plans/0X-<name>.md`.

## Completed

| Item | Finding | Branch @ commit | Verification |
|---|---|---|---|
| **Critical 1 — split-brain resolver activated** | 03/S1 | `fix/archreview-crit1-split-brain-resolver` `a81dea10` | `BuildClusterOptions` sets `KeepOldestOption{DownIfAlone=true}`; 3 unit guards (Cluster.Tests 29/29); **e2e-verified** the resolved ActorSystem config carries `SplitBrainResolverProvider` + `stable-after=15s` survives the HOCON/Hosting merge (throwaway spike, removed). HOCON cross-ref comment + Redundancy.md corrected. |
| **Critical 2a — real VT script timeout** | 02/U2 | `fix/archreview-crit2-vt-timeout` `7fd44f0f` | Routes through `TimedScriptEvaluator`; infinite-loop test (bounded by WaitAsync) proves no hang. Host.Integration VT 18/18. |
| **Critical 2b — ALC-safe compile cache** | 02/U3 | same `7fd44f0f` | Swapped raw dict → `CompiledScriptCache`; new `IScriptCacheOwner` seam; apply-boundary clear in `VirtualTagHostActor`; wiring guard test. Runtime VT 12/12. |
| **Doc drift — KNOWN LIMITATION 2 stale** | 03/U1 = 06/U-1 | `docs/…` `9fadead6` (CLAUDE.md) | historized-ref feed IS wired; rewrote to "value-capture code-complete, live-verify pending". |
| **Doc drift — ScriptAnalysis policy** | theme #5 | same `9fadead6` (CLAUDE.md) | corrected `FleetAdmin` → `Administrator,Designer` roles. |
| **Critical 3 — S7 lazy reconnect** | 05/STAB-1 | `fix/archreview-crit3-s7-reconnect` `25c0c6f6` | New `IS7Plc`/`IS7PlcFactory` seam + `EnsureConnectedAsync` (dispose-dead-handle → reopen on next data call); connection-fatal faults (socket/`ErrorCode.ConnectionError`) mark the handle dead, data-address errors do NOT; probe loop routes through it as a backstop. 4 unit guards + full S7 suite 234/234; **LIVE-verified** against real python-snap7 — bounced the container (`docker restart`), driver observed the outage and resumed Good reads with no redeploy (`S7_1500ReconnectTests`, double-gated on sim + `S7_RECONNECT_BOUNCE_CMD`). Also closes the S7 TEST-1 gap. |

## Task list (TaskCreate IDs)

| # | Task | Status |
|---|---|---|
| 1 | Critical 1 — split-brain resolver | ✅ completed |
| 2 | Critical 2a — VT timeout | ✅ completed |
| 3 | Critical 2b — CompiledScriptCache | ✅ completed |
| 4 | Critical 3 — S7 reconnect (05/STAB-1) | ✅ completed |
| 5 | Critical 4 — TwinCAT ADS re-registration (05/STAB-2) | ⬜ pending |
| 6 | Guard — DeferredAddressSpaceSink reflection forwarding test (03/U2) | ⬜ pending — **must precede** 03/P1 surgical-adds + any new sink capability |
| 7 | Guard — wire OTOPCUA0001 analyzer + triage (07/C-1) | ⬜ pending — triage before Warning severity; C-1 triage → C-2 |
| 8 | Guard — CI to all unit suites + fail-on-skip (07/S-1,S-2, pair S-4) | ⬜ pending |
| 9 | Critical 1 follow-up — hard-kill failover integration test (03/S1) | ⬜ pending — the effort-M harness half; activation itself is done+verified |

## Suggested next (from 00-INDEX execution order)

1. **Critical 4 (05/STAB-2)** — TwinCAT ADS notification re-registration after reconnect. Store a
   replayable registration intent (symbol/type/bitIndex/interval/onChange) per subscribed tag and replay
   it on client swap; the fake `ITwinCATClientFactory`/`ITwinCATClient` already exist, so a
   `TwinCATReconnectReplayTests` can be deterministic. **No TwinCAT docker fixture exists** (13 integration
   tests need a real TC3 target), so unit-only — no live gate available like S7 had. New branch off master.
   *(Critical 3 (05/STAB-1) DONE — see Completed table, LIVE-verified against real snap7.)*
2. **Systemic guards** — task 7 (analyzer) then task 8 (CI); task 6 (forwarding test) before any P1/P2 work.
3. **Failure-visibility Highs** — 01/S-1 (AddressSpaceApplyOutcome failure field), 06/S-1 (Galaxy fail-closed),
   03/S4 (primary-gate default-deny).

## Key resume facts

- **Verification bar met so far:** each fix has a deterministic unit guard AND (for SBR) an end-to-end
  config-resolution check. Follow the same pattern — the review's whole thesis is "unit-green ≠ wired".
- **The forwarding-test guard (task 6) is load-bearing:** 03/P1 (surgical pure-adds) and 02/P-… batch-write
  each add new sink capability methods that ship inert unless forwarded through `DeferredAddressSpaceSink`
  (F10b/PR#423 precedent). Land task 6 first.
- **Nothing is pushed.** When the user asks to integrate: PR each `fix/archreview-crit*` branch; the docs
  branch can merge first (plans + doc fixes are low-risk).
- **Plans are on the docs branch only** — see topology note above for cross-branch reads.