lmxopcua/archreview/plans/00-INDEX.md

Arch-Review Remediation Plans — Index

📊 Remediation status → STATUS.MD. Round 1 (2026-07-08 review at 9cad9ed0) is fully remediated and merged to master — all 4 Criticals + guards + follow-ups #9–#13. The 2026-07-12 re-review at f6eaa267 produced an updated 12-item action list (../00-OVERALL.md) — see Round 2 plans below.

Round 2 plans (2026-07-12, verified at f6eaa267)

One plan per action item in the updated 00-OVERALL.md prioritized list. Each verifies its findings against the tree, gives root cause → design (with alternatives) → file-level steps → tests → effort/risk, and ends with a bite-sized TDD task breakdown (classification / estimate / parallelizability) plus a co-located .tasks.json for resumable execution.

#	Plan	Findings	Tasks	Effort
1	R2-01 S7 fault-path hardening	05/STAB-14 (High regression), STAB-15, STAB-8 seam note	13	S-M (~2–3 h)
2	R2-02 ResilienceConfig hardening	01/S-6 (High, +2nd brick vector), U-6 (delete), S-8, 04/C-7, S-7 race	19	S-M (~1 day)
3	R2-03 VT failure quality	02/S13, S12, P7	12	S (~2–3 h)
4	R2-04 Failure-visibility trio	01/S-1, 06/S-1, 03/S4 (+ scripted-alarm emit gate)	15	M (~1.5–2 d + rig)
5	R2-05 AdminUI authz	04/C-1 (38-page census; ConfigEditor + AuthenticatedRead policies + reflection guard)	16	S-M (~2.5–4 h)
6	R2-06 ServerHistorian fail-fast + 0.2.0 DataType	06/S-11, U-7 (EnsureTags = upsert ⇒ retype probe), C-7	12	S (~1 h + VPN gate)
7	R2-07 Surgical pure-adds	03/P1 — 3 phases; Phase 1 needs zero new sink members	15	L (~4–6 d)
8	R2-08 Async LDAP + HistoryRead	03/S2 (SDK raises callback under lock — worse than reported), S3	14	M (~1.5–2 d)
9	R2-09 Driver fleet batch	05/STAB-3/4/5/8/12/16/17, ResolveHost, onError — 6 PR-sized sub-batches	29	L (~5.5–7 d)
10	R2-10 Resilience observability	03/U10 = 04/U-5 — DPS mirror of the driver-health flow (+2 tracker bugs)	11	M (~1 day)
11	R2-11 TagConfig consolidation	01/C-1, P-1 + 05 ReadEnum/Writable — 3-phase strictness rollout	24	M (~2–2.5 d)
12	R2-12 Repo hygiene	07/U-3/4/5/6, S-3, P-5, C-4/5/6 — destructive steps gated on sign-off	13	S (~½ day)

Suggested execution order: 1 → 2 → 3 (small, close everything new-and-sharp from the re-review) → 5 → 4 (the two-round-old Highs) → 6 → 12 (quick wins) → 10 → 11 → 8 → 9 → 7 (large). R2-01/02/03/05/06/12 have no cross-plan dependencies and can run in parallel branches; R2-09's B3 (PollGroupEngine v2) has explicit landing-order notes against R2-01; R2-11 Part 1 must precede any parse-site edits elsewhere.

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Round 1 (2026-07-08 at 9cad9ed0) — COMPLETE, kept for reference

Design + implementation plans for every finding in the 2026-07-08 architecture review (archreview/*.md, review commit 9cad9ed0). Each plan verifies every finding against the current tree, then gives root cause → design (with alternatives) → concrete file-level steps → tests → effort/risk.

Plan documents

#	Plan	Findings	Verification
01	Core & composition	21	all confirmed, 0 stale
02	Scripting & alarms	30	all confirmed, 0 stale
03	Server & runtime	28	all confirmed (U1 = stale doc only)
04	AdminUI	20	all confirmed (C-3/C-4 good, no action)
05	Protocol drivers	37 + 1 positive	all confirmed, 0 stale
06	Gateway integrations	28 (23 actionable)	all confirmed (U-1 = stale doc)
07	Client, tooling & engineering	26	all confirmed, 0 stale

Total: ~190 findings planned. Zero were stale-because-already-fixed; the only "stale" items are two documentation drifts (CLAUDE.md Known Limitation 2) both flagged for correction.

The 4 Criticals (fix first)

#	Critical	Plan	Fix shape
1	Split-brain resolver never activated → no hard-crash failover	03 S1	ClusterOptions.SplitBrainResolver = KeepOldestOption + hard-kill failover test
2	Production VT script timeout is dead code → one loop wedges the actor	02 U2 (+U3)	Route through TimedScriptEvaluator + CompiledScriptCache
3	S7 has no reconnect path → PLC reboot kills the driver	05 STAB-1	IS7PlcFactory seam + lazy EnsureConnectedAsync
4	TwinCAT ADS subs orphaned after reconnect → silent data stop	05 STAB-2	Store replayable registration intent, replay on client swap

Cross-cutting guardrails (from OVERALL themes, span multiple plans)

• Theme #1 built-but-never-wired — the recurring failure mode. Guardrails proposed across plans: reflection-exhaustive DeferredAddressSpaceSink forwarding test (03 U2, sequenced before the surgical-add work), wiring the OTOPCUA0001 analyzer repo-wide (07 C-1), a startup log line proving SBR is active (03 S1), and wiring/removing the dormant historian health surface (06 S-6).
• Theme #2/#6 fixes don't flow to shared templates — Part B of plan 05: PollGroupEngine v2 (backoff + onError + delete the S7 fork), shared strict ReadEnum/ReadBool, ConnectionBackoff primitive, ResolveHost-via-resolver; plus TagConfigIntent.Parse in Commons (01 C-1) killing the 4-project byte-parity duplication.
• Theme #3 optimistic success — failure-visibility fixes: AddressSpaceApplyOutcome failure field (01 S-1), Galaxy write fail-closed (06 S-1), primary-gate default-deny on unknown role (03 S4).
• Theme #4 verification gap — CI to all unit suites + fail-on-skip (07 S-1/S-2), fault-injection tier (hard-kill / drop-PLC), the missing bUnit substitute = reflection/policy guards (04 C-1).
• Theme #5 doc drift — fix CLAUDE.md Known Limitation 2 + scadaproj index (03 U1 / 06 U-1), ScriptAnalysis policy doc, Client.CLI docs (07 U-3).
• Theme #7 repo hygiene — git rm -r lib/ AVEVA DLLs, untrack planning files, delete Wonderware husks (07 U-4/U-5/U-6).

Suggested execution order

Front-loaded per the OVERALL prioritized action list — items 1–6 eliminate every Critical plus the two systemic guards (analyzer + CI) that stop the built-but-never-wired pattern recurring:

1. Criticals — 03 S1, 02 U2+U3, 05 STAB-1, 05 STAB-2 (each with its missing test)
2. Systemic guards — 07 C-1 (analyzer) + 07 S-1/S-2 (CI to all suites, fail-on-skip); 03 U2 (Deferred-sink forwarding test)
3. Silent-corruption Highs — 05 STAB-4/5 (AbCip lock, FOCAS caches), 05 Modbus timeout-fatal classification
4. Failure-visibility Highs — 01 S-1, 06 S-1, 03 S4
5. AdminUI authz — 04 C-1 (ConfigEditor policy + reflection guard)
6. Perf — 03 P1 (surgical pure-adds, after 03 U2 guard)
7. Consolidation + hygiene + docs — 01 C-1, 05 Part B, 07 U-4/U-5, doc fixes

Open maintainer decision

• Prune vs. keep the dormant machinery (01 U-2 / 02 U-1): the callerless Tier-C recycle machinery + IDriverSupervisor, and the ~2.4k-line Core.VirtualTags engine that production bypasses. Plans recommend retiring both after the live paths are hardened (02 U2/U3 first), but the delete-vs-keep call is the maintainer's.