Resolve all 33 medium-severity architecture review findings

Second slice of the 2026-09-09 whole-system review remediation
(docs/plans/2026-09-09-arch-review.md §10), on top of the High slice 146a1323.

Runtime/devices: SR-2 alarm on-trigger integration scope; SR-3 correlated NativeAlarmActor
subscribe retry; SR-4 immutable audited DB target; SR-5 ordered InstanceActor stop/flush;
SR-12 rehydration fence; SR-13 S&F gate recheck per delivery; DC-4 no OPC UA security
downgrade; DC-5 alarm snapshot for every new subscriber; ORCH-1 sync-dispose joins the pump.

Management/UI: MG-2 site scope on audit tree + Flow Debugger Replay; MG-3 stale-probe memo
removed; MG-4 server-owned bulk-deploy deadline; UI-5 sandbox runs in a killable child
process (new CentralUI.SandboxWorker project); UI-14 bounded sandbox output/IPC.

Edge/audit: EI-1 relay audit ownership; EI-2 SkipBodyCapture suppresses error text; EI-3/EI-11
error-field redaction + caps; EI-4 single relay deadline, pre-execution-only retry; EI-5
authenticated relay provenance; EI-10 body cap before audit read.

Persistence/contracts: DL-1 global Instance.UniqueName unique index + conflict translation;
DL-2 DataConnection protocol config encrypted at rest (migration
20260909203046_EnforceGlobalInstanceNamesAndProtectProtocolConfiguration — coordinated
central upgrade, old binaries cannot read protected rows); DL-3 bounded Replay paging;
DL-6 cross-site Overwrite of a deployed instance rejected; XC-4 proto descriptor contract test.

Config/hygiene: XC-1 central listener isolation by local port; XC-2/XC-3 inert SMTP + cron
keys removed from rig settings; CM-2 env2 bootstrap guard enabled; DC-6 deploy site exit code;
DC-7 notifier retries only explicit standby rejection; XC-5 ClusterClient purged from docs.

Gates recorded in the report: build 0/0, 9 397 passed / 0 failed, rig redeployed on all
eight nodes with the migration applied. 46 Low findings remain open.

src/ZB.MOM.WW.ScadaBridge.AuditLog/Configuration/PerTargetRedactionOverride.cs

@@ -22,7 +22,8 @@ public sealed class PerTargetRedactionOverride
     /// whose name matches are replaced with <c>&lt;redacted&gt;</c>. Null (the
     /// default) means parameter values are captured verbatim. Only applied to
     /// <see cref="ZB.MOM.WW.ScadaBridge.Commons.Types.Enums.AuditChannel.DbOutbound"/>
-    /// rows.
+    /// rows. When configured, free-text SQL errors are suppressed because they can echo
+    /// sensitive parameter values without their names.
     /// </summary>
     public string? RedactSqlParamsMatching { get; set; }
 
@@ -31,8 +32,9 @@ public sealed class PerTargetRedactionOverride
     /// request/response headers and metadata (status, duration, actor, etc.)
     /// but the request and response body strings are omitted
     /// (<c>RequestSummary</c> / <c>ResponseSummary</c> are left null). The
-    /// audit row itself is always emitted — only the body content is suppressed.
-    /// Null (the default, equivalent to <c>false</c>) means body capture
+    /// audit row itself is still emitted; exception message/detail are also suppressed
+    /// because failures may quote body values.
+    /// The default <c>false</c> means body capture
     /// proceeds normally up to <see cref="AuditLogOptions.InboundMaxBytes"/>.
     /// </summary>
     public bool SkipBodyCapture { get; set; }

src/ZB.MOM.WW.ScadaBridge.AuditLog/Redaction/ScadaBridgeAuditRedactor.cs

@@ -192,6 +192,7 @@ public sealed class ScadaBridgeAuditRedactor : IAuditRedactor, IDisposable
             var request = RedactHeaders(d.RequestSummary, opts.HeaderRedactList);
             var response = RedactHeaders(d.ResponseSummary, opts.HeaderRedactList);
             var errorDetail = d.ErrorDetail;
+            var errorMessage = d.ErrorMessage;
             var extra = d.Extra;
 
             // --- Body-regex stage (also runs BEFORE truncation) -----------
@@ -211,6 +212,7 @@ public sealed class ScadaBridgeAuditRedactor : IAuditRedactor, IDisposable
                 request = RedactBody(request, bodyRegexes);
                 response = RedactBody(response, bodyRegexes);
                 errorDetail = RedactBody(errorDetail, bodyRegexes);
+                errorMessage = RedactBody(errorMessage, bodyRegexes);
                 extra = RedactBody(extra, bodyRegexes);
             }
 
@@ -223,6 +225,10 @@ public sealed class ScadaBridgeAuditRedactor : IAuditRedactor, IDisposable
                         opts, rawEvent.Target, out var sqlParamRegex, out var sqlRedactorUnavailable))
                 {
                     request = RedactSqlParameters(request, sqlParamRegex!);
+                    // Parameter policy matches names, whereas SQL exceptions can echo VALUES.
+                    // Free text cannot be safely filtered with a name regex. Keep status/category.
+                    if (errorMessage is not null) errorMessage = "Database operation failed (sensitive SQL error suppressed)";
+                    if (errorDetail is not null) errorDetail = "<redacted: SQL parameter privacy policy>";
                 }
                 else if (sqlRedactorUnavailable)
                 {
@@ -235,6 +241,7 @@ public sealed class ScadaBridgeAuditRedactor : IAuditRedactor, IDisposable
             request = TruncateField(request, cap, ref truncated);
             response = TruncateField(response, cap, ref truncated);
             errorDetail = TruncateField(errorDetail, cap, ref truncated);
+            errorMessage = TruncateField(errorMessage, cap, ref truncated);
             extra = TruncateField(extra, cap, ref truncated);
 
             var rewritten = d with
@@ -242,6 +249,7 @@ public sealed class ScadaBridgeAuditRedactor : IAuditRedactor, IDisposable
                 RequestSummary = request,
                 ResponseSummary = response,
                 ErrorDetail = errorDetail,
+                ErrorMessage = errorMessage,
                 Extra = extra,
                 PayloadTruncated = d.PayloadTruncated || truncated,
             };