refactor(management): FlowDebugRunner — extract WriteAndPollAsync from RunValueChangeAsync (no behaviour change)

Claude-Session: https://claude.ai/code/session_01NcMG6xXdsJbmD2wYAgkK29

src/ZB.MOM.WW.ScadaBridge.ManagementService/FlowDebug/FlowDebugRunner.cs

@@ -3,6 +3,8 @@ using System.Text.Json;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
 using ZB.MOM.WW.Audit;
+using ZB.MOM.WW.ScadaBridge.Commons.Entities.Instances;
+using ZB.MOM.WW.ScadaBridge.Commons.Entities.Sites;
 using ZB.MOM.WW.ScadaBridge.Commons.Interfaces.Repositories;
 using ZB.MOM.WW.ScadaBridge.Commons.Interfaces.Services;
 using ZB.MOM.WW.ScadaBridge.Commons.Messages.InboundApi;
@@ -211,6 +213,22 @@ public sealed class FlowDebugRunner
             .GetSiteByIdAsync(instance.SiteId, ct).ConfigureAwait(false)
             ?? throw new ManagementCommandException($"Site with ID {instance.SiteId} not found.", NotFoundCode);
 
+        return await WriteAndPollAsync(
+            sp, user, instance, site, cmd.AttributeName, cmd.Value, cmd.WaitSeconds, triggerScript: null, ct)
+            .ConfigureAwait(false);
+    }
+
+    /// <summary>
+    /// The traced attribute write + spawned-run poll shared by <see cref="RunValueChangeAsync"/> and
+    /// the write-kind branch of the script entry's <c>RunScriptAsync</c> (design 2026-09-08 §4.3). The
+    /// caller has already gated the active node, loaded and scope-checked the instance, and loaded the
+    /// site. <paramref name="triggerScript"/> is null for the attribute-level command and the script's
+    /// canonical name for the script entry — it only changes the NO_TRIGGER message.
+    /// </summary>
+    private async Task<FlowDebugRunResult> WriteAndPollAsync(
+        IServiceProvider sp, AuthenticatedUser user, Instance instance, Site site,
+        string attributeName, string? value, int waitSeconds, string? triggerScript, CancellationToken ct)
+    {
         var root = Guid.NewGuid();
         var startedAt = DateTimeOffset.UtcNow;
         var sw = Stopwatch.StartNew();
@@ -223,7 +241,7 @@ public sealed class FlowDebugRunner
             site.SiteIdentifier,
             new RouteToSetAttributesRequest(
                 Guid.NewGuid().ToString(), instance.UniqueName,
-                new Dictionary<string, string> { [cmd.AttributeName] = cmd.Value ?? string.Empty },
+                new Dictionary<string, string> { [attributeName] = value ?? string.Empty },
                 DateTimeOffset.UtcNow, ParentExecutionId: root, Trace: true),
             ct).ConfigureAwait(false);
 
@@ -232,18 +250,18 @@ public sealed class FlowDebugRunner
             write.Success ? AuditStatus.Delivered : AuditStatus.Failed,
             occurredAtUtc: startedAt.UtcDateTime,
             actor: user.Username,
-            target: cmd.AttributeName,
+            target: attributeName,
             sourceNode: sp.GetService<INodeIdentityProvider>()?.NodeName,
             executionId: root,
             sourceSiteId: site.SiteIdentifier,
             sourceInstanceId: instance.UniqueName,
             durationMs: (int)Math.Min(sw.ElapsedMilliseconds, int.MaxValue),
             errorMessage: write.ErrorMessage,
-            requestSummary: JsonSerializer.Serialize(new { attribute = cmd.AttributeName, value = cmd.Value }, ScriptTraceExtra.JsonOptions),
+            requestSummary: JsonSerializer.Serialize(new { attribute = attributeName, value = value }, ScriptTraceExtra.JsonOptions),
             extra: new ScriptTraceExtra
             {
                 Source = SourceTag,
-                Writes = [new AttributeWriteDetail(cmd.AttributeName, cmd.Value, write.Success, write.ErrorMessage)],
+                Writes = [new AttributeWriteDetail(attributeName, value, write.Success, write.ErrorMessage)],
             }.ToJson());
         await WriteCentralAsync(sp, rootRow, ct).ConfigureAwait(false);
         var redactedRoot = redactor?.Apply(rootRow) ?? rootRow;
@@ -258,7 +276,7 @@ public sealed class FlowDebugRunner
         // == root, then their children — until a ScriptRun parented to root exists AND the
         // set has been quiet for SettleWindow, or WaitSeconds elapses.
         var puller = sp.GetRequiredService<IPullTraceEventsClient>();
-        var deadline = _now() + TimeSpan.FromSeconds(Math.Max(1, cmd.WaitSeconds));
+        var deadline = _now() + TimeSpan.FromSeconds(Math.Max(1, waitSeconds));
         var known = new Dictionary<Guid, AuditEvent>();
         DateTimeOffset? lastNew = null;
         var since = startedAt.UtcDateTime.AddSeconds(-5);
@@ -298,7 +316,9 @@ public sealed class FlowDebugRunner
         });
         return new FlowDebugRunResult(
             root, completed,
-            completed ? null : $"No traced run was spawned within {cmd.WaitSeconds}s (no value-change trigger on '{cmd.AttributeName}', or no device echo).",
+            completed ? null : triggerScript is null
+                ? $"No traced run was spawned within {waitSeconds}s (no value-change trigger on '{attributeName}', or no device echo)."
+                : $"No traced run of '{triggerScript}' was spawned within {waitSeconds}s after writing '{attributeName}' (trigger condition not met, or no device echo).",
             completed ? null : NoTriggerCode,
             ordered, false, startedAt, DateTimeOffset.UtcNow);
     }