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fix(health-monitoring): resolve HealthMonitoring-015 — nullable LastReportReceivedAt

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A heartbeat-registered site that has never sent a full report now has
LastReportReceivedAt = null instead of the year-0001 sentinel. TimestampDisplay
accepts DateTimeOffset? and renders null as a placeholder ('awaiting first
report') rather than a ~2000-year-stale date. Cross-module: HealthMonitoring +
CentralUI.
This commit is contained in:
Joseph Doherty
2026-05-17 05:43:05 -04:00
parent 7da303d7bb
commit e55bd46ca1
7 changed files with 137 additions and 32 deletions
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2
src/ScadaLink.CentralUI/Components/Pages/Monitoring/Health.razor
View File

@@ -71,7 +71,7 @@
<strong class="fs-5">@siteName@(isCentral ? "" : $" ({siteId})")</strong>
</div>
<small class="text-muted">
Last report: <TimestampDisplay Value="@state.LastReportReceivedAt" Format="HH:mm:ss" />
Last report: <TimestampDisplay Value="@state.LastReportReceivedAt" Format="HH:mm:ss" NullText="awaiting first report" />
| Last heartbeat: <TimestampDisplay Value="@state.LastHeartbeatAt" Format="HH:mm:ss" />
| Seq: @state.LastSequenceNumber
</small>

18
src/ScadaLink.CentralUI/Components/Shared/TimestampDisplay.razor
View File

@@ -1,8 +1,20 @@
@* Displays a UTC DateTimeOffset formatted for display. Tooltip shows UTC value. *@
@* Displays a UTC DateTimeOffset formatted for display. Tooltip shows UTC value.
A null Value renders as a plain "never" placeholder — used for timestamps that
have not happened yet (e.g. a heartbeat-only site with no full report). *@
<span title="@Value.UtcDateTime.ToString("yyyy-MM-dd HH:mm:ss") UTC">@Value.LocalDateTime.ToString(Format)</span>
@if (Value is { } value)
{
<span title="@value.UtcDateTime.ToString("yyyy-MM-dd HH:mm:ss") UTC">@value.LocalDateTime.ToString(Format)</span>
}
else
{
<span class="text-muted">@NullText</span>
}
@code {
[Parameter, EditorRequired] public DateTimeOffset Value { get; set; }
[Parameter, EditorRequired] public DateTimeOffset? Value { get; set; }
[Parameter] public string Format { get; set; } = "yyyy-MM-dd HH:mm:ss";
/// <summary>Text shown when <see cref="Value"/> is null.</summary>
[Parameter] public string NullText { get; set; } = "never";
}

6
src/ScadaLink.HealthMonitoring/CentralHealthAggregator.cs
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@@ -118,12 +118,14 @@ public class CentralHealthAggregator : BackgroundService, ICentralHealthAggregat
if (!_siteStates.TryGetValue(siteId, out var existing))
{
// Unknown site — register it as online, awaiting its first
// full report. LatestReport stays null until ProcessReport runs.
// full report. LatestReport and LastReportReceivedAt both stay
// null until ProcessReport runs — "no report yet" is an explicit
// nullable state, not a year-0001 sentinel the UI must special-case.
var registered = new SiteHealthState
{
SiteId = siteId,
LatestReport = null,
LastReportReceivedAt = default,
LastReportReceivedAt = null,
LastHeartbeatAt = receivedAt,
LastSequenceNumber = 0,
IsOnline = true

9
src/ScadaLink.HealthMonitoring/SiteHealthState.cs
View File

@@ -21,10 +21,13 @@ public sealed record SiteHealthState
public SiteHealthReport? LatestReport { get; init; }
/// <summary>
/// Time the latest full <see cref="SiteHealthReport"/> was processed.
/// Used by the UI to surface report staleness during failover.
/// Time the latest full <see cref="SiteHealthReport"/> was processed, or
/// <c>null</c> if the site is known only via heartbeats and has not yet sent
/// a report. Used by the UI to surface report staleness during failover;
/// the <c>null</c> case must be rendered as "no report yet" rather than as a
/// timestamp (a <c>default</c> sentinel would display as year-0001).
/// </summary>
public DateTimeOffset LastReportReceivedAt { get; init; }
public DateTimeOffset? LastReportReceivedAt { get; init; }
/// <summary>
/// Time the most recent signal of any kind (full report OR heartbeat) was