prep docs and service updates

src/AirGap/StellaOps.AirGap.Time/Health/TimeAnchorHealthCheck.cs

@@ -0,0 +1,49 @@
+using Microsoft.Extensions.Diagnostics.HealthChecks;
+using Microsoft.Extensions.Options;
+using StellaOps.AirGap.Time.Models;
+using StellaOps.AirGap.Time.Services;
+
+namespace StellaOps.AirGap.Time.Health;
+
+public sealed class TimeAnchorHealthCheck : IHealthCheck
+{
+    private readonly TimeStatusService _statusService;
+    private readonly IOptions<AirGapOptions> _options;
+
+    public TimeAnchorHealthCheck(TimeStatusService statusService, IOptions<AirGapOptions> options)
+    {
+        _statusService = statusService;
+        _options = options;
+    }
+
+    public async Task<HealthCheckResult> CheckHealthAsync(HealthCheckContext context, CancellationToken cancellationToken = default)
+    {
+        var opts = _options.Value;
+        var status = await _statusService.GetStatusAsync(opts.TenantId, DateTimeOffset.UtcNow, cancellationToken);
+
+        if (status.Anchor == TimeAnchor.Unknown)
+        {
+            return HealthCheckResult.Unhealthy("time-anchor-missing");
+        }
+
+        if (status.Staleness.IsBreach)
+        {
+            return HealthCheckResult.Unhealthy("time-anchor-stale");
+        }
+
+        var data = new Dictionary<string, object?>
+        {
+            ["anchorDigest"] = status.Anchor.TokenDigest,
+            ["ageSeconds"] = status.Staleness.AgeSeconds,
+            ["warningSeconds"] = status.Staleness.WarningSeconds,
+            ["breachSeconds"] = status.Staleness.BreachSeconds
+        };
+
+        if (status.Staleness.IsWarning)
+        {
+            return HealthCheckResult.Degraded("time-anchor-warning", data);
+        }
+
+        return HealthCheckResult.Healthy("time-anchor-healthy", data);
+    }
+}