save checkpoint: save features

src/Scanner/StellaOps.Scanner.WebService/Services/InMemoryScanMetadataRepository.cs

@@ -0,0 +1,54 @@
+using StellaOps.Scanner.Core;
+
+namespace StellaOps.Scanner.WebService.Services;
+
+/// <summary>
+/// Resolves scan metadata from stored scan manifests.
+/// </summary>
+public sealed class InMemoryScanMetadataRepository : IScanMetadataRepository
+{
+    private readonly IScanManifestRepository _manifestRepository;
+
+    public InMemoryScanMetadataRepository(IScanManifestRepository manifestRepository)
+    {
+        _manifestRepository = manifestRepository ?? throw new ArgumentNullException(nameof(manifestRepository));
+    }
+
+    public async Task<ScanMetadata?> GetScanMetadataAsync(string scanId, CancellationToken cancellationToken = default)
+    {
+        if (string.IsNullOrWhiteSpace(scanId))
+        {
+            return null;
+        }
+
+        var manifest = await _manifestRepository
+            .GetManifestAsync(scanId.Trim(), cancellationToken: cancellationToken)
+            .ConfigureAwait(false);
+
+        if (manifest is null)
+        {
+            return null;
+        }
+
+        return new ScanMetadata(
+            BaseDigest: null,
+            TargetDigest: NormalizeDigest(manifest.Manifest.ArtifactDigest),
+            ScanTime: manifest.Manifest.CreatedAtUtc);
+    }
+
+    private static string? NormalizeDigest(string? digest)
+    {
+        if (string.IsNullOrWhiteSpace(digest))
+        {
+            return null;
+        }
+
+        var normalized = digest.Trim();
+        if (!normalized.Contains(':', StringComparison.Ordinal))
+        {
+            normalized = $"sha256:{normalized}";
+        }
+
+        return normalized.ToLowerInvariant();
+    }
+}