feat(releases): add SelfUpdater.DecideUpdateAsync

src/ClaudeDo.Releases/SelfUpdater.cs

@@ -1,3 +1,4 @@
+using System.Net.Http;
 using System.Text.RegularExpressions;
 
 namespace ClaudeDo.Releases;
@@ -19,4 +20,40 @@ public static partial class SelfUpdater
         }
         return null;
     }
+
+    public static async Task<SelfUpdateDecision> DecideUpdateAsync(
+        IReleaseClient releases,
+        string currentVersion,
+        CancellationToken ct)
+    {
+        GiteaRelease? release;
+        try
+        {
+            release = await releases.GetLatestReleaseAsync(ct);
+        }
+        catch (Exception ex) when (ex is HttpRequestException or TaskCanceledException)
+        {
+            return new SelfUpdateDecision(SelfUpdateDecisionKind.NoUpdate);
+        }
+
+        if (release is null)
+            return new SelfUpdateDecision(SelfUpdateDecisionKind.NoUpdate);
+
+        var match = FindInstallerAsset(release.Assets);
+        if (match is null)
+            return new SelfUpdateDecision(SelfUpdateDecisionKind.NoUpdate);
+
+        var cmp = VersionComparer.Compare(match.Version, currentVersion);
+        if (!cmp.IsNewer)
+            return new SelfUpdateDecision(SelfUpdateDecisionKind.NoUpdate);
+
+        var checksums = release.Assets.FirstOrDefault(
+            a => string.Equals(a.Name, "checksums.txt", StringComparison.OrdinalIgnoreCase));
+
+        return new SelfUpdateDecision(
+            SelfUpdateDecisionKind.UpdateAvailable,
+            LatestVersion: match.Version,
+            InstallerAsset: match.Asset,
+            ChecksumsAsset: checksums);
+    }
 }