fix: pr-closed-lookup (follow gh: find closed and merged pull requests by branch)

Signed-off-by: bircni <bircni@icloud.com>

internal/services/pulls.go

@@ -276,6 +276,26 @@ func (s Pulls) ListOpen(ctx context.Context) ([]Pull, error) {
 	})
 }
 
+// NewestClosed returns the most recently updated closed or merged pull request that keep
+// accepts, and whether there is one. It reads pages newest first and stops at the first match.
+func (s Pulls) NewestClosed(ctx context.Context, keep func(Pull) bool) (Pull, bool, error) {
+	for page := 1; page <= maxListPages; page++ {
+		items, _, err := s.List(ctx, PullListOptions{State: "closed", Sort: "recentupdate", Limit: 50, Page: page})
+		if err != nil {
+			return Pull{}, false, err
+		}
+		if len(items) == 0 {
+			return Pull{}, false, nil
+		}
+		for _, item := range items {
+			if keep(item) {
+				return item, true, nil
+			}
+		}
+	}
+	return Pull{}, false, nil
+}
+
 // Create opens a pull request.
 func (s Pulls) Create(ctx context.Context, opts PullOptions) (Pull, error) {
 	// TODO(sdk): CreatePullRequestOption lacks allow_maintainer_edit.