all the refactor

internal/ucp/signing_test.go

@@ -63,6 +63,7 @@ func TestWithSigning_AddsHeaders(t *testing.T) {
 	sigInput := rec.Header().Get("Signature-Input")
 	sig := rec.Header().Get("Signature")
 	ts := rec.Header().Get("x-ucp-timestamp")
+	digest := rec.Header().Get("Content-Digest")
 
 	if sigInput == "" {
 		t.Fatal("expected Signature-Input header")
@@ -73,9 +74,12 @@ func TestWithSigning_AddsHeaders(t *testing.T) {
 	if ts == "" {
 		t.Fatal("expected x-ucp-timestamp header")
 	}
+	if digest == "" {
+		t.Fatal("expected Content-Digest header")
+	}
 
 	// Verify the signature input format.
-	if !strings.HasPrefix(sigInput, `sig1=(@status "content-type" "x-ucp-timestamp");`) {
+	if !strings.HasPrefix(sigInput, `sig1=(@status "content-type" "x-ucp-timestamp" "content-digest");`) {
 		t.Fatalf("unexpected Signature-Input format: %q", sigInput)
 	}
 	if !strings.Contains(sigInput, `keyid="k6n-ecdsa-2026"`) {
@@ -155,6 +159,9 @@ func TestWithSigning_WithUCPCartHandler(t *testing.T) {
 	if rec.Header().Get("x-ucp-timestamp") == "" {
 		t.Fatal("expected x-ucp-timestamp on UCP cart response")
 	}
+	if rec.Header().Get("Content-Digest") == "" {
+		t.Fatal("expected Content-Digest on UCP cart response")
+	}
 }
 
 // mustLoadTestKey loads the test PEM for signing tests.