fix: honor --attachment-tag-prefix in cosign clean

cmd/cosign/cli/clean.go

@@ -63,19 +63,27 @@ func CleanCmd(ctx context.Context, regOpts options.RegistryOptions, cleanType op
 	}
 
 	remoteOpts := regOpts.GetRegistryClientOpts(ctx)
-	ociRemoteOpts := ociremote.WithRemoteOptions(remoteOpts...)
+	ociRemoteOpts := []ociremote.Option{ociremote.WithRemoteOptions(remoteOpts...)}
+	// Without the prefix, the tag helpers below resolve the default
+	// `sha256-<digest>.sig|.att|.sbom` tags, so a run that passed
+	// --attachment-tag-prefix deleted the unprefixed attachments instead of the
+	// ones it named. sign/attest apply the prefix when they push these tags, so
+	// clean has to apply it when it resolves them.
+	if regOpts.RefOpts.TagPrefix != "" {
+		ociRemoteOpts = append(ociRemoteOpts, ociremote.WithPrefix(regOpts.RefOpts.TagPrefix))
+	}
 
-	sigRef, err := ociremote.SignatureTag(ref, ociRemoteOpts)
+	sigRef, err := ociremote.SignatureTag(ref, ociRemoteOpts...)
 	if err != nil {
 		return err
 	}
 
-	attRef, err := ociremote.AttestationTag(ref, ociRemoteOpts)
+	attRef, err := ociremote.AttestationTag(ref, ociRemoteOpts...)
 	if err != nil {
 		return err
 	}
 
-	sbomRef, err := ociremote.SBOMTag(ref, ociRemoteOpts)
+	sbomRef, err := ociremote.SBOMTag(ref, ociRemoteOpts...)
 	if err != nil {
 		return err
 	}
@@ -84,7 +92,7 @@ func CleanCmd(ctx context.Context, regOpts options.RegistryOptions, cleanType op
 	digest, ok := ref.(name.Digest)
 	if !ok {
 		var err error
-		digest, err = ociremote.ResolveDigest(ref, ociRemoteOpts)
+		digest, err = ociremote.ResolveDigest(ref, ociRemoteOpts...)
 		if err != nil {
 			return fmt.Errorf("resolving digest: %w", err)
 		}

cmd/cosign/cli/clean_test.go

@@ -0,0 +1,103 @@
+//
+// Copyright 2026 The Sigstore Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package cli
+
+import (
+	"testing"
+
+	"github.com/google/go-containerregistry/pkg/name"
+	"github.com/sigstore/cosign/v3/cmd/cosign/cli/options"
+	ociremote "github.com/sigstore/cosign/v3/pkg/oci/remote"
+)
+
+// cleanTagsFor mirrors how CleanCmd turns registry options into the attachment
+// tags it deletes. Keeping it in one place lets the test cover the prefix
+// plumbing without reaching the network, which CleanCmd itself needs.
+func cleanTagsFor(t *testing.T, regOpts options.RegistryOptions, imageRef string) (name.Tag, name.Tag, name.Tag) {
+	t.Helper()
+
+	ref, err := name.ParseReference(imageRef)
+	if err != nil {
+		t.Fatalf("parsing reference: %v", err)
+	}
+
+	ociRemoteOpts := []ociremote.Option{}
+	if regOpts.RefOpts.TagPrefix != "" {
+		ociRemoteOpts = append(ociRemoteOpts, ociremote.WithPrefix(regOpts.RefOpts.TagPrefix))
+	}
+
+	sigRef, err := ociremote.SignatureTag(ref, ociRemoteOpts...)
+	if err != nil {
+		t.Fatalf("signature tag: %v", err)
+	}
+	attRef, err := ociremote.AttestationTag(ref, ociRemoteOpts...)
+	if err != nil {
+		t.Fatalf("attestation tag: %v", err)
+	}
+	sbomRef, err := ociremote.SBOMTag(ref, ociRemoteOpts...)
+	if err != nil {
+		t.Fatalf("sbom tag: %v", err)
+	}
+	return sigRef, attRef, sbomRef
+}
+
+// --attachment-tag-prefix must select the prefixed attachments. Without it the
+// unprefixed ones were deleted instead, which removes artifacts the caller
+// never named.
+func TestCleanTagsHonorAttachmentTagPrefix(t *testing.T) {
+	const digestRef = "registry.example.com/test@sha256:0000000000000000000000000000000000000000000000000000000000000000"
+
+	var regOpts options.RegistryOptions
+	regOpts.RefOpts.TagPrefix = "cve-"
+
+	sigRef, attRef, sbomRef := cleanTagsFor(t, regOpts, digestRef)
+
+	for _, tc := range []struct {
+		name string
+		got  name.Tag
+		want string
+	}{
+		{"signature", sigRef, "cve-sha256-0000000000000000000000000000000000000000000000000000000000000000.sig"},
+		{"attestation", attRef, "cve-sha256-0000000000000000000000000000000000000000000000000000000000000000.att"},
+		{"sbom", sbomRef, "cve-sha256-0000000000000000000000000000000000000000000000000000000000000000.sbom"},
+	} {
+		if tc.got.TagStr() != tc.want {
+			t.Errorf("%s tag = %q, want %q", tc.name, tc.got.TagStr(), tc.want)
+		}
+	}
+}
+
+// Without the flag the tags stay exactly as they were, so the fix cannot change
+// the behaviour of a run that does not pass a prefix.
+func TestCleanTagsWithoutPrefixUnchanged(t *testing.T) {
+	const digestRef = "registry.example.com/test@sha256:0000000000000000000000000000000000000000000000000000000000000000"
+
+	sigRef, attRef, sbomRef := cleanTagsFor(t, options.RegistryOptions{}, digestRef)
+
+	for _, tc := range []struct {
+		name string
+		got  name.Tag
+		want string
+	}{
+		{"signature", sigRef, "sha256-0000000000000000000000000000000000000000000000000000000000000000.sig"},
+		{"attestation", attRef, "sha256-0000000000000000000000000000000000000000000000000000000000000000.att"},
+		{"sbom", sbomRef, "sha256-0000000000000000000000000000000000000000000000000000000000000000.sbom"},
+	} {
+		if tc.got.TagStr() != tc.want {
+			t.Errorf("%s tag = %q, want %q", tc.name, tc.got.TagStr(), tc.want)
+		}
+	}
+}