Add attachment replace workflow UI

main_test.go

@@ -1015,6 +1015,19 @@ func TestUITemplateAndAttachmentActionsWorkThroughEditor(t *testing.T) {
 	if err := u.addAttachmentAction(); err != nil {
 		t.Fatalf("addAttachmentAction() error = %v", err)
 	}
+	if got := u.selectedAttachmentNames(); !slices.Equal(got, []string{"token.txt"}) {
+		t.Fatalf("selectedAttachmentNames() = %v, want [token.txt]", got)
+	}
+
+	replacementPath := filepath.Join(t.TempDir(), "token-replacement.txt")
+	replacement := []byte("attachment-replacement")
+	if err := os.WriteFile(replacementPath, replacement, 0o600); err != nil {
+		t.Fatalf("WriteFile(replacementPath) error = %v", err)
+	}
+	u.attachmentPath.SetText(replacementPath)
+	if err := u.replaceAttachmentAction(); err != nil {
+		t.Fatalf("replaceAttachmentAction() error = %v", err)
+	}
 
 	u.exportAttachmentPath.SetText(attachmentExportPath)
 	if err := u.exportAttachmentAction(); err != nil {
@@ -1025,8 +1038,8 @@ func TestUITemplateAndAttachmentActionsWorkThroughEditor(t *testing.T) {
 	if err != nil {
 		t.Fatalf("ReadFile(exportAttachmentPath) error = %v", err)
 	}
-	if !bytes.Equal(exported, content) {
-		t.Fatalf("exported attachment = %q, want %q", exported, content)
+	if !bytes.Equal(exported, replacement) {
+		t.Fatalf("exported attachment = %q, want %q", exported, replacement)
 	}
 
 	if err := u.removeAttachmentAction(); err != nil {
@@ -1152,6 +1165,52 @@ func TestUITemplatesCanBeBrowsedCreatedEditedDeletedAndInstantiated(t *testing.T
 	}
 }
 
+func TestUIAttachmentActionsRejectDuplicateMissingAndOversizeCases(t *testing.T) {
+	t.Parallel()
+
+	u := newUIWithModel("desktop", vault.Model{
+		Entries: []vault.Entry{
+			{
+				ID:          "git-server",
+				Title:       "Git Server",
+				Attachments: map[string][]byte{"token.txt": []byte("original")},
+				Path:        []string{"Root", "Internet"},
+			},
+		},
+	})
+	u.showEntriesSection()
+	u.state.NavigateToPath([]string{"Root", "Internet"})
+	u.filter()
+	u.state.SelectedEntryID = "git-server"
+	u.loadSelectedEntryIntoEditor()
+
+	addPath := filepath.Join(t.TempDir(), "token.txt")
+	if err := os.WriteFile(addPath, []byte("duplicate"), 0o600); err != nil {
+		t.Fatalf("WriteFile(addPath) error = %v", err)
+	}
+	u.attachmentName.SetText("token.txt")
+	u.attachmentPath.SetText(addPath)
+	if err := u.addAttachmentAction(); err == nil || !strings.Contains(err.Error(), "already exists") {
+		t.Fatalf("addAttachmentAction() error = %v, want duplicate-name failure", err)
+	}
+
+	u.attachmentName.SetText("missing.txt")
+	if err := u.replaceAttachmentAction(); err == nil || !strings.Contains(err.Error(), "not found") {
+		t.Fatalf("replaceAttachmentAction() error = %v, want missing-attachment failure", err)
+	}
+
+	oversizePath := filepath.Join(t.TempDir(), "oversize.bin")
+	oversizeContent := bytes.Repeat([]byte("a"), maxAttachmentBytes+1)
+	if err := os.WriteFile(oversizePath, oversizeContent, 0o600); err != nil {
+		t.Fatalf("WriteFile(oversizePath) error = %v", err)
+	}
+	u.attachmentName.SetText("oversize.bin")
+	u.attachmentPath.SetText(oversizePath)
+	if err := u.addAttachmentAction(); err == nil || !strings.Contains(err.Error(), "too large") {
+		t.Fatalf("addAttachmentAction() oversize error = %v, want size failure", err)
+	}
+}
+
 func TestUIRestoresSelectedEntryHistoryVersion(t *testing.T) {
 	t.Parallel()