Let a Working Folder delete a basename.

CheckDNS needs that to Remove Domain without a second storage path.

Co-authored-by: Cursor <cursoragent@cursor.com>

CONTEXT.md

@@ -9,7 +9,7 @@ The root of that Nextcloud user's files tree. Working Folder paths are relative
 _Avoid_: absolute WebDAV URLs, numeric file IDs
 
 **Working Folder**:
-The single folder an ExApp uses for the current operation. Its path is relative to the User Files Root. Each ExApp defines what files inside that folder mean; this Library only opens, lists, reads, and writes there.
+The single folder an ExApp uses for the current operation. Its path is relative to the User Files Root. Each ExApp defines what files inside that folder mean; this Library only opens, lists, reads, writes, and removes there.
 _Avoid_: catalog folder, zones directory, app-specific suffixes in Library code
 
 **Saved Default**:
@@ -21,5 +21,5 @@ One inbound ExApp request bound to one Working Folder. App-icon launch uses the
 _Avoid_: silently switching folders, creating a visit path that was not saved as default
 
 **Files seam**:
-The `Root` and `Folder` interfaces: open or ensure a relative path, then list, read, write, and test existence. Local disk and WebDAV are two implementations of the same seam.
+The `Root` and `Folder` interfaces: open or ensure a relative path, then list, read, write, remove, and test existence. Local disk and WebDAV are two implementations of the same seam.
 _Avoid_: coupling the seam to a specific on-disk layout beyond basename rules

files.go

@@ -32,6 +32,8 @@ type Folder interface {
 	Write(name string, data []byte) error
 	// Exists reports whether name is a non-directory file in the Working Folder.
 	Exists(name string) (bool, error)
+	// Remove deletes a basename in the Working Folder.
+	Remove(name string) error
 }
 
 // Root is User Files Root–relative folder access.
@@ -181,6 +183,18 @@ func (f localFolder) Exists(name string) (bool, error) {
 	return !info.IsDir(), nil
 }
 
+// Remove implements Folder for a local directory.
+func (f localFolder) Remove(name string) error {
+	if err := RequireBasename(name); err != nil {
+		return err
+	}
+	err := os.Remove(filepath.Join(f.dir, name))
+	if err != nil && os.IsNotExist(err) {
+		return fmt.Errorf("%w: %s", ErrNotExist, name)
+	}
+	return err
+}
+
 // RequireBasename rejects path segments that are not a single basename.
 func RequireBasename(name string) error {
 	if name == "" || name != path.Base(name) || strings.ContainsAny(name, `/\`) || strings.Contains(name, "..") {

webdav.go

@@ -335,6 +335,41 @@ func (f webdavFolder) Write(name string, data []byte) error {
 	return fmt.Errorf("webdav PUT %s: %s", name, res.Status)
 }
 
+// Remove implements Folder via WebDAV DELETE.
+func (f webdavFolder) Remove(name string) error {
+	u, err := f.childURL(name)
+	if err != nil {
+		return err
+	}
+	req, err := http.NewRequest(http.MethodDelete, u, nil)
+	if err != nil {
+		return err
+	}
+	for k, vs := range f.root.Cred.AuthHeaders() {
+		for _, v := range vs {
+			req.Header.Set(k, v)
+		}
+	}
+	res, err := f.root.client().Do(req)
+	if err != nil {
+		return err
+	}
+	defer res.Body.Close()
+	if _, err := io.Copy(io.Discard, res.Body); err != nil {
+		return err
+	}
+	switch res.StatusCode {
+	case http.StatusOK, http.StatusNoContent, http.StatusAccepted:
+		return nil
+	case http.StatusNotFound:
+		return fmt.Errorf("%w: %s", ErrNotExist, name)
+	case http.StatusForbidden, http.StatusUnauthorized:
+		return fmt.Errorf("%w", ErrForbidden)
+	default:
+		return fmt.Errorf("webdav DELETE %s: %s", name, res.Status)
+	}
+}
+
 // Exists implements Folder via WebDAV HEAD (falls back to GET when needed).
 func (f webdavFolder) Exists(name string) (bool, error) {
 	u, err := f.childURL(name)

webdav_test.go

@@ -56,6 +56,13 @@ func TestWebDAVReadWriteListExists(t *testing.T) {
 				return
 			}
 			w.WriteHeader(http.StatusOK)
+		case http.MethodDelete:
+			if _, ok := store[path]; !ok {
+				http.NotFound(w, r)
+				return
+			}
+			delete(store, path)
+			w.WriteHeader(http.StatusNoContent)
 		case "MKCOL":
 			dirs[strings.TrimSuffix(path, "/")] = true
 			w.WriteHeader(http.StatusCreated)
@@ -102,6 +109,13 @@ func TestWebDAVReadWriteListExists(t *testing.T) {
 	if !found {
 		t.Fatalf("list: %+v", entries)
 	}
+	if err := folder.Remove("note.txt"); err != nil {
+		t.Fatal(err)
+	}
+	ok, err = folder.Exists("note.txt")
+	if err != nil || ok {
+		t.Fatalf("after remove: ok=%v err=%v", ok, err)
+	}
 }
 
 func TestWebDAVOpenMissingIsNotExist(t *testing.T) {