diff --git a/medium.go b/medium.go
index f83ec9f..da8ff18 100644
--- a/medium.go
+++ b/medium.go
@@ -4,7 +4,6 @@ package store
 
 import (
 	"bytes"
-	goio "io"
 
 	core "dappco.re/go/core"
 	"dappco.re/go/core/io"
@@ -13,24 +12,11 @@ import (
 // Medium is the minimal storage transport used by the go-store workspace
 // import and export helpers and by Compact when writing cold archives.
 //
-// Any `dappco.re/go/core/io.Medium` implementation (local, memory, S3, cube,
-// sftp) satisfies this interface by structural typing — go-store only needs a
-// handful of methods to ferry bytes between the workspace buffer and the
-// underlying medium.
+// This is an alias of `dappco.re/go/core/io.Medium`, so callers can pass any
+// upstream medium implementation directly without an adapter.
 //
 // Usage example: `medium, _ := local.New("/tmp/exports"); storeInstance, err := store.New(":memory:", store.WithMedium(medium))`
-type Medium interface {
-	Read(path string) (string, error)
-	Write(path, content string) error
-	EnsureDir(path string) error
-	Create(path string) (goio.WriteCloser, error)
-	Exists(path string) bool
-}
-
-// staticMediumCheck documents that `dappco.re/go/core/io.Medium` satisfies the
-// in-package `store.Medium` interface — agents pass an `io.Medium` directly to
-// `store.WithMedium` without an adapter.
-var _ Medium = io.Medium(nil)
+type Medium = io.Medium
 
 // Usage example: `medium, _ := local.New("/srv/core"); storeInstance, err := store.NewConfigured(store.StoreConfig{DatabasePath: ":memory:", Medium: medium})`
 // WithMedium installs an io.Medium-compatible transport on the Store so that
diff --git a/medium_test.go b/medium_test.go
index 483c597..54d52f5 100644
--- a/medium_test.go
+++ b/medium_test.go
@@ -43,12 +43,32 @@ func (medium *memoryMedium) Write(path, content string) error {
 	return nil
 }
 
+func (medium *memoryMedium) WriteMode(path, content string, _ fs.FileMode) error {
+	return medium.Write(path, content)
+}
+
 func (medium *memoryMedium) EnsureDir(string) error { return nil }
 
 func (medium *memoryMedium) Create(path string) (goio.WriteCloser, error) {
 	return &memoryWriter{medium: medium, path: path}, nil
 }
 
+func (medium *memoryMedium) Append(path string) (goio.WriteCloser, error) {
+	medium.lock.Lock()
+	defer medium.lock.Unlock()
+	return &memoryWriter{medium: medium, path: path, buffer: *bytes.NewBufferString(medium.files[path])}, nil
+}
+
+func (medium *memoryMedium) ReadStream(path string) (goio.ReadCloser, error) {
+	medium.lock.Lock()
+	defer medium.lock.Unlock()
+	return goio.NopCloser(bytes.NewReader([]byte(medium.files[path]))), nil
+}
+
+func (medium *memoryMedium) WriteStream(path string) (goio.WriteCloser, error) {
+	return medium.Create(path)
+}
+
 func (medium *memoryMedium) Exists(path string) bool {
 	medium.lock.Lock()
 	defer medium.lock.Unlock()
@@ -56,6 +76,56 @@ func (medium *memoryMedium) Exists(path string) bool {
 	return ok
 }
 
+func (medium *memoryMedium) IsFile(path string) bool { return medium.Exists(path) }
+
+func (medium *memoryMedium) Delete(path string) error {
+	medium.lock.Lock()
+	defer medium.lock.Unlock()
+	delete(medium.files, path)
+	return nil
+}
+
+func (medium *memoryMedium) DeleteAll(path string) error {
+	medium.lock.Lock()
+	defer medium.lock.Unlock()
+	for key := range medium.files {
+		if key == path || core.HasPrefix(key, path+"/") {
+			delete(medium.files, key)
+		}
+	}
+	return nil
+}
+
+func (medium *memoryMedium) Rename(oldPath, newPath string) error {
+	medium.lock.Lock()
+	defer medium.lock.Unlock()
+	content, ok := medium.files[oldPath]
+	if !ok {
+		return core.E("memoryMedium.Rename", "file not found: "+oldPath, nil)
+	}
+	medium.files[newPath] = content
+	delete(medium.files, oldPath)
+	return nil
+}
+
+func (medium *memoryMedium) List(path string) ([]fs.DirEntry, error) { return nil, nil }
+
+func (medium *memoryMedium) Stat(path string) (fs.FileInfo, error) {
+	if !medium.Exists(path) {
+		return nil, core.E("memoryMedium.Stat", "file not found: "+path, nil)
+	}
+	return fileInfoStub{name: core.PathBase(path)}, nil
+}
+
+func (medium *memoryMedium) Open(path string) (fs.File, error) {
+	if !medium.Exists(path) {
+		return nil, core.E("memoryMedium.Open", "file not found: "+path, nil)
+	}
+	return newMemoryFile(path, medium.files[path]), nil
+}
+
+func (medium *memoryMedium) IsDir(string) bool { return false }
+
 type memoryWriter struct {
 	medium *memoryMedium
 	path   string
@@ -75,6 +145,31 @@ func (writer *memoryWriter) Close() error {
 	return writer.medium.Write(writer.path, writer.buffer.String())
 }
 
+type fileInfoStub struct {
+	name string
+}
+
+func (fileInfoStub) Size() int64        { return 0 }
+func (fileInfoStub) Mode() fs.FileMode  { return 0 }
+func (fileInfoStub) ModTime() time.Time { return time.Time{} }
+func (fileInfoStub) IsDir() bool        { return false }
+func (fileInfoStub) Sys() any           { return nil }
+func (info fileInfoStub) Name() string  { return info.name }
+
+type memoryFile struct {
+	*bytes.Reader
+	name string
+}
+
+func newMemoryFile(name, content string) *memoryFile {
+	return &memoryFile{Reader: bytes.NewReader([]byte(content)), name: name}
+}
+
+func (file *memoryFile) Stat() (fs.FileInfo, error) {
+	return fileInfoStub{name: core.PathBase(file.name)}, nil
+}
+func (file *memoryFile) Close() error { return nil }
+
 // Ensure memoryMedium still satisfies the internal Medium contract.
 var _ Medium = (*memoryMedium)(nil)