backup: pre-hardening baseline

backend/internal/config/adapters/docker.go

@@ -0,0 +1,43 @@
+package adapters
+
+// DockerAdapter is a stub for future Docker label management.
+// Phase 2 does not implement Docker label adapter; it only defines the interface
+// so Phase 3 can plug it in without changing call sites.
+
+type DockerAdapter interface {
+	// ListContainers returns containers that could be managed via labels
+	ListContainers() ([]Container, error)
+	// PreviewLabels returns diff for label changes (no write)
+	PreviewLabels(containerID string, labels map[string]string) (string, error)
+	// ApplyLabels writes label changes (requires confirmation)
+	ApplyLabels(containerID string, labels map[string]string, confirm bool) error
+}
+
+type Container struct {
+	ID     string            `json:"id"`
+	Name   string            `json:"name"`
+	Labels map[string]string `json:"labels"`
+}
+
+// StubDockerAdapter returns not-implemented for all operations
+type StubDockerAdapter struct{}
+
+func (s *StubDockerAdapter) ListContainers() ([]Container, error) {
+	return nil, errNotImplemented("docker")
+}
+func (s *StubDockerAdapter) PreviewLabels(string, map[string]string) (string, error) {
+	return "", errNotImplemented("docker")
+}
+func (s *StubDockerAdapter) ApplyLabels(string, map[string]string, bool) error {
+	return errNotImplemented("docker")
+}
+
+func errNotImplemented(provider string) error {
+	return &NotImplementedError{Provider: provider}
+}
+
+type NotImplementedError struct{ Provider string }
+
+func (e *NotImplementedError) Error() string {
+	return "provider " + e.Provider + " adapter not implemented in Phase 2 (stub only)"
+}