Volt CLI: source-available under AGPSL v5.0

Complete infrastructure platform CLI:
- Container runtime (systemd-nspawn)
- VoltVisor VMs (Neutron Stardust / QEMU)
- Stellarium CAS (content-addressed storage)
- ORAS Registry
- GitOps integration
- Landlock LSM security
- Compose orchestration
- Mesh networking

Copyright (c) Armored Gates LLC. All rights reserved.
Licensed under AGPSL v5.0

pkg/backend/detect.go

@@ -0,0 +1,66 @@
+/*
+Backend Detection - Auto-detect the best available container backend.
+
+Uses a registration pattern to avoid import cycles: backend packages
+register themselves via init() by calling Register().
+*/
+package backend
+
+import (
+	"fmt"
+	"sync"
+)
+
+var (
+	mu       sync.Mutex
+	registry = map[string]func() ContainerBackend{}
+	// order tracks registration order for priority-based detection
+	order []string
+)
+
+// Register adds a backend factory to the registry.
+// Backends should call this from their init() function.
+func Register(name string, factory func() ContainerBackend) {
+	mu.Lock()
+	defer mu.Unlock()
+	registry[name] = factory
+	order = append(order, name)
+}
+
+// DetectBackend returns the best available backend for the current platform.
+// Tries backends in registration order, returning the first that is available.
+func DetectBackend() ContainerBackend {
+	mu.Lock()
+	defer mu.Unlock()
+
+	for _, name := range order {
+		b := registry[name]()
+		if b.Available() {
+			return b
+		}
+	}
+
+	// If nothing is available, return the first registered backend anyway
+	// (allows --help and other non-runtime operations to work)
+	if len(order) > 0 {
+		return registry[order[0]]()
+	}
+
+	return nil
+}
+
+// GetBackend returns a backend by name, or an error if unknown.
+func GetBackend(name string) (ContainerBackend, error) {
+	mu.Lock()
+	defer mu.Unlock()
+
+	if factory, ok := registry[name]; ok {
+		return factory(), nil
+	}
+
+	available := make([]string, 0, len(registry))
+	for k := range registry {
+		available = append(available, k)
+	}
+	return nil, fmt.Errorf("unknown backend: %q (available: %v)", name, available)
+}