feat: snapshot upload async allows restore

internal/daemon/daemon_test.go

@@ -641,6 +641,55 @@ func TestRestoreSnapshotUsesLocalSnapshotArtifacts(t *testing.T) {
 	}
 }
 
+func TestGetSnapshotArtifactReturnsLocalArtifactPath(t *testing.T) {
+	root := t.TempDir()
+	cfg := testConfig(root)
+	fileStore, err := store.NewFileStore(cfg.StatePath, cfg.OperationsPath)
+	if err != nil {
+		t.Fatalf("create file store: %v", err)
+	}
+
+	hostDaemon, err := New(cfg, fileStore, &fakeRuntime{})
+	if err != nil {
+		t.Fatalf("create daemon: %v", err)
+	}
+
+	snapshotDir := filepath.Join(root, "snapshots", "snap-artifact")
+	if err := os.MkdirAll(snapshotDir, 0o755); err != nil {
+		t.Fatalf("create snapshot dir: %v", err)
+	}
+	memoryPath := filepath.Join(snapshotDir, "memory.bin")
+	if err := os.WriteFile(memoryPath, []byte("mem"), 0o644); err != nil {
+		t.Fatalf("write memory: %v", err)
+	}
+	if err := fileStore.CreateSnapshot(context.Background(), model.SnapshotRecord{
+		ID:            "snap-artifact",
+		MachineID:     "source",
+		MemFilePath:   memoryPath,
+		StateFilePath: filepath.Join(snapshotDir, "vmstate.bin"),
+		Artifacts: []model.SnapshotArtifactRecord{
+			{ID: "memory", Kind: contracthost.SnapshotArtifactKindMemory, Name: "memory.bin", LocalPath: memoryPath, SizeBytes: 3},
+		},
+		CreatedAt: time.Now().UTC(),
+	}); err != nil {
+		t.Fatalf("create snapshot: %v", err)
+	}
+
+	artifact, err := hostDaemon.GetSnapshotArtifact(context.Background(), "snap-artifact", "memory")
+	if err != nil {
+		t.Fatalf("GetSnapshotArtifact returned error: %v", err)
+	}
+	if artifact == nil {
+		t.Fatalf("GetSnapshotArtifact returned nil artifact")
+	}
+	if artifact.Name != "memory.bin" {
+		t.Fatalf("artifact name = %q, want memory.bin", artifact.Name)
+	}
+	if artifact.Path != memoryPath {
+		t.Fatalf("artifact path = %q, want %q", artifact.Path, memoryPath)
+	}
+}
+
 func TestRestoreSnapshotUsesDurableSnapshotSpec(t *testing.T) {
 	root := t.TempDir()
 	cfg := testConfig(root)

internal/daemon/snapshot.go

@@ -14,6 +14,7 @@ import (
 	"golang.org/x/sync/errgroup"
 
 	"github.com/getcompanion-ai/computer-host/internal/firecracker"
+	"github.com/getcompanion-ai/computer-host/internal/httpapi"
 	"github.com/getcompanion-ai/computer-host/internal/model"
 	"github.com/getcompanion-ai/computer-host/internal/store"
 	contracthost "github.com/getcompanion-ai/computer-host/contract"
@@ -441,6 +442,37 @@ func (d *Daemon) GetSnapshot(ctx context.Context, snapshotID contracthost.Snapsh
 	return &contracthost.GetSnapshotResponse{Snapshot: snapshotToContract(*snap)}, nil
 }
 
+func (d *Daemon) GetSnapshotArtifact(ctx context.Context, snapshotID contracthost.SnapshotID, artifactID string) (*httpapi.SnapshotArtifactContent, error) {
+	snapshot, err := d.store.GetSnapshot(ctx, snapshotID)
+	if err != nil {
+		return nil, err
+	}
+	artifactID = strings.TrimSpace(artifactID)
+	if artifactID == "" {
+		return nil, fmt.Errorf("snapshot artifact id is required")
+	}
+	for _, artifact := range snapshot.Artifacts {
+		if artifact.ID != artifactID {
+			continue
+		}
+		path := strings.TrimSpace(artifact.LocalPath)
+		if path == "" {
+			return nil, fmt.Errorf("snapshot %q artifact %q not found", snapshotID, artifactID)
+		}
+		if _, err := os.Stat(path); err != nil {
+			if os.IsNotExist(err) {
+				return nil, fmt.Errorf("snapshot %q artifact %q not found", snapshotID, artifactID)
+			}
+			return nil, fmt.Errorf("stat snapshot %q artifact %q: %w", snapshotID, artifactID, err)
+		}
+		return &httpapi.SnapshotArtifactContent{
+			Name: artifact.Name,
+			Path: path,
+		}, nil
+	}
+	return nil, fmt.Errorf("snapshot %q artifact %q not found", snapshotID, artifactID)
+}
+
 func (d *Daemon) ListSnapshots(ctx context.Context, machineID contracthost.MachineID) (*contracthost.ListSnapshotsResponse, error) {
 	records, err := d.store.ListSnapshotsByMachine(ctx, machineID)
 	if err != nil {

internal/httpapi/handlers.go

@@ -23,6 +23,7 @@ type Service interface {
 	UploadSnapshot(context.Context, contracthost.SnapshotID, contracthost.UploadSnapshotRequest) (*contracthost.UploadSnapshotResponse, error)
 	ListSnapshots(context.Context, contracthost.MachineID) (*contracthost.ListSnapshotsResponse, error)
 	GetSnapshot(context.Context, contracthost.SnapshotID) (*contracthost.GetSnapshotResponse, error)
+	GetSnapshotArtifact(context.Context, contracthost.SnapshotID, string) (*SnapshotArtifactContent, error)
 	DeleteSnapshotByID(context.Context, contracthost.SnapshotID) error
 	RestoreSnapshot(context.Context, contracthost.SnapshotID, contracthost.RestoreSnapshotRequest) (*contracthost.RestoreSnapshotResponse, error)
 	CreatePublishedPort(context.Context, contracthost.MachineID, contracthost.CreatePublishedPortRequest) (*contracthost.CreatePublishedPortResponse, error)
@@ -30,6 +31,11 @@ type Service interface {
 	DeletePublishedPort(context.Context, contracthost.MachineID, contracthost.PublishedPortID) error
 }
 
+type SnapshotArtifactContent struct {
+	Name string
+	Path string
+}
+
 type Handler struct {
 	service Service
 }
@@ -298,6 +304,27 @@ func (h *Handler) handleSnapshot(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	if len(parts) == 3 && parts[1] == "artifacts" {
+		if r.Method != http.MethodGet {
+			writeMethodNotAllowed(w)
+			return
+		}
+		artifact, err := h.service.GetSnapshotArtifact(r.Context(), snapshotID, parts[2])
+		if err != nil {
+			writeError(w, statusForError(err), err)
+			return
+		}
+		if artifact == nil {
+			writeError(w, http.StatusNotFound, fmt.Errorf("snapshot artifact %q not found", parts[2]))
+			return
+		}
+		if artifact.Name != "" {
+			w.Header().Set("Content-Disposition", fmt.Sprintf("attachment; filename=%q", artifact.Name))
+		}
+		http.ServeFile(w, r, artifact.Path)
+		return
+	}
+
 	writeError(w, http.StatusNotFound, fmt.Errorf("route not found"))
 }