diff --git a/internal/authz/toolregistry/registry_test.go b/internal/authz/toolregistry/registry_test.go
new file mode 100644
index 0000000..de8d4cd
--- /dev/null
+++ b/internal/authz/toolregistry/registry_test.go
@@ -0,0 +1,146 @@
+package toolregistry
+
+import (
+	"context"
+	"errors"
+	"reflect"
+	"testing"
+
+	"github.com/evalops/asb/internal/core"
+)
+
+func TestPutRejectsMissingRequiredFields(t *testing.T) {
+	t.Parallel()
+
+	registry := New()
+
+	for _, tc := range []struct {
+		name string
+		tool core.Tool
+	}{
+		{
+			name: "missing tenant",
+			tool: core.Tool{
+				Tool: "github",
+			},
+		},
+		{
+			name: "missing tool",
+			tool: core.Tool{
+				TenantID: "tenant_123",
+			},
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			err := registry.Put(context.Background(), tc.tool)
+			if !errors.Is(err, core.ErrInvalidRequest) {
+				t.Fatalf("Put() error = %v, want ErrInvalidRequest", err)
+			}
+		})
+	}
+}
+
+func TestGetReturnsNotFoundForUnknownTool(t *testing.T) {
+	t.Parallel()
+
+	registry := New()
+
+	_, err := registry.Get(context.Background(), "tenant_123", "github")
+	if !errors.Is(err, core.ErrNotFound) {
+		t.Fatalf("Get() error = %v, want ErrNotFound", err)
+	}
+}
+
+func TestPutAndGetRoundTrip(t *testing.T) {
+	t.Parallel()
+
+	registry := New()
+	want := core.Tool{
+		TenantID:             "tenant_123",
+		Tool:                 "github",
+		ManifestHash:         "sha256:abc123",
+		RuntimeClass:         core.RuntimeClassHosted,
+		AllowedDeliveryModes: []core.DeliveryMode{core.DeliveryModeProxy},
+		AllowedCapabilities:  []string{"repo:read", "repo:write"},
+		EgressAllowlist:      []string{"api.github.com"},
+		LoggingMode:          "full",
+		TrustTags:            []string{"gitops"},
+	}
+
+	if err := registry.Put(context.Background(), want); err != nil {
+		t.Fatalf("Put() error = %v", err)
+	}
+
+	got, err := registry.Get(context.Background(), want.TenantID, want.Tool)
+	if err != nil {
+		t.Fatalf("Get() error = %v", err)
+	}
+	if got == nil {
+		t.Fatal("Get() returned nil tool")
+	}
+	if !reflect.DeepEqual(*got, want) {
+		t.Fatalf("Get() = %#v, want %#v", *got, want)
+	}
+}
+
+func TestGetReturnsCopy(t *testing.T) {
+	t.Parallel()
+
+	registry := New()
+	tool := core.Tool{
+		TenantID:     "tenant_123",
+		Tool:         "github",
+		ManifestHash: "sha256:abc123",
+	}
+
+	if err := registry.Put(context.Background(), tool); err != nil {
+		t.Fatalf("Put() error = %v", err)
+	}
+
+	got, err := registry.Get(context.Background(), tool.TenantID, tool.Tool)
+	if err != nil {
+		t.Fatalf("Get() error = %v", err)
+	}
+	got.ManifestHash = "sha256:mutated"
+
+	reloaded, err := registry.Get(context.Background(), tool.TenantID, tool.Tool)
+	if err != nil {
+		t.Fatalf("Get() reload error = %v", err)
+	}
+	if reloaded.ManifestHash != tool.ManifestHash {
+		t.Fatalf("reloaded ManifestHash = %q, want %q", reloaded.ManifestHash, tool.ManifestHash)
+	}
+}
+
+func TestPutOverwritesExistingEntry(t *testing.T) {
+	t.Parallel()
+
+	registry := New()
+	original := core.Tool{
+		TenantID:     "tenant_123",
+		Tool:         "github",
+		ManifestHash: "sha256:old",
+	}
+	updated := core.Tool{
+		TenantID:     "tenant_123",
+		Tool:         "github",
+		ManifestHash: "sha256:new",
+	}
+
+	if err := registry.Put(context.Background(), original); err != nil {
+		t.Fatalf("Put() original error = %v", err)
+	}
+	if err := registry.Put(context.Background(), updated); err != nil {
+		t.Fatalf("Put() updated error = %v", err)
+	}
+
+	got, err := registry.Get(context.Background(), updated.TenantID, updated.Tool)
+	if err != nil {
+		t.Fatalf("Get() error = %v", err)
+	}
+	if got.ManifestHash != updated.ManifestHash {
+		t.Fatalf("ManifestHash = %q, want %q", got.ManifestHash, updated.ManifestHash)
+	}
+}