diff --git a/cmd/uatu/main.go b/cmd/uatu/main.go
new file mode 100644
index 0000000..e5b42b4
--- /dev/null
+++ b/cmd/uatu/main.go
@@ -0,0 +1,97 @@
+package main
+
+import (
+	"errors"
+	"flag"
+	"fmt"
+	"io"
+	"os"
+	"time"
+)
+
+type testOptions struct {
+	spec     string
+	bundleID string
+	platform string
+	avd      string
+	duration time.Duration
+	seed     int64
+	output   string
+}
+
+const topUsage = `uatu is a property-based UI fuzzer for mobile apps.
+
+Usage:
+  uatu <command> [flags]
+
+Commands:
+  test     Run a spec against an app for a fixed duration.
+  doctor   Check that the host environment is ready to run uatu.
+
+Run "uatu <command> -h" for command-specific flags.
+`
+
+func parseTestArgs(args []string, stderr io.Writer) (testOptions, error) {
+	flagSet := flag.NewFlagSet("test", flag.ContinueOnError)
+	flagSet.SetOutput(stderr)
+	var options testOptions
+	flagSet.StringVar(&options.spec, "spec", "", "path to the TypeScript spec (required)")
+	flagSet.StringVar(&options.bundleID, "bundle-id", "", "target app bundle ID (required)")
+	flagSet.StringVar(&options.platform, "platform", "android", "target platform: android (ios deferred)")
+	flagSet.StringVar(&options.avd, "avd", "", "Android AVD name (required on android)")
+	flagSet.DurationVar(&options.duration, "duration", 5*time.Minute, "total test duration")
+	flagSet.Int64Var(&options.seed, "seed", 0, "RNG seed (0 = random)")
+	flagSet.StringVar(&options.output, "output", "./runs", "output directory for traces")
+	if err := flagSet.Parse(args); err != nil {
+		return testOptions{}, err
+	}
+	if options.spec == "" {
+		return testOptions{}, errors.New("--spec is required")
+	}
+	if options.bundleID == "" {
+		return testOptions{}, errors.New("--bundle-id is required")
+	}
+	if options.platform == "android" && options.avd == "" {
+		return testOptions{}, errors.New("--avd is required on android")
+	}
+	if options.platform != "android" {
+		return testOptions{}, fmt.Errorf("unsupported platform: %q (only android in v0.1)", options.platform)
+	}
+	return options, nil
+}
+
+func runTest(options testOptions, stdout io.Writer) error {
+	fmt.Fprintf(stdout, "uatu test (stub): %+v\n", options)
+	return nil
+}
+
+func runDoctor(stdout io.Writer) error {
+	fmt.Fprintln(stdout, "uatu doctor (stub): all checks pending implementation")
+	return nil
+}
+
+func run(args []string, stdout, stderr io.Writer) error {
+	if len(args) < 2 || args[1] == "-h" || args[1] == "--help" || args[1] == "help" {
+		fmt.Fprint(stdout, topUsage)
+		return nil
+	}
+	switch args[1] {
+	case "test":
+		options, err := parseTestArgs(args[2:], stderr)
+		if err != nil {
+			return err
+		}
+		return runTest(options, stdout)
+	case "doctor":
+		return runDoctor(stdout)
+	default:
+		return fmt.Errorf("unknown command: %q (try 'uatu help')", args[1])
+	}
+}
+
+func main() {
+	if err := run(os.Args, os.Stdout, os.Stderr); err != nil {
+		fmt.Fprintf(os.Stderr, "error: %v\n", err)
+		os.Exit(1)
+	}
+}
diff --git a/cmd/uatu/main_test.go b/cmd/uatu/main_test.go
new file mode 100644
index 0000000..d3cc76f
--- /dev/null
+++ b/cmd/uatu/main_test.go
@@ -0,0 +1,129 @@
+package main
+
+import (
+	"bytes"
+	"io"
+	"strings"
+	"testing"
+	"time"
+)
+
+func TestParseTestArgs_Defaults(t *testing.T) {
+	options, err := parseTestArgs([]string{
+		"--spec", "s.ts",
+		"--bundle-id", "com.example",
+		"--avd", "Pixel_5_API_33",
+	}, io.Discard)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if options.spec != "s.ts" || options.bundleID != "com.example" {
+		t.Errorf("unexpected options: %+v", options)
+	}
+	if options.platform != "android" {
+		t.Errorf("platform default: got %q, want android", options.platform)
+	}
+	if options.duration != 5*time.Minute {
+		t.Errorf("duration default: got %v, want 5m", options.duration)
+	}
+	if options.output != "./runs" {
+		t.Errorf("output default: got %q, want ./runs", options.output)
+	}
+	if options.seed != 0 {
+		t.Errorf("seed default: got %d, want 0", options.seed)
+	}
+}
+
+func TestParseTestArgs_AllFlags(t *testing.T) {
+	options, err := parseTestArgs([]string{
+		"--spec", "s.ts",
+		"--bundle-id", "com.example",
+		"--platform", "android",
+		"--avd", "Pixel_5_API_33",
+		"--duration", "10m",
+		"--seed", "42",
+		"--output", "./out",
+	}, io.Discard)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if options.avd != "Pixel_5_API_33" || options.duration != 10*time.Minute || options.seed != 42 || options.output != "./out" {
+		t.Errorf("unexpected options: %+v", options)
+	}
+}
+
+func TestParseTestArgs_RequiresSpec(t *testing.T) {
+	_, err := parseTestArgs([]string{"--bundle-id", "com.example", "--avd", "x"}, io.Discard)
+	if err == nil || !strings.Contains(err.Error(), "--spec") {
+		t.Fatalf("expected missing --spec error, got %v", err)
+	}
+}
+
+func TestParseTestArgs_RequiresBundleID(t *testing.T) {
+	_, err := parseTestArgs([]string{"--spec", "s.ts", "--avd", "x"}, io.Discard)
+	if err == nil || !strings.Contains(err.Error(), "--bundle-id") {
+		t.Fatalf("expected missing --bundle-id error, got %v", err)
+	}
+}
+
+func TestParseTestArgs_RequiresAVDOnAndroid(t *testing.T) {
+	_, err := parseTestArgs([]string{"--spec", "s.ts", "--bundle-id", "com.example"}, io.Discard)
+	if err == nil || !strings.Contains(err.Error(), "--avd") {
+		t.Fatalf("expected missing --avd error, got %v", err)
+	}
+}
+
+func TestParseTestArgs_RejectsNonAndroidPlatform(t *testing.T) {
+	_, err := parseTestArgs([]string{
+		"--spec", "s.ts",
+		"--bundle-id", "com.example",
+		"--platform", "ios",
+		"--avd", "x",
+	}, io.Discard)
+	if err == nil || !strings.Contains(err.Error(), "unsupported platform") {
+		t.Fatalf("expected unsupported-platform error, got %v", err)
+	}
+}
+
+func TestRun_HelpPrintsUsage(t *testing.T) {
+	var stdout bytes.Buffer
+	if err := run([]string{"uatu"}, &stdout, io.Discard); err != nil {
+		t.Fatal(err)
+	}
+	if !strings.Contains(stdout.String(), "uatu <command>") {
+		t.Errorf("usage missing, got: %q", stdout.String())
+	}
+}
+
+func TestRun_UnknownCommand(t *testing.T) {
+	err := run([]string{"uatu", "wat"}, io.Discard, io.Discard)
+	if err == nil || !strings.Contains(err.Error(), "unknown command") {
+		t.Fatalf("expected unknown-command error, got %v", err)
+	}
+}
+
+func TestRun_Doctor(t *testing.T) {
+	var stdout bytes.Buffer
+	if err := run([]string{"uatu", "doctor"}, &stdout, io.Discard); err != nil {
+		t.Fatal(err)
+	}
+	if !strings.Contains(stdout.String(), "doctor") {
+		t.Errorf("doctor output missing, got: %q", stdout.String())
+	}
+}
+
+func TestRun_TestSubcommand(t *testing.T) {
+	var stdout bytes.Buffer
+	err := run([]string{
+		"uatu", "test",
+		"--spec", "s.ts",
+		"--bundle-id", "com.example",
+		"--avd", "Pixel_5_API_33",
+	}, &stdout, io.Discard)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !strings.Contains(stdout.String(), "uatu test (stub)") {
+		t.Errorf("test stub output missing, got: %q", stdout.String())
+	}
+}