feat(cmd): add --generator llm|seeded flag

cmd/sanderling/main.go

@@ -30,6 +30,7 @@ type testOptions struct {
 	seed           int64
 	output         string
 	clearData      bool
+	generator      string
 }
 
 const topUsage = `sanderling is a property-based UI fuzzer for mobile apps.
@@ -62,6 +63,7 @@ func parseTestArgs(args []string, stderr io.Writer) (testOptions, error) {
 	flagSet.Int64Var(&options.seed, "seed", 0, "RNG seed (0 = random)")
 	flagSet.StringVar(&options.output, "output", "./runs", "output directory for traces")
 	flagSet.BoolVar(&options.clearData, "clear-data", true, "clear app data before launching so each run starts from a fresh install; pass --clear-data=false to resume prior state")
+	flagSet.StringVar(&options.generator, "generator", "seeded", "action generator: seeded (weighted random) or llm (model picks from the same candidate set; requires generator = llm() in the spec)")
 	if err := flagSet.Parse(args); err != nil {
 		return testOptions{}, err
 	}
@@ -76,6 +78,11 @@ func parseTestArgs(args []string, stderr io.Writer) (testOptions, error) {
 	default:
 		return testOptions{}, fmt.Errorf("unsupported platform: %q (android, ios, web)", options.platform)
 	}
+	switch options.generator {
+	case "seeded", "llm":
+	default:
+		return testOptions{}, fmt.Errorf("unsupported generator: %q (seeded, llm)", options.generator)
+	}
 	return options, nil
 }
 

cmd/sanderling/test_run.go

@@ -21,5 +21,6 @@ func runTestPipeline(ctx context.Context, options testOptions, stdout io.Writer)
 		Seed:           options.seed,
 		Output:         options.output,
 		ClearData:      options.clearData,
+		Generator:      options.generator,
 	}, stdout)
 }

internal/testrun/testrun.go

@@ -34,6 +34,8 @@ type Options struct {
 	Seed           int64
 	Output         string
 	ClearData      bool
+	// Generator selects the action picker: "llm" or the default seeded picker.
+	Generator string
 
 	// iosUDID, iosIsSimulator, and iosCoreDeviceID are filled by Execute after
 	// resolving the iOS target, then read by buildDriver to choose the simulator
@@ -166,6 +168,7 @@ func Execute(ctx context.Context, options Options, stdout io.Writer) error {
 		Verifier:    verifierInstance,
 		TraceWriter: traceWriter,
 		Logger:      newProgressLogger(stdout),
+		Generator:   options.Generator,
 	})
 
 	terminateCtx, terminateCancel := context.WithTimeout(context.Background(), 5*time.Second)