fix(testrun): a run that judged nothing is not a green run

every step skipped means no property ever evaluated, so no violations is the
absence of a verdict rather than a clean one. the hold makes that reachable
now, so the run says it instead of exiting 0.

internal/testrun/testrun.go

@@ -242,7 +242,15 @@ func Execute(ctx context.Context, options Options, stdout io.Writer) error {
 // --exit-on-violation a run that found violations is still a successful run
 // (the summary reports them), which is the behaviour every existing caller
 // depends on.
+//
+// A run none of whose steps reached the verifier fails whatever the flags say,
+// because it holds no verdict to report. The threshold is every step and not a
+// fraction of them: a screen that composes now and then costs a healthy android
+// run a step or two, and a check that fired on those would be red on every run.
 func runOutcome(options Options, summary runner.Summary) error {
+	if summary.Steps > 0 && summary.SkippedVerification == summary.Steps {
+		return VacuousRunError{Steps: summary.Steps}
+	}
 	if options.ExitOnViolation && len(summary.Violations) > 0 {
 		return ViolationsError{Count: len(summary.Violations)}
 	}
@@ -261,6 +269,22 @@ func (e ViolationsError) Error() string {
 	return fmt.Sprintf("%d violation record(s)", e.Count)
 }
 
+// VacuousRunError reports a run in which no step reached the verifier, so no
+// property ever judged anything. It is not a clean run and it is not a found
+// bug: it is a run that produced no evidence either way, and the absence of
+// violations in it says nothing about the app. It stays untyped to the CLI's
+// violation path on purpose, so it exits 1 as a broken run rather than 2.
+type VacuousRunError struct {
+	Steps int
+}
+
+func (e VacuousRunError) Error() string {
+	return fmt.Sprintf(
+		"%d step(s) ran and none of them reached the verifier: the screen was "+
+			"still moving every time it was read, so no property judged this run",
+		e.Steps)
+}
+
 // bundleInputs holds the pre-driver assembly: alias map, seed, esbuild defines,
 // and the resolved spec-API/goja-runtime paths the bundler consumes.
 type bundleInputs struct {

internal/testrun/testrun_test.go

@@ -266,6 +266,31 @@ func TestRunOutcome_ReportsViolationsOnlyUnderTheFlag(t *testing.T) {
 	}
 }
 
+// A step the verifier skipped was judged by nothing, so a run whose every step
+// was skipped holds no verdict at all: "no violations" there is the absence of
+// an answer rather than a clean one. Reporting it as a successful run is the
+// green and vacuous outcome structuralShape's own design notes call worse than
+// the composition it catches, and the runner's hold is what makes a fully
+// skipped run reachable.
+func TestRunOutcome_ARunThatJudgedNothingIsNotASuccess(t *testing.T) {
+	nothingJudged := runner.Summary{Steps: 6, SkippedVerification: 6}
+	err := runOutcome(Options{}, nothingJudged)
+	var vacuous VacuousRunError
+	if !errors.As(err, &vacuous) {
+		t.Fatalf("a run that judged none of its 6 steps came back %v, want a VacuousRunError", err)
+	}
+	if vacuous.Steps != 6 {
+		t.Errorf("steps: got %d, want 6", vacuous.Steps)
+	}
+
+	// A screen that composes now and then costs a run steps, not its verdict. A
+	// check that fired here would turn every healthy android run red.
+	mostlyJudged := runner.Summary{Steps: 6, SkippedVerification: 5}
+	if err := runOutcome(Options{}, mostlyJudged); err != nil {
+		t.Errorf("a run that judged one of its 6 steps must succeed, got %v", err)
+	}
+}
+
 // wedgedLaunchDriver never returns from Launch, standing in for a driver whose
 // device-side session is stuck.
 type wedgedLaunchDriver struct {