test(transcribe): a shutdown in the middle of either engine stops the job

Mutation-testing showed each of the two cancellation checks was redundant with the
other in my first test. Now a cancel during the first engine must not start the second
or the cloud, and a cancel during the second must not be recorded as a single-engine
success ('kb-whisper failed').

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

internal/adapters/transcribe/ensemble_test.go

@@ -164,3 +164,43 @@ func TestEnsemble_AModelThatIsDownGivesTheBaseTextUnreconciledNotAFailedJob(t *t
 	assert.Equal(t, domain.ReconcileSkipped, got.Reconciliation.Status)
 	assert.Equal(t, 3, adj.calls)
 }
+
+// cancelling is a backend that cancels the job's context while it runs, the way a
+// shutdown arrives in the middle of a long transcription.
+type cancelling struct {
+	name   string
+	cancel context.CancelFunc
+	calls  *[]string
+}
+
+func (c *cancelling) Name() string { return c.name }
+func (c *cancelling) Transcribe(_ context.Context, _ string) (domain.Transcription, error) {
+	*c.calls = append(*c.calls, c.name)
+	c.cancel()
+	return domain.Transcription{}, context.Canceled
+}
+
+func TestEnsemble_AShutdownDuringTheFirstEngineStopsBeforeTheSecondOrTheCloud(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	calls := &[]string{}
+	base := &cancelling{name: "iguana/pianissimo", cancel: cancel, calls: calls}
+	alt := &orderedBackend{name: "iguana/kb-whisper", text: "alt", calls: calls}
+	fb := &orderedBackend{name: "berget/kb-whisper", text: "fb", calls: calls}
+
+	_, err := transcribe.NewEnsemble(base, alt, fb, &verdictAdj{}, ensembleOpts).Transcribe(ctx, "/a.wav")
+
+	assert.ErrorIs(t, err, context.Canceled)
+	assert.Equal(t, []string{"iguana/pianissimo"}, *calls, "no second engine and no cloud once the job is cancelled")
+}
+
+func TestEnsemble_AShutdownDuringTheSecondEngineIsAnErrorNotASingleEngineSuccess(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	calls := &[]string{}
+	base := &orderedBackend{name: "iguana/pianissimo", text: "base", calls: calls}
+	alt := &cancelling{name: "iguana/kb-whisper", cancel: cancel, calls: calls}
+
+	got, err := transcribe.NewEnsemble(base, alt, nil, &verdictAdj{}, ensembleOpts).Transcribe(ctx, "/a.wav")
+
+	assert.ErrorIs(t, err, context.Canceled, "a cancelled job must not be recorded as 'kb-whisper failed'")
+	assert.Empty(t, got.Text)
+}