feat(uploads): an auto-language job is planned without the engines it never runs (#61)

PlanFor(lang) on the Ensemble and a LanguagePlanner the worker prefers: the page lists
the other engine (and the fallback if configured), not the base engine, the comparison and
the decisions as coming. Found by the PR #62 review.

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

internal/uploads/worker_progress_test.go

@@ -213,3 +213,47 @@ func TestWorkerProgress_AStoreFailureLogsItsSQLStateNeverTheValueItQuotes(t *tes
 	assert.Contains(t, out, "upload: store transcript")
 	assert.Contains(t, out, "kind=sql_22P02")
 }
+
+// langPlannedTr plans per language, like the Ensemble: an auto job has no base engine.
+type langPlannedTr struct{ *fakeTranscriber }
+
+func (langPlannedTr) Plan() []progress.Planned { return plannedTr{}.Plan() }
+func (langPlannedTr) PlanFor(l domain.Language) []progress.Planned {
+	if l == domain.LangAuto {
+		return []progress.Planned{{Key: "engine_b", Label: "Transcribing with B"}}
+	}
+	return plannedTr{}.Plan()
+}
+
+func (p langPlannedTr) Transcribe(ctx context.Context, wav string) (domain.Transcription, error) {
+	r := progress.From(ctx)
+	if domain.LanguageFrom(ctx) != domain.LangAuto {
+		r.Begin("engine_a", 0)
+		r.Done("engine_a")
+	}
+	r.Begin("engine_b", 0)
+	r.Done("engine_b")
+	return p.fakeTranscriber.Transcribe(ctx, wav)
+}
+
+func TestWorkerProgress_AJobGetsThePlanOfItsLanguage(t *testing.T) {
+	for name, tt := range map[string]struct {
+		lang domain.Language
+		want []string
+	}{
+		"auto":    {domain.LangAuto, []string{"received:done", "audio:done", "engine_b:done", "save:done"}},
+		"swedish": {domain.LangSwedish, []string{"received:done", "audio:done", "engine_a:done", "engine_b:done", "save:done"}},
+		"no language (queued before the choice existed)": {"", []string{"received:done", "audio:done", "engine_a:done", "engine_b:done", "save:done"}},
+	} {
+		t.Run(name, func(t *testing.T) {
+			r := newWRig(t, time.Minute)
+			w := newProgressWorker(t, r, langPlannedTr{r.tr})
+			job := r.spool(t, "a")
+			job.Language = tt.lang
+
+			w.Process(context.Background(), job)
+
+			assert.Equal(t, tt.want, keysAndStates(r.st.lastSteps()))
+		})
+	}
+}