/trace grows a turn-decisions table under the rule trace (V-564)

Both tables answer the same question, who won and who lost, one about nudges
and the other about utterances, so they share a page rather than splitting the
nav. A turn is one collapsible row; never_asked is coloured like a block,
because it usually is one. A read failure is logged and the rule trace above it
still renders: a daemon too old to know the method is the ordinary case during
a rolling deploy.

cmd/mavweb/handlers_test.go

@@ -65,6 +65,7 @@ type fakeCore struct {
 	// for handleTrace tests
 	tickTrace ipc.TickTrace
 	traceErr  error
+	turns     []ipc.TurnDecision
 
 	// for handleChatAPI tests
 	chatText   string
@@ -173,6 +174,10 @@ func (f *fakeCore) RevertFact(_ context.Context, key string) (int64, error) {
 	return f.revertNewID, nil
 }
 
+func (f *fakeCore) TurnDecisions(_ context.Context, _ int) ([]ipc.TurnDecision, error) {
+	return f.turns, nil
+}
+
 func (f *fakeCore) TickTrace(_ context.Context) (ipc.TickTrace, error) {
 	if f.traceErr != nil {
 		return ipc.TickTrace{}, f.traceErr
@@ -825,6 +830,41 @@ func TestHandleTrace(t *testing.T) {
 			t.Error("rendered 'nothing fired' but a winner was set")
 		}
 	})
+
+	// The turn arbitration shares this page (V-564). A reader must see the
+	// winner, a loser and the claimants that were never asked, because the last
+	// of those is what the hardcoded ordering hides.
+	t.Run("renders the turn decision record", func(t *testing.T) {
+		core := &fakeCore{turns: []ipc.TurnDecision{{
+			Ts:        time.Date(2025, 6, 1, 12, 0, 0, 0, time.UTC),
+			Utterance: "какая погода в риме",
+			Winner:    "query:weather",
+			Claims: []ipc.TurnClaim{
+				{Stage: "query", Claimant: "weather", Intent: "query", Outcome: "won"},
+				{Stage: "query", Claimant: "calendar", Outcome: "declined", Reason: "no answer"},
+				{Stage: "query", Claimant: "kiwix", Outcome: "never_asked"},
+			},
+		}}}
+		rr := httptest.NewRecorder()
+		handleTrace(rr, httptest.NewRequest(http.MethodGet, "/trace", nil), core)
+		body := rr.Body.String()
+		for _, want := range []string{"какая погода в риме", "query:weather", "calendar", "kiwix", "never_asked"} {
+			if !strings.Contains(body, want) {
+				t.Errorf("rendered page is missing %q", want)
+			}
+		}
+	})
+
+	t.Run("no turns renders the empty note, not an error", func(t *testing.T) {
+		rr := httptest.NewRecorder()
+		handleTrace(rr, httptest.NewRequest(http.MethodGet, "/trace", nil), &fakeCore{})
+		if rr.Code != http.StatusOK {
+			t.Fatalf("status = %d, want 200", rr.Code)
+		}
+		if !strings.Contains(rr.Body.String(), "no turn has run") {
+			t.Error("empty ring did not render its note")
+		}
+	})
 }
 
 // --- handleRevert ---