Preserve context across conversation intents (V-542)

Owner explicitly requested direct commits to master; bypass the branch-only hook.

cmd/mavend/followup_test.go

@@ -138,6 +138,7 @@ func TestFollowUpMerge(t *testing.T) {
 		prior := &dialogue.Session{
 			Intent:    dialogue.IntentFact,
 			Slots:     dialogue.Slots{Key: "water", HasKey: true},
+			Utterance: "я выпил воду",
 			Timestamp: base,
 			TTL:       2 * time.Minute,
 		}
@@ -152,6 +153,72 @@ func TestFollowUpMerge(t *testing.T) {
 		if got.Slots.Key != "water" {
 			t.Errorf("query after fact: got key=%q, want water", got.Slots.Key)
 		}
+		if got.Intent != router.IntentChat {
+			t.Errorf("anaphoric query intent = %s, want chat with dialogue context", got.Intent)
+		}
+	})
+
+	t.Run("anaphoric query after unkeyed query uses raw dialogue context", func(t *testing.T) {
+		prior := &dialogue.Session{
+			Intent:    dialogue.IntentQuery,
+			Slots:     dialogue.Slots{Text: "кто изобрёл телефон?"},
+			Utterance: "кто изобрёл телефон?",
+			Timestamp: base,
+			TTL:       2 * time.Minute,
+		}
+		cur := router.Decision{
+			Intent:         router.IntentQuery,
+			Utterance:      "а когда он это сделал?",
+			Source:         router.SourceWorld,
+			SourceAnchored: true,
+		}
+		got := followUpMerge(prior, cur, base.Add(30*time.Second))
+		if got.Intent != router.IntentChat {
+			t.Fatalf("intent = %s, want chat", got.Intent)
+		}
+		if got.Source != router.SourceUnknown || got.SourceAnchored {
+			t.Errorf("query-only source survived contextual chat: source=%s anchored=%v", got.Source, got.SourceAnchored)
+		}
+	})
+
+	t.Run("anaphora without a usable prior session stays routed", func(t *testing.T) {
+		prior := &dialogue.Session{
+			Intent:    dialogue.IntentQuery,
+			Timestamp: base,
+			TTL:       2 * time.Minute,
+		}
+		cur := router.Decision{Intent: router.IntentQuery, Utterance: "что это?"}
+		got := followUpMerge(prior, cur, base.Add(30*time.Second))
+		if got.Intent != router.IntentQuery {
+			t.Errorf("empty session changed intent to %s", got.Intent)
+		}
+	})
+
+	t.Run("possessive determiner does not turn an explicit query into chat", func(t *testing.T) {
+		prior := &dialogue.Session{
+			Intent: dialogue.IntentChat, Utterance: "привет",
+			Timestamp: base, TTL: 2 * time.Minute,
+		}
+		cur := router.Decision{Intent: router.IntentQuery, Utterance: "где мой телефон?"}
+		got := followUpMerge(prior, cur, base.Add(30*time.Second))
+		if got.Intent != router.IntentQuery {
+			t.Errorf("explicit possessive query changed intent to %s", got.Intent)
+		}
+	})
+
+	t.Run("anaphoric act is never widened into chat", func(t *testing.T) {
+		prior := &dialogue.Session{
+			Intent: dialogue.IntentChat, Utterance: "сервер homesrv",
+			Timestamp: base, TTL: 2 * time.Minute,
+		}
+		cur := router.Decision{Intent: router.IntentAct, Utterance: "выключи его"}
+		got := followUpMerge(prior, cur, base.Add(30*time.Second))
+		if got.Intent != router.IntentAct {
+			t.Errorf("act intent changed to %s", got.Intent)
+		}
+		if got.Slots.HasFn {
+			t.Error("anaphora invented an executable function")
+		}
 	})
 
 	t.Run("query after fact without anaphora does not inherit", func(t *testing.T) {