research: compare Jev intent state with the previous turn

V0 on the existing 157 real rows matches the 09-19 cache. The staging extract has no case linkage, so V1/V2 are unmeasured and the verdict stays 缺数据.

tests/test_jev_intent_research.py

@@ -17,6 +17,7 @@ from scripts.research.jev_intent_corpus_build import (  # noqa: E402
     source_a_samples,
 )
 from scripts.research.jev_intent_questions import (
+    CONTINUES_PREVIOUS_TURN_INSTRUCTIONS,
     CRITERION_MAP,
     INTENT_CRITERIA,
     LOST_SEMANTICS,
@@ -25,6 +26,7 @@ from scripts.research.jev_intent_questions import (
     enforce_combo,
     parse_jev_answers,
 )
+from scripts.research.jev_intent_source_b_v2 import attach_previous_turns
 
 ROOT = Path(__file__).resolve().parents[1]
 
@@ -70,6 +72,95 @@ class JevIntentQuestionsTests(unittest.TestCase):
         self.assertEqual(parsed["confidence"], 0.9)
 
 
+class JevIntentPreviousTurnTests(unittest.TestCase):
+    def test_v1_v2_state_shape_keeps_v0_questions(self) -> None:
+        sample = dict(source_a_samples()[0])
+        sample["previous_turn"] = {"assistant_message": "上一问", "user_message": "上一句"}
+        sample["previous_decision"] = {"intent": "unclear", "answer_class": None}
+        v0 = build_state(sample, variant="v0")
+        self.assertEqual(set(v0), {"current_question", "options", "user_message", "case_status"})
+        v1 = build_state(sample, variant="v1")
+        self.assertEqual(v1["previous_turn"], {"assistant_message": "上一问", "user_message": "上一句"})
+        self.assertNotIn("previous_decision", v1)
+        v2 = build_state(sample, variant="v2")
+        self.assertEqual(v2["previous_decision"], {"intent": "unclear", "answer_class": None})
+        v0_questions = build_questions(sample)
+        v2_questions = build_questions(sample, variant="v2")
+        self.assertNotIn("continues_previous_turn", v0_questions)
+        self.assertEqual(set(v0_questions["intent"]["criteria"]), set(v2_questions["intent"]["criteria"]))
+        self.assertEqual(v2_questions["continues_previous_turn"]["type"], "noul")
+        self.assertEqual(
+            v2_questions["continues_previous_turn"]["instructions"],
+            CONTINUES_PREVIOUS_TURN_INSTRUCTIONS,
+        )
+
+    def test_continues_rule_adopts_previous_intent_only_at_threshold(self) -> None:
+        answers = {
+            "intent": {"choice": "answer_current_focus", "confidence": 0.95, "probabilities": {}},
+            "answer_class": {"choice": "yes", "confidence": 0.91, "probabilities": {}},
+            "has_new_dated_event": {"noul": 0.1},
+            "continues_previous_turn": {"noul": 0.9},
+        }
+        adopted = parse_jev_answers(
+            answers,
+            previous_decision={"intent": "unclear", "answer_class": None},
+            apply_continue=True,
+        )
+        self.assertEqual(adopted["intent"], "unclear")
+        self.assertIsNone(adopted["answer_class"])
+        self.assertTrue(adopted["continued"])
+        self.assertEqual(adopted["confidence"], 0.9)
+        kept = parse_jev_answers(
+            {**answers, "continues_previous_turn": {"noul": 0.89}},
+            previous_decision={"intent": "stop_rectification", "answer_class": None},
+            apply_continue=True,
+        )
+        self.assertEqual(kept["intent"], "answer_current_focus")
+        self.assertEqual(kept["answer_class"], "yes")
+        self.assertFalse(kept["continued"])
+        focused = parse_jev_answers(
+            answers,
+            previous_decision={"intent": "answer_current_focus", "answer_class": "no"},
+            apply_continue=True,
+        )
+        self.assertEqual(focused["intent"], "answer_current_focus")
+        self.assertEqual(focused["answer_class"], "no")
+
+    def test_case_first_turn_previous_turn_is_null(self) -> None:
+        rows = attach_previous_turns([
+            {
+                "id": "first",
+                "case_id": "case-1",
+                "created_at": "2026-09-01T00:00:00Z",
+                "user_message": "第一句",
+                "assistant_message": "第一答",
+            },
+            {
+                "id": "second",
+                "case_id": "case-1",
+                "created_at": "2026-09-01T00:01:00Z",
+                "user_message": "继续",
+                "assistant_message": "第二答",
+            },
+            {
+                "id": "orphan",
+                "user_message": "没有案件",
+                "assistant_message": "答",
+            },
+        ])
+        by_id = {row["id"]: row for row in rows}
+        self.assertIsNone(by_id["first"]["previous_turn"])
+        self.assertEqual(by_id["first"]["previous_turn_source"], "case_first")
+        self.assertEqual(by_id["second"]["previous_turn"], {
+            "assistant_message": "第一答",
+            "user_message": "第一句",
+        })
+        self.assertIsNone(by_id["orphan"]["previous_turn"])
+        state = build_state(by_id["first"], variant="v1")
+        self.assertIsNone(state["previous_turn"])
+        self.assertIn("user_message", state)
+
+
 class JevIntentCorpusTests(unittest.TestCase):
     def test_source_a_has_ten_labeled_rows(self) -> None:
         rows = source_a_samples()