fix(cefr): resolve authentic context sentence per term and repair legacy SRS cards

- Add resolve_context_sentence_for_term to replace placeholder blanks and lookup authentic sentences from cefr_questions or books
- Fix dual mistake ingestion in process_cefr_answer to assign distinct context to target and chosen distractor
- Provide authentic context_sentence in options_breakdown and pass it via data-context in cefr.js
- Add repair_mismatched_cefr_contexts in database.py to automatically repair cards with placeholder blanks
- Bump Service Worker cache to notes-v5.9
- Add test_cefr_context_resolution_and_repair covering resolution, dual ingestion, manual add, and DB repair

tests/test_api.py

@@ -1756,6 +1756,118 @@ Authors' Addresses
     assert rfc_books[0]["id"] == book_id
 
 
+def test_cefr_context_resolution_and_repair():
+    from app.cefr import resolve_context_sentence_for_term, process_cefr_answer, ingest_cefr_word
+    from app.database import repair_mismatched_cefr_contexts
+
+    with get_db() as conn:
+        # 1. Test resolve_context_sentence_for_term
+        # Case A: candidate has the term and placeholder '___'
+        res_a = resolve_context_sentence_for_term(
+            conn,
+            "decision",
+            "Choosing a career path is a major life ___."
+        )
+        assert res_a == "Choosing a career path is a major life decision."
+        assert "___" not in res_a
+
+        # Case B: candidate does NOT match the term, term exists in cefr_questions
+        res_b = resolve_context_sentence_for_term(
+            conn,
+            "opportunity",
+            "Choosing a career path is a major life ___."
+        )
+        assert "opportunity" in res_b.lower()
+        assert "career path" not in res_b
+        assert "___" not in res_b
+
+        # 2. Test process_cefr_answer mistake ingestion
+        # Seed test user
+        user_row = conn.execute("SELECT id FROM users WHERE username = 'testadmin'").fetchone()
+        if not user_row:
+            create_user("testadmin", "testpass12345")
+            user_row = conn.execute("SELECT id FROM users WHERE username = 'testadmin'").fetchone()
+        assert user_row is not None
+        user_id = user_row["id"]
+
+        # Find or create a question for 'decision'
+        q = conn.execute(
+            "SELECT id, level, term, sentence, options_json FROM cefr_questions WHERE term = 'decision' LIMIT 1"
+        ).fetchone()
+        if not q:
+            conn.execute(
+                """
+                INSERT INTO cefr_questions (level, term, translation, sentence, options_json, explanation)
+                VALUES ('B1', 'decision', 'решение', 'Choosing a career path is a major life ___.', '["decision", "opportunity", "behavior", "relationship"]', 'Major decision.')
+                """
+            )
+            q = conn.execute("SELECT id, level, term, sentence, options_json FROM cefr_questions WHERE term = 'decision' LIMIT 1").fetchone()
+
+        result = process_cefr_answer(conn, user_id, q["id"], "opportunity")
+        assert result["correct"] is False
+        assert result["correct_option"] == "decision"
+        assert result["selected_option"] == "opportunity"
+
+        # Check options_breakdown has distinct authentic context sentences
+        breakdown = result["options_breakdown"]
+        assert len(breakdown) == 4
+        for item in breakdown:
+            assert "context_sentence" in item
+            assert "___" not in item["context_sentence"]
+            assert item["term"].lower() in item["context_sentence"].lower()
+
+        # Check vocabulary_cards in DB:
+        target_card = conn.execute(
+            "SELECT * FROM vocabulary_cards WHERE user_id = ? AND lower(term) = 'decision'",
+            (user_id,)
+        ).fetchone()
+        assert target_card is not None
+        assert "decision" in target_card["context_sentence"].lower()
+        assert "___" not in target_card["context_sentence"]
+
+        chosen_card = conn.execute(
+            "SELECT * FROM vocabulary_cards WHERE user_id = ? AND lower(term) = 'opportunity'",
+            (user_id,)
+        ).fetchone()
+        assert chosen_card is not None
+        assert "opportunity" in chosen_card["context_sentence"].lower()
+        assert "career path" not in chosen_card["context_sentence"]
+        assert "___" not in chosen_card["context_sentence"]
+
+        # 3. Test ingest_cefr_word
+        added_word = ingest_cefr_word(
+            conn,
+            user_id=user_id,
+            level="B1",
+            term="behavior",
+            context_sentence="Choosing a career path is a major life ___."
+        )
+        assert added_word["term"] == "behavior"
+        assert "behavior" in added_word["context_sentence"].lower()
+        assert "career path" not in added_word["context_sentence"]
+        assert "___" not in added_word["context_sentence"]
+
+        # 4. Test repair_mismatched_cefr_contexts
+        # Insert a card with corrupted blank
+        conn.execute("DELETE FROM vocabulary_cards WHERE user_id = ? AND lower(term) = 'negotiate'", (user_id,))
+        conn.execute(
+            """
+            INSERT INTO vocabulary_cards (user_id, term, translation, context_sentence, tags)
+            VALUES (?, 'negotiate', 'вести переговоры', 'With persistent practice, you can ___ fluency in English.', 'cefr-test')
+            """,
+            (user_id,)
+        )
+        corrupted = conn.execute("SELECT context_sentence FROM vocabulary_cards WHERE user_id = ? AND term = 'negotiate'", (user_id,)).fetchone()
+        assert "___" in corrupted["context_sentence"]
+
+        repair_mismatched_cefr_contexts(conn)
+
+        repaired = conn.execute("SELECT context_sentence FROM vocabulary_cards WHERE user_id = ? AND term = 'negotiate'", (user_id,)).fetchone()
+        assert "___" not in repaired["context_sentence"]
+        assert "negotiate" in repaired["context_sentence"].lower()
+
+
+