feat(narayana-rath): flag Wadiyar pairs as book_software_rule8_exception (BUG-1226)

Round-6 ruling Q6b: Table 25 Gemini/Sagittarius and Virgo/Pisces are the
book software's seventh-level Rule 8 special case; keep the general result
(Sagittarius, Pisces at level 5), every Rath output carries the note
(known_book_differences), test pins the two pairs.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N4f2nya58RoRu4yEmJgRGE

scripts/narayana_rath.py

@@ -96,6 +96,26 @@ BOOK_EXAMPLES = {
                      "stronger than Cancer. Audit docs/research/shared_engine_reuse_audit_2026_10_03.md N1."),
     },
 }
+# Book software verdicts the general rule does not follow (round-6 ruling
+# Q6b, BUG-1226): Table 25 (Krishnaraja Wadiyar IV) takes Gemini over
+# Sagittarius and Virgo over Pisces; the seven general levels decide
+# Sagittarius / Pisces at level 5 (Mercury 1.3 deg vs Jupiter 10.0 deg). Only
+# the book software's Rule 8 at the seventh level separates them that way — a
+# software special case. The general result is kept and every output carries
+# this note.
+BOOK_SOFTWARE_RULE8 = "book_software_rule8_exception"
+BOOK_SOFTWARE_DIFFERENCES = {
+    BOOK_SOFTWARE_RULE8: {
+        "book_table": "Table 25",
+        "pairs": [{"book": "Gemini", "general_rule": "Sagittarius", "general_level": 5},
+                  {"book": "Virgo", "general_rule": "Pisces", "general_level": 5}],
+        "kept": "general_rule",
+        "note": "原书软件判定差异：原书软件用第 7 级 Rule 8 取双子、处女；通则第 5 级取射手、双鱼，保持通则",
+        "note_en": ("Book software verdict differs: the book's software used Rule 8 at the seventh level to take "
+                    "Gemini and Virgo; the general rule takes Sagittarius and Pisces at level 5 and is kept"),
+        "ruling": "astrologer round 6, 2026-10-04, Q6b (p.36, p.95)",
+    },
+}
 KETU_FIRST_NOTE = "PyJHora 兼容：计都优先"
 KETU_FIRST_NOTE_EN = "PyJHora-compatible: Ketu takes precedence"
 SOURCE = {
@@ -461,6 +481,7 @@ def calc_narayana_rath(lagna_sign_idx: int, planet_lons: Dict[str, float],
         "source": SOURCE,
         "lagna_sign": SIGNS[lagna_sign_idx],
         "antardasha_start_rule": "stronger_of_md_sign_and_seventh_then_its_lord_sign (p.48, p.50 note 2)",
+        "known_book_differences": BOOK_SOFTWARE_DIFFERENCES,
     }
     if seed_sign_idx is not None:
         selection = {"status": "explicit", "selected_sign_idx": seed_sign_idx,

tests/test_narayana_rath_book_tables.py

@@ -164,7 +164,9 @@ VERDICT_TABLES = {
 # Expected misses, documented: Wadiyar Gemini/Sagittarius and Virgo/Pisces —
 # the book takes Gemini and Virgo; the general rule decides at level 5
 # (Mercury 1.3 deg vs Jupiter 10.0 deg) for Sagittarius and Pisces. Not
-# sensitive to node mode or ayanamsa (audit). Open question to the astrologer.
+# sensitive to node mode or ayanamsa (audit). Round-6 ruling Q6b: the book's
+# software used Rule 8 at the seventh level — a software special case; keep
+# the general result, flagged `book_software_rule8_exception` (BUG-1226).
 EXPECTED_SIGN_MISSES = {("Table 25", "Gemini", "Sagittarius"), ("Table 25", "Virgo", "Pisces")}
 # Dual lords (Aquarius, Scorpio): book Table 23 Aquarius = Saturn (ours Rahu),
 # Table 25 Scorpio = Ketu (ours Mars).
@@ -264,3 +266,22 @@ def test_table25_taurus_md_is_the_saturn_exception_and_carries_the_book_divergen
     assert rule["direction"]["direction"] == "zodiacal"
     p47, js = rule["direction"]["book_divergence"]
     assert (p47["direction"], p47["differs"]) == ("reverse", True)  # Taurus is even: p.47 would run the ADs backwards
+
+
+def test_wadiyar_pairs_are_the_flagged_book_software_rule8_exception() -> None:
+    """Round-6 ruling Q6b (BUG-1226): the two Table 25 misses are exactly the
+    registered `book_software_rule8_exception` pairs; the general result is
+    kept and the note travels with every Rath output."""
+    from scripts.narayana_rath import BOOK_SOFTWARE_DIFFERENCES, BOOK_SOFTWARE_RULE8, compare_signs
+
+    entry = BOOK_SOFTWARE_DIFFERENCES[BOOK_SOFTWARE_RULE8]
+    assert BOOK_SOFTWARE_RULE8 == "book_software_rule8_exception"
+    flagged = {(entry["book_table"], pair["book"], pair["general_rule"]) for pair in entry["pairs"]}
+    assert flagged == EXPECTED_SIGN_MISSES
+    assert entry["kept"] == "general_rule" and entry["note"] and entry["note_en"]
+    chart, asc, *_ = compute_chart_data(*VERDICT_TABLES["Table 25"][0], ayanamsa_name="lahiri")
+    lons = {name: row["degree"] for name, row in chart["planets"].items()}
+    for pair in entry["pairs"]:
+        result = compare_signs(SIGNS.index(pair["book"]), SIGNS.index(pair["general_rule"]), lons)
+        assert (result["selected_sign"], result["strength_level_decided"]) == (pair["general_rule"], pair["general_level"])
+    assert calc_narayana_rath(asc, lons, cycle_count=1)["known_book_differences"][BOOK_SOFTWARE_RULE8] == entry