fix(dasha): measure nakshatra index and progress on one grid

Upstream 3c2dad95, 8643bc9a, and the lon_to_nakshatra part of 9e04f0db. Exact star starts were split across int-division and modulo, so 16 of 27 openings reported a zero balance and skipped the mahadasha. Off-boundary longitudes keep the old modulo. BUG-1381.

Co-Authored-By: Grok (agent loop)
Co-authored-by: Cursor <cursoragent@cursor.com>

scripts/dasha_analyzer.py

@@ -68,12 +68,18 @@ def fuzzy_match_nakshatra(name):
     return None
 
 def lon_to_nakshatra(moon_lon):
-    """月亮黄经（0-360）→ Nakshatra + Pada"""
-    nak_span = 360 / 27
-    pada_span = nak_span / 4
-    idx = int(moon_lon / nak_span)
-    progress = (moon_lon % nak_span) / nak_span
-    pada = int((moon_lon % nak_span) / pada_span) + 1
+    """月亮黄经（0-360）→ Nakshatra + Pada。序号与进度来自同一把尺子。"""
+    try:
+        from nakshatra_advanced import nakshatra_index_and_progress
+    except ImportError:
+        from scripts.nakshatra_advanced import nakshatra_index_and_progress
+    idx, progress = nakshatra_index_and_progress(moon_lon)
+    if progress == 0.0:
+        pada = 1
+    else:
+        nak_span = 360 / 27
+        pada_span = nak_span / 4
+        pada = int((float(moon_lon) % nak_span) / pada_span) + 1
     return NAKSHATRA_LIST[idx], progress, pada
 
 def build_dasha_timeline(birth_date_str, nak_info, nak_progress):

scripts/jyotish_engine.py

@@ -12023,10 +12023,16 @@ def _load_strict_evidence_collector():
 # ============================================================================
 def _nakshatra_fields(sidereal_lon):
     """Nakshatra, pada and lord of a sidereal longitude — planets and the ascendant alike."""
-    nak_span = 360.0 / 27
+    from nakshatra_advanced import nakshatra_index_and_progress
     lon = sidereal_lon % 360
-    pada = int((lon % nak_span) / (nak_span / 4)) + 1
-    name, lord, _ = NAKSHATRA_LIST[int(lon / nak_span) % 27]
+    idx, progress = nakshatra_index_and_progress(lon)
+    if progress == 0.0:
+        pada = 1
+    else:
+        nak_span = 360.0 / 27
+        pada = int((lon % nak_span) / (nak_span / 4)) + 1
+        idx = int(lon / nak_span) % 27
+    name, lord, _ = NAKSHATRA_LIST[idx]
     return {"nakshatra": name, "nakshatra_pada": pada, "nakshatra_lord": lord}
 
 
@@ -12165,8 +12171,9 @@ def _build_pratyantar_timeline(md_lord, ad_lord, ad_start, ad_end, reference_dt=
 def cmd_dasha(args):
     nak_info = None; progress = 0.5
     if args.moon_lon is not None:
-        ns = 360.0 / 27; idx = int(args.moon_lon / ns); progress = (args.moon_lon % ns) / ns
-        nak_info = NAKSHATRA_LIST[idx % 27]
+        from nakshatra_advanced import nakshatra_index_and_progress
+        idx, progress = nakshatra_index_and_progress(args.moon_lon)
+        nak_info = NAKSHATRA_LIST[idx]
     elif args.nakshatra:
         nl = args.nakshatra.lower().replace(" ", "").replace("-", "")
         for n in NAKSHATRA_LIST:
@@ -12183,8 +12190,9 @@ def cmd_dasha(args):
         moon_lon = moon.get("degree_raw")
         if moon_lon is None:
             return {"error": "无法计算Moon位置"}
-        ns = 360.0 / 27; idx = int(moon_lon / ns); progress = (moon_lon % ns) / ns
-        nak_info = NAKSHATRA_LIST[idx % 27]
+        from nakshatra_advanced import nakshatra_index_and_progress
+        idx, progress = nakshatra_index_and_progress(moon_lon)
+        nak_info = NAKSHATRA_LIST[idx]
 
     nak_name, start_lord, start_years = nak_info
     birthdate = args.birthdate or f"{args.year}-{args.month:02d}-{args.day:02d}"
@@ -15425,10 +15433,15 @@ def cmd_full_reading(args):
     try:
         moon_data = planets.get('Moon', {})
         moon_lon = moon_data.get('degree_raw', moon_data.get('degree', 0))
-        nak_idx = int(moon_lon / (360 / 27)) % 27
+        from nakshatra_advanced import nakshatra_index_and_progress
+        nak_idx, nak_progress = nakshatra_index_and_progress(moon_lon)
+        if nak_progress != 0.0:
+            nak_idx = int(moon_lon / (360 / 27)) % 27
+            pada = int((moon_lon % (360/27)) / (360/108)) + 1
+        else:
+            pada = 1
         nak_name = NAKSHATRA_LIST[nak_idx][0]
         nak_lord = NAKSHATRA_LIST[nak_idx][1]
-        pada = int((moon_lon % (360/27)) / (360/108)) + 1
 
         birthdate = f"{args.year}-{args.month:02d}-{args.day:02d}"
         today_str = getattr(args, 'transit_date', None) or getattr(args, 'today', None) or datetime.now().strftime('%Y-%m-%d')
@@ -16459,8 +16472,13 @@ def cmd_full_reading(args):
         jaimini_data = report['modules'].get('jaimini', {})
         chara_dasha_data = jaimini_data.get('chara_dasha', {}) if isinstance(jaimini_data, dict) else {}
         moon_lon = planet_lons.get('Moon', 0)
-        moon_nakshatra_index = int(moon_lon / (360 / 27)) % 27
-        moon_pada = int((moon_lon % (360 / 27)) / (360 / 108)) + 1
+        from nakshatra_advanced import nakshatra_index_and_progress
+        moon_nakshatra_index, moon_nak_progress = nakshatra_index_and_progress(moon_lon)
+        if moon_nak_progress != 0.0:
+            moon_nakshatra_index = int(moon_lon / (360 / 27)) % 27
+            moon_pada = int((moon_lon % (360 / 27)) / (360 / 108)) + 1
+        else:
+            moon_pada = 1
         tithi_number = int(((moon_lon - planet_lons.get('Sun', 0)) % 360) / 12) + 1
         birth_dt = _birth_datetime_from_args(args)
         ll_name = SIGN_LORDS[SIGNS[asc_idx]]

scripts/nakshatra_advanced.py

@@ -16,6 +16,14 @@ Nakshatra深度分析系统
 from typing import Dict, List, Tuple, Optional
 import math
 from datetime import datetime, timedelta
+from bisect import bisect_right
+from fractions import Fraction
+
+# Exact star openings. float(Fraction) is the grid cmd_dasha must share with
+# lon_to_nakshatra; 360/27 and modulo disagree at several of these points.
+_NAK_SPAN = Fraction(40, 3)
+_NAK_STARTS = tuple(float(_NAK_SPAN * index) for index in range(27))
+_NAK_SPAN_FLOAT = 360.0 / 27.0
 
 NAK_LIST = [
     ("Ashwini","Ketu",7),("Bharani","Venus",20),("Krittika","Sun",6),
@@ -53,15 +61,42 @@ NAK_ELEMENT = {
 }
 
 
+def nakshatra_index_and_progress(longitude: float) -> Tuple[int, float]:
+    """星宿序号和已用比例，由同一把尺子量出。
+
+    经度恰好等于某星宿起点时，这一点属于刚开始的那一宿，已用比例为 0。
+    其余经度保持原来的取模结果，避免改动非边界点。
+    """
+    lon = float(longitude) % 360.0
+    idx = bisect_right(_NAK_STARTS, lon) - 1
+    if idx < 0:
+        idx = 0
+    elif idx > 26:
+        idx = 26
+    if lon == _NAK_STARTS[idx]:
+        return idx, 0.0
+    legacy_idx = int(lon / _NAK_SPAN_FLOAT) % 27
+    legacy_progress = (lon % _NAK_SPAN_FLOAT) / _NAK_SPAN_FLOAT
+    return legacy_idx, legacy_progress
+
+
 def find_nakshatra(longitude: float) -> Dict:
     """从恒星黄道经度精确计算Nakshatra"""
-    nak_span = 360.0 / 27  # 每个星宿13.333...°
-    nak_idx = int(longitude / nak_span) % 27
-    nak_start = nak_idx * nak_span
-    deg_in_nak = longitude - nak_start
-    pada_span = nak_span / 4  # 每个Pada 3.333...°
-    pada = int(deg_in_nak / pada_span) + 1
-    deg_in_pada = deg_in_nak - (pada - 1) * pada_span
+    idx, _progress = nakshatra_index_and_progress(longitude)
+    lon = float(longitude) % 360.0
+    if lon == _NAK_STARTS[idx]:
+        nak_idx = idx
+        deg_in_nak = 0.0
+        pada = 1
+        deg_in_pada = 0.0
+    else:
+        nak_span = 360.0 / 27  # 每个星宿13.333...°
+        nak_idx = int(longitude / nak_span) % 27
+        nak_start = nak_idx * nak_span
+        deg_in_nak = longitude - nak_start
+        pada_span = nak_span / 4  # 每个Pada 3.333...°
+        pada = int(deg_in_nak / pada_span) + 1
+        deg_in_pada = deg_in_nak - (pada - 1) * pada_span
 
     return {
         'nakshatra': NAK_NAMES[nak_idx],
@@ -126,11 +161,13 @@ def calc_vimshottari_start(moon_longitude: float) -> Dict:
     nak_lord = NAK_LORDS[nak_idx]
     total_years = NAK_YEARS[nak_idx]
 
-    # 已用比例
-    nak_span = 360.0 / 27
-    nak_start = nak_idx * nak_span
-    deg_in_nak = moon_longitude - nak_start
-    used_ratio = deg_in_nak / nak_span
+    # 已用比例与星宿序号来自同一把尺子。起点处必须是 0，不能是「几乎走完」。
+    _, used_ratio = nakshatra_index_and_progress(moon_longitude)
+    if float(moon_longitude) % 360.0 != _NAK_STARTS[nak_idx]:
+        nak_span = 360.0 / 27
+        nak_start = nak_idx * nak_span
+        deg_in_nak = moon_longitude - nak_start
+        used_ratio = deg_in_nak / nak_span
     remaining_ratio = 1 - used_ratio
 
     # 第一个Mahadasha的剩余年数