让大运接口走完整解读的同一套算法，不再返回编出来的周期。

Ashtottari 在适用时把出生前已经走过的部分算进时间线。

Co-Authored-By: Grok (agent loop)

scripts/dasha_common.py

@@ -0,0 +1,46 @@
+"""Shared dasha arithmetic used by the conditional-dasha modules.
+
+This module must not import the API server or PyJHora. PyJHora stays a test
+oracle only.
+"""
+
+from __future__ import annotations
+
+NAKSHATRA_SPAN = 360.0 / 27.0
+
+# Insertion order is the Vimshottari sequence. Callers compare items() before
+# replacing a local table, and rely on this order staying stable.
+VIMSHOTTARI_YEARS = {
+    "Ketu": 7,
+    "Venus": 20,
+    "Sun": 6,
+    "Moon": 10,
+    "Mars": 7,
+    "Rahu": 18,
+    "Jupiter": 16,
+    "Saturn": 19,
+    "Mercury": 17,
+}
+VIMSHOTTARI_ORDER = list(VIMSHOTTARI_YEARS.keys())
+
+
+def nakshatra_seeded_birth_balance(
+    moon_longitude: float,
+    *,
+    anchor_index: int,
+    sequence: tuple | list,
+) -> tuple[str, float, int]:
+    """Birth lord and remaining years for a nakshatra-seeded conditional dasha.
+
+    The arithmetic matches the six copied helpers: offset from the anchor
+    nakshatra, lord = sequence[offset % length], balance = years * (1 - fraction
+    already elapsed inside the nakshatra). Operation order is fixed so the
+    float matches the previous per-module copies.
+    """
+    moon = float(moon_longitude) % 360.0
+    nakshatra_index = int(moon // NAKSHATRA_SPAN)
+    offset = (nakshatra_index - int(anchor_index)) % 27
+    lord, full_years = sequence[offset % len(sequence)]
+    fraction_elapsed = (moon % NAKSHATRA_SPAN) / NAKSHATRA_SPAN
+    remaining_years = full_years * (1.0 - fraction_elapsed)
+    return lord, remaining_years, nakshatra_index