Subscription dasha-change alerts — the COMPUTE half of subscription delivery/alerts. Builds the member's personal Jyotish bundle and returns every Vimshottari Mahadasha / Antardasha / Pratyantardasha boundary that falls inside the look-ahead window_days, i.e. the dates the running period's ruling planet changes. Pure planetary-period arithmetic over the deterministic timeline the bundle already carries — no astrological judgement, no fabrication.

Scheduled DELIVERY (recurring push / email on a cadence) is a separate infrastructure layer that needs a worker + prod-config and is NOT performed here; this endpoint computes the alert content on demand and discloses that in the report's delivery_note. §12 guidance-not-fatalism; no scripture quoted.