Three scoping tiers (ledger-only / +Payment+Dispute / all five financial
models) with concrete time estimates grounded in actual reference counts
from the codebase. Recommends Option 1 (ledger only, 3–4 weeks) as the
right dual-DB shape if a forcing function appears, and explains why it's
not yet worth doing over the 2-week in-place hardening.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Records the current recommendation (stay on Mongo + targeted hardening),
the realistic full-migration cost (3.5–6 months), and the trigger
conditions under which we should revisit the decision. Prompted by the
multi-seller orphan-payment bug on 2026-05-28 — exactly the FK-shaped
class of bug Postgres would prevent, but not by itself worth a migration.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
