fix: address account valuation review findings

docs/data-model.md

@@ -31,7 +31,7 @@
 
 ### account-valuations — 기준일 계좌 평가
 
-- 책임: 날짜가 지정된 평가 evidence와 선택/correction provenance
+- 책임: 날짜가 지정된 평가 evidence와 선택/correction provenance. investment `principal`은 reported principal amount이고 loan `principal`은 outstanding principal이다.
 - 식별자: `id`
 - 생명 주기: insert-only; correction은 `supersedes_id` child
 
@@ -134,9 +134,11 @@
 
 ### 불변조건
 
-- `idx_account_valuations_single_correction` ensures one direct child; idempotency index ensures one non-empty key per account.
-- only verified leaves are authority; unknown/future/unverified are excluded or warning evidence.
-- preview does not insert; close inserts run and rows atomically; latest run is report authority.
+- `idx_account_valuations_single_correction` ensures one direct child; correction parent scope is same account/date/currency/purpose. Cyclic or self parent, second child, missing reason, and conflict are no-write failures.
+- `source_ref` is account-scoped evidence identity even when an explicit key is supplied; key/source mismatch conflicts. This is evidence idempotency. There is no generic label; only source-declared `reported_principal_kind` and `reported_principal_label` are physical fields.
+- only verified leaves are authority; unknown/future/unverified are excluded or warning evidence. `last_balance` is external current comparison, not opening evidence; missing balance_after/opening evidence is `INCOMPLETE_CALCULATION`.
+- preview does not insert; close inserts run and rows atomically; latest run is report authority. Reports expose actual valuation_date, age, carry, verification, run, approval, correction, warnings, and exclusions across close response, live, closed, timeseries, and monthly.
+- `monthly_source_snapshot_id` is a read-model alias of `snapshot_run_id`, not a persistence field. Investment unavailable and unavailable investment, loan purpose/definition/ambiguity, and reconciliation completeness remain explicit; no fake writes.
 - `asset_buckets - loan` is the net-worth formula; representative loan only, no fake transactions.
 
 ## 저장과 마이그레이션