feat: implement asset snapshot and manual asset read model

docs/data-model.md

@@ -4,8 +4,8 @@
 - Baseline Seed: `.stage-pilot/bootstrap/baseline.yaml`
 - Status: draft
 - Owner: Jarca / project maintainer
-- Last Updated (KST): 2026-06-29
-- Source Discovery / Batch: bootstrap-baseline
+- Last Updated (KST): 2026-06-30
+- Source Discovery / Batch: bootstrap-baseline, BAT-008
 
 ## Project Summary
 - Jarca 가계부 전용 MCP 서버와 Streamlit 대시보드로 계좌/카드 거래, 예산, 분류 규칙, import, 현금흐름 분석을 SQLite에 저장하고 운영한다.
@@ -40,9 +40,51 @@
   - `active=false` hides accounts from default lists without deleting history.
   - `manual_only` is the statement-unavailable class; `partial_import` remains eligible for manual supplementation and balance reconciliation.
   - Balance reconciliation is report/preview first: compare `baseline_balance`/`baseline_at` against the latest `balance_after` or net account transaction delta, with 1,000 KRW absolute tolerance.
-  - 비거래 자산/부채는 별도 평가 테이블 없이 `last_balance`를 현재 평가액/잔액, `last_synced_at`을 기준일, `memo`를 출처 메모로 사용한다.
+  - 계좌 기반 자산/부채는 `last_balance`를 현재 평가 권위 소스로 사용하고, `last_synced_at`을 기준일, `memo`를 출처 메모로 보존한다.
+  - 거래로 산출되지 않는 비거래 자산/부채는 `ManualAsset`에 별도 저장한다. 계좌와 수기 자산을 같은 항목으로 중복 등록하지 않는다.
   - `liquidity_bucket='loan'`은 자산 구성 비율 분모에서 제외하고 총부채/순자산 산식에만 반영한다. `last_balance`가 없는 계좌/자산은 임의 거래 합계로 추정하지 않는다.
 
+## Entity: ManualAsset
+- Source of Truth: `manual_assets`
+- Purpose: Stores non-transaction-derived assets/liabilities such as real estate, deposits, loans, and other manually valued holdings that should not be mixed into account rows.
+- Lifecycle: created -> revalued/updated -> inactive/archived
+- Key Fields:
+  - `id` :: text :: stable manual asset identifier
+  - `name` :: text :: operator-facing asset/liability name
+  - `liquidity_bucket` :: text :: `cash`, `investment`, `deposit`, `real_estate`, `loan`, `other`
+  - `valuation_amount` :: integer nullable :: latest manually entered valuation/balance; null means excluded from valuation totals
+  - `valuation_date` :: date text :: valuation basis date
+  - `currency` :: text :: default `KRW`
+  - `source_note` :: text :: valuation evidence/source memo
+  - `memo` :: text :: operator note
+  - `active` :: integer/bool :: inactive rows are excluded from default read reports
+- Relationships:
+  - Referenced by `asset_snapshots.source_type='manual_asset'` and `source_id` when a month-end valuation is snapshotted.
+- State Rules:
+  - `manual_assets` is the live authority source for non-transaction assets/liabilities.
+  - Missing `valuation_amount` rows are excluded; transaction sums are not used as a substitute.
+  - `loan` bucket values are treated as liabilities and subtracted from asset-bucket totals.
+
+## Entity: AssetSnapshot
+- Source of Truth: `asset_snapshots`
+- Purpose: Append-only item-level record of a basis-date asset/liability valuation produced from the live authority sources.
+- Lifecycle: appended at month-end/manual close -> read for point-in-time reports and timeseries
+- Key Fields:
+  - `id` :: text :: snapshot row identifier
+  - `basis_date` :: date text :: valuation date represented by the row
+  - `source_type` :: text :: `account` or `manual_asset`
+  - `source_id` :: text :: source entity identifier when available
+  - `name` :: text :: snapshot display name copied from the source at capture time
+  - `amount` :: integer nullable :: snapshotted valuation amount
+  - `liquidity_bucket` :: text :: bucket copied from the source at capture time
+  - `valuation_source`, `source_note`, `memo` :: text :: evidence and operator context
+  - `created_at` :: text :: snapshot row creation timestamp
+- Relationships:
+  - Represents a historical record of `LedgerAccount.last_balance` or `ManualAsset.valuation_amount` rather than a new primary input source.
+- State Rules:
+  - Snapshot rows are append-only for BAT-008. Existing rows are not destructively overwritten.
+  - Basis-date snapshot reports prefer stored `asset_snapshots` rows when rows exist for the date; otherwise read reports can fall back to live authority sources.
+
 ## Entity: Transaction
 - Source of Truth: `transactions`
 - Purpose: Represents imported or manually entered financial event evidence.
@@ -148,7 +190,8 @@
 - External counterparty securities transfers are review items unless matched or explicitly confirmed.
 - Import evidence fields are retained for audit and future correction.
 - DB corrections should be narrow and memo-tagged.
-- Dashboard asset liquidity/net-worth reports use `accounts.liquidity_bucket` and `accounts.last_balance` only; transactions are not used to infer non-transaction asset values.
+- Dashboard/MCP asset and net-worth reports use a shared valuation helper: account-backed items from `accounts.last_balance` plus non-transaction items from `manual_assets`.
+- Net worth is asset buckets (`cash`, `investment`, `deposit`, `real_estate`, `other`) minus absolute `loan` liabilities; missing valuations are excluded and reported, never inferred from transactions.
 
 ## Persistence Notes
 - Schema changes should be additive/idempotent unless a destructive migration is explicitly approved and backed up.
@@ -161,10 +204,11 @@
 - Formal schema migration documentation should be added before larger DB changes.
 - Some UI workflows need final E2E verification against real rows.
 - Statement-unavailable account handling is tracked by REQ-003/BAT-003; future work may add a dedicated reconciliation workbench and persistent review-decision queue.
-- REQ-005/BAT-005 adds dashboard operations hub semantics and account-level liquidity buckets; future work may add separate asset snapshots only after a new REQ.
+- BAT-008 adds `manual_assets` and `asset_snapshots` with read-only MCP/report support. Future work may add mutation MCP for snapshot creation/manual asset CRUD and automatic market/real-estate valuation.
 
 ## Change Log
 - 2026-06-26 22:24 KST: Created by `bootstrap-baseline` from repository observation.
 - 2026-06-27 10:17 KST: BAT-002/REQ-002 기준으로 LedgerBackupArtifact와 metadata-only evidence 정책 추가.
 - 2026-06-29 KST: REQ-003/BAT-003 기준으로 `accounts.statement_status`와 수동 잔액대조 preview 모델 추가.
 - 2026-06-29 KST: REQ-005/BAT-005 기준으로 `accounts.liquidity_bucket`, `last_balance` 기반 자산 유동성/부채/순자산 규칙 추가.
+- 2026-06-30 KST: REQ-009/REQ-010/BAT-008 기준으로 `manual_assets`, `asset_snapshots`, 권위 소스(`accounts.last_balance` + `manual_assets`), 순자산 산식/미평가 제외 정책 추가.