jarca-ledger-mcp/docs/interface-contract.md

# Jarca Ledger MCP Interface Contract

- Baseline Mode: observed
- Baseline Seed: `.stage-pilot/bootstrap/baseline.yaml`
- Status: draft
- Owner: Jarca / project maintainer
- Last Updated (KST): 2026-06-27 10:17
- Source Discovery / Batch: bootstrap-baseline

## Project Summary
- Jarca 가계부 전용 MCP 서버와 Streamlit 대시보드로 계좌/카드 거래, 예산, 분류 규칙, import, 현금흐름 분석을 SQLite에 저장하고 운영한다.

## Purpose
- This document captures the current external and operator-facing interface baseline.
- It is a reference for future Discovery, REQ, Batch, and Release work that changes tool signatures, dashboard behavior, or file import contracts.

## Interface: MCP Tool Surface
- Type: internal-service
- Actors: Hermes Agent and MCP clients
- Entrypoint: `jarca-ledger-mcp` script -> `jarca_ledger_mcp.server:main`
- Stability: internal but should preserve existing success response shapes for compatibility.

### Representative Tool Groups
- Health: `ledger_health_check`, `get_ledger_db_status`
- Operational backup: `create_ledger_backup`, `list_ledger_backups`, `get_ledger_backup_status` (restore is intentionally not exposed as MCP)
- Accounts: `create_ledger_account`, `list_ledger_accounts`
- Transactions: `create_ledger_transaction`, `list_ledger_transactions`, `update_ledger_transaction`, `delete_ledger_transaction`
- Budgets/reports: `create_ledger_budget`, `list_ledger_budgets`, monthly/category/fixed/budget/investable reports
- Imports: KB Bank PDF, Toss Bank PDF, Toss Securities PDF, SeoulPay XLSX, CSV preview/import where implemented
- Categories/rules: category CRUD, rule CRUD, categorization preview/apply, uncategorized summaries
- Reconciliation: cross-account preview/run/review queue, self-transfer candidates/linking, cancel-original candidates/linking

### Inputs
- Structured MCP tool arguments as declared in `server.py` signatures.
- File paths and optional passwords for encrypted or password-protected documents.
- Transaction/account/category identifiers for update, delete, and link operations.

### Outputs
- Python dictionary payloads containing success data, counts, records, previews, reports, or error details.
- Backup/status tools return metadata-only DB evidence: path, size, mtime, sha256, integrity check, table row counts, and aggregate totals.
- Existing success shape compatibility is preferred; new fields should be additive where possible.

### Errors
- Validation errors for invalid parameters or missing IDs.
- Parser errors for unreadable or unsupported source files.
- Password/validation errors for encrypted import files.
- Candidate-not-found errors for link operations when the chosen pair is not in the preview set.

### Compatibility Rules
- Preserve existing success response shapes unless a migration/REQ explicitly approves a breaking change.
- Additive backup/status/list/hash tools are allowed; restore execution must not be added as an MCP tool.
- Do not write secrets, raw passwords, raw_payload, full merchant/counterparty dumps, or full account identifiers into persistent output, skill files, or committed documentation.
- Source evidence should remain auditable through raw fields and import batch records.

## Interface: Streamlit Dashboard
- Type: web-app
- Actors: Local operator
- Entrypoint: `streamlit run dashboard/app.py --server.address 0.0.0.0 --server.port 8501`
- Stability: internal operator UI

### Pages
- 요약
- 거래내역
- 확인필요 큐
- 미분류
- 분류 규칙
- 카테고리
- 계좌
- Import

### Inputs
- Local SQLite database selected by `JARCA_LEDGER_DB_PATH` or default path.
- Uploaded transaction history files.
- User edits for categories, rules, transactions, and manual links.

### Outputs
- Tables, charts, dialogs, previews, import results, and transaction/category updates.

### UI Contract Rules
- Surface `cashflow_kind` where classification affects actual cashflow interpretation.
- Keep actual income/expense separated from account movement summaries.
- Rule page should support create/edit/delete and condition fields `amount_min`, `amount_max`, `day_of_month`.
- Dialog-based triage actions should avoid losing context where possible.

## Interface: File Import Contracts
- KB Bank PDF: encrypted/password-protected PDF account history; preserve transaction datetime, counterparty, balance, branch, raw summary, and raw payload.
- Toss Bank PDF: transaction history PDF parsed into ledger transaction candidates.
- Toss Securities PDF: securities transaction history with investment movement, dividend, interest, and external transfer handling.
- SeoulPay XLSX: possibly encrypted Office XLSX/OLE file; decrypt with supplied password and import usage details as actual spending evidence.
- CSV: generic preview-first import path.

## Shared Constraints
- All import flows should support preview before mutation where implemented.
- Dedupe should use deterministic source/external IDs or same-account/date/type/amount/merchant evidence.
- Import batch metadata should support rollback and audit.
- Broad mutation workflows should capture metadata-only DB status and backup evidence before/after risky operations.
- Restore execution is limited to script/runbook workflows and explicit approval, not MCP tools.
- Financial data and passwords are sensitive runtime inputs and should not be committed.

## Current Gaps / Planned Changes
- Formal versioning for MCP response contracts is not yet defined.
- Browser-level UI acceptance criteria for Streamlit flows are not yet captured as REQ documents.
- CI contract for tests/lint is not yet present.

## 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 backup/status/list/hash MCP contract와 restore 비노출 정책 추가.