# Ledger Integration Walkthrough

This document outlines the changes made to integrate Ledger functionality into the Transaction flow and provides steps for verification.

## Changes Overview

### Backend (Go)
- **`TransactionInput`**: Added `LedgerID` field to potential input.
- **`TransactionService`**:
  - Updated `CreateTransaction` to assign the user's default ledger if no `LedgerID` is provided.
  - Updated `CreateTransaction` and `UpdateTransaction` to validate and link the `LedgerID`.
  - Injected `LedgerRepository` to allow fetching default ledgers and validating IDs.
- **`Router`**: Updated dependency injection to pass `LedgerRepository` to `TransactionService`.

### Frontend (React/TypeScript)
- **Global State**: Created `SettingsContext` to provide global access to the currently selected `ledgerId`.
- **Types**: Updated `TransactionFormInput`, `TransactionFilter`, and other interfaces to support `this.ledgerId`.
- **Service (`transactionService.ts`)**: Updated `getTransactions`, `createTransaction`, and `updateTransaction` to map `ledgerId` to the backend API parameters (`ledger_id`).
- **Components**:
  - **`TransactionForm`**: Now accepts `currentLedgerId` and submits it with new transactions.
  - **`CommandPalette`**: Now filters transaction search results by the current active ledger.
- **Pages**:
  - **`Home`**: Updated to use `SettingsContext` for ledger selection and data refreshing.
  - **`Transactions`**: Updated to filter the transaction list by the global `currentLedgerId` and pass it to the creation form.

## Verification Steps

### 1. Ledger Switching
1. Navigate to the **Home** page.
2. Click the Ledger selector in the header (top left pill).
3. Select a different ledger (e.g., "Business" vs "Personal").
4. **Verify**: The "Recent Transactions" list update to show only transactions for the selected ledger.
5. **Verify**: The Dashboard stats (Income, Expense) update to reflect the selected ledger.

### 2. Transaction Creation with Ledger
1. Ensure you are in a specific ledger (e.g., "Personal").
2. Click **"记一笔" (Add Transaction)**.
3. Create a new transaction.
4. **Verify**: The transaction appears in the "Personal" ledger list.
5. Switch to a "Business" ledger.
6. **Verify**: The newly created transaction does **NOT** appear in the "Business" ledger list.

### 3. Transaction List Filtering
1. Go to the **Transactions** page.
2. **Verify**: The list only shows transactions for the currently selected ledger.
3. Switch ledger using the global context (if accessible) or go back Home to switch, then return.
4. **Verify**: The list refreshes to show the new ledger's transactions.

### 4. Global Search
1. Press `Ctrl+K` (or `Cmd+K`) to open the Command Palette.
2. Type a search term for a transaction that exists in the *current* ledger.
3. **Verify**: The transaction appears in results.
4. Type a search term for a transaction that exists in a *different* ledger.
5. **Verify**: The transaction does **NOT** appear in results.

### 5. Exchange Rates (Regression Test)
1. Go to **Exchange Rates** page.
2. **Verify**: Net Worth and History still load correctly (this calculates based on *global* accounts, so it should remain unaffected by ledger selection).

## Technical Notes
- **Default Behavior**: If a transaction is created via API without a `ledger_id` (e.g., older clients), the backend now automatically assigns it to the user's **Default Ledger**.
- **Context Persistence**: The selected ledger ID is stored in User Settings, so it persists across sessions if the backend supports saving settings (which it does).