expense-report

生成给定期间按类别的详细费用明细。当用户请求费用报告、支出摘要、Ausgabenübersicht、成本分析或想要了解他们的钱花在哪里时使用。

## 概述（中文）

生成给定期间按类别的详细费用明细。当用户请求费用报告、支出摘要、Ausgabenübersicht、成本分析或想要了解他们的钱花在哪里时使用。

## 原文

Generate a comprehensive expense report for the user:

## Step 1: Gather data
- Call `search_transactions` for the specified period (default: last month)
- Filter for outgoing transactions (expenses only, exclude income)
- Call `get_company_balance` for current balance context

## Step 2: Categorize and group
Group expenses by bookkeeping category. For each category show:
- Category name
- Total amount (EUR)
- Number of transactions
- Percentage of total expenses

Present as a ranked list, largest category first.

## Step 3: Top vendors
List the top 10 vendors/payees by total spend:
- Vendor name
- Total amount
- Number of transactions
- Average transaction amount

## Step 4: Trends and insights
If the user asks for a longer period (quarter or year), provide:
- Month-over-month comparison of total expenses
- Categories that increased or decreased significantly
- Recurring vs. one-time expenses
- Largest single transactions in the period

## Step 5: Comparison (if possible)
If data is available for the previous equivalent period:
- Total expenses this period vs. last period
- Percentage change
- Categories with the biggest increase/decrease
- Flag any unusual or new expense categories

## Presentation format
Structure the report clearly:

```
Expense Report: [Period]
========================
Total Expenses: X,XXX.XX EUR

By Category:
  1. [Category]     X,XXX.XX EUR  (XX%)  [N transactions]
  2. [Category]       XXX.XX EUR  (XX%)  [N transactions]
  ...

Top Vendors:
  1. [Vendor]       X,XXX.XX EUR  [N transactions]
  2. [Vendor]         XXX.XX EUR  [N transactions]
  ...

Key Insights:
  - [Notable finding]
  - [Notable finding]
```

Keep amounts in EUR. Use clear formatting for readability. Offer to drill down into any specific category if the user wants more detail.