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Please help me create a plan first, don't modify the code directly. I want to add email verification to the user system.

## Execution Plan: Add Email Verification Feature

### Goal
Add email verification to the user registration flow.

### Impact Analysis

- Files to modify: 6
- Files to create: 3
- Database changes: 1 new table needed
- Risk points: Existing users are not affected, but migration scripts are needed

### Execution Steps

**Phase 1: Database Layer**
1. Create migration script for `email_verifications` table
2. Modify `users` table, add `email_verified` field

**Phase 2: Backend Logic**
3. Create new `email_verification_service.py`
4. Modify `auth_router.py`, add verification-related endpoints
5. Modify `user_service.py`, trigger verification email in registration flow

**Phase 3: Frontend Adaptation**
6. Modify registration page, add verification prompts
7. Create new email verification page
8. Modify routing configuration

### Risks and Notes

- SMTP configuration must be prepared in advance
- Need to consider expiration time for verification links
- Existing users should skip verification

The plan looks good overall, but I have a few adjustments:
1. No need to create a new verification page, just use the existing toast notification
2. Set verification link expiration to 24 hours
3. Don't modify the users table in phase 1, use the status in email_verifications table instead
Please update the plan.

The plan looks good, please start executing according to the plan. Start with phase one.

Execute phase one (database layer) first, then stop and let me verify.

My FastAPI project has no user authentication currently. Please help me create a plan to add a JWT-based user authentication system.
Requirements:

- User registration and login
- JWT token issuance and verification
- Route protection (some endpoints require login)
- Use SQLAlchemy to manage user table
Please analyze the existing code structure first, then create a detailed execution plan.

I have analyzed your project structure. Here are my findings and execution plan:

## Current Project Analysis

- Framework: FastAPI 0.115.x
- Database: Existing SQLAlchemy configuration (database.py), using PostgreSQL
- Existing models: Product, Order (in models/ directory)
- Routers: product_router.py, order_router.py (both without authentication protection)
- Dependency management: Using requirements.txt

## Execution Plan

### Phase 1: Infrastructure (2 files)
1. Add python-jose[cryptography], passlib[bcrypt] to requirements.txt
2. Add JWT-related configuration items to config.py (SECRET_KEY, ALGORITHM, TOKEN_EXPIRE)

### Phase 2: User Model and Database (2 files)
3. Create new models/user.py — User model
4. Create new alembic migration script

### Phase 3: Authentication Logic (3 files)
5. Create new services/auth_service.py — password hashing, JWT issuance/verification
6. Create new schemas/auth.py — request/response models
7. Create new routers/auth_router.py — /register, /login, /me endpoints

### Phase 4: Route Protection (3 files)
8. Create new dependencies/auth.py — get_current_user dependency
9. Modify product_router.py — write operations require authentication
10. Modify order_router.py — all operations require authentication

### Risk Notes

- SECRET_KEY in config.py must use environment variables, cannot be hardcoded
- Existing API clients need to adapt to authentication headers
- Recommend verifying in test environment first

The plan is good. Two adjustments:
1. Don't use alembic, use SQLAlchemy's create_all directly
2. Read operations on product_router don't need authentication, only create and delete need it
Everything else looks fine, please execute the plan.

utils.py has ballooned to 3000 lines with everything mixed in. Please help me analyze this file and create a refactoring plan to split it into multiple modules with clear responsibilities. Requirements:
1. Analyze the responsibilities of all functions in utils.py
2. Design a new module structure
3. List all files that import utils.py and their affected imports
4. Ensure all existing functionality remains unaffected after refactoring

## utils.py Refactoring Plan

### Current State Analysis
utils.py contains 47 functions, which can be categorized into 5 types based on their responsibilities:

| Category | Function Count | Example Functions |
|----------|---------------|-------------------|
| String processing | 12 | slugify, truncate, sanitize_html |
| Date and time | 8 | parse_date, format_datetime, get_timezone |
| File operations | 9 | read_file, ensure_dir, get_file_hash |
| Data validation | 11 | validate_email, validate_phone, check_url |
| HTTP utilities | 7 | retry_request, parse_response, build_url |

### Import Analysis
A total of 23 files import utils.py, detailed list as follows:
(List each file and the specific functions used...)

### New Module Structure
utils/
├── __init__.py      # Re-exports for backward compatibility
├── strings.py       # String processing
├── datetime.py      # Date and time
├── files.py         # File operations
├── validators.py    # Data validation
└── http.py          # HTTP utilities

### Execution Steps
(List step by step...)

### Backward Compatibility Strategy
Keep all original exports in utils/__init__.py:
from .strings import *
from .datetime import *
...
This way, undiscovered references won't break.

Users report that order amounts are occasionally calculated incorrectly, but not every time. Please help me investigate this issue:
1. Find all code involved in amount calculations
2. Analyze possible causes of occasional errors
3. Create a fix plan

## Bug Investigation Report

### Amount Calculation Related Code
After comprehensive search, code related to amount calculations is distributed across 4 files:

- order_service.py:calculate_total() — main calculation logic
- discount_service.py:apply_discount() — discount calculation
- tax_service.py:calculate_tax() — tax calculation
- cart_service.py:get_cart_total() — cart total

### Issues Found
**Root cause: Floating point precision problem**

In order_service.py line 127:
  total = sum(item.price * item.quantity for item in items)

Python's floating point arithmetic has precision issues:
  >>> 0.1 + 0.2
  0.30000000000000004

When orders contain multiple items with decimal amounts, cumulative errors may cause the final amount to be off by 1 cent.

**Secondary issue: Discount calculation order**
discount_service.py's discount calculation is executed after tax_service.py's tax calculation,
but in some concurrent scenarios, the order may be reversed (because they are called asynchronously).

### Fix Plan
1. Change all amount calculations to use Decimal type
2. Modify the call order of discount and tax to be synchronous and sequential
3. Add unit tests for amount consistency

Please add a verify_email method to user.py that accepts a token parameter,
queries the email_verifications table, and if the token matches and hasn't
expired, sets user.email_verified to True.

We need to allow users to verify their email addresses. Users will receive
an email with a verification link after registration. After clicking the
link, their email status becomes verified. Please help me plan the implementation.

Please pay special attention to the following in the plan:
1. What existing functionality might this modification break?
2. Are there configuration files that need to be modified together?
3. Do database changes require migration scripts?
4. Are there any concurrency safety concerns?

This plan has 4 phases, please execute as follows:

- Stop after completing each phase
- Report the completion status of that phase
- Wait for my confirmation before continuing to the next phase

# Create plan in Plan mode first
(Switch to Plan mode, describe requirements, review plan)

# After satisfied, switch back to default mode
Please create a new branch feature/email-verification first, then execute the plan.

What is your task?
│
├─ Simple modification (1-2 files, clear direction)
│   → Default mode, start directly
│
├─ Medium task (3-5 files, clear logic)
│   → Can use Plan mode first for quick scan, then switch to execute
│
└─ Complex task (multiple files, uncertain solutions, high risk)
    → Must use Plan mode, plan in detail before executing

## Plan Mode Requirements

When entering Plan mode, please generate plans according to the following template:

### Required Sections
1. **Current State Analysis**: Current code structure and relevant files
2. **Solution Design**: Specific implementation approach, including alternatives
3. **Impact Scope**: Which files will be modified, which features will be affected
4. **Risk Assessment**: Possible issues and countermeasures
5. **Execution Steps**: In sequential order, each step verifiable independently
6. **Testing Plan**: How to verify the correctness of changes

### Format Requirements

- Each execution step should indicate the files involved
- New files should be marked with [NEW]
- Files to modify should be marked with [MODIFY]
- Risk points should be marked with High/Medium/Low severity

Before creating the plan, please help me figure out the following:
1. What does the current database schema look like? Use a sub-agent to analyze all model files
2. What is the list of existing API endpoints? Use a sub-agent to scan all router files
3. What third-party libraries does the project use? Check requirements.txt or pyproject.toml

Please save the plan we just created to docs/plans/add-email-verification.md.
We can reference it when working on similar features in the future.

Please refer to the plan structure in docs/plans/add-email-verification.md
and create a similar plan for SMS verification.

(Enter Plan mode)

Please review all service files in the src/services/ directory, focusing on:
1. Is error handling comprehensive?
2. Are there any SQL injection risks?
3. Are there unclosed resources (database connections, file handles)?
4. Do async code have race conditions?
Please provide a detailed review report and improvement suggestions.

/compact Keep the complete execution plan and impact analysis, compress the intermediate exploration process