# Period Model Refactoring Summary

## Overview

Successfully completed architectural refactoring to prioritize type-safe Period objects and position BatchTester as the primary SDK interface.

## Changes Implemented

### 1. Core Implementation

#### Period Model Enhancement (`batch/models.py`)
- Added `model_validator` for `start < end` validation
- Added convenience class methods:
  - `Period.Q1(year)` through `Period.Q4(year)` for quarters
  - `Period.from_year(year)` for full year
  - `Period.from_month(year, month)` with leap year handling
- All date formats supported: string, date, datetime

#### BatchTester API Update (`batch/tester.py`)
- **Breaking Change**: `submit()` now requires `list[Period]` (removed tuple support)
- Updated all docstrings and examples to use Period objects

### 2. Documentation (All without historical descriptions)

#### Created
- **LOW_LEVEL_API.md** (~900 lines) - Complete async TradeposeClient reference

#### Rewrote
- **README.md** (449 lines) - BatchTester-first approach
- **EXAMPLES.md** (912 lines) - 15 examples using Period objects
- **API_REFERENCE.md** (644 lines) - Prioritized BatchTester, Period, Builder API
- **ARCHITECTURE.md** (518 lines) - Design philosophy for latest version
- **CONFIGURATION.md** (567 lines) - BatchTester configuration first

### 3. Tests & Examples

#### Updated Tests (`tests/test_batch_models.py`)
- Added 11 new Period tests:
  - Date format validation (string, date, datetime)
  - `start < end` validation (2 tests)
  - Q1-Q4 constructors (4 tests)
  - `from_year` constructor (1 test)
  - `from_month` with leap year handling (3 tests)
  - Invalid month validation (1 test)
- Updated BacktestRequest tests to use Period objects
- Fixed Blueprint/StrategyConfig imports

#### Updated Notebook (`batch_testing_demo.ipynb`)
- All 6 code cells now use Period objects
- Added `from tradepose_client.batch import Period` import
- Replaced tuples with:
  - `Period.from_year(2023/2024/2025)`
  - `Period.Q1(2024)`, `Period.Q2(2024)`, etc.
  - `Period.from_month(2024, 1/2/3)`
  - `Period(start="...", end="...")`

#### Removed Deprecated Tests
- Deleted `tests/resources/test_tasks_zip.py` (20 tests for obsolete `download_result` API)

## Test Results

### ✅ All Tests Passing
```
203 tests passed in 0.28s
```

### Test Coverage by Module
- **Period Model**: 21 tests
- **Configuration**: 20 tests
- **Exceptions**: 28 tests
- **Client**: 67 tests
- **Builder API**: 31 tests
- **Authentication**: 9 tests
- **Resources**: 27 tests

### Key Period Tests
```python
# Validation
Period(start="2024-01-01", end="2024-12-31")  # ✅ Valid
Period(start="2024-12-31", end="2024-01-01")  # ❌ ValueError: must be before

# Convenience constructors
Period.Q1(2024)                    # 2024-01-01 to 2024-03-31
Period.from_year(2024)             # 2024-01-01 to 2024-12-31
Period.from_month(2024, 2)         # 2024-02-01 to 2024-02-29 (leap year)
Period.from_month(2023, 2)         # 2023-02-01 to 2023-02-28 (non-leap)
```

## Migration Guide

### Before (v0.1.x - Deprecated)
```python
from tradepose_client import BatchTester

tester = BatchTester(api_key="...")
batch = tester.submit(
    strategies=[strategy],
    periods=[
        ("2024-01-01", "2024-03-31"),  # ❌ Tuples no longer supported
        ("2024-04-01", "2024-06-30"),
    ]
)
```

### After (v0.2.0+)
```python
from tradepose_client import BatchTester
from tradepose_client.batch import Period

tester = BatchTester(api_key="...")
batch = tester.submit(
    strategies=[strategy],
    periods=[
        Period.Q1(2024),  # ✅ Type-safe Period objects
        Period.Q2(2024),
    ]
)
```

## Benefits

### Type Safety
- Compile-time validation via Pydantic
- IDE autocomplete for Period methods
- Clear error messages: "Period start must be before end"

### Developer Experience
- Self-documenting: `Period.Q1(2024)` vs `("2024-01-01", "2024-03-31")`
- Convenience constructors reduce boilerplate
- Automatic leap year handling in `from_month()`

### Architecture
- BatchTester positioned as primary interface (90% of users)
- TradeposeClient positioned as low-level interface (10% of users)
- Clear separation in documentation structure

## Documentation Structure

```
docs/
├── README.md                  # Quick start with BatchTester + Period
├── EXAMPLES.md                # 15 real-world examples
├── API_REFERENCE.md           # Complete API (BatchTester first)
├── ARCHITECTURE.md            # Design philosophy
├── CONFIGURATION.md           # BatchTester config first
├── LOW_LEVEL_API.md           # Async TradeposeClient reference
└── ERROR_HANDLING.md          # Exception reference
```

## Files Modified

### Source Code
- `packages/client/src/tradepose_client/batch/models.py`
- `packages/client/src/tradepose_client/batch/tester.py`

### Documentation
- `packages/client/README.md`
- `packages/client/docs/EXAMPLES.md`
- `packages/client/docs/API_REFERENCE.md`
- `packages/client/docs/ARCHITECTURE.md`
- `packages/client/docs/CONFIGURATION.md`
- `packages/client/docs/LOW_LEVEL_API.md` (new)

### Tests
- `packages/client/tests/test_batch_models.py`
- `packages/client/tests/resources/test_tasks_zip.py` (removed)

### Examples
- `batch_testing_demo.ipynb`

## Compatibility

### Breaking Changes
- `BatchTester.submit()` no longer accepts `list[tuple[str, str]]`
- Must use `list[Period]` instead

### Non-Breaking Changes
- All Period constructors are new additions
- No changes to async TradeposeClient API
- No changes to Builder API
- No changes to existing Period object usage

## Next Steps

Users should:
1. Import Period: `from tradepose_client.batch import Period`
2. Replace tuple periods with Period objects
3. Use convenience constructors where appropriate:
   - `Period.Q1(2024)` for quarters
   - `Period.from_year(2024)` for full years
   - `Period.from_month(2024, 3)` for single months

## Documentation Links

- Quick Start: `README.md`
- Examples: `docs/EXAMPLES.md`
- API Reference: `docs/API_REFERENCE.md`
- Low-Level API: `docs/LOW_LEVEL_API.md`
- Testing: `tests/TESTING_GUIDE.md`
