# Changelog

All notable changes to this project will be documented in this file.

The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).

## [Unreleased]

## [0.1.1] - 2025-12-06

### Added

#### Agent Interface (Phase 1)
- Abstract `AgentInterface` base class for model abstraction
- `LoremTesterAgent`: Full-featured mock agent with realistic behavior
  - Configurable reasoning effort levels (none, minimal, low, medium, high, xhigh)
  - Random tool/function call generation for testing
  - Error triggers: rate_limit, context_overflow, invalid_tool
  - Temperature-based response variation
- `TatlockAgent`: Placeholder for future PydanticAI integration
- `ModelRegistry`: Centralized model management and discovery
- 18 agent tests with comprehensive coverage

#### Responses API (Phases 2, 3, 6)
- OpenAI Responses API format with structured output (`/v1/responses`)
  - Reasoning items (thinking summaries with configurable effort)
  - Function call items (tool execution simulation)
  - Message items (assistant responses with output_text)
  - Streaming and non-streaming modes
- Real-time streaming with SSE-Starlette
- Conversation history management (Phase 3):
  - Hybrid client/server approach (client maintains state, server tracks)
  - Auto-generated deterministic conversation IDs from message hash
  - Configurable max turns with automatic trimming (default: 20)
  - Context window management with approximate token counting
  - Token usage statistics
  - Placeholder for future vector memory (Qdrant)
- Advanced features (Phase 6):
  - Parameter validation with Pydantic field validators
  - Temperature: 0.0-2.0 range enforcement
  - Reasoning effort: 6 levels validation
  - Max output tokens: positive integer enforcement
  - Stop sequences: up to 4, non-empty strings
  - Real-time stop sequence detection during streaming
  - Real-time max tokens enforcement with token counting
- 45 Responses API tests (router, error handling, history, advanced features)

#### Chat Completions Wrapper (Phase 5)
- OpenAI Chat Completions compatibility layer (`/v1/chat/completions`)
- Single source of truth architecture (wraps Responses API)
- Automatic reasoning generation
- Converts reasoning items to `<think>` tags for Open WebUI
- Pipeline prefix preservation
- System message support
- Enhanced error types (RateLimitError, ContextLengthError)
- 12 Chat Completions tests (router + streaming wrapper)

#### Application Infrastructure
- FastAPI application factory pattern
- CORS middleware with configurable origins
- Global exception handlers:
  - AppException handler for custom errors
  - RequestValidationError handler for Pydantic validation
  - General exception handler for unexpected errors
- Lifespan management for startup/shutdown
- OpenAPI schema with interactive documentation
- 16 main application tests

#### Testing Infrastructure
- Comprehensive test suite: 95 tests, 78.95% coverage (up from 62%)
- Async test support with pytest-asyncio
- Test fixtures for sync and async clients
- Integration tests for all API endpoints
- Streaming functionality tests
- Parameter validation tests
- Error handling tests
- Conversation history tests

#### Documentation
- Complete README.md rewrite with hybrid architecture
- Architecture diagrams and decision documentation
- AGENTS.md with technical implementation details
- API usage examples for all endpoints
- Conversation history guide
- Open WebUI integration instructions
- Troubleshooting section
- Implementation planning documents

### Changed
- Hybrid architecture with Responses API as primary endpoint
- Chat Completions now wraps Responses API (no duplicate logic)
- Enhanced error handling with OpenAI-compatible format
- Improved streaming with word-by-word delivery
- Better test organization with domain-based structure

### Security
- Minor version locking for all dependencies
- All packages CVE-checked (as of 2025-12-06)
- Environment variable protection via .gitignore
- No known vulnerabilities in dependency tree
- Input validation on all API endpoints

## [0.1.0] - 2025-12-06

### Added
- Project initialization
- Python 3.12.11 environment
- FastAPI 0.123.9 web framework
- PydanticAI 1.27.0 dependency (ready for future integration)
- Mock chat completions (lorem ipsum responses)
- Mock model listing (mistral-nemo:latest)
- Testing infrastructure (pytest, coverage, ruff, mypy)
- Configuration management with pydantic-settings
- CORS middleware
- Exception handlers (OpenAI-compatible error format)

[Unreleased]: https://git.schweitz.net/jpmschweitzer/tatlock/compare/v0.1.1...main
[0.1.1]: https://git.schweitz.net/jpmschweitzer/tatlock/compare/v0.1.0...v0.1.1
[0.1.0]: https://git.schweitz.net/jpmschweitzer/tatlock/releases/tag/v0.1.0