docs(GEMINI.md): add development guidelines and architecture overview for Gemini project

GEMINI.md

@@ -0,0 +1,89 @@
+# GEMINI.md
+
+This file provides guidance to Gemini when working with code in this repository.
+
+## Development Commands
+
+### Installation
+- `make install-dev` - Install core development dependencies
+- `make install-proxy-dev` - Install proxy development dependencies with full feature set
+- `make install-test-deps` - Install all test dependencies
+
+### Testing
+- `make test` - Run all tests
+- `make test-unit` - Run unit tests (tests/test_litellm) with 4 parallel workers
+- `make test-integration` - Run integration tests (excludes unit tests)
+- `pytest tests/` - Direct pytest execution
+
+### Code Quality
+- `make lint` - Run all linting (Ruff, MyPy, Black, circular imports, import safety)
+- `make format` - Apply Black code formatting
+- `make lint-ruff` - Run Ruff linting only
+- `make lint-mypy` - Run MyPy type checking only
+
+### Single Test Files
+- `poetry run pytest tests/path/to/test_file.py -v` - Run specific test file
+- `poetry run pytest tests/path/to/test_file.py::test_function -v` - Run specific test
+
+## Architecture Overview
+
+LiteLLM is a unified interface for 100+ LLM providers with two main components:
+
+### Core Library (`litellm/`)
+- **Main entry point**: `litellm/main.py` - Contains core completion() function
+- **Provider implementations**: `litellm/llms/` - Each provider has its own subdirectory
+- **Router system**: `litellm/router.py` + `litellm/router_utils/` - Load balancing and fallback logic
+- **Type definitions**: `litellm/types/` - Pydantic models and type hints
+- **Integrations**: `litellm/integrations/` - Third-party observability, caching, logging
+- **Caching**: `litellm/caching/` - Multiple cache backends (Redis, in-memory, S3, etc.)
+
+### Proxy Server (`litellm/proxy/`)
+- **Main server**: `proxy_server.py` - FastAPI application
+- **Authentication**: `auth/` - API key management, JWT, OAuth2
+- **Database**: `db/` - Prisma ORM with PostgreSQL/SQLite support
+- **Management endpoints**: `management_endpoints/` - Admin APIs for keys, teams, models
+- **Pass-through endpoints**: `pass_through_endpoints/` - Provider-specific API forwarding
+- **Guardrails**: `guardrails/` - Safety and content filtering hooks
+- **UI Dashboard**: Served from `_experimental/out/` (Next.js build)
+
+## Key Patterns
+
+### Provider Implementation
+- Providers inherit from base classes in `litellm/llms/base.py`
+- Each provider has transformation functions for input/output formatting
+- Support both sync and async operations
+- Handle streaming responses and function calling
+
+### Error Handling
+- Provider-specific exceptions mapped to OpenAI-compatible errors
+- Fallback logic handled by Router system
+- Comprehensive logging through `litellm/_logging.py`
+
+### Configuration
+- YAML config files for proxy server (see `proxy/example_config_yaml/`)
+- Environment variables for API keys and settings
+- Database schema managed via Prisma (`proxy/schema.prisma`)
+
+## Development Notes
+
+### Code Style
+- Uses Black formatter, Ruff linter, MyPy type checker
+- Pydantic v2 for data validation
+- Async/await patterns throughout
+- Type hints required for all public APIs
+
+### Testing Strategy
+- Unit tests in `tests/test_litellm/`
+- Integration tests for each provider in `tests/llm_translation/`
+- Proxy tests in `tests/proxy_unit_tests/`
+- Load tests in `tests/load_tests/`
+
+### Database Migrations
+- Prisma handles schema migrations
+- Migration files auto-generated with `prisma migrate dev`
+- Always test migrations against both PostgreSQL and SQLite
+
+### Enterprise Features
+- Enterprise-specific code in `enterprise/` directory
+- Optional features enabled via environment variables
+- Separate licensing and authentication for enterprise features