agents: Add AGENTS.md file (#71)

* agents: Add AGENTS.md file

* Apply suggestion from @echarrod

* gitignore: Remove .DS_STORE

Author: echarrod

.DS_Store

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+# AGENTS.md
+
+This file provides guidance to agents (e.g. Claude Code / GitHub CoPilot) when working with code in this repository.
+
+## Project Overview
+
+This is the **Luno Python SDK**, a wrapper for the Luno API (cryptocurrency exchange platform). The package provides a Python client for interacting with Luno's REST API, supporting operations like account management, trading, fund transfers, and market data queries.
+
+## Architecture Overview
+
+### Core Structure
+
+- **`luno_python/base_client.py`**: Base HTTP client class (`BaseClient`) that handles:
+  - HTTP requests using the `requests` library
+  - Basic auth with API key and secret
+  - Error handling and JSON parsing
+  - User-Agent generation
+  - URL construction with parameter substitution
+
+- **`luno_python/client.py`**: Main `Client` class extending `BaseClient`. Contains ~100+ API methods auto-generated from the Luno API specification. Each method:
+  - Wraps a specific API endpoint
+  - Constructs the request object with parameters
+  - Calls `do()` to make the HTTP request
+  - Returns the API response as a dictionary
+
+- **`luno_python/error.py`**: Custom `APIError` exception class for handling API errors
+
+- **`luno_python/__init__.py`**: Exports package version
+
+### Request/Response Flow
+
+1. User calls a method on `Client` (e.g., `get_ticker(pair='XBTZAR')`)
+2. Method builds a request dict with parameters
+3. Method calls `self.do(method, path, req, auth)` from `BaseClient`
+4. `do()` makes HTTP request via `requests.Session`
+5. `do()` parses JSON response and checks for API error codes
+6. If error found, raises `APIError`; otherwise returns response dict
+
+### API Design Patterns
+
+- **Authentication**: HTTP Basic Auth with `api_key_id` and `api_key_secret`
+- **Path parameters**: Substituted using `{param_name}` syntax in paths
+- **Query parameters**: Passed via `params` in GET requests
+- **Error handling**: API returns `{"error_code": "...", "error": "..."}` on errors
+
+## Development Commands
+
+### Setup
+
+```bash
+# Create and activate virtual environment
+python -m venv env
+source env/bin/activate  # On Windows: env\Scripts\activate
+
+# Install package in development mode with test dependencies
+pip install -e '.[test]'
+```
+
+### Testing
+
+```bash
+# Run all tests
+pytest
+
+# Run specific test file
+pytest tests/test_client.py
+
+# Run specific test
+pytest tests/test_client.py::test_client_do_basic
+
+# Run with verbose output
+pytest -v
+
+# Run with coverage
+pytest --cov=luno_python
+```
+
+### Dependencies
+
+- **Runtime**: `requests>=2.18.4`, `six>=1.11.0`
+- **Test**: `pytest`, `pytest-cov`, `requests_mock`
+
+## Testing Approach
+
+Tests use `requests_mock` to mock HTTP responses. The pattern:
+
+1. Create a `Client` instance
+2. Mount mock adapter to session: `adapter.register_uri(method, url, ...)`
+3. Call client method and assert response
+
+Recent additions test the `get_balances()` method with `account_id` parameter for filtering results by account.
+
+## Git Workflow
+
+When making changes:
+
+1. Run `git pull` before creating a new branch
+2. Branch naming: `{username}-{issue-number}-{description}`
+3. Commit messages: Present tense, describe *why* not *what*
+4. Example: `"client: Add account_id parameter to get_balances method"`
+5. Push and create PR when ready
+
+## Notes on Code Generation
+
+The `client.py` file contains ~100+ methods that are auto-generated from Luno's API specification. When modifying or adding methods:
+
+- Follow existing docstring format (includes HTTP method, path, permissions, parameter descriptions)
+- Each method constructs a `req` dict with parameters and calls `self.do()`
+- Type hints in docstrings use `:type param: type_name` format for Python 2 compatibility
+
+## File Editing Requirements
+
+Always ensure files end with a newline character. This maintains consistency with Git diffs and repository standards.

AGENTS.md

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+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+For compatibility with multiple agents, the instructions are located at @AGENTS.md (see [AGENTS.md](./AGENTS.md).