[SiddardhaShayini]

Summary of Changes

This pull request addresses cross-platform Windows test failures, fixes tool parameter schema generation bugs, and introduces quality-of-life client enhancements:

1. Bug Fixes

• Windows NamedTemporaryFile file-locking (Fixes Tests fail on Windows due to NamedTemporaryFile locking behavior #676): Replaced tempfile.NamedTemporaryFile() in tests with pytest's standard tmp_path fixture (matching existing tests like test_client_chat_images) to avoid Windows PermissionError: [Errno 13] Permission denied. All 8 previously failing Windows tests now pass.
• Crash on None tool functions (Fixes ChatRequest.model_dump() crashes when a tool has no parameters or no function #733): Guarded ChatRequest.serialize_model against tools where function or parameters is None.
• Function tool variable arguments (Fixes convert_function_to_tool exposes *args and **kwargs as required string parameters #735): Filtered *args (VAR_POSITIONAL) and **kwargs (VAR_KEYWORD) in convert_function_to_tool so arbitrary arguments are not exposed as required parameters.
• Tool parameter defaults: Inspected parameter default values so arguments with defaults are not erroneously included in required.
• Array items & Enum schema preservation: Preserved items (e.g. list[str]) and enum / $ref on properties produced by convert_function_to_tool.
• Preserve empty string content: Fixed _copy_messages in _client.py using if v is not None: so empty content (content='') is retained.
• Bearer token check consistency: Added missing bearer authorization validation in AsyncClient.web_search and AsyncClient.web_fetch to match Client.
• Dead code removal: Removed unused _as_path helper function and unused PathLike import from _client.py.

2. Improvements & Features

• Direct api_key argument: Added first-class api_key: Optional[str] = None support directly to Client(..., api_key=...) and AsyncClient(..., api_key=...).
• Message.ToolCall enhancements: Added id: Optional[str] = None and type: Optional[str] = 'function' fields to Message.ToolCall.
• Expose public client methods in __all__: Added public functions (chat, generate, embed, etc.) to ollama.__all__ and added module-level create_blob = _client.create_blob.

3. Documentation & Examples

• Added CONTRIBUTING.md with development setup, testing, formatting, and PR submission guidelines.
• Added examples/web-fetch.py and examples/context-manager.py.
• Updated README.md and examples/README.md.

Verification

• Tested with uvx hatch test: 133 / 133 tests passing.
• Validated formatting and linting: uv run ruff check . and uv run ruff format --check . (49 files clean).
• Confirmed lockfile integrity: uv lock --check.