Changes in version 0.3.1                        

New Features

  - Custom Agent Builder API
    Added build_custom_agent() for creating user-defined
    graph/state-machine agents from custom node functions, static edges,
    and conditional edges.

  - Exported State-Graph Primitives
    Exported StateGraph(), make_node(), make_edge(), make_command(), and
    interrupt() to support custom workflow construction.

  - LangGraph-Style Mermaid Export
    Added compile_graph() and as_mermaid() for Mermaid visualization,
    including optional subgraph grouping and graph direction control.

  - PNG Graph Export Utility
    Added save_mermaid_png() to render Mermaid graph text (or compiled
    graph objects) into PNG files via Mermaid CLI (mmdc).

  - Reusable Code Agent with Builder Pattern
    The build_code_agent() function now supports a builder pattern. If
    user_input is omitted, the function returns a reusable agent
    (closure) that can handle multiple queries interactively. This
    allows for flexible integration in iterative coding workflows,
    similar to the existing build_researcher_agent().

  - Reusable Interpreter Agent
    The build_interpreter_agent() function now also supports a builder
    pattern. When code_output is omitted, it returns a reusable
    interpreter function that can process multiple outputs (tables,
    model results, charts, etc.) on demand. This provides a consistent
    interface for explaining analysis results dynamically.

Improvements

  - Dual Invocation Support
    Users can now call both build_code_agent() and
    build_interpreter_agent() in two ways:
    
    1.  One-shot mode – Provide the input (e.g., user_input,
        code_output) for immediate interpretation or code generation.
    2.  Builder mode – Omit the input to return a persistent agent
        function.

  - Enhanced Documentation
    The roxygen examples have been expanded to illustrate both usage
    patterns clearly for both agents, including structured return
    objects and typical use cases.

Compatibility

  - This update is fully backward-compatible. Existing calls to
    build_code_agent() and build_interpreter_agent() that use the
    one-shot pattern will continue to work without modification.