character-ai/prompt-poet

Combines YAML-based prompt structure with Jinja2 templating to support conditional logic, dynamic message lists, and LangChain integration—enabling features like context-aware few-shot examples and automatic message truncation by priority. Built-in tokenization provides granular token accounting across nested prompt sections, helping optimize context length constraints. Handles complex, compositional prompts through template includes and variable interpolation while maintaining clean separation between prompt logic and data.

1,139 stars and 11,757 monthly downloads. Available on PyPI.