With the rapid improvement of LLMs’ coding capabilities, the bottleneck of LLM-based automated software development is shifting from generating code to developing requirements. In this paper, we present iReDev, the first interactive human-agent collaborative platform that supports both initial requirements development and continuous requirements evolution. iReDev orchestrates seven specialized roles through an event-driven publish/subscribe mechanism over a Git-backed artifact pool, minimizing the manual effort required throughout the requirements development process. Besides, iReDev introduces a set of human-agent collaboration modes that allow humans to engage at the critical points that inherently require human interaction, ensuring that the resulting artifacts faithfully reflect stakeholders’ real intent. Our evaluation on three software systems shows that iReDev produces higher-quality requirements artifacts than a single-prompt baseline. iReDev is open-sourced at https://github.com/jdm4pku/iReDev, with a demonstration video available at https://youtu.be/Lj0zAc67idw.