This study aims to develop CocoNote, an agent-aided collaborative learning platform that enhances students' Socially Shared Regulation (SSRL) in collaborative learning.CocoNote integrates reactive agents to facilitate students' planning, monitoring, and reflection alongside a proactive agent that actively intervenes to provide metacognitive, socio-emotional, and motivational support.A quasi-experimental study involving sixth-grade students examined their SSRL abilities in a STEM course.Quantitative findings indicated that students using CocoNote (n = 38) demonstrated significant improvements in SSRL and exhibited more balanced group interactions compared to the control group (n = 40).Qualitative data analysis illustrated how agents guided discussions, increased participation and improved metacognitive processes.These findings highlight the effectiveness of AI-assisted tools in fostering SSRL abilities and suggest design principles for agent-aided collaborative learning environments.