NeedTracer: Tracking Dynamic User Needs with Focus Anchors in Multi-Turn Emotional Support

In multi-turn emotional support, accurately understanding user needs is key to effective emotional support. Existing methods can continuously update implicit needs through ongoing interaction, but they have not explicitly determined whether observed need changes reflect further confirmation and refinement of the current need or indicate that a new need stage has formed. Consequently, when a cross-stage need transition occurs, the model may still organize subsequent support based on the previous need and gradually deviate from the user's current need. To address this issue, we propose NeedTracer, a dynamic user need tracking framework for multi-turn emotional support that aims to continuously identify the user's current need and its stage-wise changes. NeedTracer identifies and maintains the focus anchor based on user-side evidence accumulated through ongoing interaction, representing the specific unresolved concern that the user currently prioritizes, and uses it to organize within-stage updates and cross-stage transitions of the current user need. For within-stage updates, when the focus anchor remains stable, NeedTracer updates the current user need based on continuously arriving user-side evidence to capture further confirmation and refinement of the need within the same need stage. For cross-stage transitions, after the current need has received stage-wise sufficient support, NeedTracer confirms a new focus anchor based on new event developments and changes in the user's concern, and accordingly enters a new need stage. For support generation, NeedTracer uses a Theory of Mind (ToM)-based evaluator to select the support response that best matches the current user state and current user need. Experimental results show that NeedTracer consistently improves performance across multiple models, benchmarks, and long-horizon interaction settings, validating focus-anchor-based dynamic user need tracking.