This folder contains the complete set of supplementary materials for "Developer Needs and Feasible Features for AI Assistants in IDEs". It includes documents used to recruit participants, collect and analyze data, and report on findings. Materials cover both phases of the study: the interview-based exploration of developer needs and the follow-up prediction market. Included are the full interview guide, recruitment screener, participant metadata, codebook for qualitative analysis, detailed descriptions of AI feature ideas, the anonymized prediction market dataset, and a report summarizing how prediction questions were defined and resolved.