After diffusion, candidate concepts are partitioned by their graph role relative to the seed: child (successors and focal-local material), bridge (direct prerequisites of the seed), and global (shallow anchors near the top of the prerequisite hierarchy). This three-role partition is what the role-aware ranker enforces quotas over, and it lets the returned context preserve a small, interpretable mix of downstream, prerequisite, and anchor concepts rather than collapsing onto one direction of the graph.