Attention degradation — context saturation & attentional residue

A formal account of why long contexts degrade. Research operationalises two
mechanisms: context saturation, where extraneous task-irrelevant information
crowds the workspace, and attentional residue, where interference from
task-switching lingers and impairs subsequent reasoning. These are tied to
architectural causes — the quadratic scaling of attention and "attention sinks" that
distribute focus unevenly across a sequence. This gives the "context rot" students
met at Basic++ a rigorous, measurable foundation.