Auditing a skills folder as a system: one synonymous alias takes noncanonical routes from 0/32 to 15/32.

SkillSeam treats the collection, not the file, as the unit of failure (arXiv 2609.13321). Flattening the persistence hierarchy raises loaded-skill tokens 60%. A dangling anchor raises total tokens 64% and costs 3.1pp accuracy. With skill count and context size held fixed, swapping an unrelated control for a synonymous alias drives noncanonical routes from 0/32 to 15/32 and flips half of matched paraphrase pairs. Overlapping lanes raise ownership conflicts from 0/16 to 14/16, bland triggers drive routing conflicts from 3/32 to 30/32 and inflate loaded-skill tokens 3.7x, and one granularity mis-mix costs 12.5pp accuracy. Byte-differenced variants and a one-screen checklist are released.