Generates and verifies eval scenarios for a repository plugin — covering its skills, commands, and hooks — using the tessl-compatible evals/ layout (task.md, criteria.json, scenario.json) so they run under `tessl eval run` and grade offline with any judge. Authors self-gradable scenarios, runs the offline verification ladder, and commits. This skill never restructures plugins. Use when the user asks to build evals for a plugin, generate eval scenarios, or verify that a skill actually works.