What problem does it solve? jsgui3 renders on the server and reattaches in the browser, and failures at that seam are silent: controls render empty, stale, or blank-but-correctly-shaped, so green tests and plausible code reviews routinely miss real UI defects. This Skill enforces runtime measurement over source inference when changing, reviewing, or debugging jsgui3 controls. ## Core Features & Use Cases - Reattachment contract reference: Documents exactly what survives server-to-client activation (control tree, _ctrl_fields, _fields) and what does not (this.* assignments, data.model, text nodes), all verified in a live browser. - Discriminating proof techniques: Provides concrete checks such as marker-then-refresh to prove repaints, reading content instead of counting nodes, and testing exactly-one behavior twice across mouse and deep-link paths. - Trap catalog: Lists known failure modes including persist_activation_state for SSR'd Data_Grids, stock control spec mismatches (Chip takes label, not text), and the pre_activate() requirement for late-composed controls. - Use Case: After editing a control under src/ui/server/*/controls/, restart the server, load the page, check the console is clean, and assert on actual DOM content before writing "verified" in a commit message. ## Quick Start Use the jsgui3-verify skill to check whether my change to the Data_Grid control actually works in the browser before I mark it verified.
