Userscript work usually breaks at the runtime and metadata boundary, not in the page logic. Choose the runtime first, declare the minimum permissions up front, then debug in the environment where the script actually runs. When to Use Use this skill for: - writing or fixing a Tampermonkey or ScriptCat userscript - debugging injection timing, missing permissions, CSP workarounds, update checks, or behavior - deciding between a portable foreground script and ScriptCat-only or - adding config UI with - packaging a ScriptCat bundle or preparing a CloudCat-compatible script Do not use this skill fo…