develop-userscripts

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 GM_* behavior
• deciding between a portable foreground script and ScriptCat-only @background or @crontab
• adding config UI with ==UserConfig==
• packaging a ScriptCat ==UserSubscribe== bundle or preparing a CloudCat-compatible script

Do not use this skill for full browser extension development or general browser automation outside userscript managers.

Runtime Selection

digraph userscript_runtime {
    "Need page DOM or page context?" [shape=diamond];