Writing a TokenCap Plugin, and What the Sandbox Stops It From Doing

Question

TokenCap 3 plugins are local JS files listed under tokencapPlugins in your package.json.

Two hooks:

• afterBuild gets the build's output path, file count and token estimate
• beforeRedact can rewrite content before core redaction runs

Plus named tools: tokencap analyze plugins run <tool-name> --text "input".

The sandbox:

• Own V8 realm; no require, no process, no network
• File access only inside .tokencap/plugins/<name>/, with symlinks and junctions rejected
• 1 s per call, 150 ms to load; overruns get disabled
• A failing beforeRedact never blocks redaction

One honest caveat from the source: node:vm is not a security boundary. Plugins are trusted code.

Read more at tokencap.vansharora.app