Tracing into node_modules

You can add crumbs directly to files inside node_modules/ to trace into library internals. See what a dependency is actually doing, what it receives, what it returns. These files are gitignored and never committed, so no // @crumbs markers are needed.

Raw fetch, no import required

Paste this anywhere in a node_modules file:

fetch("http://localhost:8374/crumb", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({
    ts: new Date().toISOString(),
    ns: "library-name",
    msg: "what is happening here",
    type: "crumb",
    dt: 0,
    pid: process.pid,
    data: { arg1, arg2 }
  })
}).catch(() => {});

This sends a crumb directly to the collector via HTTP. No import needed. fetch is available globally in Node 18+ and Bun.

Why this works

• node_modules/ is gitignored, so changes never get committed
• No // @crumbs markers needed since the files aren't tracked
• A fresh npm install resets everything back to normal
• The collector receives crumbs from any source. It doesn't care if they come from your code or a library.

Tips

• Change ns to the library name so crumbs show up with a clear label in tail
• Include relevant variables in data: function arguments, return values, internal state
• Add .catch(() => {}) so the crumb never throws if the collector isn't running
• For one-liner insertion: keep it on a single line

fetch("http://localhost:8374/crumb", { method: "POST", headers: { "Content-Type": "application/json" }, body: JSON.stringify({ ts: new Date().toISOString(), ns: "lib-name", msg: "debug", type: "crumb", dt: 0, pid: process.pid, data: { val } }) }).catch(() => {});