Reading anything dense online is a negotiation between comprehension and focus. You hit an unfamiliar term, you either open a tab and lose your place, or you skip it and carry a gap through the rest of the article. Neither is good.
So I built rabbitholes: a Chrome extension that renders an explanation next to your cursor the moment you release a text selection, then lets you keep digging without ever leaving the page.
The tooltip renders in a shadow DOM so it doesn't touch the host page's styles or layout. Explanations come from Claude Haiku 4.5. Zero intermediary server — requests go directly from your browser to api.anthropic.com. Your API key lives in chrome.storage.sync and never leaves the browser.
The part I use most: every explanation ends with two suggested rabbit-hole topics. Click one and the tooltip pivots. You can also drag across any word or phrase in the explanation itself to go deeper on that. The extension tracks how many hops you've taken — hit something like 'philosophy' through a chain of concepts and you get a shareable trail of your path.
When I want sourced answers instead of model knowledge, the globe icon re-runs the query enriched with Brave Search results, with clickable source chips inline.
Manifest V3. No analytics, no telemetry.
// Shadow DOM keeps rabbitholes isolated from host-page CSS
const shadow = container.attachShadow({ mode: 'open' });
const style = document.createElement('style');
style.textContent = tooltipStyles; // scoped, never leaks
shadow.appendChild(style);
github.com/robertnowell/rabbitholes
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