Can I vibe code FullStory?
Session replay: watch real users struggle with your product.
Session replay looks like 'record the DOM, play it back' and is anything but: efficient DOM-mutation capture that doesn't tank page performance, privacy masking that never leaks a password field, storage economics for millions of sessions, and the search index that finds 'rage clicks on checkout' across them. The open-source rrweb library gets a demo working — the production gap between demo and product is precisely what you're paying for. PostHog's free tier makes DIY doubly pointless here.
Build a session-replay learning toy (explicitly not production — use PostHog free tier for real work). Wire rrweb into one demo page, batching events to an API route that stores sessions in Postgres with page, duration, and event counts. Replay viewer: list sessions, play one back with rrweb-player, speed controls, and a click-marker timeline. Add basic input masking (all inputs → asterisks) and document in the README exactly why this shouldn't watch real users: performance, privacy masking gaps, storage growth math (show the math).
A toy: rrweb capture on one page posting to your server, with a replay viewer — instructive to build, unwise to rely on.
- Performance-safe capture at production traffic volumes
- Bulletproof privacy masking (one leak is a breach)
- Search across sessions: rage clicks, dead clicks, funnels
- Storage/replay infrastructure that scales past a demo
Replay is only useful with search over thousands of sessions, and that's an infrastructure product, not a script tag.
A prompt is the first move, not the whole game. Course 01 teaches you to take a prompt like this one to a shipped, working app — reviewing, correcting, and steering the agent the whole way.
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