Time travel & compare
Every checkpoint is an immutable deployed snapshot. Put "now" next to "three sessions ago" and watch the idea evolve.
Cloudflare Pages creates an immutable preview URL for every deployment, so snapshots are free. Northstar checkpoints instead of snapshotting every commit: at meaningful moments the agent cuts a git tag with a human label and a one-line summary, appended to the checkpoint manifest at deploy time.
The timeline becomes a narrated evolution of the idea — the changelog before the product exists — and feeds each reconciliation pass.
Compare mode beats scrubbing: two iframes side by side, pinned to the same
path. Sliders compose, so ?v= works inside a time-travel iframe — “what
did MVP scope look like two weeks ago” comes for free.