Cairn
A capture-first, offline PWA: anything you notice lands in seconds, gets turned into action, and shows up on one Today screen.
Thoughts arrive everywhere (a task over coffee, a cracked wall in the garden, an article worth acting on) and then get forgotten. Cairn is one fast inbox for every intake, a daily habit of turning intakes into tasks, fixes, ideas or plans, and one screen that shows everything needing attention.
- Started as a PRD with numbered features and acceptance criteria. Every screen traces back to one (F04 capture, F06 Today, F20 side hustles…).
- AI coding agents built against the spec, not vibes; acceptance criteria became the tests in Vitest and Playwright.
- Offline-first: a Dexie local store and custom outbox sync over Supabase, with row-level security on every table.
A 21-feature PRD, turned into a working offline app.
Writing the spec first gave the agents something to be checked against. The PRD was the contract; the tests were the receipts.
Where AI fits next
roadmap, not shippedThe v2 plan is an assistant: AI summaries for saved links and scoring for the idea vault. The PRD deliberately leaves the provider undecided, so it goes behind the AI SDK and stays swappable.