Most "save this for later" tools I've used eventually want a server: an account system, a database for your notes, a sync service with its own outage history. I wanted something narrower — capture text or a whole page while browsing, turn it into a spaced-repetition flashcard, and have it show up on my other machine — without running any infrastructure at all.
MindStack is a Manifest V3 Chrome extension that does exactly that: capture, spaced-repetition scheduling, a full dashboard, and cross-device sync, built entirely on chrome.storage.sync and chrome.identity. No backend, no bundler, no npm install before you can load it unpacked. Here's what that constraint forces you to get right.
Decision 1: The scheduler is SM-2-shaped, not SM-2
Spaced repetition apps usually reach for a full SuperMemo SM-2 implementation — ease factors computed from response quality on a 0–5 scale, per-review interval history. MindStack's actual scheduler is a compressed version that captures the two properties that matter for a lightweight capture tool and drops the rest:
const scoreReview = async (score) => {
