A study plan you can finish

Study plans, their phases, and how the work inside them is ordered.

4 steps · every panel is the real interface, on sample data

Each module says what you should be able to do after.

Exactly-once delivery on a write path

4 hours.

Explain idempotency keys and where they belong in a transaction
Say what your failure mode is when the client retries

Wordless, 4 steps

The scene timing comes from tools/video; the panels are components from apps/web/src/components. Because the panels are the product's own components, this page changes when the product does — which is the entire reason it is markup rather than a file.