-- pricing — Phase 13 demo entry point.
-- (Design artifact: Stage 2 parses and discards `main` blocks; this executes
--  from Phase 6. The annotated walkthrough mirrors docs/examples/hello/main.wo.)

main {
  insert Product { sku: "WO-001", name: "writeonce mug" };

  -- LIVE binding (13c): the handle receives a delta at every commit that
  -- touches a matching row — the "pointer that observes stores". A plain
  -- `let p = select ...` would be a snapshot and never see later changes.
  -- Brace rule: bare identifiers are projections, so this subscribes to
  -- the { name, prices } shape of all products.
  -- (Spec: docs/runtime/database/02-wo-language.md § Schema-Layer DML)
  let live = LIVE select Product{ name, prices };

  -- Method call (13b): row-scoped transaction — inserts a Price, commits,
  -- and the commit fans the delta out to `live` and to every browser on
  -- the /pricing screen (13d). At scale: one commit → one message per
  -- core → batched socket writes to millions of subscribers (13e).
  Product{ sku == "WO-001" }.set_price(4999);

  for delta in live {
    print(delta.kind, delta.row.name);   -- update "writeonce mug"
  }
}