Async and pending

Async state travels through the graph alongside values. A pending read suspends its reader; when the source settles, the reader runs again from the start. Boundaries turn pending and failed states into values your application can display.

• Pending and failures: Status, Reading, tracked suspension and error propagation.
• Async sources: publish values or failures from external work.
• Async memos: tracked task bodies, flight policies and previous results.
• Streams: fold the items of an observable, async enumerable or channel into one state.
• Boundaries: loading fallbacks, error recovery and stale results during refresh.
• Threading and dispatch: apply completions on the graph's owning thread.
• Testing async state: decide exactly when each flight completes.
• Fable: promise microtasks, untracked reads after every await, and single-threaded dispatch in JavaScript.

Start with Signals, Memos and Effects for the synchronous primitives. For async collection rows, see Projections.