Interface AsyncOperation

Every cancellable or disposable async operation in the viewer, and the test that proves its abort / dispose / failure / retry behaviour.

unit/conformance/async-operations.test.ts keeps this table honest: it scans src/ for exported functions and class methods that take an AbortSignal, and for exported classes that define dispose() beside an async method, and fails for any such symbol that no row names and that carries no // lifecycle-exempt: <reason> comment. It also fails for a row naming a symbol that no longer exists or a test file that does not exist.

A row with a contract runs the shared lifecycle contract (unit/_shared/lifecycle-contract.ts, defineLifecycleContract(<contract>, …)) in one of its test files; a row without one is covered by the operation's own tests, which must name one of its symbols. New operations should prefer the contract: it states abort, dispose, failure, retry, supersede and double-dispose once, and an operation that cannot express a case says why.