rust-tokiolisted

# Rust Tokio **Ownership.** For the affected work, identify who admits it, observes its failure, requests cancellation, and waits for completion. Honor supplied requirements and preserve settled choices outside the requested change; resolve only what the task leaves open. Background work spawns through the task tracker in bootstrap with a child of the root cancellation token, and the shutdown sequence cancels, closes the tracker, and waits under the background-join budget. A bare spawn whose handle is dropped has no owner: its panic is invisible and its completion unprovable. Use a JoinSet when results must be collected and the tracker for fire-and-forget work under a lifecycle. Cancelling a parent token cancels its children, never the reverse. A select drops the losing futures, so only cancellation-safe futures may lose without corrupting state: channel receives, sleeps, watch changes, and cancellation waits are safe; a partially completed read or a send on a bounded channel is not. Use biased ordering when arm priority matters. Bound channels and queues together with the work they feed; an unbounded channel moves overload into memory. Blocking or CPU-bound calls go through spawn_blocking, which cannot be aborted once started, so bound its input and let the caller enforce the deadline. Never block on a runtime worker thread, and never call the OpenTelemetry provider shutdown there; the telemetry stage runs it on a blocking thread under a timeout. Use tokio's Instant and