This issue tracks the implementation PRs for adopting proven Trio/anyio patterns natively into asyncio, as proposed in the discuss.python.org thread: Adopt proven anyio/Trio patterns natively into asyncio (multi-release roadmap).

PRs

Tier 1 — Structured concurrency foundations

• Add asyncio.CancelScope with level-triggered cancellation #145345 — CancelScope: asyncio.CancelScope with level-triggered cancellation, cancel_scope() / cancel_scope_at() convenience APIs. Implements per-task scope stack with zero overhead for code not using scopes. (51 tests)
• Add TaskGroup.start() and TaskStatus for task readiness signaling #145353 — TaskGroup.start(): TaskGroup.start() and TaskStatus for task readiness signaling — lets a long-running task signal when it's ready while continuing to run in the group. (8 tests)

Tier 2 — Resource management & communication

• Add asyncio.CapacityLimiter with borrower tracking and dynamic capacity #145354 — CapacityLimiter: asyncio.CapacityLimiter with borrower tracking, dynamic total_tokens, on_behalf_of API, and FIFO fairness. Improves on Semaphore by preventing same-task deadlocks. (15 tests)
• Add asyncio memory object channels (open_channel) #145356 — Memory channels: asyncio.open_channel() with split SendChannel / ReceiveChannel endpoints, bounded backpressure, clone + ref-counting, and clean shutdown signaling. Improves on asyncio.Queue. (40 tests)
• Add asyncio async file I/O (open_file, AsyncFile, wrap_file, Path) #145358 — Async file I/O: asyncio.open_file(), AsyncFile, wrap_file(), Path — thread-delegated async file I/O wrapping open() and pathlib.Path. (55 tests)

Design principles

All implementations follow the same approach:

• Adopt proven patterns — APIs closely mirror battle-tested Trio/anyio designs
• Pure Python where possible (only CancelScope touches C code for Task internals)
• Zero overhead for existing code — no behavioral changes unless new APIs are explicitly used
• Reuse existing asyncio infra — to_thread(), create_future(), create_task(), etc.
• Comprehensive test coverage — 169 new tests total across all PRs