trio 0.34.0 on Python PyPI

Full Changelog: v0.33.0...v0.34.0

Features

MemoryChannelStatistics now has a peak_buffer_used field, which reports the largest number of items that have ever been in the channel's buffer at once. This makes it easier to pick a sensible max_buffer_size based on data from a real run, instead of guessing. (#1723)
Support Python 3.15, as of beta 4. Things may still change and so this support may break in the future. (#3456)

Nursery.start() now preserves the __cause__ and __context__ of exceptions raised before task_status.started() is called. (#3261)
Fixed incorrect error message in run_process: the stdout pipe check now correctly says "stdout" instead of "stdin". (#3409)
Fixed trio.Path.as_uri() on Python 3.14+ to avoid the deprecated pathlib.PurePath.as_uri() path. (#3460)
Fixed trio.to_thread.run_sync workers leaking spawner's Context on py314t+ free-threaded builds. (#3472)

Trying to use absolute deadlines on a trio.CancelScope constructed with a relative deadline now raises, after being deprecated since Trio 0.27.0.
To switch a cancel scope from being relative to absolute, replace the trio.CancelScope object instead of trying to mutate it. (#3403)