Deeper ZIO integration: The kyo-zio module now provides bi-directional transformations between Kyo's and ZIO's layers and streams. (by @hearnadam in #1299, @HollandDM #1298)

Direct syntax overhaul: The direct syntax had a series of major fixes and improvements, greatly improving its usability. New integrations with dotty-cps-async's AsyncShift enable transformations using .now in functions for collection types, Maybe, and multiple issues with edge cases were fixed. (by @ahoy-jon in #1197, #1212, #1202, #1235, #1204, #1303, #1310, #1311)

Better resource safety: Kyo's default APIs used to not register finalizers automatically. In this release, Channel, Meter, Hub, and Queue automatically register finalizers in the init method and a new set of initUnscoped methods is provided to initialize without finalizers. Additionally, finalizers are able to inspect errors when executing and an edge case with finalization backpressure got fixed. (by @johnhungerford in #1313, #1322, #1324, @fwbrasil in #1194)

Effectful fibers and simplified isolates: Fibers used to have two type parameters representing the possible successful or failure outcomes without being able to express other pending effects like Stream and other APIs do. This release changes it to Fiber[+A, -S] where S represents a pending effect set. To enable this change, contextual and stateful isolates were merged into a single Isolate[Remove, -Keep, Restore]. When forking, the proper isolate is automatically inferred and any Restore effects are added to the pending S set of the the Fiber.

Async improvements: Fibers used to change identity on each asynchronous boundary, which prevented the implementation of some features. Fibers now keep a stable identity until completion. A new Async.raceFirst method has been added, Async.timeout was improved to better handle timeouts with zero duration, and the Timeout exception now shows the timeout duration. (by @fwbrasil in #1190, @hearnadam in #1229, #1340, #1225)

Channel draining and closing on empty: Channels didn't have a convenient way for a producer to handle termination. In this release, a new closeAndWaitEmpty enables an atomic close once the channel is empty, pendingPuts and pendingTakes provide full visibility of the state of the channel, and streaming from channels was optimized via internal optimistic draining. (by @fwbrasil in #1191, #1203, @steinybot in #1193, #1264)

Kyo companion: The Kyo companion object provides APIs for common operations. Its collection methods now keep the original collection types instead of just returning Chunk and a new set of Kyo.when combinators provides convenient composition of branching logic. (by @HollandDM in #1218, @johnhungerford in #1304)

Data structures improvements: Record now offers a getField method to enable access of fields with special or reserved names and Chunk now has a lastMaybe method. (by @road21 in #1201, #1187, @steinybot in #1226)

Lifting usability: Kyo's automatic lifting of values had an edge case where it prevented value discard warnings in the direct syntax that got fixed. Also, there was a usability issue with IDEs suggesting lifting of companion objects, which doesn't make sense. The lifting was changed to not allow lifting of companion objects. (by @ahoy-jon in #1314, #1291)

Parameterized generic aspects: The Aspect effect couldn't be used in scenarios where the aspect has a parameterized generic parameter. The effect was changed to operate on tags instead of object instances to overcome the limitation. (by @fwbrasil in #1327)

Combinators cleanups: The zipping combinators now use a Zippable type to automatically flatten multiple zipped computations, the ensuring method was fixed to accept Abort[Throwable], and several cleanups were made in the APIs. (by @hearnadam in #1295, #1336, #1337, @johnhungerford in #1319, @ahoy-jon in #1307)

Scalafix migration rules: The initial setup of Scalafix rewrites was done to support the RC cycle and rules to facilitate the migration from 0.19.0 to 1.0-RC1 were added.