9.19.0 (2026-11-02)

Breaking changes to the experimental async client

The async client is experimental, so these changes do not cause a major version bump. If you use AsyncLDClient with hooks or plugins, update your code:

• Remove the experimental AsyncHook class. The async client now uses the same synchronous Hook class as the sync client. Change each AsyncHook subclass to subclass Hook, and change its async def stages to def. The stages run on the event loop, so they must not block. (#548) (2457311)
• AsyncPlugin.get_hooks now returns a list of Hook instances. AsyncPlugin.register stays async. (#548) (2457311)

Features

• Accept synchronous hooks on the async client (#548) (2457311)

Bug Fixes

• Run after-evaluation hooks when an async evaluation is cancelled or raises (2457311)

This PR was generated with Release Please. See documentation.

9.18.4 (2026-10-26)

Bug Fixes

• Use monotonic clocks for migration latency and FDv2 stream-init timing (#539) (346e9be)

This PR was generated with Release Please. See documentation.

9.18.3 (2026-10-20)

Bug Fixes

• Require certifi 2026.10.19 or newer (#544) (518819d)

This PR was generated with Release Please. See documentation.

9.18.2 (2026-10-12)

Bug Fixes

• Use monotonic clocks for stream-init durations and FDv2 state windows (#537) (e8501c5)

This PR was generated with Release Please. See documentation.

9.18.1 (2026-10-06)

Bug Fixes

• Reuse an in-flight big segment status poll instead of always querying twice (#535) (66013b5)

This PR was generated with Release Please. See documentation.

9.18.0 (2026-09-25)

Features

• Add retry state for RETRY-spec backoff (#522) (e734558)
• Drive repeating tasks from a delay source (9abe8cb)
• Retry indefinitely after a data source failure instead of stopping permanently in FDv1 (e17e173)
• warn that payload filtering has no effect with FDv2 (#518) (296311f)
• Warn when the SDK is used in a forked process without postfork (#512) (75402e9)

Bug Fixes

• Add async modules to the readthedocs API reference (#513) (f40d3b2)
• Log the cached-data evaluation warning only once per client (#520) (59ce998)
• Read all items when a collection is empty (#524) (1087147)
• Repeating task wait duration is no longer reduced by a slow callback duration. (9abe8cb)
• Report a distinct User-Agent for the async client (#516) (514c467)
• Warn and use the documented default for an invalid poll interval or initial reconnect delay (e17e173)

This PR was generated with Release Please. See documentation.

9.17.0 (2026-08-28)

Features

• Add async big segment store manager and async Redis adapter (#462) (aa492d2)
• Add async DynamoDB persistent feature store (#490) (cb010df)
• Add async event processor (ec7c113)
• Add async event processor (#472) (ec7c113)
• Add async FDv1 polling data source and feature requester (#475) (cca37a8)
• Add async FDv1 streaming and data source status tracking (#464) (4bf7067)
• Add async FDv2 data sources (#485) (5da1515)
• Add async FDv2 data system (#486) (6a70132)
• Add async hook, plugin, and flag tracker (#463) (686a70a)
• Add async migration support (#470) (577d51e)
• Add async persistent feature store foundation and Redis adapter (f9c76ee)
• Add AsyncConfig for the async SDK client (#471) (0587a78)
• Add AsyncLDClient with FDv1 data system and public API (#480) (fd041a5)
• Add Config.with_wrapper_information (#501) (8a98583)
• Add environment ID support for hooks. (#484) (49e809f)
• Add read-only store views and async persistence foundation for the data system (#503) (0eb61fa)

Bug Fixes

• Allow tombstones without a key property (#502) (5f44e61)
• Escape attribute names reported in redactedAttributes (#505) (90059cb)
• Prevent a persistent-store outage from throwing in the sync FDv2 evaluation (#506) (467da53)
• Return empty prerequisites for a flag that fails to evaluate in all_flags_state (#483) (73e9b07)

This PR was generated with Release Please. See documentation.

9.16.1 (2026-07-24)

Bug Fixes

• Bump python-eventsource to 1.7.1 to correct pool ownership when closing connections (25c2b8d)
• Correct data source error reporting (25c2b8d)
• Remove dead BUILTINS constant (#461) (eb0ecfd)

Documentation

• clarify is_initialized() semantics (SDK-2641) (#454) (bab14db)

This PR was generated with Release Please. See documentation.

9.16.0 (2026-06-08)

Features

• Drop persistent-store cache after FDv2 in-memory store init (#426) (563b87a)

Bug Fixes

• align FDv2 goodbye event with spec (reason-only) (#422) (84b442d)
• honor server-directed FDv1 Fallback Directive in initializer phase (#423) (7c49bc0)
• Keep booleans and numbers distinct in the in operator (#433) (da595ab)
• Replace Python 2-style ABC patterns with Python 3 equivalents (22b8fe5)

This PR was generated with Release Please. See documentation.

9.15.1 (2026-04-10)

Bug Fixes

• Improve fallback behavior when using custom data system configuration (#407) (60272b2)

This PR was generated with Release Please. See documentation.