chore(main): release 0.3.9 (#493)

🤖 I have created a release *beep* *boop*
---


##
[0.3.9](v0.3.8...v0.3.9)
(2025-10-15)


### Features

* custom ID generators
([051ab20](051ab20))


### Bug Fixes

* apply `history_length` for `message/send` requests
([#498](#498))
([a49f94e](a49f94e))
* **client:** `A2ACardResolver.get_agent_card` will auto-populate with
`agent_card_path` when `relative_card_path` is empty
([#508](#508))
([ba24ead](ba24ead))


### Documentation

* Fix Docstring formatting for code samples
([#492](#492))
([dca66c3](dca66c3))

---
This PR was generated with [Release
Please](https://github.com/googleapis/release-please). See
[documentation](https://github.com/googleapis/release-please#release-please).

Author: a2a-bot

CHANGELOG.md

@@ -1,5 +1,23 @@
 # Changelog
 
+## [0.3.9](https://github.com/a2aproject/a2a-python/compare/v0.3.8...v0.3.9) (2025-10-15)
+
+
+### Features
+
+* custom ID generators ([051ab20](https://github.com/a2aproject/a2a-python/commit/051ab20c395daa2807b0233cf1c53493e41b60c2))
+
+
+### Bug Fixes
+
+* apply `history_length` for `message/send` requests ([#498](https://github.com/a2aproject/a2a-python/issues/498)) ([a49f94e](https://github.com/a2aproject/a2a-python/commit/a49f94ef23d81b8375e409b1c1e51afaf1da1956))
+* **client:** `A2ACardResolver.get_agent_card` will auto-populate with `agent_card_path` when `relative_card_path` is empty ([#508](https://github.com/a2aproject/a2a-python/issues/508)) ([ba24ead](https://github.com/a2aproject/a2a-python/commit/ba24eadb5b6fcd056a008e4cbcef03b3f72a37c3))
+
+
+### Documentation
+
+* Fix Docstring formatting for code samples ([#492](https://github.com/a2aproject/a2a-python/issues/492)) ([dca66c3](https://github.com/a2aproject/a2a-python/commit/dca66c3100a2b9701a1c8b65ad6853769eefd511))
+
 ## [0.3.8](https://github.com/a2aproject/a2a-python/compare/v0.3.7...v0.3.8) (2025-10-06)