diff --git a/.github/.release-please-manifest.json b/.github/.release-please-manifest.json
index a3906fc0848..bb18e556171 100644
--- a/.github/.release-please-manifest.json
+++ b/.github/.release-please-manifest.json
@@ -1,3 +1,3 @@
 {
-  ".": "2.9.0"
+  ".": "2.9.1"
 }
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7e6034ef873..19726943b13 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,18 @@
 # Changelog
 
+## [2.9.1](https://github.com/google/adk-python/compare/v2.9.0...v2.9.1) (2026-09-15)
+
+
+### Highlights
+
+This release focuses on improving visibility into model reasoning steps when utilizing Claude's adaptive thinking capabilities.
+
+* **Claude Integration**: Access the step-by-step reasoning process of Claude models by ensuring visible thoughts are requested during adaptive thinking tasks. ([ba0d542](https://github.com/google/adk-python/commit/ba0d542181df87b6e1da9709fa0410082484443a))
+
+### Bug Fixes
+
+* request visible thoughts for Claude adaptive thinking ([ba0d542](https://github.com/google/adk-python/commit/ba0d542181df87b6e1da9709fa0410082484443a))
+
 ## [2.9.0](https://github.com/google/adk-python/compare/v2.8.0...v2.9.0) (2026-09-10)
 
 
diff --git a/src/google/adk/version.py b/src/google/adk/version.py
index 9db3f7b4913..602b624acbb 100644
--- a/src/google/adk/version.py
+++ b/src/google/adk/version.py
@@ -13,4 +13,4 @@
 # limitations under the License.
 
 # version: major.minor.patch
-__version__ = "2.9.0"
+__version__ = "2.9.1"