diff --git a/.release-please-manifest.json b/.release-please-manifest.json
index 099626f4..4fcfdf7a 100644
--- a/.release-please-manifest.json
+++ b/.release-please-manifest.json
@@ -1,3 +1,3 @@
 {
-  ".": "1.8.0"
+  ".": "1.9.0"
 }
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7515958b..8af5b00a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,22 @@
 # Changelog
 
+## [1.9.0](https://github.com/agentclientprotocol/typescript-sdk/compare/v1.8.0...v1.9.0) (2026-10-16)
+
+
+### Features
+
+* isolate NES behind an experimental entrypoint ([#284](https://github.com/agentclientprotocol/typescript-sdk/issues/284)) ([e3678c2](https://github.com/agentclientprotocol/typescript-sdk/commit/e3678c27d1826e126652286fd77434afe73bab4c))
+* update schemas to v1.26.0 and v2.0.0-alpha.9 ([#285](https://github.com/agentclientprotocol/typescript-sdk/issues/285)) ([93599f3](https://github.com/agentclientprotocol/typescript-sdk/commit/93599f34d2d682bd690dedada9a032deec2b9a56))
+
+
+### Bug Fixes
+
+* accept omitted and null params for optional requests ([#282](https://github.com/agentclientprotocol/typescript-sdk/issues/282)) ([a2fbbb9](https://github.com/agentclientprotocol/typescript-sdk/commit/a2fbbb9db5b17d76f1852def45d804523a7f7c3b))
+* **examples:** report v2 turn failures on idle ([#279](https://github.com/agentclientprotocol/typescript-sdk/issues/279)) ([28b1291](https://github.com/agentclientprotocol/typescript-sdk/commit/28b1291f7c320d7d9070dadcdc6dfa42298ac292))
+* preserve outgoing v2 initialize payloads ([#283](https://github.com/agentclientprotocol/typescript-sdk/issues/283)) ([b98857b](https://github.com/agentclientprotocol/typescript-sdk/commit/b98857b3f0342915728d7e30d8a7258311054f8f))
+* **v2:** align protocol version negotiation ([#286](https://github.com/agentclientprotocol/typescript-sdk/issues/286)) ([4197b89](https://github.com/agentclientprotocol/typescript-sdk/commit/4197b8925d52cefec9c065926a3f605a2cf2a2b7))
+* **v2:** decouple session updates from prompt completion ([#280](https://github.com/agentclientprotocol/typescript-sdk/issues/280)) ([0154528](https://github.com/agentclientprotocol/typescript-sdk/commit/015452892b1aca42202b59ddc934c6a7481938e2))
+
 ## [1.8.0](https://github.com/agentclientprotocol/typescript-sdk/compare/v1.7.0...v1.8.0) (2026-10-09)
 
 
diff --git a/package-lock.json b/package-lock.json
index e53a8708..b7da7ed3 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "@agentclientprotocol/sdk",
-  "version": "1.8.0",
+  "version": "1.9.0",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "@agentclientprotocol/sdk",
-      "version": "1.8.0",
+      "version": "1.9.0",
       "license": "Apache-2.0",
       "devDependencies": {
         "@eslint/js": "^10.0.1",
diff --git a/package.json b/package.json
index b6cdf225..c94bff85 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@agentclientprotocol/sdk",
-  "version": "1.8.0",
+  "version": "1.9.0",
   "publishConfig": {
     "access": "public"
   },