diff --git a/.release-please-manifest.json b/.release-please-manifest.json
index 09abf21a..895bf0e3 100644
--- a/.release-please-manifest.json
+++ b/.release-please-manifest.json
@@ -1,3 +1,3 @@
 {
-  ".": "1.13.1"
+  ".": "2.0.0"
 }
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 48819a5a..997b9229 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,28 @@
 # Changelog
 
+## [2.0.0](https://github.com/agentclientprotocol/codex-acp/compare/v1.13.1...v2.0.0) (2026-09-28)
+
+
+### ⚠ BREAKING CHANGES
+
+* AIR tool call contract, exact diff patches, and fixes for every client ([#530](https://github.com/agentclientprotocol/codex-acp/issues/530))
+
+### Features
+
+* add  _meta.mcpStartupAwaitTimeoutMs option to allow awaiting for requested MCP servers startup outcome on session start ([#517](https://github.com/agentclientprotocol/codex-acp/issues/517)) ([cf6609e](https://github.com/agentclientprotocol/codex-acp/commit/cf6609e6be2f932251a7a379a0f3d2d79efd23d0))
+* AIR tool call contract, exact diff patches, and fixes for every client ([#530](https://github.com/agentclientprotocol/codex-acp/issues/530)) ([966a544](https://github.com/agentclientprotocol/codex-acp/commit/966a544bdb798de7f965df05ef66d2e3cb055364))
+
+
+### Bug Fixes
+
+* report authentication failures through ACP login flow ([#550](https://github.com/agentclientprotocol/codex-acp/issues/550)) ([2a26ee4](https://github.com/agentclientprotocol/codex-acp/commit/2a26ee44e07bdfbd6f2416a528fa2a6c18ff696d))
+* resolve ACP v1 conformance failures found by acp-tck ([#536](https://github.com/agentclientprotocol/codex-acp/issues/536)) ([1cc6223](https://github.com/agentclientprotocol/codex-acp/commit/1cc62233fb6f2abde7cadd518a53de9d0826ea77))
+* restore read-only mode and clarify access presets ([#480](https://github.com/agentclientprotocol/codex-acp/issues/480)) ([7fee150](https://github.com/agentclientprotocol/codex-acp/commit/7fee150a55098f7140a03907fec5f11edbe45086))
+* specify correct default behavior in mcp-stratup-await-timeout.md ([#551](https://github.com/agentclientprotocol/codex-acp/issues/551)) ([bf37821](https://github.com/agentclientprotocol/codex-acp/commit/bf37821e8f3c1f1e9b6954171855a9e2579cd2c9))
+* update codex to 0.157.0 ([#549](https://github.com/agentclientprotocol/codex-acp/issues/549)) ([7839796](https://github.com/agentclientprotocol/codex-acp/commit/78397963740f7263fdb8ae9178682d0fc714790e))
+* update codex to 0.157.1 ([#554](https://github.com/agentclientprotocol/codex-acp/issues/554)) ([9510cf1](https://github.com/agentclientprotocol/codex-acp/commit/9510cf18248023e1e165b422416919e43776b93e))
+* update codex to 0.158.0 ([#559](https://github.com/agentclientprotocol/codex-acp/issues/559)) ([59d0fb0](https://github.com/agentclientprotocol/codex-acp/commit/59d0fb0b6fd9dc85bf7c45f841f39a5225bea232))
+
 ## [1.13.1](https://github.com/agentclientprotocol/codex-acp/compare/v1.13.0...v1.13.1) (2026-09-23)
 
 
diff --git a/package-lock.json b/package-lock.json
index 5044799d..dd5cdcf6 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "@agentclientprotocol/codex-acp",
-  "version": "1.13.1",
+  "version": "2.0.0",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "@agentclientprotocol/codex-acp",
-      "version": "1.13.1",
+      "version": "2.0.0",
       "license": "Apache-2.0",
       "dependencies": {
         "@agentclientprotocol/sdk": "^1.5.0",
diff --git a/package.json b/package.json
index 482f3e68..7501dc32 100644
--- a/package.json
+++ b/package.json
@@ -3,7 +3,7 @@
   "publishConfig": {
     "access": "public"
   },
-  "version": "1.13.1",
+  "version": "2.0.0",
   "description": "",
   "main": "dist/index.js",
   "bin": {