diff --git a/changelog.md b/changelog.md
index 4a06f0f..0a897b6 100644
--- a/changelog.md
+++ b/changelog.md
@@ -1,9 +1,17 @@
 # changelog
 
-## unreleased
+## v0.4.0 (2026-01-02)
+
+### changes
 
 - add auto-router runner selection with configurable default engine
 - add `/cancel` + `/{engine}` command menu sync on startup
+- show engine name in progress and final message headers
+- filter command log lines from final output for cleaner answers
+
+### fixes
+
+- improve codex exec error rendering with stderr extraction
 
 ## v0.3.0 (2026-01-01)
 
diff --git a/pyproject.toml b/pyproject.toml
index e3537bc..aac960f 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,7 +1,7 @@
 [project]
 name = "takopi"
 authors = [{name = "banteg"}]
-version = "0.4.0.dev0"
+version = "0.4.0"
 description = "Run OpenAI Codex CLI with Telegram as the human-in-the-loop interface."
 readme = "readme.md"
 license = { file = "LICENSE" }
diff --git a/src/takopi/__init__.py b/src/takopi/__init__.py
index 52c6947..6a9beea 100644
--- a/src/takopi/__init__.py
+++ b/src/takopi/__init__.py
@@ -1 +1 @@
-__version__ = "0.4.0.dev0"
+__version__ = "0.4.0"
diff --git a/uv.lock b/uv.lock
index 89ed3d5..89079a4 100644
--- a/uv.lock
+++ b/uv.lock
@@ -354,7 +354,7 @@ wheels = [
 
 [[package]]
 name = "takopi"
-version = "0.4.0.dev0"
+version = "0.4.0"
 source = { editable = "." }
 dependencies = [
     { name = "anyio" },