diff --git a/.release-please-manifest.json b/.release-please-manifest.json
index 0ee8c01..2537c1f 100644
--- a/.release-please-manifest.json
+++ b/.release-please-manifest.json
@@ -1,3 +1,3 @@
 {
-  ".": "0.3.0"
+  ".": "0.4.0"
 }
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2567f4d..5cbb9ed 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,17 @@
 # Changelog
 
+## [0.4.0](https://github.com/togethercomputer/detect_agent/compare/detect_agent-v0.3.0...detect_agent-v0.4.0) (2026-07-24)
+
+
+### Features
+
+* port upstream agents.json detection engine ([#14](https://github.com/togethercomputer/detect_agent/issues/14)) ([1e986c5](https://github.com/togethercomputer/detect_agent/commit/1e986c51b9fdb10bc9385c2b30c08e5e8838ab38))
+
+
+### Documentation
+
+* sync README with upstream detect-agent ([#12](https://github.com/togethercomputer/detect_agent/issues/12)) ([852c73f](https://github.com/togethercomputer/detect_agent/commit/852c73f2c41ca6a6e282bee3648dd4b0867f5bcc))
+
 ## [0.3.0](https://github.com/togethercomputer/detect_agent/compare/detect_agent-v0.2.1...detect_agent-v0.3.0) (2026-05-29)
 
 
diff --git a/pyproject.toml b/pyproject.toml
index 4631134..91a43cf 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -10,7 +10,7 @@ packages = ["detect_agent"]
 
 [project]
 name = "detect_agent"
-version = "0.3.0"
+version = "0.4.0"
 description = "Detect if code is running in an AI agent or automated development environment"
 readme = "README.md"
 requires-python = ">=3.9"
diff --git a/uv.lock b/uv.lock
index 32e19e1..f3429c1 100644
--- a/uv.lock
+++ b/uv.lock
@@ -58,7 +58,7 @@ wheels = [
 
 [[package]]
 name = "detect-agent"
-version = "0.3.0"
+version = "0.4.0"
 source = { editable = "." }
 
 [package.optional-dependencies]