diff --git a/CHANGELOG.md b/CHANGELOG.md
index 932266d..874823c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,12 @@ adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
 
+## [0.4.0] - 2026-08-20
+
+Session indexing becomes a reusable, role-aware host capability with related
+Codex reviews, bounded AntiGravity metadata, accurate Cowork paths, and MCP
+connections that fail and clean up explicitly under desktop-scale load.
+
 ### Added
 - **Codex Auto Review relationships.** Guardian rollouts now encode their
   original root session id in `providerVariant` as `auto-review:<session-id>`,
diff --git a/Sources/AgentSessionKit/AgentSessionKitInfo.swift b/Sources/AgentSessionKit/AgentSessionKitInfo.swift
index 27d8631..6aacc5b 100644
--- a/Sources/AgentSessionKit/AgentSessionKitInfo.swift
+++ b/Sources/AgentSessionKit/AgentSessionKitInfo.swift
@@ -19,7 +19,7 @@ public enum AgentSessionKitInfo {
     ///
     /// Semver, bare — no `v` prefix, matching the tags. Bumping it is part
     /// of the release commit; see `RELEASING.md`.
-    public static let version = "0.3.0"
+    public static let version = "0.4.0"
 
     /// Where the package lives. Public because a host that shows the
     /// version usually wants somewhere to send the reader.