diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4faabff..dcc8559 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,15 @@ While the major version is 0, minor version bumps may contain breaking changes.
 
 ## [Unreleased]
 
+## [0.4.0] - 2026-08-11
+
+A task's ID is derived from its title rather than stored, so a change to the
+derivation rules moves every unpinned ID while every content hash stays
+identical — and incremental indexing, which keys off those hashes, never
+notices. This release makes the index aware of the rules it was built under,
+and adds `lash migrate-ids` to repair the `@depends-on` references a past move
+left dangling.
+
 ### Added
 
 - `lash migrate-ids` rewrites `@depends-on` references left dangling by a
@@ -168,7 +177,8 @@ Initial release.
 - Project scaffolding: `lash init` and the PixelQuest `lash playground`
 - Configuration management, shell completions, and `lash explain` error catalog
 
-[Unreleased]: https://github.com/fixture-dev/lash/compare/v0.3.1...HEAD
+[Unreleased]: https://github.com/fixture-dev/lash/compare/v0.4.0...HEAD
+[0.4.0]: https://github.com/fixture-dev/lash/compare/v0.3.1...v0.4.0
 [0.3.1]: https://github.com/fixture-dev/lash/compare/v0.3.0...v0.3.1
 [0.3.0]: https://github.com/fixture-dev/lash/compare/v0.2.0...v0.3.0
 [0.2.0]: https://github.com/fixture-dev/lash/compare/v0.1.0...v0.2.0
diff --git a/Cargo.lock b/Cargo.lock
index 4d56045..b9e7bee 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1093,7 +1093,7 @@ dependencies = [
 
 [[package]]
 name = "lash"
-version = "0.3.1"
+version = "0.4.0"
 dependencies = [
  "anyhow",
  "assert_cmd",
@@ -1133,7 +1133,7 @@ dependencies = [
 
 [[package]]
 name = "lash-agent"
-version = "0.3.1"
+version = "0.4.0"
 dependencies = [
  "lash-core",
  "lash-types",
@@ -1145,7 +1145,7 @@ dependencies = [
 
 [[package]]
 name = "lash-core"
-version = "0.3.1"
+version = "0.4.0"
 dependencies = [
  "blake3",
  "chrono",
@@ -1165,7 +1165,7 @@ dependencies = [
 
 [[package]]
 name = "lash-db"
-version = "0.3.1"
+version = "0.4.0"
 dependencies = [
  "anyhow",
  "blake3",
@@ -1187,7 +1187,7 @@ dependencies = [
 
 [[package]]
 name = "lash-tui"
-version = "0.3.1"
+version = "0.4.0"
 dependencies = [
  "crossterm",
  "filetime",
@@ -1208,7 +1208,7 @@ dependencies = [
 
 [[package]]
 name = "lash-types"
-version = "0.3.1"
+version = "0.4.0"
 dependencies = [
  "blake3",
  "chrono",
diff --git a/Cargo.toml b/Cargo.toml
index 32e5ce6..24bce05 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -10,7 +10,7 @@ members = [
 ]
 
 [workspace.package]
-version = "0.3.1"
+version = "0.4.0"
 authors = ["Lash Contributors"]
 edition = "2021"
 rust-version = "1.75"