diff --git a/CHANGELOG.md b/CHANGELOG.md
index 09ff84c..6a20bcf 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [0.31.2] - 2026-08-30
+
+### Fixed
+
+- **docs:** update README and ROADMAP for struct-based `UpdateRegion` API (`image.Rectangle` + `ImageDataLayout`). v0.31.1 shipped with stale documentation showing old 6-parameter signature.
+
 ## [0.31.1] - 2026-08-30
 
 ### Changed
diff --git a/README.md b/README.md
index a8fb4ae..6c982ab 100644
--- a/README.md
+++ b/README.md
@@ -232,9 +232,17 @@ type TextureUpdater interface {
     UpdateData(data []byte) error
 }
 
+// ImageDataLayout describes the memory layout of pixel data for region uploads.
+// Mirrors W3C GPUTexelCopyBufferLayout at the application level.
+type ImageDataLayout struct {
+    BytesPerRow  int // 0 = tight packed (w * bytesPerPixel)
+    RowsPerImage int // 0 = height (for 3D/array textures)
+    Offset       int // byte offset into data
+}
+
 // TextureRegionUpdater uploads only a sub-rectangle (partial upload)
 type TextureRegionUpdater interface {
-    UpdateRegion(x, y, w, h int, data []byte) error
+    UpdateRegion(region image.Rectangle, data []byte, layout ImageDataLayout) error
 }
 ```
 
diff --git a/ROADMAP.md b/ROADMAP.md
index bfa35ba..046b9f4 100644
--- a/ROADMAP.md
+++ b/ROADMAP.md
@@ -4,9 +4,9 @@
 
 `gpucontext` is the shared foundation for the [gogpu](https://github.com/gogpu) ecosystem, providing interfaces and utilities for GPU resource sharing without circular dependencies.
 
-## Current: v0.31.0
+## Current: v0.31.2
 
-- `TextureRegionUpdater.UpdateRegion` strided upload (`bytesPerRow`, #484)
+- `TextureRegionUpdater.UpdateRegion` struct API (`image.Rectangle` + `ImageDataLayout`, #484)
 - `DeviceProvider.DownlevelCapabilities()` (ADR-071)
 - `DeviceProvider.Features()` — query device capabilities (FeatureRayQuery, etc.)
 - SurfaceCompositor interface (ADR-067)
@@ -21,6 +21,12 @@
 
 ## Released
 
+### v0.31.2 (2026-08-30)
+- docs: fix README and ROADMAP for struct-based UpdateRegion API
+
+### v0.31.1 (2026-08-30)
+- `TextureRegionUpdater.UpdateRegion` — struct API: `image.Rectangle` + `ImageDataLayout` (#484)
+
 ### v0.31.0 (2026-08-30)
 - `TextureRegionUpdater.UpdateRegion` — `bytesPerRow` parameter (pre-v1.0, #484)