diff --git a/CHANGELOG.md b/CHANGELOG.md
index 203e195..1604527 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,11 @@ user-facing notes live in [`docs/updates/`](docs/updates/) (English and
 
 ## Unreleased
 
+## 2.2.1 — 2026-10-13
+
+The first stable release of the 2.2 line (2.2.0b1 was a pre-release): everything
+below was added since 2.1.4, the notebook runtime of 2.2.0b1 included.
+
 ### Removed
 
 - Re-Studio, the reverse-engineering studio (the `Re-mode` workspace of the
@@ -16,6 +21,14 @@ user-facing notes live in [`docs/updates/`](docs/updates/) (English and
 
 ### Added
 
+- Modeling: `scale`, affine `transform`, signed `offset`, `draft`, tapered and
+  until-limited extrusions and multisection sweeps are recorded features, and
+  boolean results can keep every output of a set operation; graph nodes keep
+  ordered input references so a replay selects the same entities.
+- `tools/research/build123dftc`: an execution-based build123d to FTC converter
+  (isolated tracing, exact profile reconstruction, generated notebooks and
+  assemblies) with independent geometry and STEP acceptance. It is research
+  tooling, not part of the installed package.
 - Editor: light mode. The editor follows the system theme and a button in the
   header cycles system, light and dark (remembered); the 3D viewport, edges,
   grid, axes and the code editor switch with it, in place, without reloading
@@ -64,6 +77,11 @@ user-facing notes live in [`docs/updates/`](docs/updates/) (English and
 
 ### Changed
 
+- Volumes and centres of mass integrate NURBS by knot spans (Gauss-Kronrod)
+  instead of the fixed-order routine: exact for rational patches (a sewn
+  80 mm cube measures 512000 mm3, the old routine overshot by ~19 mm3) and
+  safe on affine-transformed trims. A degenerate blend result now measures 0
+  and is still reported as `BlendVolumeViolation`.
 - The cell cache is per cell: an entry is stored under a digest of the local
   modules, child notebooks and input files *that cell* depends on (and what the
   cells it reads from depend on), no longer one digest for the whole notebook. A
diff --git a/README.md b/README.md
index 9bdc4d6..ad8d5cd 100644
--- a/README.md
+++ b/README.md
@@ -149,10 +149,10 @@ the full crank cycle sweeps clean in the same sim ·
 
 ---
 
-## Update Notes (2.2)
+## Update Notes (2.2.1)
 
-> **Release notice:** Pre-release (beta). Validate generated definitions,
-> assembly constraints, and manufacturing geometry before production use.
+> Validate generated definitions, assembly constraints, and manufacturing
+> geometry before production use.
 
 - **New editor.** `sca edit` is part of the SDK now (`pip install
   "simplecadapi[editor]"`). It runs a workspace's notebooks in a marimo kernel
@@ -199,7 +199,7 @@ in a compact public API for creating solids, applying features, tagging semantic
 intent, querying topology, exporting manufacturing files, and translating recorded
 models into FreeCAD workflows.
 
-Package: `simplecadapi` on PyPI (the 2.2 line is pre-release; 2.1.4 is the latest stable).
+Current release: `simplecadapi==2.2.1`.
 
 ## What It Provides
 
@@ -714,6 +714,7 @@ and the [STEP reconstruction workflow](docs/skill/references/workflows/step-reco
 
 ## Documentation
 
+- 2.2.1 update notes: [`docs/updates/2.2.1.md`](docs/updates/2.2.1.md)
 - 2.1.3b1 update notes: [`docs/updates/2.1.3b1.md`](docs/updates/2.1.3b1.md)
 - 2.1.2 update notes: [`docs/updates/2.1.2.md`](docs/updates/2.1.2.md)
 - 2.1.1 update notes: [`docs/updates/2.1.1.md`](docs/updates/2.1.1.md)
diff --git a/README.zh-CN.md b/README.zh-CN.md
index 00af8ec..161501c 100644
--- a/README.zh-CN.md
+++ b/README.zh-CN.md
@@ -133,9 +133,9 @@ CalculiX 静力 FEM（边界面按保真的 `interface.*` 标签选取，仿真
 
 ---
 
-## 更新日志（2.2）
+## 更新日志（2.2.1）
 
-> **版本提示：** 预发布（beta）。投入生产前请验证生成的定义、装配约束和制造几何。
+> 投入生产前请验证生成的定义、装配约束和制造几何。
 
 - **新编辑器。** `sca edit` 现在是 SDK 的一部分（`pip install
   "simplecadapi[editor]"`）。它用 SDK 自己的 cell 执行器在 marimo 内核里运行工作
@@ -173,7 +173,7 @@ CalculiX 静力 FEM（边界面按保真的 `interface.*` 标签选取，仿真
 
 SimpleCADAPI 是一个基于 OCP 的 Python CAD SDK，提供清晰的函数式建模操作和可重放的模型图。它在 OpenCascade 几何内核之上提供精简的公共 API，可用于创建实体、应用特征、添加语义标签、查询拓扑、导出制造文件，以及将记录的模型转换为 FreeCAD 工作流。
 
-包：PyPI 上的 `simplecadapi`（2.2 系列为预发布；2.1.4 是最新稳定版）。
+当前版本：`simplecadapi==2.2.1`。
 
 ## 核心能力
 
@@ -599,6 +599,7 @@ uv run --extra fem python examples/ap242_gmsh_volume_mesh/run_calculix.py
 
 ## 文档
 
+- 2.2.1 更新说明：[`docs/updates/2.2.1.zh-CN.md`](docs/updates/2.2.1.zh-CN.md)
 - 2.1.3b1 更新说明：[`docs/updates/2.1.3b1.zh-CN.md`](docs/updates/2.1.3b1.zh-CN.md)
 - 2.1.2 更新说明：[`docs/updates/2.1.2.zh-CN.md`](docs/updates/2.1.2.zh-CN.md)
 - 2.1.1 更新说明：[`docs/updates/2.1.1.zh-CN.md`](docs/updates/2.1.1.zh-CN.md)
diff --git a/docs/skill/SKILL.md b/docs/skill/SKILL.md
index 8d52b23..9cd131c 100644
--- a/docs/skill/SKILL.md
+++ b/docs/skill/SKILL.md
@@ -4,9 +4,9 @@ description: Build, assemble, inspect, reconstruct, and export parametric CAD mo
 license: Apache-2.0
 metadata:
   project: simplecadapi
-  version: 2.2.0b1
+  version: 2.2.1
   package-name: simplecadapi
-  package-version: 2.2.0b1
+  package-version: 2.2.1
 ---
 
 # SimpleCAD SDK Skill
diff --git a/docs/updates/2.2.1.md b/docs/updates/2.2.1.md
new file mode 100644
index 0000000..826db0d
--- /dev/null
+++ b/docs/updates/2.2.1.md
@@ -0,0 +1,37 @@
+# 2.2.1 Update Notes
+
+The first stable release of the 2.2 line. It brings the code-first editor, the
+notebook runtime of 2.2.0b1 and the agent landing path to a stable version.
+
+## Editor: `sca edit`
+
+- A web editor over a directory of notebooks, part of the SDK
+  (`pip install "simplecadapi[editor]"`). It runs the notebooks in a marimo
+  kernel with the SDK's own cell executor, previews the live model straight
+  from the solids, and shares one per-cell cache with `sca run`.
+- Parameters from `# ---- params ----` cells (an optional `# ui:` comment picks
+  the control); local modules (shared dimensions) have their own view.
+- Picking a solid, face, edge or vertex writes a `scad.ql` selection cell
+  (`selected_<kind>`, `selected_item`) into the notebook; edits autosave; a cell
+  reference can be copied for a coding agent; `sca snapshot` shows an agent what
+  the person sees. A log dock reports what ran and what failed.
+- Light and dark themes (follows the system, with a manual switch).
+- **Re-Studio is removed**: the reverse-engineering studio (`Re-mode` of the
+  standalone sca-web-editor) is gone; `sca edit` replaces the standalone editor.
+
+## Landing path for agents
+
+`docs/landing.md` is the script an agent follows to install the SDK and its
+skill and to open an example in the editor. `sca example u_link` copies the
+bundled workspace; `sca skill where` shows where the skill is installed. The
+wheel now carries the built editor UI, the skill sources and the example.
+
+## Modeling
+
+`scale`, affine `transform`, signed `offset`, `draft`, tapered and
+until-limited extrusion and multisection sweep are recorded features. Volumes
+and centres of mass integrate NURBS by knot spans, which is exact for rational
+patches. A build123d to FTC converter is included under
+`tools/research/build123dftc` (research tooling).
+
+See the [changelog](../../CHANGELOG.md) for the complete list.
diff --git a/docs/updates/2.2.1.zh-CN.md b/docs/updates/2.2.1.zh-CN.md
new file mode 100644
index 0000000..614193a
--- /dev/null
+++ b/docs/updates/2.2.1.zh-CN.md
@@ -0,0 +1,32 @@
+# 2.2.1 更新说明
+
+2.2 系列的第一个稳定版。它把 code-first 编辑器、2.2.0b1 的 notebook 运行时和面向
+agent 的落地路径带到稳定版本。
+
+## 编辑器：`sca edit`
+
+- 面向一个 notebook 目录的网页编辑器，是 SDK 的一部分
+  （`pip install "simplecadapi[editor]"`）。它用 SDK 自己的 cell 执行器在 marimo
+  内核里运行 notebook，直接由实体生成实时预览，并与 `sca run` 共用一份逐 cell 缓存。
+- 参数来自 `# ---- params ----` cell（可用 `# ui:` 注释选择控件）；本地模块（共用
+  尺寸）有独立视图。
+- 点选实体、面、边或顶点会向 notebook 写入一个 `scad.ql` 选择 cell
+  （`selected_<kind>`、`selected_item`）；编辑自动保存；可复制 cell 引用交给 coding
+  agent；`sca snapshot` 让 agent 看到用户所见。底部日志面板显示运行了什么、哪里失败。
+- 浅色与深色主题（跟随系统，可手动切换）。
+- **Re-Studio 已移除**：逆向工程 studio（独立 sca-web-editor 的 `Re-mode`）不再存在，
+  独立编辑器由 `sca edit` 取代。
+
+## 面向 agent 的落地路径
+
+`docs/landing.md` 是 agent 安装 SDK 和 skill、并在编辑器里打开示例时遵循的脚本。
+`sca example u_link` 复制内置工作区；`sca skill where` 显示 skill 的安装位置。wheel
+现在包含已构建的编辑器 UI、skill 源码和示例。
+
+## 建模
+
+`scale`、仿射 `transform`、带符号 `offset`、`draft`、带锥度和直到限定的拉伸、多截面
+扫掠都成为可记录的特征。体积与质心按节点区间积分 NURBS，对有理曲面是精确的。
+`tools/research/build123dftc` 下附带 build123d 到 FTC 的转换器（研究工具）。
+
+完整列表见[更新日志](../../CHANGELOG.md)。
diff --git a/pyproject.toml b/pyproject.toml
index c905f0e..91a9e5e 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "simplecadapi"
-version = "2.2.0b1"
+version = "2.2.1"
 description = "A simplified OCP-native CAD modeling Python API"
 readme = "README.md"
 license = { file = "LICENSE" }
diff --git a/uv.lock b/uv.lock
index 55fd8de..7d795ef 100644
--- a/uv.lock
+++ b/uv.lock
@@ -3227,7 +3227,7 @@ wheels = [
 
 [[package]]
 name = "simplecadapi"
-version = "2.2.0b1"
+version = "2.2.1"
 source = { editable = "." }
 dependencies = [
     { name = "cadquery-ocp" },