diff --git a/docs/en/release-notes/changelog.md b/docs/en/release-notes/changelog.md
index dffa69e90..583ed5f9d 100644
--- a/docs/en/release-notes/changelog.md
+++ b/docs/en/release-notes/changelog.md
@@ -6,6 +6,38 @@ outline: 2
 
 This page documents the changes in each Kimi Code CLI release.
 
+## 0.21.0 (2026-07-01)
+
+### Features
+
+- Plugins can now provide slash commands via a `commands` field in their manifest, registered as `<plugin>:<command>` and invoked with `$ARGUMENTS` expansion.
+- Add Mermaid diagram rendering to the web chat. Fenced `mermaid` blocks in assistant responses now render as diagrams. KaTeX math and Mermaid diagram parsing also run in Web Workers to keep the UI responsive during live streaming.
+
+### Bug Fixes
+
+- Stop a malformed message history from permanently bricking a session on strict providers (Anthropic). The request is repaired before sending — orphaned tool calls are closed and empty/whitespace-only text blocks dropped — and if the provider still rejects its structure, it is resent once with a wire-compliant rebuild.
+- Force-exit headless runs (`kimi -p`) so a stray ref'd handle left over from the run can't keep a completed run alive until an external timeout, and bound prompt cleanup so a wedged shutdown step can't hang shutdown.
+- Fix @ file mentions not opening when typed inside a slash command argument.
+- Fix adding a workspace by path in the web UI failing silently when the daemon rejects the path; it now shows an error instead of a broken workspace.
+- Fix duplicate workspaces showing in the web sidebar when the same folder is registered more than once.
+- Fix the web workspace rename not persisting after a page refresh.
+
+### Polish
+
+- Add a double-Esc shortcut to open the undo selector. Press Esc twice while idle to undo.
+- Show file path completions when typing `/` in shell mode (`!`).
+- Always show the usage-data opt-out toggle in the web settings with a clearer label and description.
+
+### Refactors
+
+- Rework conversation compaction:
+  - Keep only recent user prompts plus a single user-role summary; drop assistant and tool messages.
+  - Repair tool_use/tool_result adjacency before sending, fixing a strict-provider HTTP 400 when a tool call and its result became non-adjacent.
+  - Merge consecutive user turns for strict providers (Gemini/Vertex), fixing an HTTP 400 ("roles must alternate") after compaction or when a turn is steered in right after a tool result.
+  - Micro-compaction now defaults off.
+- Refactor the thinking effort system
+- Add a server-side key-value store API for persisting web UI preferences to the user's data directory.
+
 ## 0.20.3 (2026-06-30)
 
 ### Bug Fixes
diff --git a/docs/zh/release-notes/changelog.md b/docs/zh/release-notes/changelog.md
index e4947b934..86dc56142 100644
--- a/docs/zh/release-notes/changelog.md
+++ b/docs/zh/release-notes/changelog.md
@@ -6,6 +6,38 @@ outline: 2
 
 本页记录 Kimi Code CLI 每个版本的变更内容。
 
+## 0.21.0（2026-07-01）
+
+### 新功能
+
+- 插件现支持在清单的 `commands` 字段中声明斜杠命令，注册为 `<plugin>:<command>` 形式，调用时展开 `$ARGUMENTS`。
+- web 聊天新增 Mermaid 图表渲染，助手回复中的 `mermaid` 代码块会渲染为图表。KaTeX 数学公式与 Mermaid 图表的解析移至 Web Workers 执行，提升流式渲染时的界面响应速度。
+
+### 修复
+
+- 修复格式异常的消息历史会在严格供应商（Anthropic）上永久卡死会话的问题。发送前会修复请求：关闭孤立的工具调用、丢弃空白或纯空白文本块；若供应商仍拒绝其结构，则按 wire 协议合规格式重建并重发一次。
+- 强制退出无头运行（`kimi -p`），以免运行残留的引用句柄让已完成的运行一直存活到外部超时；同时为 prompt 清理加上时限，避免某个卡住的关闭步骤拖挂整个关闭流程。
+- 修复在斜杠命令参数中输入 `@` 文件提及时无法打开的问题。
+- 修复 web UI 中通过路径添加工作区时，daemon 拒绝路径会静默失败的问题；现在会显示错误，而不是生成一个无法使用的工作区。
+- 修复同一文件夹被重复注册时，web 侧边栏显示重复工作区的问题。
+- 修复 web 工作区重命名在页面刷新后不保留的问题。
+
+### 优化
+
+- 新增连按两次 Esc 打开撤销选择器的快捷键，空闲时连按两次 Esc 即可撤销。
+- 在 shell 模式（`!`）下输入 `/` 时显示文件路径补全。
+- web 设置中始终显示用量数据退出开关，并优化其标签与说明文案。
+
+### 重构
+
+- 重构对话压缩机制：
+  - 仅保留最近的用户提示词与一条用户角色的摘要，丢弃助手与工具消息。
+  - 发送前修复 `tool_use`/`tool_result` 的相邻关系，修复工具调用与其结果不相邻时严格供应商返回 HTTP 400 的问题。
+  - 为严格供应商（Gemini/Vertex）合并连续的用户轮次，修复压缩后或在工具结果后立即插入引导轮次时出现的 HTTP 400（"roles must alternate"）问题。
+  - micro-compaction 现在默认关闭。
+- 重构 thinking effort 系统。
+- 新增服务端键值存储 API，用于将 web UI 偏好持久化到用户数据目录。
+
 ## 0.20.3（2026-06-30）
 
 ### 修复