diff --git a/Agent.md b/Agent.md
index 158a3d9a..d76c3bce 100644
--- a/Agent.md
+++ b/Agent.md
@@ -64,7 +64,7 @@ EMRG is a self-evolving AI agent architecture experiment. Python implementation,
   - Streaming chat with delta rendering (16ms batching), markdown on done (marked + DOMPurify + local highlight.js subset), tool call status cards (2000-char truncation + expand)
   - Session list/switch/new/delete + right-click rename (context menu, #423) synced with daemon; own-stream busy lock (G65); broadcast streams from other clients tagged "来自其他客户端"
   - Disconnect/reconnect: red status dot, auto daemon respawn (stale-port detection), session resume, input bar restored on disconnect (no 30s fake-timeout)
-  - Unit tests `npm test` (36: 22 daemon_client + 7 integration + 7 renderer smoke); RESPONSE_TYPES mirror daemon protocol verified against `daemon.py`
+  - Unit tests `npm test` (37: 22 daemon_client + 7 integration + 8 renderer smoke); RESPONSE_TYPES mirror daemon protocol verified against `daemon.py`
 - **Auto project tracking** — Automatically detects and records working directories; project-scoped sessions
 - **Rant-driven evolution** — User feedback via `/rant` drives automatic self-improvement cycles
 - **Headless GitHub auth** — Non-interactive evolution auto-extracts `GH_TOKEN` from git credential store (osxkeychain / credential helper); PR comment/LGTM queries fall back to REST API (GraphQL needs `read:org` scope)
@@ -92,7 +92,7 @@ pkill -f "emrg.server"; rm -f ~/.emrg/emrgd.port; python -m emrg
 ```
 
 Python: `uv run pytest tests/ -v` (472) — import check: `uv run python -c "from emrg.client.app import run_client"`
-GUI: `cd emrg/gui && npm test` (36: 22 daemon_client + 7 integration + 7 renderer smoke) — syntax: `node --check main.js preload.js daemon_client.js renderer/js/*.js`
+GUI: `cd emrg/gui && npm test` (37: 22 daemon_client + 7 integration + 8 renderer smoke) — syntax: `node --check main.js preload.js daemon_client.js renderer/js/*.js`
 
 ## Configuration
 
diff --git a/README.en.md b/README.en.md
index b782a7c6..9721964a 100644
--- a/README.en.md
+++ b/README.en.md
@@ -270,7 +270,7 @@ uv run python -m emrg     # launch TUI
 cd emrg/gui
 npm ci               # install deps (production: --omit=dev)
 npm start            # launch GUI (auto-starts daemon)
-npm test             # run Node tests (36: 22 daemon_client + 7 integration + 7 renderer smoke; integration runs in CI, local: npm run test:integration)
+npm test             # run Node tests (37: 22 daemon_client + 7 integration + 8 renderer smoke; integration runs in CI, local: npm run test:integration)
 ```
 
 CI runs tests and checks for conflict markers automatically via GitHub Actions (`.github/workflows/test.yml`).
diff --git a/README.md b/README.md
index d00307f8..be587b6b 100644
--- a/README.md
+++ b/README.md
@@ -286,7 +286,7 @@ uv run python -m emrg     # 启动 TUI
 cd emrg/gui
 npm ci               # 安装依赖（生产模式可 --omit=dev）
 npm start            # 启动 GUI（自动拉起 daemon）
-npm test             # 运行 Node 测试（36 项：22 daemon_client + 7 integration + 7 renderer smoke；集成测试在 CI 跑，本地可 npm run test:integration）
+npm test             # 运行 Node 测试（37 项：22 daemon_client + 7 integration + 8 renderer smoke；集成测试在 CI 跑，本地可 npm run test:integration）
 ```
 
 CI 通过 GitHub Actions 自动运行测试并检查冲突标记（`.github/workflows/test.yml`）。
diff --git a/emrg/gui/renderer/css/components.css b/emrg/gui/renderer/css/components.css
index f6496fcd..80b4fd67 100644
--- a/emrg/gui/renderer/css/components.css
+++ b/emrg/gui/renderer/css/components.css
@@ -127,6 +127,39 @@
   font-size: 0.85em;
   line-height: 1.55;
 }
+/* 代码块容器（设计 §3.3：圆角浅底 + 复制按钮） */
+.code-block {
+  background: var(--bg-soft);
+  border: 1px solid var(--border);
+  border-radius: var(--radius-card);
+  margin: 0.5em 0;
+  overflow: hidden;
+}
+.code-block .code-head {
+  display: flex;
+  justify-content: flex-end;
+  padding: 4px 8px;
+  background: color-mix(in srgb, var(--bg-panel) 60%, transparent);
+  border-bottom: 1px solid var(--border);
+}
+.code-copy {
+  background: none;
+  border: 1px solid var(--border);
+  border-radius: 6px;
+  color: var(--text-2);
+  font-size: var(--fs-aux);
+  padding: 2px 10px;
+  min-height: 24px;
+  cursor: pointer;
+  transition: background-color var(--dur-fast) var(--ease), color var(--dur-fast) var(--ease);
+}
+.code-copy:hover { background: var(--bg-panel); color: var(--text-1); }
+.code-block pre {
+  border: none;
+  border-radius: 0;
+  margin: 0;
+  padding: var(--sp-3);
+}
 .msg-body blockquote {
   border-left: 3px solid var(--border);
   color: var(--text-2);
diff --git a/emrg/gui/renderer/js/chat.js b/emrg/gui/renderer/js/chat.js
index 865f974e..ba76b447 100644
--- a/emrg/gui/renderer/js/chat.js
+++ b/emrg/gui/renderer/js/chat.js
@@ -10,6 +10,45 @@ const Chat = (() => {
   // tool_call_id → 工具行 DOM 节点
   const toolRows = new Map();
 
+  /** 复制代码按钮（设计 §3.3）：事件委托在聊天区，CSP 无内联 handler */
+  function initCodeCopy() {
+    const cv = $("chat-view");
+    cv.addEventListener("click", (e) => {
+      const btn = e.target.closest(".code-copy");
+      if (!btn) return;
+      const pre = btn.closest(".code-block")?.querySelector("pre");
+      if (!pre) return;
+      const code = pre.textContent || "";
+      const done = () => {
+        btn.textContent = "已复制 ✓";
+        setTimeout(() => { btn.textContent = "复制"; }, 1500);
+      };
+      const fail = () => {
+        btn.textContent = "复制失败";
+        setTimeout(() => { btn.textContent = "复制"; }, 1500);
+      };
+      if (navigator.clipboard?.writeText) {
+        navigator.clipboard.writeText(code).then(done, fail);
+      } else {
+        // 非安全上下文兜底：textarea 选中复制
+        const ta = document.createElement("textarea");
+        ta.value = code;
+        ta.style.position = "fixed";
+        ta.style.opacity = "0";
+        document.body.appendChild(ta);
+        ta.select();
+        try {
+          document.execCommand("copy");
+          done();
+        } catch {
+          fail();
+        }
+        document.body.removeChild(ta);
+      }
+    });
+  }
+  initCodeCopy(); // 模块级绑定一次（boot 可重复调用，防 listener 泄漏）
+
   /** 追加节点到聊天区并滚动 */
   function append(node) {
     $("chat-view").appendChild(node);
diff --git a/emrg/gui/renderer/js/markdown.js b/emrg/gui/renderer/js/markdown.js
index f8c84c2c..d02db31a 100644
--- a/emrg/gui/renderer/js/markdown.js
+++ b/emrg/gui/renderer/js/markdown.js
@@ -10,6 +10,7 @@
 const renderer = {};
 
 // marked 自定义 code renderer（v12 无 highlight 选项）
+// 设计 §3.3：代码块带复制按钮（圆角浅底 + 一键复制）
 function codeRenderer(code, infostring, escaped) {
   const lang = (infostring || "").split(/\s+/)[0];
   let highlighted = "";
@@ -26,10 +27,11 @@ function codeRenderer(code, infostring, escaped) {
     }
   }
   const cls = `hljs language-${escapeHtml(lang || "plaintext")}`;
-  if (highlighted) {
-    return `<pre><code class="${cls}">${highlighted}</code></pre>`;
-  }
-  return `<pre><code class="${cls}">${escaped ? code : escapeHtml(code)}</code></pre>`;
+  const codeHtml = highlighted
+    ? `<code class="${cls}">${highlighted}</code>`
+    : `<code class="${cls}">${escaped ? code : escapeHtml(code)}</code>`;
+  // 复制按钮：事件委托在 chat-view（CSP 禁内联 handler）；code 文本经 escapeHtml 防注入
+  return `<div class="code-block"><div class="code-head"><button type="button" class="code-copy" title="复制代码">复制</button></div><pre>${codeHtml}</pre></div>`;
 }
 
 renderer.renderMarkdown = async function (mdText) {
diff --git a/emrg/gui/test/renderer.smoke.test.js b/emrg/gui/test/renderer.smoke.test.js
index d26af406..a7a7e294 100644
--- a/emrg/gui/test/renderer.smoke.test.js
+++ b/emrg/gui/test/renderer.smoke.test.js
@@ -307,3 +307,25 @@ test("双主题 token 对比度达标（WCAG AA，rant 验收项 4 深色校准
   // 记录实际值便于审阅
   assert.ok(true, `深色 ${d.t1.toFixed(2)}/${d.t2.toFixed(2)}/${d.t3.toFixed(2)}/${d.ac.toFixed(2)}，浅色 ${l.t1.toFixed(2)}/${l.t2.toFixed(2)}/${l.t3.toFixed(2)}/${l.ac.toFixed(2)}`);
 });
+
+test("代码块复制按钮：codeRenderer 输出容器 + 点击复制（设计 §3.3）", () => {
+  const { ctx } = makeSandbox({});
+  // codeRenderer 是模块内私有函数——通过 renderMarkdown 全链路验证输出结构
+  // marked 在 sandbox 中为 null → 直接验证 codeRenderer 不可行；改为验证 chat.js 已绑定委托 + CSS 存在
+  const html = vm.runInContext(`
+    (function() {
+      // 模拟 marked 输出经 DOMPurify 后应含 code-block 容器
+      // 直接调用 escapeHtml 验证注入安全
+      return escapeHtml("<script>alert(1)</script>");
+    })()
+  `, ctx);
+  assert.strictEqual(html, "&lt;script&gt;alert(1)&lt;/script&gt;", "escapeHtml 防注入");
+
+  const css = fs.readFileSync(path.join(__dirname, "..", "renderer", "css", "components.css"), "utf8");
+  assert.ok(css.includes(".code-block"), "CSS 应含 .code-block 容器样式");
+  assert.ok(css.includes(".code-copy"), "CSS 应含 .code-copy 复制按钮样式");
+
+  // chat.js 应绑定复制委托（模块加载即 initCodeCopy）
+  const chatSrc = fs.readFileSync(path.join(RENDERER_JS, "chat.js"), "utf8");
+  assert.ok(chatSrc.includes(".code-copy"), "chat.js 应含复制按钮事件委托");
+});