diff --git a/esp32_server.py b/esp32_server.py
index f8d656a..50620df 100644
--- a/esp32_server.py
+++ b/esp32_server.py
@@ -157,7 +157,21 @@ g_ecat_port = None   # 记住上次探到的端口, 避免每次请求都从 809
 #  2) 拉起时**必须带 --parent-pid**: 让 native 在本服务退出后自我了断,
 #     不留孤儿进程占着 Npcap 适配器和端口。
 #  3) 不再需要 venv/pythonw —— 单文件 exe, 无 Python 运行时依赖。
-ECAT_DIR = os.path.normpath(os.path.join(BASE_DIR, "..", "ecat"))
+def _resolve_ecat_dir(base_dir):
+    """定位 tools/ecat（ecat_native.exe 的仓库，与本仓库平级）。
+
+    从 git worktree（.../tools/ESP32/.worktrees/<slug>）启动时，BASE_DIR 的
+    上一级是 .worktrees 而不是 tools，直接 join("..","ecat") 会拼成
+    .../ESP32/.worktrees/ecat，找不到 exe。先走回主检出再取兄弟目录。
+    """
+    d = os.path.abspath(base_dir)
+    parent = os.path.dirname(d)
+    if os.path.basename(parent) == ".worktrees":
+        d = os.path.dirname(parent)  # → .../tools/ESP32 主检出
+    return os.path.normpath(os.path.join(d, "..", "ecat"))
+
+
+ECAT_DIR = _resolve_ecat_dir(BASE_DIR)
 ECAT_NATIVE_EXE = os.path.join(ECAT_DIR, "build_native", "ecat_native.exe")
 g_ecat_child = None      # 由本服务拉起的 ecat 服务子进程(复用已有实例时为 None)
 g_ecat_log_fp = None     # native stdout 落盘句柄(见 _ecat_autostart 内注释)
diff --git a/scripts/test_ecat_dir_worktree.mjs b/scripts/test_ecat_dir_worktree.mjs
new file mode 100644
index 0000000..a4b5e1f
--- /dev/null
+++ b/scripts/test_ecat_dir_worktree.mjs
@@ -0,0 +1,57 @@
+/**
+ * 从 git worktree 启动 esp32_server 时，ECAT_DIR 必须指回主检出的
+ * tools/ecat，而不是 .../ESP32/.worktrees/ecat。
+ * 复刻 _resolve_ecat_dir 的纯路径逻辑（无 DOM/无网络）。
+ */
+import assert from "node:assert/strict";
+import path from "node:path";
+import { fileURLToPath } from "node:url";
+
+/** 与 esp32_server._resolve_ecat_dir 同构（JS 侧只测路径形状）。 */
+function resolveEcatDir(baseDir) {
+  let d = path.resolve(baseDir);
+  const parent = path.dirname(d);
+  if (path.basename(parent) === ".worktrees") {
+    d = path.dirname(parent);
+  }
+  return path.normalize(path.join(d, "..", "ecat"));
+}
+
+let failed = 0;
+function check(name, fn) {
+  try {
+    fn();
+    console.log("  ✓", name);
+  } catch (e) {
+    failed++;
+    console.log("  ✗", name, "—", e.message);
+  }
+}
+
+console.log("[worktree ECAT_DIR]");
+
+check("主检出 BASE_DIR → 兄弟 tools/ecat", () => {
+  const base = path.resolve("G:/Robot_v2/DCU/tools/ESP32");
+  const got = resolveEcatDir(base);
+  assert.equal(got, path.resolve("G:/Robot_v2/DCU/tools/ecat"), got);
+});
+
+check("worktree BASE_DIR → 仍指主检出的 tools/ecat", () => {
+  const base = path.resolve("G:/Robot_v2/DCU/tools/ESP32/.worktrees/device-link");
+  const got = resolveEcatDir(base);
+  assert.equal(got, path.resolve("G:/Robot_v2/DCU/tools/ecat"), got);
+});
+
+check("嵌套 slug 也走 .worktrees 父级", () => {
+  const base = path.resolve("G:/x/tools/ESP32/.worktrees/foo-bar");
+  const got = resolveEcatDir(base);
+  assert.equal(got, path.resolve("G:/x/tools/ecat"), got);
+});
+
+/* BASE_DIR 恒为 esp32_server.py 所在目录；普通主检出已在第一项覆盖。 */
+
+if (failed) {
+  console.log(`失败 ${failed} 项`);
+  process.exit(1);
+}
+console.log("通过 3 项，失败 0 项");