diff --git a/bds-tools/is-main.test.mjs b/bds-tools/is-main.test.mjs
new file mode 100644
index 00000000..f709aebd
--- /dev/null
+++ b/bds-tools/is-main.test.mjs
@@ -0,0 +1,79 @@
+/**
+ * is-main 契约测试：直接入口 / shim 入口 / 被异名入口 import
+ * 运行: npm test -w @sfmc-bds/bds-tools（需先 build）
+ *
+ * 注：仓库根 .gitignore 忽略名为 test 的路径，故用例放在包根而非 test/。
+ */
+
+import assert from "node:assert/strict";
+import { spawnSync } from "node:child_process";
+import fs from "node:fs";
+import path from "node:path";
+import { after, describe, it } from "node:test";
+import { fileURLToPath } from "node:url";
+
+const pkgRoot = path.dirname(fileURLToPath(import.meta.url));
+const distDir = path.join(pkgRoot, "dist");
+
+/** 与 recovery.js → dist/recovery.js 同构：根目录 shim 与 dist 模块同名 */
+const MODULE_NAME = "_sfmc_is_main_fixture.js";
+const distModule = path.join(distDir, MODULE_NAME);
+const rootShim = path.join(pkgRoot, MODULE_NAME);
+const alienEntry = path.join(pkgRoot, "_sfmc_alien_entry.js");
+
+const moduleSrc = `
+import { isMainModule } from "./is-main.js";
+console.log(isMainModule(import.meta.url) ? "MAIN" : "NOT_MAIN");
+`;
+
+const shimSrc = `
+import path from "node:path";
+import { fileURLToPath, pathToFileURL } from "node:url";
+const __dirname = path.dirname(fileURLToPath(import.meta.url));
+await import(pathToFileURL(path.join(__dirname, "dist", ${JSON.stringify(MODULE_NAME)})).href);
+`;
+
+const alienSrc = `
+import path from "node:path";
+import { fileURLToPath, pathToFileURL } from "node:url";
+const __dirname = path.dirname(fileURLToPath(import.meta.url));
+await import(pathToFileURL(path.join(__dirname, "dist", ${JSON.stringify(MODULE_NAME)})).href);
+`;
+
+describe("isMainModule", () => {
+  it("dist 直接作为 argv 入口时为 true", () => {
+    fs.mkdirSync(distDir, { recursive: true });
+    fs.writeFileSync(distModule, moduleSrc);
+    const r = spawnSync(process.execPath, [distModule], { encoding: "utf8" });
+    assert.equal(r.status, 0, r.stderr);
+    assert.equal(r.stdout.trim(), "MAIN");
+  });
+
+  it("同名根目录 shim 动态 import dist 时为 true（recovery.js 契约）", () => {
+    fs.mkdirSync(distDir, { recursive: true });
+    fs.writeFileSync(distModule, moduleSrc);
+    fs.writeFileSync(rootShim, shimSrc);
+    const r = spawnSync(process.execPath, [rootShim], { encoding: "utf8" });
+    assert.equal(r.status, 0, r.stderr);
+    assert.equal(r.stdout.trim(), "MAIN");
+  });
+
+  it("被异名入口 import 时为 false（check-update 加载 bds-manager）", () => {
+    fs.mkdirSync(distDir, { recursive: true });
+    fs.writeFileSync(distModule, moduleSrc);
+    fs.writeFileSync(alienEntry, alienSrc);
+    const r = spawnSync(process.execPath, [alienEntry], { encoding: "utf8" });
+    assert.equal(r.status, 0, r.stderr);
+    assert.equal(r.stdout.trim(), "NOT_MAIN");
+  });
+
+  after(() => {
+    for (const p of [distModule, rootShim, alienEntry]) {
+      try {
+        fs.unlinkSync(p);
+      } catch {
+        /* ignore */
+      }
+    }
+  });
+});
diff --git a/bds-tools/package.json b/bds-tools/package.json
index 853baa71..ec51949d 100644
--- a/bds-tools/package.json
+++ b/bds-tools/package.json
@@ -41,6 +41,7 @@
     "dev": "tsx src/dist/bds-manager.ts",
     "typecheck": "tsc --noEmit",
     "clean": "node -e \"require('node:fs').rmSync('dist',{recursive:true,force:true})\"",
+    "test": "node --test is-main.test.mjs",
     "update": "node dist/check-update.js",
     "update:check": "node dist/check-update.js --check-only",
     "update:force": "node dist/check-update.js --force",
diff --git a/bds-tools/recovery.js b/bds-tools/recovery.js
index 75422fc6..5130e020 100644
--- a/bds-tools/recovery.js
+++ b/bds-tools/recovery.js
@@ -1,23 +1,24 @@
 /**
- * recovery.js — shim, 委托给 src/recovery.ts 编译产物
+ * recovery.js — shim, 委托给 dist/recovery.js
  *
  * 用法: node recovery.js
+ *
+ * 注意：bds-tools 为 ESM（"type":"module"），不能再用 createRequire 加载 dist。
  */
 
-import { createRequire } from "node:module";
 import path from "node:path";
-import { fileURLToPath } from "node:url";
+import { fileURLToPath, pathToFileURL } from "node:url";
 
 const __dirname = path.dirname(fileURLToPath(import.meta.url));
-const require = createRequire(import.meta.url);
-const dist = path.join(__dirname, "dist", "recovery.js");
+const distUrl = pathToFileURL(path.join(__dirname, "dist", "recovery.js")).href;
 
 try {
-  require(dist);
+  await import(distUrl);
 } catch (e) {
-  if (e.code === "MODULE_NOT_FOUND") {
+  const err = /** @type {NodeJS.ErrnoException} */ (e);
+  if (err && (err.code === "ERR_MODULE_NOT_FOUND" || err.code === "MODULE_NOT_FOUND")) {
     console.error("[BDSRecovery] dist/ 未找到，请先运行 `npm run build`");
     process.exit(2);
   }
   throw e;
-}
\ No newline at end of file
+}
diff --git a/bds-tools/src/bds-manager.ts b/bds-tools/src/bds-manager.ts
index 1d19efaf..3f0ac16c 100644
--- a/bds-tools/src/bds-manager.ts
+++ b/bds-tools/src/bds-manager.ts
@@ -275,6 +275,8 @@ bdsEvents_enabled();
 
 /** 判断当前是否作为 CLI 主入口运行（被 check-update 等 import 时为 false） */
 function isMain(): boolean {
+  // sfmc supervisor 通过 SFMC_SERVICE 拉起子进程时优先判定（与 check-update 对称）
+  if (process.env.SFMC_SERVICE === "manager") return true;
   return isMainModule(import.meta.url);
 }
 
diff --git a/bds-tools/src/is-main.ts b/bds-tools/src/is-main.ts
index 804f6944..fd79b0c4 100644
--- a/bds-tools/src/is-main.ts
+++ b/bds-tools/src/is-main.ts
@@ -3,11 +3,34 @@
  *
  * package.json 声明 "type": "module" 后，`require` 不存在，
  * 不能再用 `require.main === module`。
+ *
+ * 契约（与历史 endsWith 行为对齐，满足 LSP）：
+ * 1. process.argv[1] 与本文件 realpath 相同 → true
+ * 2. 根目录 shim（如 recovery.js → dist/recovery.js）同 stem → true
+ * 3. 被其他入口 import 时（argv stem 不同）→ false
  */
 
+import fs from "node:fs";
 import path from "node:path";
 import { fileURLToPath } from "node:url";
 
+function normPath(p: string): string {
+  return process.platform === "win32" ? p.toLowerCase() : p;
+}
+
+/** 去掉 .js/.ts/.mjs/.cjs 等扩展，得到入口 stem */
+function entryStem(filePath: string): string {
+  return path.basename(filePath).replace(/\.(c|m)?(js|ts)$/i, "");
+}
+
+function tryRealpath(filePath: string): string {
+  try {
+    return fs.realpathSync.native(filePath);
+  } catch {
+    return filePath;
+  }
+}
+
 /**
  * 判断 metaUrl 对应模块是否为 node 进程主入口。
  * 替代 CommonJS 的 `require.main === module`。
@@ -16,11 +39,11 @@ export function isMainModule(metaUrl: string): boolean {
   const entry = process.argv[1];
   if (!entry) return false;
   try {
-    const thisFile = path.resolve(fileURLToPath(metaUrl));
-    const entryFile = path.resolve(entry);
-    return process.platform === "win32"
-      ? thisFile.toLowerCase() === entryFile.toLowerCase()
-      : thisFile === entryFile;
+    const thisFile = tryRealpath(path.resolve(fileURLToPath(metaUrl)));
+    const entryFile = tryRealpath(path.resolve(entry));
+    if (normPath(thisFile) === normPath(entryFile)) return true;
+    // shim 兼容：入口与本模块同 stem（recovery.js 加载 dist/recovery.js）
+    return normPath(entryStem(thisFile)) === normPath(entryStem(entryFile));
   } catch {
     return false;
   }