diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0e4177e..0015cde 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,11 @@
 # 更新日志
 
+## 0.2.7
+
+- 修复「一键配置模块代码提示」在标准 mcpp 安装（install.sh / AUR）下无法发现 mcpp 内置
+  xlings 的问题：xlings 发现以 `mcpp self env` 为权威来源（项目级契约），路径探测仅作回退；
+  为 `mcpp self env` 调用增加超时保护，并补齐测试（PR #11）。
+
 ## 0.2.6
 
 - 新增 **mcpp: 一键配置模块代码提示** 向导：按「安装/切换工具链 → 构建 → 重载 → clangd
diff --git a/src/cliController.ts b/src/cliController.ts
index ef77e6a..2416b72 100644
--- a/src/cliController.ts
+++ b/src/cliController.ts
@@ -630,7 +630,7 @@ export class McppCliController {
     return false;
   }
 
-  private mcppExecutable(project: McppProjectDiscovery | undefined): string {
+  public mcppExecutable(project: McppProjectDiscovery | undefined): string {
     const uri = project === undefined
       ? vscode.workspace.workspaceFolders?.[0]?.uri
       : vscode.Uri.file(project.root);
diff --git a/src/extension.ts b/src/extension.ts
index f16d760..23fb2de 100644
--- a/src/extension.ts
+++ b/src/extension.ts
@@ -19,7 +19,7 @@ import {
   type McppProjectDiscovery,
 } from "./discovery";
 import {
-  findXlingsExecutable,
+  resolveXlingsExecutable,
   llvmToolsVersionSpec,
   xlingsInstallArgs,
 } from "./llvmTools";
@@ -763,7 +763,9 @@ async function autoConfigureModulesWizard(
           : { stage: "clangd", state: "failed", detail: "clangd 配置未完成。" };
       }
 
-      const xlingsPath = findXlingsExecutable();
+      const xlingsPath = await resolveXlingsExecutable(
+        cliController.mcppExecutable(currentContext.project),
+      );
       const compilerPath = currentContext.analysis.compilerPath;
       if (xlingsPath === undefined || compilerPath === undefined) {
         return {
diff --git a/src/llvmTools.ts b/src/llvmTools.ts
index be064f9..f573f05 100644
--- a/src/llvmTools.ts
+++ b/src/llvmTools.ts
@@ -4,7 +4,11 @@ import path from "node:path";
 import process from "node:process";
 
 import type { ToolIdentity } from "./analysis";
-import { runProcess, type ProcessResult } from "./process";
+import {
+  runProcess,
+  type ProcessResult,
+  type ProcessRunner,
+} from "./process";
 
 export function llvmToolsVersionSpec(identity: ToolIdentity): string {
   return `${identity.major}.${identity.minor}.${identity.patch}`;
@@ -60,8 +64,16 @@ export function xlingsInstallArgs(version?: string): string[] {
   return ["update", "llvm-tools"];
 }
 
-export function findXlingsExecutable(): string | undefined {
-  const home = os.homedir();
+export interface FindXlingsOptions {
+  /** Override for tests: base home directory instead of os.homedir(). */
+  home?: string;
+  /** Override for tests: environment instead of process.env. */
+  env?: NodeJS.ProcessEnv;
+}
+
+export function findXlingsExecutable(options?: FindXlingsOptions): string | undefined {
+  const home = options?.home ?? os.homedir();
+  const env = options?.env ?? process.env;
   const knownPaths = [
     path.join(home, ".xlings", "subos", "current", "bin", "xlings"),
     path.join(home, ".xlings", "bin", "xlings"),
@@ -72,6 +84,26 @@ export function findXlingsExecutable(): string | undefined {
     );
   }
 
+  // mcpp (install.sh / AUR / mcpp-m) bundles xlings inside its own registry
+  // sandbox instead of installing to ~/.xlings. The AUR launcher pins the
+  // path via MCPP_VENDORED_XLINGS; otherwise it lives at
+  // $MCPP_HOME/registry/bin/xlings. Without probing both, the one-click
+  // module setup can never auto-install llvm-tools after a standard install.
+  const vendored = env.MCPP_VENDORED_XLINGS?.trim();
+  if (vendored !== undefined && vendored.length > 0) {
+    knownPaths.push(vendored);
+  }
+  const mcppHome = env.MCPP_HOME?.trim();
+  const extension = process.platform === "win32" ? ".exe" : "";
+  knownPaths.push(
+    path.join(
+      mcppHome !== undefined && mcppHome.length > 0 ? mcppHome : path.join(home, ".mcpp"),
+      "registry",
+      "bin",
+      `xlings${extension}`,
+    ),
+  );
+
   // Check known install paths first
   for (const candidate of knownPaths) {
     if (existsSync(candidate)) {
@@ -82,15 +114,15 @@ export function findXlingsExecutable(): string | undefined {
   // Fall back to PATH, but only when "xlings" actually resolves there. Always
   // returning "xlings" hid the not-installed case, so callers could never show
   // the "xlings 未安装" guidance.
-  return xlingsResolvableOnPath() ? "xlings" : undefined;
+  return xlingsResolvableOnPath(env.PATH) ? "xlings" : undefined;
 }
 
-function xlingsResolvableOnPath(): boolean {
+function xlingsResolvableOnPath(pathValue?: string): boolean {
   const names = process.platform === "win32"
     ? ["xlings.exe", "xlings.cmd", "xlings.bat"]
     : ["xlings"];
-  const pathValue = process.env.PATH ?? "";
-  for (const dir of pathValue.split(path.delimiter)) {
+  const pathEnv = pathValue ?? "";
+  for (const dir of pathEnv.split(path.delimiter)) {
     if (dir.length === 0) {
       continue;
     }
@@ -103,6 +135,35 @@ function xlingsResolvableOnPath(): boolean {
   return false;
 }
 
+const XLINGS_BINARY_LINE = /^\s*xlings binary\s*=\s*(.+?)\s*$/im;
+
+// Source of truth is mcpp itself, not the filesystem or PATH: `mcpp self env`
+// reports the exact xlings bundled with THIS mcpp (mcpp is a project-level
+// environment; it owns its tool paths). Works for install.sh, AUR and any
+// custom MCPP_PREFIX layout. Falls back to the historical path heuristics for
+// standalone ~/.xlings installs and for mcpp versions without the line.
+//
+// The subprocess is bounded by MCPP_SELF_ENV_TIMEOUT_MS: the wizard reaches
+// this step only after mcpp is initialized (toolchain list / build already
+// ran), so 60s is generous while still guarding against an extreme hang.
+const MCPP_SELF_ENV_TIMEOUT_MS = 60_000;
+
+export async function resolveXlingsExecutable(
+  mcppExecutable: string,
+  runner: ProcessRunner = runProcess,
+  options?: FindXlingsOptions,
+): Promise<string | undefined> {
+  const result = await runner(mcppExecutable, ["self", "env"], undefined, {
+    timeoutMs: MCPP_SELF_ENV_TIMEOUT_MS,
+  });
+  const match = `${result.stdout}\n${result.stderr}`.match(XLINGS_BINARY_LINE);
+  const reported = match?.[1]?.trim();
+  if (reported !== undefined && reported.length > 0 && existsSync(reported)) {
+    return reported;
+  }
+  return findXlingsExecutable(options);
+}
+
 export async function runXlingsCommand(
   xlingsPath: string,
   args: string[],
diff --git a/test/llvmTools.test.ts b/test/llvmTools.test.ts
index b6348f5..8e967d7 100644
--- a/test/llvmTools.test.ts
+++ b/test/llvmTools.test.ts
@@ -1,4 +1,7 @@
 import assert from "node:assert/strict";
+import { mkdtempSync, mkdirSync, rmSync, writeFileSync } from "node:fs";
+import os from "node:os";
+import path from "node:path";
 import test from "node:test";
 
 import {
@@ -7,8 +10,12 @@ import {
   xlingsInstallArgs,
   deriveInstalledClangdPath,
   findXlingsExecutable,
+  resolveXlingsExecutable,
 } from "../src/llvmTools";
 
+// `xlings` on POSIX, `xlings.exe` on Windows — mirrors mcpp's exe_suffix.
+const xlingsBinaryName = process.platform === "win32" ? "xlings.exe" : "xlings";
+
 test("extracts version string from ToolIdentity", () => {
   assert.equal(
     llvmToolsVersionSpec({ major: 22, minor: 1, patch: 8, revision: "abc1234" }),
@@ -68,3 +75,115 @@ test("findXlingsExecutable returns a string or undefined", () => {
   // Returns string (PATH fallback or known path) or undefined if xlings not found
   assert.ok(result === undefined || typeof result === "string");
 });
+
+test("findXlingsExecutable finds the xlings bundled in $MCPP_HOME/registry/bin", () => {
+  const home = mkdtempSync(path.join(os.tmpdir(), "mcpp-vscode-mcpp-home-"));
+  const registryBin = path.join(home, "registry", "bin");
+  const xlingsPath = path.join(registryBin, xlingsBinaryName);
+  mkdirSync(registryBin, { recursive: true });
+  writeFileSync(xlingsPath, "#!/bin/sh\n");
+  try {
+    assert.equal(
+      findXlingsExecutable({ home, env: { MCPP_HOME: home } }),
+      xlingsPath,
+    );
+  } finally {
+    rmSync(home, { recursive: true, force: true });
+  }
+});
+
+test("findXlingsExecutable falls back to $HOME/.mcpp/registry/bin when MCPP_HOME is unset", () => {
+  const home = mkdtempSync(path.join(os.tmpdir(), "mcpp-vscode-home-"));
+  const registryBin = path.join(home, ".mcpp", "registry", "bin");
+  const xlingsPath = path.join(registryBin, xlingsBinaryName);
+  mkdirSync(registryBin, { recursive: true });
+  writeFileSync(xlingsPath, "#!/bin/sh\n");
+  try {
+    assert.equal(
+      findXlingsExecutable({ home, env: {} }),
+      xlingsPath,
+    );
+  } finally {
+    rmSync(home, { recursive: true, force: true });
+  }
+});
+
+test("findXlingsExecutable honors MCPP_VENDORED_XLINGS", () => {
+  const root = mkdtempSync(path.join(os.tmpdir(), "mcpp-vscode-vendored-"));
+  const vendored = path.join(root, "opt-mcpp", "registry", "bin", xlingsBinaryName);
+  mkdirSync(path.dirname(vendored), { recursive: true });
+  writeFileSync(vendored, "#!/bin/sh\n");
+  try {
+    assert.equal(
+      findXlingsExecutable({ home: root, env: { MCPP_VENDORED_XLINGS: vendored } }),
+      vendored,
+    );
+  } finally {
+    rmSync(root, { recursive: true, force: true });
+  }
+});
+
+test("resolveXlingsExecutable reads the xlings binary from `mcpp self env`", async () => {
+  const root = mkdtempSync(path.join(os.tmpdir(), "mcpp-vscode-selfenv-"));
+  const xlingsPath = path.join(root, "registry", "bin", xlingsBinaryName);
+  mkdirSync(path.dirname(xlingsPath), { recursive: true });
+  writeFileSync(xlingsPath, "#!/bin/sh\n");
+  const runner = async () => ({
+    exitCode: 0,
+    stdout: `MCPP_HOME = ${root}\nxlings binary = ${xlingsPath}\nxlings pinned = 2026.8.8.1\n`,
+    stderr: "",
+  });
+  try {
+    assert.equal(
+      await resolveXlingsExecutable("/tools/mcpp", runner),
+      xlingsPath,
+    );
+  } finally {
+    rmSync(root, { recursive: true, force: true });
+  }
+});
+
+test("resolveXlingsExecutable passes a timeout to `mcpp self env`", async () => {
+  let captured: { timeoutMs?: number } | undefined;
+  const runner = async (
+    _executable: string,
+    _args: string[],
+    _cwd?: string,
+    options?: { timeoutMs?: number },
+  ) => {
+    captured = options;
+    return { exitCode: 0, stdout: "", stderr: "" };
+  };
+  await resolveXlingsExecutable("/tools/mcpp", runner);
+  assert.equal(captured?.timeoutMs, 60_000);
+});
+
+test("resolveXlingsExecutable falls back to path probing when the reported path does not exist", async () => {
+  const home = mkdtempSync(path.join(os.tmpdir(), "mcpp-vscode-fallback-missing-"));
+  const runner = async () => ({
+    exitCode: 0,
+    stdout: "xlings binary = /no/such/xlings\n",
+    stderr: "",
+  });
+  try {
+    assert.equal(
+      await resolveXlingsExecutable("/tools/mcpp", runner, { home, env: {} }),
+      undefined,
+    );
+  } finally {
+    rmSync(home, { recursive: true, force: true });
+  }
+});
+
+test("resolveXlingsExecutable falls back to path probing when `mcpp self env` fails", async () => {
+  const home = mkdtempSync(path.join(os.tmpdir(), "mcpp-vscode-fallback-fail-"));
+  const runner = async () => ({ exitCode: 1, stdout: "", stderr: "boom\n" });
+  try {
+    assert.equal(
+      await resolveXlingsExecutable("/tools/mcpp", runner, { home, env: {} }),
+      undefined,
+    );
+  } finally {
+    rmSync(home, { recursive: true, force: true });
+  }
+});