diff --git a/.vscode/launch.json b/.vscode/launch.json
index ad78f01..61055b9 100644
--- a/.vscode/launch.json
+++ b/.vscode/launch.json
@@ -1,5 +1,13 @@
 {
   "version": "0.2.0",
+  "inputs": [
+    {
+      "id": "testWorkspace",
+      "type": "promptString",
+      "description": "Absolute path to the folder to open in the Extension Development Host",
+      "default": "${workspaceFolder}"
+    }
+  ],
   "configurations": [
     {
       "name": "Launch Client",
@@ -10,7 +18,7 @@
         "--extensionDevelopmentPath=${workspaceRoot}"
       ],
       "outFiles": [
-        "${workspaceRoot}/out/**/*.js",
+        "${workspaceRoot}/out/**/*.js"
       ],
       "preLaunchTask": {
         "type": "npm",
@@ -18,23 +26,40 @@
       }
     },
     {
-      "name":"Attach to ELS Server",
-      "type":"node",
-      "request":"attach",
-      "port":6004,
-      "sourceMaps":true,
-      "outFiles":[
-         "${workspaceRoot}/node_modules/@ember-tooling/ember-language-server/lib/**/*.js"
+      "name": "Launch Client (prompt for folder)",
+      "type": "extensionHost",
+      "request": "launch",
+      "runtimeExecutable": "${execPath}",
+      "args": [
+        "--extensionDevelopmentPath=${workspaceRoot}",
+        "${input:testWorkspace}"
+      ],
+      "outFiles": [
+        "${workspaceRoot}/out/**/*.js"
       ],
-      "restart":true,
-      "smartStep":true
-   }
+      "preLaunchTask": {
+        "type": "npm",
+        "script": "watch"
+      }
+    },
+    {
+      "name": "Attach to ELS Server",
+      "type": "node",
+      "request": "attach",
+      "port": 6004,
+      "sourceMaps": true,
+      "outFiles": [
+        "${workspaceRoot}/node_modules/@ember-tooling/ember-language-server/lib/**/*.js"
+      ],
+      "restart": true,
+      "smartStep": true
+    }
   ],
-	"compounds": [
-		{
-			"name": "Client + Server",
-			"configurations": ["Launch Client", "Attach"], //"Attach" is in ember-language-server project
-      "stopAll": true,
-		}
-	]
+  "compounds": [
+    {
+      "name": "Client + Server",
+      "configurations": ["Launch Client", "Attach"],
+      "stopAll": true
+    }
+  ]
 }
diff --git a/package.json b/package.json
index df9cb0d..1319ecb 100644
--- a/package.json
+++ b/package.json
@@ -34,7 +34,13 @@
     "onLanguage:typescript",
     "onLanguage:glimmer-js",
     "onLanguage:glimmer-ts",
-    "workspaceContains:ember-cli-build.js",
+    "workspaceContains:**/ember-cli-build.js",
+    "workspaceContains:**/ember-cli-build.cjs",
+    "workspaceContains:**/node_modules/ember-source/package.json",
+    "workspaceContains:**/node_modules/ember-template-lint/package.json",
+    "workspaceContains:**/node_modules/ember-template-imports/package.json",
+    "workspaceContains:**/node_modules/content-tag/package.json",
+    "workspaceContains:**/node_modules/@glimmerx/core/package.json",
     "onCommand:els.runInEmberCLI"
   ],
   "contributes": {
@@ -101,6 +107,11 @@
           "type": "boolean",
           "default": true,
           "description": "Folding range provider for .hbs files, disabling may improve startup performance for very large projects"
+        },
+        "els.detection.forceEnable": {
+          "type": "boolean",
+          "default": false,
+          "description": "Bypass Ember project detection and always start the language server. Useful for exotic monorepo layouts (e.g. pnpm setups) where automatic detection fails."
         }
       }
     },
@@ -148,7 +159,7 @@
   },
   "devDependencies": {
     "@types/mocha": "^2.2.33",
-    "@types/node": "^6.0.52",
+    "@types/node": "^14.18.63",
     "@types/vscode": "1.60.0",
     "@typescript-eslint/eslint-plugin": "^5.33.1",
     "@typescript-eslint/parser": "^5.33.1",
diff --git a/src/extension.ts b/src/extension.ts
index d6e79d9..4d48d2b 100644
--- a/src/extension.ts
+++ b/src/extension.ts
@@ -11,6 +11,7 @@ import {
   workspace,
   ExtensionContext,
   StatusBarItem,
+  OutputChannel,
   window,
   commands,
   languages,
@@ -18,7 +19,7 @@ import {
   StatusBarAlignment,
   Uri,
 } from 'vscode';
-import { isEmberCliProject, emberLikeProject } from './workspace-utils';
+import { isEmberProject } from './workspace-utils';
 import {
   LanguageClient,
   LanguageClientOptions,
@@ -30,6 +31,7 @@ import {
 import { provideCodeLenses } from './lenses';
 let ExtStatusBarItem: StatusBarItem;
 let ExtServerDebugBarItem: StatusBarItem;
+let ExtOutputChannel: OutputChannel;
 export async function activate(context: ExtensionContext) {
   // The server is implemented in node
   const serverModule = path.join(context.extensionPath, './start-server.js');
@@ -49,10 +51,11 @@ export async function activate(context: ExtensionContext) {
     },
   };
 
-  if (!(await isEmberCliProject())) {
-    if (!(await emberLikeProject())) {
-      return;
-    }
+  ExtOutputChannel = window.createOutputChannel('Ember Language Server');
+  context.subscriptions.push(ExtOutputChannel);
+
+  if (!(await isEmberProject(ExtOutputChannel))) {
+    return;
   }
 
   const syncExtensions = ['js', 'ts', 'hbs', 'gts', 'gjs'];
@@ -70,7 +73,7 @@ export async function activate(context: ExtensionContext) {
       'javascript',
       'typescript',
     ],
-    outputChannelName: 'Ember Language Server',
+    outputChannel: ExtOutputChannel,
     revealOutputChannelOn: RevealOutputChannelOn.Never,
     initializationOptions: { editor: 'vscode' },
     synchronize: {
diff --git a/src/workspace-utils.ts b/src/workspace-utils.ts
index df8aac3..ab85e0e 100644
--- a/src/workspace-utils.ts
+++ b/src/workspace-utils.ts
@@ -1,21 +1,257 @@
-import { workspace } from 'vscode';
+import { workspace, Uri, WorkspaceFolder, OutputChannel } from 'vscode';
 
-export async function emberLikeProject(): Promise<boolean> {
-  const emberCliBuildFile = await workspace.findFiles(
-    '**/node_modules/{glimmer-lite-core,@glimmerx/core,content-tag,ember-template-lint,ember-source,ember-template-imports}/package.json',
-    '**/{dist,tmp,.git,.cache}/**',
-    1
+/**
+ * Packages whose presence indicates an Ember-like project. If any of these
+ * resolve from a workspace folder, we activate the language server.
+ */
+const EMBER_MARKER_PACKAGES = [
+  'ember-source',
+  'ember-template-lint',
+  'ember-template-imports',
+  'content-tag',
+  'glimmer-lite-core',
+  '@glimmerx/core',
+] as const;
+
+/**
+ * File names at the root of a workspace folder that strongly indicate an
+ * Ember CLI project.
+ */
+const EMBER_CLI_BUILD_FILES = [
+  'ember-cli-build.js',
+  'ember-cli-build.cjs',
+  'ember-cli-build.mjs',
+  'ember-cli-build.ts',
+] as const;
+
+const DEPENDENCY_FIELDS = [
+  'dependencies',
+  'devDependencies',
+  'peerDependencies',
+  'optionalDependencies',
+] as const;
+
+/**
+ * Primary entry point. Returns true if the language server should start for
+ * the current workspace. Iterates all workspace folders and short-circuits on
+ * the first positive signal.
+ */
+export async function isEmberProject(
+  outputChannel: OutputChannel
+): Promise<boolean> {
+  const config = workspace.getConfiguration('els');
+  const forceEnable = config.get<boolean>('detection.forceEnable', false);
+  if (forceEnable) {
+    return true;
+  }
+
+  const folders: ReadonlyArray<WorkspaceFolder> =
+    workspace.workspaceFolders ?? [];
+  if (folders.length === 0) {
+    return false;
+  }
+
+  const results = await Promise.all(
+    folders.map((folder) => detectInFolder(folder.uri))
   );
 
-  return emberCliBuildFile.length > 0;
+  if (!results.some((r) => r === true)) {
+    const paths = folders.map((f) => f.uri.fsPath).join(', ');
+    outputChannel.appendLine(
+      `ELS: no Ember markers found in ${paths}; set \`els.detection.forceEnable\` to override.`
+    );
+    return false;
+  }
+
+  return true;
 }
 
-export async function isEmberCliProject(): Promise<boolean> {
-  const emberCliBuildFile = await workspace.findFiles(
-    '**/ember-cli-build.{js,cjs}',
-    '**/{dist,tmp,node_modules,.git,.cache}/**',
-    1
-  );
+async function detectInFolder(folderUri: Uri): Promise<boolean> {
+  // Tier 1: cheap package.json / build-file inspection.
+  if (await checkBuildFile(folderUri)) {
+    return true;
+  }
+
+  if (await checkPackageJsonDeps(folderUri)) {
+    return true;
+  }
+
+  // Tier 2: Node resolver. Handles pnpm (incl. package-level opens),
+  // npm-hoisted, and yarn classic transparently. Not available in the
+  // web-worker build; guarded by a try/catch around the dynamic import.
+  if (await checkViaResolver(folderUri)) {
+    return true;
+  }
+
+  // Tier 3: explicit ancestor walk via workspace.fs. Belt-and-braces for
+  // folders without a package.json or exotic resolver failures.
+  if (await checkViaAncestorWalk(folderUri)) {
+    return true;
+  }
+
+  return false;
+}
+
+/**
+ * Read and parse a package.json at `<dir>/package.json`. Returns undefined if
+ * the file is missing, unreadable, not valid JSON, or not a JSON object.
+ */
+async function readPackageJson(
+  dirUri: Uri
+): Promise<Record<string, unknown> | undefined> {
+  const pkgUri = Uri.joinPath(dirUri, 'package.json');
+
+  let raw: Uint8Array;
+  try {
+    raw = await workspace.fs.readFile(pkgUri);
+  } catch {
+    return undefined;
+  }
+
+  let parsed: unknown;
+  try {
+    parsed = JSON.parse(new TextDecoder('utf-8').decode(raw));
+  } catch {
+    return undefined;
+  }
+
+  if (!parsed || typeof parsed !== 'object') {
+    return undefined;
+  }
+
+  return parsed as Record<string, unknown>;
+}
+
+async function checkPackageJsonDeps(folderUri: Uri): Promise<boolean> {
+  const pkg = await readPackageJson(folderUri);
+  if (!pkg) return false;
+
+  for (const field of DEPENDENCY_FIELDS) {
+    const deps = pkg[field];
+    if (!deps || typeof deps !== 'object') continue;
+    for (const marker of EMBER_MARKER_PACKAGES) {
+      if (marker in (deps as Record<string, unknown>)) {
+        return true;
+      }
+    }
+  }
+
+  return false;
+}
+
+async function checkBuildFile(folderUri: Uri): Promise<boolean> {
+  for (const name of EMBER_CLI_BUILD_FILES) {
+    const uri = Uri.joinPath(folderUri, name);
+    try {
+      await workspace.fs.stat(uri);
+      return true;
+    } catch {
+      // not present, try next
+    }
+  }
+  return false;
+}
+
+async function checkViaResolver(folderUri: Uri): Promise<boolean> {
+  // createRequire is a Node.js built-in and is not available in the
+  // web-worker/browser build. Import it lazily so the module still loads
+  // in that environment; if the import fails we fall through gracefully.
+  let createRequire: ((filename: string) => NodeRequire) | undefined;
+  try {
+    ({ createRequire } = await import('module'));
+  } catch {
+    return false;
+  }
+  if (!createRequire) return false;
+
+  let anchoredRequire: NodeRequire;
+  try {
+    // The anchor file need not exist; createRequire only uses the parent
+    // directory as the resolution base.
+    anchoredRequire = createRequire(Uri.joinPath(folderUri, 'noop.js').fsPath);
+  } catch {
+    return false;
+  }
+
+  for (const marker of EMBER_MARKER_PACKAGES) {
+    try {
+      anchoredRequire.resolve(`${marker}/package.json`);
+      return true;
+    } catch {
+      // not resolvable from this anchor, try next
+    }
+  }
+
+  return false;
+}
+
+async function checkViaAncestorWalk(folderUri: Uri): Promise<boolean> {
+  const seen = new Set<string>();
+  let dirUri = folderUri;
+  // -1 = not yet seen a workspace root. Once set to a non-negative value,
+  // counts how many more ancestors we'll visit before stopping.
+  let stepsAfterWorkspaceRoot = -1;
+
+  // Cap the walk to avoid pathological filesystems. 40 levels is deeper than
+  // any realistic project tree.
+  for (let i = 0; i < 40; i += 1) {
+    const key = dirUri.toString();
+    if (seen.has(key)) break;
+    seen.add(key);
+
+    for (const marker of EMBER_MARKER_PACKAGES) {
+      const candidate = Uri.joinPath(
+        dirUri,
+        'node_modules',
+        marker,
+        'package.json'
+      );
+      try {
+        await workspace.fs.stat(candidate);
+        return true;
+      } catch {
+        // not here, keep looking
+      }
+    }
+
+    if (stepsAfterWorkspaceRoot < 0) {
+      // Not yet at a workspace root: once we find one, allow one more
+      // ancestor above it. pnpm-workspace.yaml or a package.json with a
+      // "workspaces" field marks the top of the workspace; going one level
+      // above handles layouts that nest the repo inside another tooling
+      // directory.
+      if (await isWorkspaceRoot(dirUri)) {
+        stepsAfterWorkspaceRoot = 0;
+      }
+    } else if (stepsAfterWorkspaceRoot === 0) {
+      break;
+    } else {
+      stepsAfterWorkspaceRoot -= 1;
+    }
+
+    const parentPath = Uri.joinPath(dirUri, '..').fsPath;
+    const parentUri = Uri.file(parentPath);
+    if (parentUri.toString() === dirUri.toString()) break;
+    dirUri = parentUri;
+  }
+
+  return false;
+}
+
+/**
+ * Returns true if `dir` is the root of a monorepo workspace. Checks for:
+ *   - pnpm: presence of a pnpm-workspace.yaml file
+ *   - npm/yarn: a package.json with a "workspaces" field
+ */
+async function isWorkspaceRoot(dirUri: Uri): Promise<boolean> {
+  const pnpmWorkspace = Uri.joinPath(dirUri, 'pnpm-workspace.yaml');
+  try {
+    await workspace.fs.stat(pnpmWorkspace);
+    return true;
+  } catch {
+    // fall through
+  }
 
-  return emberCliBuildFile.length > 0;
+  const pkg = await readPackageJson(dirUri);
+  return !!pkg && 'workspaces' in pkg;
 }
diff --git a/yarn.lock b/yarn.lock
index 3a0b630..e9922ab 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -660,10 +660,10 @@
   resolved "https://registry.yarnpkg.com/@types/node/-/node-16.10.2.tgz#5764ca9aa94470adb4e1185fe2e9f19458992b2e"
   integrity sha512-zCclL4/rx+W5SQTzFs9wyvvyCwoK9QtBpratqz2IYJ3O8Umrn0m3nsTv0wQBk9sRGpvUe9CwPDrQFB10f1FIjQ==
 
-"@types/node@^6.0.52":
-  version "6.14.9"
-  resolved "https://registry.yarnpkg.com/@types/node/-/node-6.14.9.tgz#733583e21ef0eab85a9737dfafbaa66345a92ef0"
-  integrity sha512-leP/gxHunuazPdZaCvsCefPQxinqUDsCxCR5xaDUrY2MkYxQRFZZwU5e7GojyYsGB7QVtCi7iVEl/hoFXQYc+w==
+"@types/node@^14.18.63":
+  version "14.18.63"
+  resolved "https://registry.yarnpkg.com/@types/node/-/node-14.18.63.tgz#1788fa8da838dbb5f9ea994b834278205db6ca2b"
+  integrity sha512-fAtCfv4jJg+ExtXhvCkCqUKZ+4ok/JQk01qDKhL5BDDoS3AxKXhV5/MAVUZyQnSEd2GT92fkgZl0pz0Q0AzcIQ==
 
 "@types/vscode@1.60.0":
   version "1.60.0"