feat: implement runtime package manager detection

src/cli.ts

@@ -4,7 +4,10 @@
 import { consola } from "consola";
 import { name, version, description } from "../package.json";
 import { addDependency, installDependencies, removeDependency } from "./api";
-import { detectPackageManager } from "./package-manager";
+import {
+  detectPackageManager,
+  detectRuntimePackageManager,
+} from "./package-manager";
 
 const operationArgs = {
   cwd: {
@@ -94,6 +97,22 @@
   },
 });
 
+const detectRunner = defineCommand({
+  meta: {
+    description: "Detect the current package runner using runtime checks",
+  },
+  run: () => {
+    const packageManager = detectRuntimePackageManager();
+    if (!packageManager) {
+      consola.error(`Cannot detect package runner`);
+      return process.exit(1);
+    }
+    consola.log(
+      `Detected package runner \`${packageManager.name}@${packageManager.version}\``,
+    );
+  },
+});
+
 const main = defineCommand({
   meta: {
     name,
@@ -109,6 +128,7 @@
     uninstall: remove,
     un: remove,
     detect,
+    "detect-runner": detectRunner,
   },
 });
 

src/package-manager.ts

@@ -1,6 +1,7 @@
 import { existsSync } from "node:fs";
 import { readFile } from "node:fs/promises";
 import { join, resolve } from "pathe";
+import { env, process } from "std-env";
 import { findup } from "./_utils";
 import type { PackageManager } from "./types";
 
@@ -27,7 +28,12 @@
   includeParentDirs?: boolean;
 
   /**
-   * Weather to ignore argv[1] to detect script
+   * Weather to ignore runtime checks to detect package manager or script runner
+   */
+  ignoreRuntime?: boolean;
+
+  /**
+   * Whether to ignore argv[1] to detect package manager or script runner, implied if `ignoreRuntimeChecks` is `true`
    */
   ignoreArgv?: boolean;
 };
@@ -37,30 +43,35 @@
     name: "npm",
     command: "npm",
     lockFile: "package-lock.json",
+    packageRunner: "npx",
   },
   {
     name: "pnpm",
     command: "pnpm",
     lockFile: "pnpm-lock.yaml",
     files: ["pnpm-workspace.yaml"],
+    packageRunner: "pnpm dlx",
   },
   {
     name: "bun",
     command: "bun",
     lockFile: ["bun.lockb", "bun.lock"],
+    packageRunner: "bunx",
   },
   {
     name: "yarn",
     command: "yarn",
     majorVersion: "1",
     lockFile: "yarn.lock",
+    packageRunner: undefined,
   },
   {
     name: "yarn",
     command: "yarn",
     majorVersion: "3",
     lockFile: "yarn.lock",
     files: [".yarnrc.yml"],
+    packageRunner: "yarn dlx",
   },
 ] as const;
 
@@ -127,10 +138,41 @@
     },
   );
 
-  if (!detected && !options.ignoreArgv) {
-    // 3. Try to detect based on dlx/exec command
+  if (!detected && !options.ignoreRuntime) {
+    return detectRuntimePackageManager(options);
+  }
+
+  return detected;
+}
+
+export function detectRuntimePackageManager(
+  options: DetectPackageManagerOptions = {},
+): PackageManager | undefined {
+  const userAgent = env["npm_config_user_agent"];
+
+  const engine = userAgent?.split(" ")?.[0] ?? "";
+
+  const [name, version = "0.0.0"] = engine.split("/");
+
+  if (name) {
+    const majorVersion = version.split(".")[0];
+    const packageManager =
+      packageManagers.find(
+        (pm) => pm.name === name && pm.majorVersion === majorVersion,
+      ) || packageManagers.find((pm) => pm.name === name);
+    if (packageManager) {
+      return {
+        ...packageManager,
+        command: name,
+        version,
+        majorVersion,
+      };
+    }
+  }
+  if (!options.ignoreArgv) {
+    // Fallback to detecting based on argv
     // https://github.com/unjs/nypm/issues/116
-    const scriptArg = process.argv[1];
+    const scriptArg = process.argv?.[1];
     if (scriptArg) {
       for (const packageManager of packageManagers) {
         // Check /.[name] or /[name] in path
@@ -141,6 +183,4 @@
       }
     }
   }
-
-  return detected;
 }

src/types.ts

@@ -3,6 +3,7 @@ export type PackageManagerName = "npm" | "yarn" | "pnpm" | "bun";
 export type PackageManager = {
   name: PackageManagerName;
   command: string;
+  packageRunner?: string;
   version?: string;
   majorVersion?: string;
   lockFile?: string | string[];