fix: prefer lockfile detection over env var one

src/pkg_manager.ts

@@ -216,7 +216,7 @@ export async function getPkgManager(
     );
   const rootPath = root || projectDir;
 
-  const result = pkgManagerName || fromEnv || fromLockfile || "npm";
+  const result = pkgManagerName || fromLockfile || fromEnv || "npm";
 
   let pkgManager: PackageManager;
   if (result === "yarn") {

test/commands.test.ts

@@ -503,6 +503,25 @@ describe("install", () => {
       );
     });
 
+    it("prefer lockfile detection over env detection", async () => {
+      await runInTempDir(async (tmp) => {
+        await writeJson<PkgJson>(path.join(tmp, "package.json"), {
+          name: "foo",
+          version: "0.0.1",
+          dependencies: {
+            preact: "10.23.2",
+          },
+        });
+
+        await exec("pnpm", ["install"], tmp);
+        await runJsr(["i", "@std/[email protected]"], tmp, {
+          npm_config_user_agent:
+            `npm/10.8.2 node/v22.5.1 darwin arm64 workspaces/false`,
+        });
+        assert.ok(!fs.existsSync(path.join(tmp, "package-lock.json")));
+      });
+    });
+
     it("overwrite detection with arg from npm_config_user_agent", async () => {
       await withTempEnv(
         ["i", "--npm", "@std/[email protected]"],