fix: correct dts generation for stub mode

src/auto.ts

@@ -30,8 +30,10 @@ export const autoPreset = definePreset(() => {
         if (res.cjs) {
           ctx.options.rollup.emitCJS = true;
         }
-        if (res.dts) {
-          ctx.options.declaration = res.dts;
+        if (ctx.options.declaration === undefined) {
+          // Enable auto detect based on "package.json"
+          // If "package.json" has "types" field, it will be "compatible", otherwise false.
+          ctx.options.declaration = res.dts ? "compatible" : false;
         }
         consola.info(
           "Automatically detected entries:",

src/build.ts

@@ -93,7 +93,7 @@ async function _build(
       rootDir,
       entries: [],
       clean: true,
-      declaration: false,
+      declaration: undefined,
       outDir: "dist",
       stub: _stubMode,
       stubOptions: {

src/builder/rollup.ts

@@ -142,17 +142,22 @@ export async function rollupBuild(ctx: BuildContext) {
       );
 
       // DTS Stub
-      await writeFile(
-        output + ".d.ts",
-        [
+      if (ctx.options.declaration) {
+        const dtsContent = [
           `export * from ${JSON.stringify(resolvedEntryForTypeImport)};`,
           hasDefaultExport
-            ? `export { default } from ${JSON.stringify(
-                resolvedEntryForTypeImport,
-              )};`
+            ? `export { default } from ${JSON.stringify(resolvedEntryForTypeImport)};`
             : "",
-        ].join("\n"),
-      );
+        ].join("\n");
+        await writeFile(output + ".d.cts", dtsContent);
+        await writeFile(output + ".d.mts", dtsContent);
+        if (
+          ctx.options.declaration === "compatible" ||
+          ctx.options.declaration === true
+        ) {
+          await writeFile(output + ".d.ts", dtsContent);
+        }
+      }
 
       if (shebang) {
         await makeExecutable(output + ".cjs");

test/auto.test.ts

@@ -19,7 +19,7 @@ describe("inferEntries", () => {
     const result = inferEntries({ module: "dist/index.mjs" }, [
       "src/",
       "src/event/index.ts",
-      "src/index.ts",
+      "src/index.mts",
     ]);
     expect(result).to.deep.equal({
       cjs: false,
@@ -155,7 +155,7 @@ describe("inferEntries", () => {
 
   it("gracefully handles unknown entries", () => {
     expect(
-      inferEntries({ exports: "dist/test.js" }, ["src/", "src/index.ts"]),
+      inferEntries({ exports: "dist/test.js" }, ["src/", "src/index.mts"]),
     ).to.deep.equal({
       cjs: false,
       entries: [],
@@ -169,7 +169,7 @@ describe("inferEntries", () => {
       inferEntries({ exports: { "./*": "./*" } }, [
         "src/",
         "src/",
-        "src/index.ts",
+        "src/index.mts",
       ]),
     ).to.deep.equal({
       cjs: false,
@@ -189,7 +189,7 @@ describe("inferEntries", () => {
             "./test": "./dist/test.cjs",
           },
         },
-        ["src/", "src/", "src/index.ts", "src/first-test.ts", "src/test.mjs"],
+        ["src/", "src/", "src/index.mts", "src/first-test.ts", "src/test.mjs"],
       ),
     ).to.deep.equal({
       cjs: true,

test/fixture/build.config.ts

@@ -10,7 +10,7 @@ export default defineBuildConfig([
       emitCJS: true,
     },
     entries: [
-      "./src/index.ts",
+      "./src/index.mts",
       "./src/nested/subpath.ts",
       { input: "src/runtime/", outDir: "dist/runtime" },
       {
@@ -28,7 +28,7 @@ export default defineBuildConfig([
     entries: ["src/index"],
     outDir: "dist/min",
     sourcemap: true,
-    declaration: true,
+    declaration: "compatible",
     rollup: {
       esbuild: {
         minify: true,

test/fixture/build.preset.ts

@@ -1,7 +1,7 @@
 import { definePreset } from "../../src";
 
 export default definePreset({
-  declaration: true,
+  declaration: "compatible",
   rollup: {
     cjsBridge: true,
   },

test/fixture/package.json

@@ -1,6 +1,7 @@
 {
   "name": "fixture",
   "private": "true",
+  "type": "module",
   "bin": {
     "fixture": "./bin/cli.mjs"
   },

test/validate.test.ts

@@ -20,7 +20,7 @@ describe("validatePackage", () => {
         module: "dist/mod",
         exports: {
           "./runtime/*": "./runtime/*.mjs",
-          ".": { node: "./src/index.ts" },
+          ".": { node: "./src/index.mts" },
         },
       },
       join(fileURLToPath(import.meta.url), "../fixture"),
@@ -30,7 +30,7 @@ describe("validatePackage", () => {
     const warnings = [...buildContext.warnings];
 
     expect(warnings[0]).to.include("Potential missing");
-    expect(warnings[0]).not.to.include("src/index.ts");
+    expect(warnings[0]).not.to.include("src/index.mts");
 
     for (const file of ["dist/test", "dist/cli", "dist/mod", "runtime"]) {
       expect(warnings[0]).to.include(file);