bake: provide every runtime helper from the dev server's bun:wrap module

scripts/glob-sources.ts

@@ -60,7 +60,14 @@ const patterns = {
   bakeRuntime: {
     // dev_server/mod.rs is read by bake-codegen.ts to derive the
     // MessageId/IncomingMessageId const-enums in generated.ts.
-    paths: ["src/runtime/bake/*.ts", "src/runtime/bake/*/*.{ts,css}", "src/runtime/bake/dev_server/mod.rs"],
+    // hmr-module.ts bundles every export of runtime.bun.js as `bun:wrap`.
+    paths: [
+      "src/runtime/bake/*.ts",
+      "src/runtime/bake/*/*.{ts,css}",
+      "src/runtime/bake/dev_server/mod.rs",
+      "src/runtime.js",
+      "src/runtime.bun.js",
+    ],
     exclude: ["src/runtime/bake/generated.ts"],
   },
   /** legacy bindgen input */

src/runtime/bake/bake.private.d.ts

@@ -144,14 +144,3 @@ declare module "react-dom/server.node" {
     options: RenderToPipeableStreamOptions,
   ): PipeableStream<Uint8Array>;
 }
-
-declare module "bun:wrap" {
-  export const __name: unique symbol;
-  export const __legacyDecorateClassTS: unique symbol;
-  export const __legacyDecorateParamTS: unique symbol;
-  export const __legacyMetadataTS: unique symbol;
-  export const __using: unique symbol;
-  export const __callDispose: unique symbol;
-  export const __MEMO_CACHE_SENTINEL: unique symbol;
-  export const __EARLY_RETURN_SENTINEL: unique symbol;
-}

src/runtime/bake/hmr-module.ts

@@ -6,16 +6,7 @@
 // Some build failures from the bundler surface as runtime errors here, such as
 // `require` on a module with transitive top-level await, or a missing export.
 // This was done to make incremental updates as isolated as possible.
-import {
-  __callDispose,
-  __EARLY_RETURN_SENTINEL,
-  __legacyDecorateClassTS,
-  __legacyDecorateParamTS,
-  __legacyMetadataTS,
-  __MEMO_CACHE_SENTINEL,
-  __name,
-  __using,
-} from "../../runtime.bun";
+import * as runtimeHelpers from "../../runtime.bun";
 // This import is different based on client vs server side.
 // On the server, remapping is done automatically.
 import { type SourceMapURL, derefMapping } from "#stack-trace";
@@ -906,17 +897,9 @@ declare global {
 }
 
 // bun:bake/server, bun:bake/client, and bun:wrap are
-// provided by this file instead of the bundler
-registerSynthetic("bun:wrap", {
-  __name,
-  __legacyDecorateClassTS,
-  __legacyDecorateParamTS,
-  __legacyMetadataTS,
-  __using,
-  __callDispose,
-  __MEMO_CACHE_SENTINEL,
-  __EARLY_RETURN_SENTINEL,
-});
+// provided by this file instead of the bundler.
+// The transpiler can emit any name in `Imports::ALL` (src/ast/runtime.rs) through `bun:wrap`.
+registerSynthetic("bun:wrap", { ...runtimeHelpers });
 
 if (side === "server") {
   registerSynthetic("bun:bake/server", {

test/bake/dev/bundle.test.ts

@@ -940,3 +940,90 @@ devTest("a render() that does not return a Response is reported as that", {
     }).toEqual({ status: 500, saysWhatIsWrong: true, referenceError: false });
   },
 });
+
+// TC39 decorator lowering calls runtime helpers through the HMR runtime's synthetic `bun:wrap` module.
+const tc39DecoratorFiles = {
+  "tsconfig.json": JSON.stringify({
+    compilerOptions: { experimentalDecorators: false, emitDecoratorMetadata: false },
+  }),
+  "decorators.ts": `
+    function classDecorator(value, context) {
+      context.metadata.label = "tc39";
+      context.addInitializer(function () {
+        this.ready = this.seed + 1;
+      });
+    }
+    function fieldDecorator(value, context) {
+      return initialValue => initialValue * 2;
+    }
+    function methodDecorator(value, context) {
+      return function () {
+        return value.call(this) + 4;
+      };
+    }
+    function accessorDecorator(value, context) {
+      return { init: initialValue => initialValue + 3 };
+    }
+
+    @classDecorator
+    export class Example {
+      static seed = 10;
+      static ready;
+      hasHidden() {
+        return #hidden in this;
+      }
+      @fieldDecorator value = 2;
+      @accessorDecorator accessor score = 5;
+      @fieldDecorator #hidden = 3;
+      @methodDecorator #secret() {
+        this.#hidden = this.#hidden + 1;
+        return this.#hidden;
+      }
+      @methodDecorator result() {
+        return this.value + this.score + this.#secret();
+      }
+    }
+
+    export function report() {
+      const instance = new Example();
+      const metadata = Example[Symbol.metadata ?? Symbol.for("Symbol.metadata")];
+      return [instance.value, instance.score, instance.result(), Example.ready, metadata.label, instance.hasHidden()].join(":");
+    }
+  `,
+};
+
+devTest("TC39 decorators in the client HMR runtime", {
+  files: {
+    ...tc39DecoratorFiles,
+    "index.html": emptyHtmlFile({ scripts: ["index.ts"] }),
+    "index.ts": `
+      import { report } from "./decorators";
+      console.log(report());
+      import.meta.hot.accept();
+    `,
+  },
+  async test(dev) {
+    await using c = await dev.client("/");
+    await c.expectMessage("4:8:27:11:tc39:true");
+    await dev.patch("decorators.ts", { find: "value = 2", replace: "value = 3" });
+    await c.expectMessage("6:8:29:11:tc39:true");
+  },
+});
+
+devTest("TC39 decorators in the server HMR runtime", {
+  framework: minimalFramework,
+  files: {
+    ...tc39DecoratorFiles,
+    "routes/index.ts": `
+      import { report } from "../decorators";
+      export default function () {
+        return new Response(report());
+      }
+    `,
+  },
+  async test(dev) {
+    await dev.fetch("/").equals("4:8:27:11:tc39:true");
+    await dev.patch("decorators.ts", { find: "value = 2", replace: "value = 3" });
+    await dev.fetch("/").equals("6:8:29:11:tc39:true");
+  },
+});