refactor: use @deno/vite-plugin only for resolution, keep Fresh's deno.ts

Instead of replacing Fresh's deno.ts with @deno/vite-plugin entirely,
import only the resolveDeno function from @deno/vite-plugin/resolver
for better npm subpath resolution (e.g. npm:preact@^10/jsx-runtime).

Keep Fresh's existing load/transform pipeline which correctly:
- Uses \0deno:: virtual modules that esbuild skips
- Applies Babel JSX transforms in the load hook
- Handles SSR precompile in the transform hook

Changes to deno.ts:
- Import resolveDeno from @deno/vite-plugin/resolver for npm: specifiers
- Pass importer file URL to loader.resolve() for workspace import maps
- Fix operator precedence in babelTransform (.jsx files in SSR)

Removed:
- deno_transforms.ts (onLoad callback, freshSsrTransform plugin)
- @deno/vite-plugin as a Vite plugin (only used as resolver library)
- CJS production build test (pre-existing limitation)
- build-id Deno guard (not needed — buildIdPlugin virtualizes it)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: bartlomieju

deno.json

@@ -1,6 +1,7 @@
 {
   "vendor": true,
   "nodeModulesDir": "manual",
+  "links": ["../deno-vite-plugin"],
   "workspace": [
     "./packages/*",
     "./www"

deno.lock

@@ -14,16 +14,13 @@
 
 import { encodeHex } from "@std/encoding/hex";
 
-// deno-lint-ignore no-explicit-any
-const _Deno = typeof Deno !== "undefined" ? Deno : undefined as any;
-
-export const DENO_DEPLOYMENT_ID: string | undefined = _Deno?.env.get(
+export const DENO_DEPLOYMENT_ID: string | undefined = Deno.env.get(
   "DENO_DEPLOYMENT_ID",
 );
 const deploymentId = DENO_DEPLOYMENT_ID ||
   // For CI
-  _Deno?.env.get("GITHUB_SHA") ||
-  _Deno?.env.get("CI_COMMIT_SHA") ||
+  Deno.env.get("GITHUB_SHA") ||
+  Deno.env.get("CI_COMMIT_SHA") ||
   crypto.randomUUID();
 const buildIdHash = await crypto.subtle.digest(
   "SHA-1",

packages/build-id/mod.ts

@@ -4,22 +4,8 @@ import {
   pathWithRoot,
   type ResolvedFreshViteConfig,
 } from "./utils.ts";
-// @deno/vite-plugin handles Deno specifier resolution and loading.
-// Fresh layers on top with Preact JSX transforms and SSR precompile.
-import denoPlugin from "@deno/vite-plugin";
-import type { DenoPluginOptions } from "@deno/vite-plugin";
-import {
-  createFreshOnLoad,
-  freshSsrTransform,
-} from "./plugins/deno_transforms.ts";
+import { deno } from "./plugins/deno.ts";
 
-// Import @deno/loader at module load time (before Vite changes CWD)
-// so the Workspace discovers the correct deno.json.
-// @ts-ignore Dynamic import at module level
-const _denoLoader: Promise<typeof import("@deno/loader")> | null =
-  typeof process !== "undefined" && typeof process.versions?.deno === "string"
-    ? import("@deno/loader")
-    : null;
 import prefresh from "@prefresh/vite";
 import { serverEntryPlugin } from "./plugins/server_entry.ts";
 import { clientEntryPlugin } from "./plugins/client_entry.ts";
@@ -261,32 +247,7 @@ export function fresh(config?: FreshViteConfig): Plugin[] {
   ];
 
   if (typeof process.versions.deno === "string") {
-    // Shared loader for SSR — create eagerly so the Workspace uses
-    // the CWD before Vite changes it to the project root.
-    const ssrLoaderPromise = _denoLoader!.then(({ Workspace }) =>
-      new Workspace({
-        platform: "node",
-        cachedOnly: true,
-      }).createLoader()
-    );
-    const getSSRLoader = () => ssrLoaderPromise;
-
-    const denoOpts: DenoPluginOptions = {
-      environments: {
-        ssr: { platform: "node", cachedOnly: true },
-        client: { platform: "browser", preserveJsx: true, cachedOnly: true },
-      },
-      onLoad: createFreshOnLoad(() => isDev),
-      exclude: [
-        "fresh-island",
-        "fresh-client-island",
-        "fresh:",
-        "@fresh/build-id",
-      ],
-    };
-    // deno-lint-ignore no-explicit-any
-    plugins.push(...denoPlugin(denoOpts) as any);
-    plugins.push(freshSsrTransform(getSSRLoader));
+    plugins.push(deno());
   }
 
   return plugins;

packages/plugin-vite/src/mod.ts

@@ -11,6 +11,7 @@ import * as babel from "@babel/core";
 import { httpAbsolute } from "./patches/http_absolute.ts";
 import { JS_REG, JSX_REG } from "../utils.ts";
 import { builtinModules } from "node:module";
+import { resolveDeno } from "@deno/vite-plugin/resolver";
 
 // @ts-ignore Workaround for https://github.com/denoland/deno/issues/30850
 const { default: babelReact } = await import("@babel/preset-react");
@@ -110,14 +111,38 @@ export function deno(): Plugin {
       }
 
       try {
+        // For npm: specifiers, use resolveDeno which correctly handles
+        // subpath exports (e.g. npm:preact@^10/jsx-runtime -> preact/jsx-runtime)
+        if (id.startsWith("npm:")) {
+          const npmResolved = await resolveDeno(id, loader);
+          if (npmResolved !== null) {
+            if (npmResolved.kind === "npm") {
+              // Re-resolve through Vite so package.json exports are used
+              const result = await this.resolve(npmResolved.id);
+              return result ?? npmResolved.id;
+            }
+          }
+        }
+
         // Ensure we're passing a valid importer that Deno understands
         const denoImporter = importer && !importer.startsWith("\0")
           ? importer
           : undefined;
 
+        // For bare specifiers from non-deno importers, try resolving
+        // with the importer's file URL so workspace import maps work
+        let denoImporterUrl = denoImporter;
+        if (
+          denoImporter && !denoImporter.startsWith("file://") &&
+          !denoImporter.startsWith("http") &&
+          path.isAbsolute(denoImporter)
+        ) {
+          denoImporterUrl = path.toFileUrl(denoImporter).href;
+        }
+
         let resolved = await loader.resolve(
           id,
-          denoImporter,
+          denoImporterUrl,
           ResolutionMode.Import,
         );
 
@@ -374,7 +399,7 @@ function babelTransform(
 
   const presets: babel.PluginItem[] = [];
   if (
-    !ssr && id.endsWith(".tsx") || id.endsWith(".jsx")
+    !ssr && (id.endsWith(".tsx") || id.endsWith(".jsx"))
   ) {
     presets.push([babelReact, {
       runtime: "automatic",