From 9e4a3687d188391c9fbb19fdafde14f68ac4ced2 Mon Sep 17 00:00:00 2001
From: Hajime-san <41257923+Hajime-san@users.noreply.github.com>
Date: Sun, 31 May 2026 00:41:02 +0900
Subject: [PATCH 1/7] merge config

---
 packages/plugin-vite/tests/build_test.ts | 10 +++++++---
 packages/plugin-vite/tests/test_utils.ts | 22 +++++++---------------
 2 files changed, 14 insertions(+), 18 deletions(-)

diff --git a/packages/plugin-vite/tests/build_test.ts b/packages/plugin-vite/tests/build_test.ts
index e4d8354e059..62ce2933e81 100644
--- a/packages/plugin-vite/tests/build_test.ts
+++ b/packages/plugin-vite/tests/build_test.ts
@@ -592,9 +592,13 @@ integrationTest(
   "vite build - custom rollup entryFileNames in server.js",
   async () => {
     await using res = await buildVite(DEMO_DIR, {
-      rollupOutput: {
-        entryFileNames: "[hash].mjs",
-        chunkFileNames: "[hash].mjs",
+      build: {
+        rollupOptions: {
+          output: {
+            entryFileNames: "[hash].mjs",
+            chunkFileNames: "[hash].mjs",
+          },
+        },
       },
     });
 
diff --git a/packages/plugin-vite/tests/test_utils.ts b/packages/plugin-vite/tests/test_utils.ts
index 2d7a4d5c6b6..27a8385c002 100644
--- a/packages/plugin-vite/tests/test_utils.ts
+++ b/packages/plugin-vite/tests/test_utils.ts
@@ -1,4 +1,4 @@
-import { createBuilder } from "vite";
+import { createBuilder, mergeConfig } from "vite";
 import * as path from "@std/path";
 import { walk } from "@std/fs/walk";
 import { integrationTest, withTmpDir } from "../../fresh/src/test_utils.ts";
@@ -135,24 +135,16 @@ export async function withDevServer(
 
 export async function buildVite(
   fixtureDir: string,
-  options?: {
-    base?: string;
-    rollupOutput?: {
-      entryFileNames?: string;
-      chunkFileNames?: string;
-      assetFileNames?: string;
-    };
-  },
+  config?: Parameters<typeof createBuilder>[0],
 ) {
   const tmp = await withTmpDir({
     dir: path.join(import.meta.dirname!, ".."),
     prefix: "tmp_vite_",
   });
 
-  const builder = await createBuilder({
+  const defaults = {
     logLevel: "error",
     root: fixtureDir,
-    base: options?.base,
     build: {
       emptyOutDir: true,
     },
@@ -160,9 +152,6 @@ export async function buildVite(
       ssr: {
         build: {
           outDir: path.join(tmp.dir, "_fresh", "server"),
-          rollupOptions: options?.rollupOutput
-            ? { output: options.rollupOutput }
-            : undefined,
         },
       },
       client: {
@@ -171,7 +160,10 @@ export async function buildVite(
         },
       },
     },
-  });
+  } satisfies Parameters<typeof createBuilder>[0];
+  const builder = await createBuilder(
+    mergeConfig(defaults, config ?? {}),
+  );
   await builder.buildApp();
 
   return {

From 52e5fc4346bd41fe3d4f0f6c03ea03928413ab15 Mon Sep 17 00:00:00 2001
From: Hajime-san <41257923+Hajime-san@users.noreply.github.com>
Date: Sun, 31 May 2026 01:17:16 +0900
Subject: [PATCH 2/7] adding test

---
 packages/plugin-vite/tests/build_test.ts | 74 ++++++++++++++++++++++++
 1 file changed, 74 insertions(+)

diff --git a/packages/plugin-vite/tests/build_test.ts b/packages/plugin-vite/tests/build_test.ts
index 62ce2933e81..2a24548f934 100644
--- a/packages/plugin-vite/tests/build_test.ts
+++ b/packages/plugin-vite/tests/build_test.ts
@@ -1,3 +1,4 @@
+import { createLogger } from "vite";
 import { expect } from "@std/expect";
 import { walk } from "@std/fs/walk";
 import {
@@ -832,3 +833,76 @@ integrationTest(
     );
   },
 );
+
+integrationTest(
+  "vite build - ssr sourcemap sould be generated collectly",
+  async () => {
+    await using tmp = await buildVite(DEMO_DIR, {
+      environments: {
+        ssr: {
+          build: {
+            sourcemap: true,
+          },
+        },
+      },
+    });
+
+    const serverAssetsDir = path.join(tmp.tmp, "_fresh", "server", "assets");
+
+    for await (
+      const entry of walk(serverAssetsDir, {
+        exts: [".mjs"],
+        includeDirs: false,
+      })
+    ) {
+      const js = await Deno.readTextFile(entry.path);
+      const match = js.match(/\/\/# sourceMappingURL=(.+)$/m);
+      expect(match).not.toBeNull();
+
+      const mapPath = path.join(path.dirname(entry.path), match![1]);
+      const mapText = await Deno.readTextFile(mapPath);
+      const map = JSON.parse(mapText);
+
+      expect(Array.isArray(map.sources)).toBe(true);
+      expect(map.sources.length).toBeGreaterThan(0);
+      expect(typeof map.mappings).toBe("string");
+      expect(map.mappings.length).toBeGreaterThan(0);
+    }
+  },
+);
+
+// rollup specific test
+// https://rollupjs.org/troubleshooting/#warning-sourcemap-is-likely-to-be-incorrect
+integrationTest(
+  "vite build - ssr sourcemap sould be generated without warings",
+  async () => {
+    const warnMsgs = new Set<string>();
+    const customLogger = createLogger("error");
+    customLogger.warn = (msg) => {
+      customLogger.hasWarned = true;
+      warnMsgs.add(msg);
+    };
+    customLogger.warnOnce = (msg) => {
+      customLogger.hasWarned = true;
+      warnMsgs.add(msg);
+    };
+
+    await using _ = await buildVite(DEMO_DIR, {
+      logLevel: "warn",
+      clearScreen: true,
+      customLogger,
+      environments: {
+        ssr: {
+          build: {
+            sourcemap: true,
+          },
+        },
+      },
+    });
+
+    const sourceMapIncorrectMsg = warnMsgs.has(
+      "[plugin deno] Sourcemap is likely to be incorrect: a plugin (deno) was used to transform files, but didn't generate a sourcemap for the transformation. Consult the plugin documentation for help",
+    );
+    expect(sourceMapIncorrectMsg).not.toBeTruthy();
+  },
+);

From 4b1c8b8b38f9b5dcffbe94b36b44d1cf46957bc9 Mon Sep 17 00:00:00 2001
From: Hajime-san <41257923+Hajime-san@users.noreply.github.com>
Date: Sun, 31 May 2026 06:32:05 +0900
Subject: [PATCH 3/7] fix

---
 deno.lock                                |  8 ++++----
 packages/plugin-vite/deno.json           |  2 +-
 packages/plugin-vite/src/plugins/deno.ts | 24 ++++++++++++++++++++----
 packages/plugin-vite/tests/build_test.ts | 23 ++++++++++++++---------
 4 files changed, 39 insertions(+), 18 deletions(-)

diff --git a/deno.lock b/deno.lock
index 3d5970098a8..0867329d019 100644
--- a/deno.lock
+++ b/deno.lock
@@ -9,7 +9,7 @@
     "jsr:@deno/esbuild-plugin@^1.2.0": "1.2.1",
     "jsr:@deno/graph@0.86": "0.86.9",
     "jsr:@deno/graph@~0.82.3": "0.82.3",
-    "jsr:@deno/loader@0.4": "0.4.0",
+    "jsr:@deno/loader@0.5": "0.5.0",
     "jsr:@deno/loader@~0.3.10": "0.3.14",
     "jsr:@marvinh-test/fresh-island@^0.0.3": "0.0.3",
     "jsr:@marvinh-test/import-json@^0.0.1": "0.0.1",
@@ -191,8 +191,8 @@
     "@deno/loader@0.3.14": {
       "integrity": "97bc63a6cc2d27a60bcdc953f588c5213331d866d44212eebb24cebfb9b011ca"
     },
-    "@deno/loader@0.4.0": {
-      "integrity": "6c1b18cfa18592740613ce79e15625c24268d60dbfc54bebfb5153bf512c536b"
+    "@deno/loader@0.5.0": {
+      "integrity": "a6d94408de5e6bacac404f8f6963c8b8cc278cfd1a878aa2f06b34a083d6bfee"
     },
     "@marvinh-test/fresh-island@0.0.3": {
       "integrity": "6d06b6009b7dfba9bba28e941e03e6ff652c4ef4f2fbfdf4b78741abd6c6c1c6",
@@ -6078,7 +6078,7 @@
       },
       "packages/plugin-vite": {
         "dependencies": [
-          "jsr:@deno/loader@0.4",
+          "jsr:@deno/loader@0.5",
           "jsr:@fresh/core@2",
           "jsr:@marvinh-test/import-json@^0.0.1",
           "npm:@babel/core@^7.28.0",
diff --git a/packages/plugin-vite/deno.json b/packages/plugin-vite/deno.json
index 57af17393e6..b7f5c93940a 100644
--- a/packages/plugin-vite/deno.json
+++ b/packages/plugin-vite/deno.json
@@ -23,7 +23,7 @@
   "imports": {
     "@babel/core": "npm:@babel/core@^7.28.0",
     "@babel/preset-react": "npm:@babel/preset-react@^7.27.1",
-    "@deno/loader": "jsr:@deno/loader@^0.4.0",
+    "@deno/loader": "jsr:@deno/loader@^0.5.0",
     "@marvinh-test/import-json": "jsr:@marvinh-test/import-json@^0.0.1",
     "@remix-run/node-fetch-server": "npm:@remix-run/node-fetch-server@^0.12.0",
     "@prefresh/vite": "npm:@prefresh/vite@^2.4.8",
diff --git a/packages/plugin-vite/src/plugins/deno.ts b/packages/plugin-vite/src/plugins/deno.ts
index 6cefed7e463..d46fadc8e53 100644
--- a/packages/plugin-vite/src/plugins/deno.ts
+++ b/packages/plugin-vite/src/plugins/deno.ts
@@ -2,6 +2,7 @@ import type { Plugin } from "vite";
 import {
   type Loader,
   MediaType,
+  type ModuleLoadResponse,
   RequestedModuleType,
   ResolutionMode,
   Workspace,
@@ -17,6 +18,8 @@ const { default: babelReact } = await import("@babel/preset-react");
 
 const BUILTINS = new Set(builtinModules);
 
+const decoder = new TextDecoder();
+
 interface DenoState {
   type: RequestedModuleType;
 }
@@ -180,7 +183,7 @@ export function deno(): Plugin {
           return null;
         }
 
-        const code = new TextDecoder().decode(result.code);
+        const code = decoder.decode(result.code);
 
         const maybeJsx = babelTransform({
           ssr: this.environment.config.consumer === "server",
@@ -188,6 +191,7 @@ export function deno(): Plugin {
           code,
           id: specifier,
           isDev,
+          inputSourceMap: parseSourceMap(result.sourceMap),
         });
         if (maybeJsx !== null) {
           return maybeJsx;
@@ -224,7 +228,7 @@ export function deno(): Plugin {
         return null;
       }
 
-      const code = new TextDecoder().decode(result.code);
+      const code = decoder.decode(result.code);
 
       const maybeJsx = babelTransform({
         ssr: this.environment.config.consumer === "server",
@@ -232,6 +236,7 @@ export function deno(): Plugin {
         id,
         code,
         isDev,
+        inputSourceMap: parseSourceMap(result.sourceMap),
       });
       if (maybeJsx) {
         return maybeJsx;
@@ -279,10 +284,12 @@ export function deno(): Plugin {
           return;
         }
 
-        const code = new TextDecoder().decode(result.code);
+        const code = decoder.decode(result.code);
+        const map = parseSourceMap(result.sourceMap);
 
         return {
           code,
+          map,
         };
       },
     },
@@ -375,13 +382,14 @@ function babelTransform(
     code: string;
     id: string;
     isDev: boolean;
+    inputSourceMap: babel.TransformOptions["inputSourceMap"];
   },
 ) {
   if (!isJsMediaType(options.media)) {
     return null;
   }
 
-  const { ssr, code, id, isDev } = options;
+  const { ssr, code, id, isDev, inputSourceMap } = options;
 
   const presets: babel.PluginItem[] = [];
   if (
@@ -400,6 +408,7 @@ function babelTransform(
   const result = babel.transformSync(code, {
     filename: id,
     babelrc: false,
+    inputSourceMap,
     sourceMaps: "both",
     presets: presets,
     plugins: [httpAbsolute(url)],
@@ -415,3 +424,10 @@ function babelTransform(
 
   return null;
 }
+
+function parseSourceMap(
+  sourceMap: ModuleLoadResponse["sourceMap"],
+): babel.TransformOptions["inputSourceMap"] {
+  if (!sourceMap) return undefined;
+  return JSON.parse(decoder.decode(sourceMap));
+}
diff --git a/packages/plugin-vite/tests/build_test.ts b/packages/plugin-vite/tests/build_test.ts
index 2a24548f934..ae3d972edbc 100644
--- a/packages/plugin-vite/tests/build_test.ts
+++ b/packages/plugin-vite/tests/build_test.ts
@@ -1,4 +1,5 @@
 import { createLogger } from "vite";
+import type { BabelFileResult } from "@babel/core";
 import { expect } from "@std/expect";
 import { walk } from "@std/fs/walk";
 import {
@@ -14,6 +15,7 @@ import {
   launchProd,
   usingEnv,
 } from "./test_utils.ts";
+import { toPosix } from "fresh/internal-dev";
 import * as path from "@std/path";
 import { FRESH_CSS_PLACEHOLDER } from "../src/plugins/server_snapshot.ts";
 
@@ -848,7 +850,6 @@ integrationTest(
     });
 
     const serverAssetsDir = path.join(tmp.tmp, "_fresh", "server", "assets");
-
     for await (
       const entry of walk(serverAssetsDir, {
         exts: [".mjs"],
@@ -857,22 +858,26 @@ integrationTest(
     ) {
       const js = await Deno.readTextFile(entry.path);
       const match = js.match(/\/\/# sourceMappingURL=(.+)$/m);
-      expect(match).not.toBeNull();
-
       const mapPath = path.join(path.dirname(entry.path), match![1]);
       const mapText = await Deno.readTextFile(mapPath);
-      const map = JSON.parse(mapText);
-
-      expect(Array.isArray(map.sources)).toBe(true);
-      expect(map.sources.length).toBeGreaterThan(0);
-      expect(typeof map.mappings).toBe("string");
-      expect(map.mappings.length).toBeGreaterThan(0);
+      const map: NonNullable<BabelFileResult["map"]> = JSON.parse(mapText);
+
+      // check a specific sourcemap file which contains
+      // the reference of original source file
+      if (entry.name.includes("_fresh-route___tests_feed-")) {
+        expect(
+          map.sources.some((source) =>
+            toPosix(source).endsWith("demo/routes/tests/feed.tsx")
+          ),
+        ).toBe(true);
+      }
     }
   },
 );
 
 // rollup specific test
 // https://rollupjs.org/troubleshooting/#warning-sourcemap-is-likely-to-be-incorrect
+// this test could be broke if it will migrate to rolldown
 integrationTest(
   "vite build - ssr sourcemap sould be generated without warings",
   async () => {

From 23ea2fefd8860610f973f940184fd3132374cc49 Mon Sep 17 00:00:00 2001
From: Hajime-san <41257923+Hajime-san@users.noreply.github.com>
Date: Sun, 31 May 2026 06:41:31 +0900
Subject: [PATCH 4/7] typo

---
 packages/plugin-vite/tests/build_test.ts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/plugin-vite/tests/build_test.ts b/packages/plugin-vite/tests/build_test.ts
index ae3d972edbc..855c786e526 100644
--- a/packages/plugin-vite/tests/build_test.ts
+++ b/packages/plugin-vite/tests/build_test.ts
@@ -837,7 +837,7 @@ integrationTest(
 );
 
 integrationTest(
-  "vite build - ssr sourcemap sould be generated collectly",
+  "vite build - ssr sourcemap should be generated collectly",
   async () => {
     await using tmp = await buildVite(DEMO_DIR, {
       environments: {
@@ -879,7 +879,7 @@ integrationTest(
 // https://rollupjs.org/troubleshooting/#warning-sourcemap-is-likely-to-be-incorrect
 // this test could be broke if it will migrate to rolldown
 integrationTest(
-  "vite build - ssr sourcemap sould be generated without warings",
+  "vite build - ssr sourcemap should be generated without warings",
   async () => {
     const warnMsgs = new Set<string>();
     const customLogger = createLogger("error");

From c1636771ddc7817c99983019eded744dc6c20f31 Mon Sep 17 00:00:00 2001
From: Hajime-san <41257923+Hajime-san@users.noreply.github.com>
Date: Sun, 31 May 2026 13:59:34 +0900
Subject: [PATCH 5/7] fix

---
 packages/fresh/src/dev/dev_build_cache.ts        | 13 ++++++++++++-
 packages/plugin-vite/src/plugins/server_entry.ts |  1 +
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/packages/fresh/src/dev/dev_build_cache.ts b/packages/fresh/src/dev/dev_build_cache.ts
index 3678d0ffba4..69e9c3e2e47 100644
--- a/packages/fresh/src/dev/dev_build_cache.ts
+++ b/packages/fresh/src/dev/dev_build_cache.ts
@@ -622,8 +622,19 @@ import { app } from "${serverEntry}";
 const root = ${rootPath};
 setBuildCache(app, new ProdBuildCache(root, snapshot), "production");
 
+// In dev, plugins may mutate app-level hooks such as the error interceptor
+// after this module loads. Keep the fetch target refreshable so the server
+// entry can pick up the latest app.handler() when that happens.
+let handler = app.handler();
+
+export function refreshHandler() {
+  handler = app.handler();
+}
+
 export default {
-  fetch: app.handler()
+  fetch(req, info) {
+    return handler(req, info);
+  }
 };
 `;
 }
diff --git a/packages/plugin-vite/src/plugins/server_entry.ts b/packages/plugin-vite/src/plugins/server_entry.ts
index d4b1dec8726..ce2a37a8dd6 100644
--- a/packages/plugin-vite/src/plugins/server_entry.ts
+++ b/packages/plugin-vite/src/plugins/server_entry.ts
@@ -97,6 +97,7 @@ ${code}
 
 export function setErrorInterceptor(fn) {
   internalErrorIntercept(app, fn);
+  refreshHandler();
 }
 if (import.meta.hot) import.meta.hot.accept();`;
         }

From 4f4526ef318f13dbe0bf19e801c4ec9fbfae9914 Mon Sep 17 00:00:00 2001
From: Hajime-san <41257923+Hajime-san@users.noreply.github.com>
Date: Sun, 31 May 2026 14:18:26 +0900
Subject: [PATCH 6/7] fix vite dev

---
 packages/plugin-vite/src/plugins/deno.ts | 37 +++++++++++++++++-------
 1 file changed, 26 insertions(+), 11 deletions(-)

diff --git a/packages/plugin-vite/src/plugins/deno.ts b/packages/plugin-vite/src/plugins/deno.ts
index d46fadc8e53..b873dd79e09 100644
--- a/packages/plugin-vite/src/plugins/deno.ts
+++ b/packages/plugin-vite/src/plugins/deno.ts
@@ -183,7 +183,7 @@ export function deno(): Plugin {
           return null;
         }
 
-        const code = decoder.decode(result.code);
+        const { code, map } = decodeLoadResult(result);
 
         const maybeJsx = babelTransform({
           ssr: this.environment.config.consumer === "server",
@@ -191,7 +191,7 @@ export function deno(): Plugin {
           code,
           id: specifier,
           isDev,
-          inputSourceMap: parseSourceMap(result.sourceMap),
+          inputSourceMap: map,
         });
         if (maybeJsx !== null) {
           return maybeJsx;
@@ -199,6 +199,7 @@ export function deno(): Plugin {
 
         return {
           code,
+          map,
         };
       }
 
@@ -228,7 +229,7 @@ export function deno(): Plugin {
         return null;
       }
 
-      const code = decoder.decode(result.code);
+      const { code, map } = decodeLoadResult(result);
 
       const maybeJsx = babelTransform({
         ssr: this.environment.config.consumer === "server",
@@ -236,7 +237,7 @@ export function deno(): Plugin {
         id,
         code,
         isDev,
-        inputSourceMap: parseSourceMap(result.sourceMap),
+        inputSourceMap: map,
       });
       if (maybeJsx) {
         return maybeJsx;
@@ -244,6 +245,7 @@ export function deno(): Plugin {
 
       return {
         code,
+        map,
       };
     },
     transform: {
@@ -284,8 +286,7 @@ export function deno(): Plugin {
           return;
         }
 
-        const code = decoder.decode(result.code);
-        const map = parseSourceMap(result.sourceMap);
+        const { code, map } = decodeLoadResult(result);
 
         return {
           code,
@@ -425,9 +426,23 @@ function babelTransform(
   return null;
 }
 
-function parseSourceMap(
-  sourceMap: ModuleLoadResponse["sourceMap"],
-): babel.TransformOptions["inputSourceMap"] {
-  if (!sourceMap) return undefined;
-  return JSON.parse(decoder.decode(sourceMap));
+function decodeLoadResult(
+  result: Extract<ModuleLoadResponse, { kind: "module" }>,
+): {
+  code: string;
+  map: babel.TransformOptions["inputSourceMap"];
+} {
+  const map = result.sourceMap && JSON.parse(decoder.decode(result.sourceMap));
+  // If we pass a separate sourcemap object to Vite, remove the loader's
+  // inline data URL so the module only has one sourcemap source of truth.
+  const code = !map
+    ? decoder.decode(result.code)
+    : decoder.decode(result.code).replace(
+      /\r?\n\/\/# sourceMappingURL=data:[^\r\n]+$/,
+      "",
+    );
+  return {
+    code,
+    map,
+  };
 }

From ad3fef9ae1fdd016ff0bc564d6b9f4883e8f79ca Mon Sep 17 00:00:00 2001
From: Hajime-san <41257923+Hajime-san@users.noreply.github.com>
Date: Sun, 31 May 2026 14:20:09 +0900
Subject: [PATCH 7/7] typo

---
 packages/plugin-vite/tests/build_test.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/plugin-vite/tests/build_test.ts b/packages/plugin-vite/tests/build_test.ts
index 855c786e526..2163d6e1196 100644
--- a/packages/plugin-vite/tests/build_test.ts
+++ b/packages/plugin-vite/tests/build_test.ts
@@ -879,7 +879,7 @@ integrationTest(
 // https://rollupjs.org/troubleshooting/#warning-sourcemap-is-likely-to-be-incorrect
 // this test could be broke if it will migrate to rolldown
 integrationTest(
-  "vite build - ssr sourcemap should be generated without warings",
+  "vite build - ssr sourcemap should be generated without warnings",
   async () => {
     const warnMsgs = new Set<string>();
     const customLogger = createLogger("error");