Update v86 to latest, replace string-match patches with stable shim

The previous build patched libv86.js by exact-string match against
Closure-mangled identifiers (k.load_file, H.exportSymbol, pa, qa),
which broke on every upstream rebuild.

Of the three old patches:
- exportSymbol order: now a one-line HTML shim copying module.exports.V86
  to window after libv86 loads
- this.fetch binding: fixed upstream
- load_file XHR vs fs: replaced by patching await import('node:fs/promises')
  to require('fs').promises - string literals survive Closure, fails loud
  if absent

Also adds tools/update-v86.js to pull new builds from copy.sh, and exposes
the renderer DevTools protocol on localhost:9222 in dev.

src/main/main.ts

@@ -61,6 +61,12 @@ export function main() {
     return;
   }
 
+  if (isDevMode()) {
+    // Renderer DevTools Protocol — connect Chrome to chrome://inspect
+    // or attach a debugger to localhost:9222
+    app.commandLine.appendSwitch("remote-debugging-port", "9222");
+  }
+
   // Set the app's name
   app.setName("windows95");
 

src/main/windows.ts

@@ -18,7 +18,6 @@ export function getOrCreateWindow(): BrowserWindow {
     },
   });
 
-  // mainWindow.webContents.toggleDevTools();
   mainWindow.loadFile("./dist/static/index.html");
 
   mainWindow.webContents.on("will-navigate", (event, url) =>

tools/parcel-build.js

@@ -4,27 +4,35 @@ const Bundler = require('parcel-bundler')
 const path = require('path')
 const fs = require('fs')
 
+// libv86 checks `typeof module.exports` before `typeof window` when deciding
+// where to export V86. In an Electron renderer with nodeIntegration both exist,
+// so it ends up on module.exports instead of window. This shim copies it over.
+const LIBV86_SHIM = `<script src="libv86.js"></script>
+<script>if (typeof module !== "undefined" && module.exports && module.exports.V86) window.V86 = module.exports.V86;</script>`
+
+// v86's node-path file loader uses `await import("node:fs/promises")`, but
+// dynamic import of node: URLs doesn't work in an Electron renderer — only
+// require() does. The string literal is stable across Closure builds.
+const V86_FS_IMPORT = 'await import("node:fs/promises")'
+const V86_FS_REQUIRE = 'require("fs").promises'
+
 async function copyLib() {
   const target = path.join(__dirname, '../dist/static')
   const lib = path.join(__dirname, '../src/renderer/lib')
   const index = path.join(target, 'index.html')
 
-  // Copy in lib
   await fs.promises.cp(lib, target, { recursive: true });
 
-  // Patch so that fs.read is used
   const libv86path = path.join(target, 'libv86.js')
   const libv86 = fs.readFileSync(libv86path, 'utf-8')
+  const patched = libv86.split(V86_FS_IMPORT).join(V86_FS_REQUIRE)
+  if (patched === libv86) {
+    throw new Error(`libv86.js patch failed: \`${V86_FS_IMPORT}\` not found. Check src/lib.js in copy/v86.`)
+  }
+  fs.writeFileSync(libv86path, patched)
 
-  let patchedLibv86 = libv86.replace('k.load_file="undefined"===typeof XMLHttpRequest?pa:qa', 'k.load_file=pa')
-  patchedLibv86 = patchedLibv86.replace('H.exportSymbol=function(a,b){"undefined"!==typeof module&&"undefined"!==typeof module.exports?module.exports[a]=b:"undefined"!==typeof window?window[a]=b:"function"===typeof importScripts&&(self[a]=b)}', 'H.exportSymbol=function(a,b){"undefined"!==typeof window?window[a]=b:"undefined"!==typeof module&&"undefined"!==typeof module.exports?module.exports[a]=b:"function"===typeof importScripts&&(self[a]=b)}')
-  patchedLibv86 = patchedLibv86.replace('this.fetch=fetch;', 'this.fetch=(...args)=>fetch(...args);')
-
-  fs.writeFileSync(libv86path, patchedLibv86)
-
-  // Overwrite
   const indexContents = fs.readFileSync(index, 'utf-8');
-  const replacedContents = indexContents.replace('<!-- libv86 -->', '<script src="libv86.js"></script>')
+  const replacedContents = indexContents.replace('<!-- libv86 -->', LIBV86_SHIM)
   fs.writeFileSync(index, replacedContents)
 }
 

tools/update-v86.js

@@ -0,0 +1,35 @@
+#!/usr/bin/env node
+const fs = require('fs');
+const path = require('path');
+const https = require('https');
+
+const LIB_DIR = path.join(__dirname, '../src/renderer/lib');
+const FILES = [
+  { url: 'https://copy.sh/v86/build/libv86.js', dest: path.join(LIB_DIR, 'libv86.js') },
+  { url: 'https://copy.sh/v86/build/v86.wasm', dest: path.join(LIB_DIR, 'build/v86.wasm') },
+];
+
+function download(url, dest) {
+  return new Promise((resolve, reject) => {
+    https.get(url, (res) => {
+      if (res.statusCode !== 200) {
+        return reject(new Error(`${url} → HTTP ${res.statusCode}`));
+      }
+      const chunks = [];
+      res.on('data', (c) => chunks.push(c));
+      res.on('end', () => {
+        const buf = Buffer.concat(chunks);
+        fs.writeFileSync(dest, buf);
+        console.log(`✓ ${path.relative(process.cwd(), dest)} (${(buf.length / 1024).toFixed(0)} KB)`);
+        resolve();
+      });
+      res.on('error', reject);
+    }).on('error', reject);
+  });
+}
+
+(async () => {
+  for (const { url, dest } of FILES) {
+    await download(url, dest);
+  }
+})();