fix(electron): properly dereference symlinks by copying actual content (#610)

cpSync with dereference:true does NOT convert symlinks to files.
This implements a custom copyDereferenced function that:
- Detects symlinks using lstatSync
- Follows them using statSync
- Copies actual file/directory content instead of symlink

Fixes macOS arm64 codesign failure with electron-builder 26.4.0
which now does ad-hoc signing and runs codesign --verify.

scripts/prepare-electron-build.mjs

@@ -6,13 +6,54 @@
  * that electron-builder can properly include
  */
 
-import { cpSync, existsSync, mkdirSync, rmSync } from "node:fs"
+import {
+    copyFileSync,
+    existsSync,
+    lstatSync,
+    mkdirSync,
+    readdirSync,
+    rmSync,
+    statSync,
+} from "node:fs"
 import { join } from "node:path"
 import { fileURLToPath } from "node:url"
 
 const __dirname = fileURLToPath(new URL(".", import.meta.url))
 const rootDir = join(__dirname, "..")
 
+/**
+ * Copy directory recursively, converting symlinks to regular files/directories.
+ * This is needed because cpSync with dereference:true does NOT convert symlinks.
+ * macOS codesign fails if bundle contains symlinks pointing outside the bundle.
+ */
+function copyDereferenced(src, dst) {
+    const lstat = lstatSync(src)
+
+    if (lstat.isSymbolicLink()) {
+        // Follow symlink and check what it points to
+        const stat = statSync(src)
+        if (stat.isDirectory()) {
+            // Symlink to directory: recursively copy the directory contents
+            mkdirSync(dst, { recursive: true })
+            for (const entry of readdirSync(src)) {
+                copyDereferenced(join(src, entry), join(dst, entry))
+            }
+        } else {
+            // Symlink to file: copy the actual file content
+            mkdirSync(join(dst, ".."), { recursive: true })
+            copyFileSync(src, dst)
+        }
+    } else if (lstat.isDirectory()) {
+        mkdirSync(dst, { recursive: true })
+        for (const entry of readdirSync(src)) {
+            copyDereferenced(join(src, entry), join(dst, entry))
+        }
+    } else {
+        mkdirSync(join(dst, ".."), { recursive: true })
+        copyFileSync(src, dst)
+    }
+}
+
 const standaloneDir = join(rootDir, ".next", "standalone")
 const staticDir = join(rootDir, ".next", "static")
 const targetDir = join(rootDir, "electron-standalone")
@@ -30,20 +71,19 @@ mkdirSync(targetDir, { recursive: true })
 
 // Copy standalone (includes node_modules)
 console.log("Copying standalone directory...")
-cpSync(standaloneDir, targetDir, { recursive: true, dereference: true })
+copyDereferenced(standaloneDir, targetDir)
 
 // Copy static files
 console.log("Copying static files...")
 const targetStaticDir = join(targetDir, ".next", "static")
-mkdirSync(targetStaticDir, { recursive: true })
-cpSync(staticDir, targetStaticDir, { recursive: true, dereference: true })
+copyDereferenced(staticDir, targetStaticDir)
 
 // Copy public folder (required for favicon-white.svg and other assets)
 console.log("Copying public folder...")
 const publicDir = join(rootDir, "public")
 const targetPublicDir = join(targetDir, "public")
 if (existsSync(publicDir)) {
-    cpSync(publicDir, targetPublicDir, { recursive: true, dereference: true })
+    copyDereferenced(publicDir, targetPublicDir)
 }
 
 console.log("Done! Files prepared in electron-standalone/")