build(desktop): enable macOS signing & notarization for release

desktop/build/entitlements.mac.plist

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+    <!-- Electron needs JIT and writable/executable memory for V8. -->
+    <key>com.apple.security.cs.allow-jit</key>
+    <true/>
+    <key>com.apple.security.cs.allow-unsigned-executable-memory</key>
+    <true/>
+    <!-- PyInstaller backend loads many unsigned/third-party dylibs. -->
+    <key>com.apple.security.cs.disable-library-validation</key>
+    <true/>
+    <key>com.apple.security.cs.allow-dyld-environment-variables</key>
+    <true/>
+    <!-- Allow spawning the bundled backend and other child processes. -->
+    <key>com.apple.security.inherit</key>
+    <true/>
+</dict>
+</plist>

desktop/build/sign-backend.js

@@ -0,0 +1,92 @@
+/**
+ * electron-builder afterPack hook.
+ *
+ * The Python backend is a PyInstaller onedir bundle shipped via extraResources
+ * into Contents/Resources/backend/. electron-builder's deep signing does NOT
+ * cover extraResources, so its executable + hundreds of .so/.dylib files stay
+ * unsigned — which makes notarization reject the whole app.
+ *
+ * This hook runs before electron-builder signs the .app: it code-signs every
+ * Mach-O file under the backend dir with hardened runtime + entitlements, so
+ * the outer app signature and notarization succeed.
+ */
+const { execFileSync, execSync } = require('child_process')
+const fs = require('fs')
+const path = require('path')
+
+exports.default = async function signBackend(context) {
+  const { electronPlatformName, appOutDir, packager } = context
+  if (electronPlatformName !== 'darwin') return
+
+  // Signing identity comes from CSC_NAME (set in CI and, for local builds,
+  // your shell). No identity => unsigned build (e.g. dry runs), so skip the
+  // backend signing rather than fail.
+  const identity = process.env.CSC_NAME
+  if (!identity) {
+    console.log('[sign-backend] CSC_NAME not set — unsigned build, skipping backend signing')
+    return
+  }
+
+  const appName = packager.appInfo.productFilename
+  const backendDir = path.join(
+    appOutDir,
+    `${appName}.app`,
+    'Contents',
+    'Resources',
+    'backend'
+  )
+
+  if (!fs.existsSync(backendDir)) {
+    console.log(`[sign-backend] no backend dir at ${backendDir}, skipping`)
+    return
+  }
+
+  const entitlements = path.join(__dirname, 'entitlements.mac.plist')
+
+  // Collect every Mach-O file (executables + dylibs/so) under backend/.
+  // `file` output contains "Mach-O" for native binaries.
+  const files = []
+  const walk = (dir) => {
+    for (const name of fs.readdirSync(dir)) {
+      const full = path.join(dir, name)
+      const stat = fs.lstatSync(full)
+      if (stat.isSymbolicLink()) continue
+      if (stat.isDirectory()) {
+        walk(full)
+        continue
+      }
+      try {
+        const out = execSync(`file -b "${full}"`, { encoding: 'utf8' })
+        if (out.includes('Mach-O')) files.push(full)
+      } catch {
+        // ignore unreadable entries
+      }
+    }
+  }
+  walk(backendDir)
+
+  console.log(`[sign-backend] signing ${files.length} Mach-O files under backend/`)
+
+  // Sign inner libraries first, then the main executable last (inside-out).
+  files.sort((a, b) => b.length - a.length)
+
+  for (const f of files) {
+    execFileSync(
+      'codesign',
+      [
+        '--force',
+        '--timestamp',
+        '--options',
+        'runtime',
+        '--entitlements',
+        entitlements,
+        '--sign',
+        identity,
+        f,
+      ],
+      { stdio: 'inherit' }
+    )
+  }
+
+  console.log('[sign-backend] backend signing complete')
+}