Create a small Mac app around one local tool.

AppifyHost reads Contents/Info.plist, requires an AppifyHost dictionary, and requires at least one document filename extension from CFBundleDocumentTypes or matching UTType declarations. Keep the document type focused: one app should own one clear class of local document.

<?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>
  <key>AppifyHost</key>
  <dict>
    <key>DocumentKindEnvironmentValue</key>
    <string>com.example.mytool.project</string>
    <key>DocumentMode</key>
    <string>contentPackage</string>
    <key>LogName</key>
    <string>MyTool</string>
    <key>ServerExecutable</key>
    <string>main.sh</string>
    <key>ServerInstallDirectory</key>
    <string>Contents/Resources/AppServer</string>
    <key>ServerArguments</key>
    <array>
      <string>--document={documentPath}</string>
    </array>
    <key>EnvironmentVariables</key>
    <dict>
      <key>MYTOOL_WORKSPACE</key>
      <string>{workingDirectory}</string>
    </dict>
    <key>StartupTimeoutSeconds</key>
    <integer>20</integer>
    <key>WebViewDataStore</key>
    <string>persistent</string>
    <key>WindowContentSizing</key>
    <string>automatic</string>
    <key>WindowTitlePrefix</key>
    <string>MyTool</string>
  </dict>

  <key>CFBundleDisplayName</key>
  <string>MyTool</string>
  <key>CFBundleExecutable</key>
  <string>main.sh</string>
  <key>CFBundleIdentifier</key>
  <string>com.example.mytool</string>
  <key>CFBundleName</key>
  <string>MyTool</string>
  <key>CFBundlePackageType</key>
  <string>APPL</string>
  <key>LSMinimumSystemVersion</key>
  <string>14.0</string>
  <key>NSHighResolutionCapable</key>
  <true/>

  <key>CFBundleDocumentTypes</key>
  <array>
    <dict>
      <key>CFBundleTypeExtensions</key>
      <array>
        <string>mytool</string>
      </array>
      <key>CFBundleTypeName</key>
      <string>MyTool Project</string>
      <key>CFBundleTypeRole</key>
      <string>Editor</string>
      <key>LSHandlerRank</key>
      <string>Owner</string>
      <key>LSItemContentTypes</key>
      <array>
        <string>com.example.mytool.project</string>
      </array>
      <key>LSTypeIsPackage</key>
      <true/>
      <key>NSDocumentClass</key>
      <string>AppifyHostDocument</string>
    </dict>
  </array>

  <key>UTExportedTypeDeclarations</key>
  <array>
    <dict>
      <key>UTTypeIdentifier</key>
      <string>com.example.mytool.project</string>
      <key>UTTypeDescription</key>
      <string>MyTool Project</string>
      <key>UTTypeConformsTo</key>
      <array>
        <string>com.apple.package</string>
        <string>public.directory</string>
      </array>
      <key>UTTypeTagSpecification</key>
      <dict>
        <key>public.filename-extension</key>
        <array>
          <string>mytool</string>
        </array>
      </dict>
    </dict>
  </array>
</dict>
</plist>

Use this shape for checked-in root apps while iterating inside this repo. It keeps the built AppifyHost artifact out of every app bundle and makes a stale host binary obvious.

#!/usr/bin/env bash
set -euo pipefail

APP="$(cd "$(dirname "$0")/../.." && pwd)"
cursor="$APP"
while [[ "$cursor" != "/" ]]; do
  launcher="$cursor/Scripts/appify-host-launcher.sh"
  if [[ -x "$launcher" ]]; then
    exec "$launcher" "$APP" "$@"
  fi
  cursor="$(dirname "$cursor")"
done

printf 'Cannot find Appify UI repo launcher for %s. Use Scripts/eject-app.sh for a standalone app.\n' "$APP" >&2
exit 1

AppifyHost starts the configured executable with Contents/Resources/AppServer as the current directory. The server may open a loopback HTTP(S) URL or a local file URL under the document or app bundle. It must print exactly one ready line before the startup timeout.

#!/usr/bin/env bash
set -euo pipefail

DOCUMENT_PATH="$APPIFY_HOST_DOCUMENT_PATH"
SERVER_DIR="$APPIFY_HOST_SERVER_DIR"

if [[ -z "$DOCUMENT_PATH" || -z "$SERVER_DIR" ]]; then
  printf 'AppifyHost document and server paths are required.\n' >&2
  exit 1
fi

cd "$SERVER_DIR"
./server --document "$DOCUMENT_PATH" &
server_pid="$!"

# Print the real URL only after the app is ready to load.
printf 'APPIFY_HOST_OPEN_URL=http://127.0.0.1:8787/\n'

wait "$server_pid"

AppifyHost can ask the loaded page whether it is dirty, call a save hook before native save completes, and measure preferred content size. Most static pages need none of this. Editors should implement the hooks explicitly.

<script>
  let dirty = false;

  window.AppifyHost = window.AppifyHost || {};
  window.AppifyHost.isDirty = () => dirty;
  window.AppifyHost.save = async () => {
    await persistDocumentState();
    dirty = false;
    return true;
  };

  window.AppifyHost.preferredContentSize = () => ({
    width: document.documentElement.scrollWidth,
    height: document.documentElement.scrollHeight,
  });
</script>