MacNewFileKit

MacNewFileKit is a native macOS Finder extension that adds a Windows-style New File menu. It creates text, Markdown, JSON, Word, Excel, PowerPoint, and user-defined text templates without overwriting existing files.

Current scope

• Finder background, selected folder, and Desktop context menus
• Collision-safe names such as untitled.txt and untitled 2.txt
• Text, Markdown, JSON, Word (.docx), Excel (.xlsx), PowerPoint (.pptx), and custom text templates
• Editable custom-template names, extensions, initial content, and ordering
• Shared settings through an App Group for distribution or a local shared preferences domain for ad hoc development
• Global Finder coverage on the startup disk and mounted volumes for local ad hoc builds
• User-authorized folders backed by security-scoped bookmarks for signed distribution builds
• Finder selection after creation

MacNewFileKit does not use Accessibility permission or keyboard simulation. The public Finder API can select a newly created file, but it does not expose an API for entering inline rename mode.

Architecture

MacNewFileKit.app
├── MacNewFileKitApp       settings and extension onboarding
├── MacNewFileKitFinder    Finder Sync extension
├── FileCreationCore       exclusive creation and filename allocation
└── MacNewFileKitShared    shared settings and Finder access policy

FileCreationCore uses open(2) with O_CREAT | O_EXCL. Name selection and creation therefore form one exclusive operation instead of a vulnerable "check, then write" sequence.

Requirements

• macOS 13 or later
• Full Xcode installation
• XcodeGen to generate MacNewFileKit.xcodeproj from project.yml
• No Apple Developer account is required for local ad hoc builds

The checked-in identifiers use io.github.ywu73.MacNewFileKit and group.io.github.ywu73.MacNewFileKit. Register the identifiers with an Apple Developer team before creating a distributable build.

Development

Run the platform-independent core tests with Command Line Tools:

scripts/verify-core.sh

After installing full Xcode and XcodeGen:

scripts/verify.sh

The verification script builds with Xcode-managed signing disabled, then signs the embedded Finder extension before the containing app with a local ad hoc identity (codesign --sign -). The local build uses a shared preferences domain instead of an App Group container, because an ad hoc signature has no Team ID with which macOS can authorize the App Group. An ad hoc app and its extension also cannot restore each other's app-scoped security bookmarks. The local Finder extension therefore receives a development-only absolute-path exception and monitors the startup disk plus mounted volumes. It refreshes the mounted-volume set every three seconds. The signed app is written to .build/xcode/Build/Products/Debug/MacNewFileKit.app.

This remains an ad hoc developer build. It proves which entitlements are embedded and supports local runtime testing, but it is not a substitute for Developer ID signing, notarization, or App Review.

To run the Finder integration, launch that app and use Manage Finder Extensions inside MacNewFileKit. Local ad hoc builds expose the Finder menu in ordinary writable folders without requiring per-folder authorization. Distribution builds keep the narrower authorized-folder mode: they resolve each security-scoped bookmark and refresh their monitored roots after a cross-process notification from the containing app.

The shared-preference temporary exception is for local testing only. Distribution to other Macs still requires an appropriate Apple signing identity, an authorized App Group, notarization, and App Review.

Local installation

After scripts/verify.sh succeeds, install the ad hoc build in a stable location:

scripts/install-local.sh

The installer verifies the source and installed signatures, places the app at /Applications/MacNewFileKit.app, disables the pre-rename RightClick extension, registers the embedded MacNewFileKit Finder extension, and reloads Finder. It refuses to overwrite an existing installation.

Open the app once to inspect the extension status or use Manage Finder Extensions if macOS still requires approval. After the extension is enabled, the settings app may be quit; Finder loads the extension independently.

This installation path is for local development only. It uses the ad hoc global access mode described above and is not a distributable release.

Verification boundary

Unit tests validate filename safety, content, collision handling, concurrent creation, custom-template editing rules, authorized-directory matching, and shared preference persistence. Tests also verify that global access is opt-in and that its monitoring roots contain / plus mounted volumes. The build script validates the local ad hoc signature; Finder integration still requires extension enablement and live Finder interaction on macOS.

scripts/verify.sh is deliberately fail-closed: it exits unsuccessfully when full Xcode or XcodeGen is missing instead of reporting a skipped integration build as a complete verification.