Cross-Platform File Opening Backend

Description

Implement the backend infrastructure for opening files with default and specific applications across macOS, Windows, and Linux. This ports v1's sophisticated platform-specific implementation to v2's architecture.

Implementation Notes

Create platform-specific crates following v1's proven architecture:

• apps/tauri/crates/file-opening/ - Shared types and traits
• apps/tauri/crates/file-opening-macos/ - Swift via FFI using NSWorkspace APIs
• apps/tauri/crates/file-opening-windows/ - COM Shell APIs (SHAssocEnumHandlers)
• apps/tauri/crates/file-opening-linux/ - GTK/GIO with content type detection

Each platform implementation must:

1. Query OS for applications that can open a file
2. Return intersection of compatible apps for multi-file selection
3. Open file with default application
4. Open file(s) with specific application

See DESIGN-open-with.md for complete architecture details.

Acceptance Criteria

• Shared file-opening crate with FileOpener trait and types
• macOS implementation using Swift FFI + NSWorkspace
  • Query apps using urlsForApplications(toOpen:) API
  • Filter to /Applications/ directory
  • Open with default via NSWorkspace
  • Open with specific app by bundle ID
• Windows implementation using COM Shell APIs
  • Query apps using SHAssocEnumHandlers
  • Thread-local COM initialization
  • Open with default via ShellExecute
  • Open with specific app via IAssocHandler
• Linux implementation using GTK/GIO
  • Content type detection from file magic bytes
  • Query apps via AppInfo::recommended_for_type
  • Open with default via launch_default_for_uri
  • Open with specific app via DesktopAppInfo
• Tauri commands registered:
  • get_apps_for_paths(paths) - returns Vec<OpenWithApp>
  • open_path_default(path) - returns OpenResult
  • open_path_with_app(path, app_id) - returns OpenResult
  • open_paths_with_app(paths, app_id) - returns Vec<OpenResult>
• Intersection logic for multi-file selections works correctly
• Error handling returns proper OpenResult variants
• All commands are async and non-blocking

Implementation Files

To be created:

• apps/tauri/crates/file-opening/src/lib.rs
• apps/tauri/crates/file-opening/src/types.rs
• apps/tauri/crates/file-opening-macos/src/lib.rs
• apps/tauri/crates/file-opening-macos/src-swift/FileOpening.swift
• apps/tauri/crates/file-opening-windows/src/lib.rs
• apps/tauri/crates/file-opening-linux/src/lib.rs
• apps/tauri/src-tauri/src/commands/file_opening.rs

To be modified:

• apps/tauri/src-tauri/src/main.rs (register commands and service)
• apps/tauri/src-tauri/Cargo.toml (add dependencies)

Reference Implementation

v1 implementation can be found at:

• ~/Projects/spacedrive_v1/apps/desktop/src-tauri/src/file.rs
• ~/Projects/spacedrive_v1/apps/desktop/crates/macos/src-swift/files.swift
• ~/Projects/spacedrive_v1/apps/desktop/crates/windows/src/lib.rs
• ~/Projects/spacedrive_v1/apps/desktop/crates/linux/src/app_info.rs

Testing

• Unit tests for intersection logic
• Platform-specific tests with mock file system
• Manual testing on macOS, Windows, Linux
• Test edge cases: no apps available, permission denied, file not found