sweetch

A tiny macOS keyboard-layout switcher in the spirit of Punto Switcher. Runs as a menubar utility with no Dock icon.

Features

• Cmd+Space — instant toggle between the two configured layouts (default: ABC ↔ Russian PC) via the Text Input Sources API. Bypasses the system layout switcher's animation entirely.
• Option+Space — context-aware "convert":
  • With selection: reads the selected text via Accessibility, deletes it with Backspace, switches layout, and re-types the converted string character-by-character. Works in native Cocoa apps (Notes, TextEdit, Mail, Safari, Xcode, …) and Electron apps (Slack, Discord, VS Code, …).
  • No selection: converts the last typed word using a ring buffer of recent keystrokes — backspaces it, switches layout, replays the keyCodes. A second press toggles back.

Requirements

• macOS 13+
• Xcode 15+ / Swift 5.10+
• Two installed input sources whose IDs match primaryIDs and secondaryIDs in Sources/sweetch/InputSourceSwitcher.swift (default: com.apple.keylayout.ABC or com.apple.keylayout.US, and com.apple.keylayout.RussianWin).

Build & install

make app          # builds Sources/ into build/sweetch.app and ad-hoc-codesigns
make run          # the same, plus opens the bundle

The first run will:

1. Prompt for Accessibility (System Settings → Privacy & Security → Accessibility). The tap that intercepts hotkeys and synthesizes replays requires this.
2. Create a self-signed code-signing identity called sweetch-dev in your login keychain (make setup-signing runs implicitly via make app). This gives the bundle a stable designated requirement, so the Accessibility grant survives rebuilds — without it every rebuild looks like a different app to TCC and the permission resets.

If you ever switch identity or the TCC entry gets confused, make tcc-reset clears the Accessibility entry for com.spaceorc.sweetch.

Configuration

Hotkeys and layout choices are currently constants in source — edit and rebuild:

What	Where
Toggle hotkey	AppDelegate.swift — switchHotkey
Convert hotkey	AppDelegate.swift — convertHotkey
Layout IDs	InputSourceSwitcher.swift — primaryIDs, secondaryIDs
Buffer invalidation rules	AppDelegate.handleKeyDown

To discover input source IDs installed on your machine, watch the log on startup — sweetch dumps every keyboard source it sees:

/usr/bin/log stream --predicate 'subsystem == "com.spaceorc.sweetch"' --level info

Limitations

• Terminal-like apps (iTerm2, Terminal.app) don't expose an editable selection through Accessibility, so selection-convert falls back to last-word convert there. The displayed text in a terminal isn't a text field; there's no way to programmatically replace it short of pasting.
• Single Backspace deletes the whole selection assumption: holds in every text widget I've tested. If you find one where it doesn't, the selection read still works — just the write needs more Backspaces.
• Distribution outside this machine would need a real Developer ID and notarization — the ad-hoc / self-signed bundle here is for personal use.

Design notes

A few non-obvious decisions worth knowing if you go reading the code:

• The selection-convert path uses AX read + synthesized typing, not AX write. AXUIElementSetAttributeValue(kAXSelectedTextAttribute, …) returns .success in Electron apps but silently no-ops the contenteditable underneath — Electron's AX layer is a read-only mirror. Typing each char via CGEvent is the lowest common denominator that actually works.
• Convert is dispatched off the event-tap thread because CGEventSource.flagsState lies while the tap callback is blocked — the hotkey-release wait can only see clean modifier state once the callback has returned.
• Synthesized events are tagged with a marker in eventSourceUserData (ASCII "sweetch\0") so the tap can recognise and pass through its own events without re-processing them.