feat: support multiple keyboard layouts per language (Dvorak, Colemak)

[chernistry]

Summary

RightLayout currently assumes QWERTY as the base layout for Latin scripts. Users who use alternative layouts like Dvorak or Colemak cannot use RightLayout effectively because the key-to-character mapping is completely different. Supporting alternative layouts would unlock a passionate and vocal user community.

Why This Matters

• Dvorak and Colemak users are a small but highly engaged community
• These users are often power users and early adopters — exactly the audience that spreads word of mouth
• Alternative layout users already deal with software compatibility issues daily — a tool that supports them earns loyalty
• Proves the layout engine is truly layout-agnostic, not QWERTY-hardcoded

Layouts to Support

Dvorak

' , . p y f g c r l / =
a o e u i d h t n s -
; q j k x b m w v z

Colemak

q w f p g j l u y ; [ ]
a r s t d h n e i o '
z x c v b k m , . /

Colemak-DH (popular variant)

q w f p b j l u y ; [ ]
a r s t g m n e i o '
z x c d v k h , . /

Implementation Plan

1. Extend layouts.json structure

File: RightLayout/Sources/Resources/layouts.json

Current structure (assumed):

{
  "english": { "a": "a", "b": "b", ... },
  "russian": { "a": "ф", "b": "и", ... }
}

New structure:

{
  "english": {
    "qwerty": { "a": "a", "b": "b", ... },
    "dvorak": { "a": "a", "b": "x", ... },
    "colemak": { "a": "a", "b": "b", ... }
  },
  "russian": {
    "qwerty": { "a": "ф", "b": "и", ... }
  }
}

2. Auto-detect active keyboard layout

• macOS provides the current input source via TISCopyCurrentKeyboardInputSource()
• Map input source IDs to layout types:
  • com.apple.keylayout.Dvorak → Dvorak
  • com.apple.keylayout.Colemak → Colemak
  • com.apple.keylayout.US → QWERTY

3. Update detection engine

• When detecting wrong layout, use the ACTIVE layout's mapping, not hardcoded QWERTY
• Character-to-key mapping must be reversible for any supported layout

4. Settings UI

Allow manual override in case auto-detection fails:

Keyboard Layout: [Auto-detect ▼]
  - Auto-detect
  - QWERTY
  - Dvorak
  - Colemak
  - Colemak-DH

Test Cases

• Dvorak user types Russian text on Dvorak → correct detection and correction
• Colemak user types English text on Russian layout → correct detection and correction
• Auto-detection identifies Dvorak layout correctly
• Auto-detection identifies Colemak layout correctly
• Layout switch mid-session is handled (user switches from QWERTY to Dvorak)
• Unknown layout falls back to QWERTY gracefully

Edge Cases

• Users with custom layouts (Karabiner-Elements remapping) — may not match any known layout
• Workman, Norman, and other niche layouts — out of scope initially but architecture should support adding them
• Layout detection should refresh when input source changes (subscribe to kTISNotifySelectedKeyboardInputSourceChanged)

References

• Dvorak layout
• Colemak layout
• TISCopyCurrentKeyboardInputSource